Updated on 2023/02/06

写真a

 
HIRASAWA, Izumi
 
Scopus Paper Info  
Paper Count: 0  Citation Count: 0  h-index: 11

Citation count denotes the number of citations in papers published for a particular year.

Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Research Institute

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

Education

  •  
    -
    1978

    Waseda University   Graduate School, Division of Science and Engineering   Applied Chemistry  

  •  
    -
    1976

    Waseda University   Faculty of Science and Engineering   Applied Chemistry  

Degree

  • 早稲田大学(日本)   工学博士

  • Waseda Univ.(Japan)   Dr. Engineering(PhD)

  • 早稲田大学   工学修士

  • Waseda Univ.(Japan)   Master

  • 早稲田大学(日本)   学士

  • Waseda Univ.(Japan)   Bachelor

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Research Experience

  • 2013
    -
     

    Waseda University   Enrironmenal Safty Center   Executive

  • 2013
    -
     

    Waseda University   Enrironmenal Safty Center   Executive

  • 1995
    -
    1996

    ,2004-2006,2009-2011,2012- Committee Member in Central Council of Environmental Protection

  • 1995
    -
     

    Professor of Waseda Univ.

  • 1989
    -
    1994

    Associate Professor of Waseda Univ.

  • 1978
    -
    1989

    Chief Researcher of Ebara Infilco and Ebara Research Co. Ltd

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Professional Memberships

  •  
     
     

    Soc. of Separation Engineers Japan

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    American Institute of Chem. Engr.

  •  
     
     

    Soc. of Chemistry Japan

  •  
     
     

    Japan Society of Water Environment

  •  
     
     

    Soc. of Crystal Growth Japan

  •  
     
     

    Soc. of Chemical Engineers Japan

  •  
     
     

    Soc. of Sea Water Science Japan

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    Soc. of Chemical Engineers Japan

  •  
     
     

    Soc. of Sea Water Science Japan

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    Soc. of Chemical Engineers Japan

  •  
     
     

    Soc. of Chemical Engineers Japan

  •  
     
     

    EFCE

  •  
     
     

    Atomic Energy of Japan

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Research Areas

  • Chemical reaction and process system engineering

Research Interests

  • Crystallization,Wastewater treatment,Heat Storage,Industrial Crystallization,Nano Crystallization,Pharmaceuticals,Food

Papers

  • Observation of Phase Segregation Phenomenon of Latent Heat Storage Material Na2HPO4 center dot 12H(2)O Melt and Supposition on Its Generation Mechanism

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   48 ( 4 ) 152 - 160  2022

     View Summary

    Disodium hydrogen phosphate dodecahydrate is as a latent heat storage material that is expected to be applied to indoor air conditioning and floor heating, especially medical applications. However, the heptahydrate, which has adifferent number of crystal water from the dodecahydrate, can exist stably at a temperature higher than the melting point of the dodecahydrate. Owing to the crystallization and the subsequent accumulation of the heptahydrate in the do-decahydrate melt, during a long-term thermal cycle of heat storage and heat release, the amount of latent heat of the dodecahydrate gradually decreases. In this study, in order to suppress the occurrence of such phase segregation, the melting and freezing behavior when applying a thermal cycle to the dodecahydrate was observed in detail. As a result, it was clarified that the occurrence of phase segregation not only reduces the latent heat amount of the dodecahydrate, but also lowers the nuclearization temperature thereof. The occurrence of phase segregation due to the crystallization of heptahydrate was thought to be due to the decrease in the diffusion rate during the dissolution process of the heptahydrate. It was suggested that, if the concentration polarization of the Na2HPO4 component forming in the melt was eliminated, for example, by installing a stirring mechanism in the heat storage device, the liquidus line of the heptahydrate would be substantially dissolved and the occurrence of phase segregation could be prevented.

    DOI J-GLOBAL

    Scopus

    1
    Citation
    (Scopus)
  • Linearized Parameter Estimation Methods for Modeled Crystallization Phenomena Using In-Line Measurements and Their Application to Optimization of Partially Seeded Crystallization in Pharmaceutical Processes

    Izumi Hirasawa, Joi Unno, Ikuma Masaki

    Springer Optimization and Its Applications   189   53 - 77  2022

     View Summary

    In this chapter, we show some parameter estimation methods for modeled crystallization phenomena, and we make comments on the application of the models to optimization of batch cooling crystallization. At first, in Sect. 1 we show linearized parameter estimation methods developed by using in-line measurements with process analytical technologies (PATs). The phenomena occurring in crystallization, such as growth, nucleation, breakage, and agglomeration, are modeled by typical numerical expressions. At the same time, we show the methods for the data acquisition and processing by using in-line measurements. Then, linearized methods and a few non-linear ones for estimation of the model parameters in each phenomenon are developed by using processed in-line data. Next, we show in Sect. 2 how the developed models are applied to the optimization of partially seeded crystallization in pharmaceutical processes. Several seeding policies are discussed to emphasize the importance of partial seeding for pharmaceutical processes. Then, the operating conditions of partially seeded crystallization are optimized, and the process designed optimally is assumed to be implemented. In addition, we show a case study of partially seeded crystallization of l-arginine, and we make a few comments on quality and stability of the crystallization products, with regard to stochastic nucleation.

    DOI

    Scopus

  • The moment of initial crystallization captured on functionalized nanoparticles

    Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa

    Communications Materials   2 ( 1 )  2021.12

     View Summary

    Even if a liquid is cooled below its melting point, the liquid state can be maintained under certain conditions. This state is called supercooling. Spraying fine particles of dry ice or silver iodide induces a phase change from supercooled droplets to ice grains. However, the mechanism by which crystallization seeds diminish supercooling is not well understood. Here, we captured the moment when a cluster, which is the smallest structural unit of a crystal, envelops a silver nanoparticle. As a result of observing the structure of a supercooled aqueous solution of a clathrate hydrate, we found that silver nanoparticles accelerate the formation of clusters, whereas the noble metals palladium, gold and iridium likewise form nanoparticles but do not promote crystallization. Our discoveries elucidate the mechanism of heterogeneous nucleation during a phase change in clathrate hydrates. We anticipate our discovery to be the starting point for the control of supercooling, a technique that can be applied to enhance the production efficiency and quality of manufactured products.

    DOI

    Scopus

    6
    Citation
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  • Enzymatic Synthesis of l-threo-β-Hydroxy-α-Amino Acids via Asymmetric Hydroxylation Using 2-Oxoglutarate-Dependent Hydroxylase from Sulfobacillus thermotolerans Y0017.

    Ryotaro Hara, Yuta Nakajima, Hiroaki Yanagawa, Ryo Gawasawa, Izumi Hirasawa, Kuniki Kino

    Applied and environmental microbiology   87 ( 20 ) AEM0133521 - 10  2021.08  [Refereed]  [International journal]

    Authorship:Last author

     View Summary

    β-Hydroxy-α-amino acids are useful compounds for pharmaceutical development. Enzymatic synthesis of β-hydroxy-α-amino acids has attracted considerable interest as a selective, sustainable, and environmentally benign process. In this study, we identified a novel amino acid hydroxylase, AEP14369, from Sulfobacillus thermotolerans Y0017, which is included in a previously constructed CAS-like superfamily protein library, to widen the variety of amino acid hydroxylases. The detailed structures determined by nuclear magnetic resonance and X-ray crystallography analysis of the enzymatically produced compounds revealed that AEP14369 catalyzed threo-β-selective hydroxylation of l-His and l-Gln in a 2-oxoglutarate-dependent manner. Furthermore, the production of l-threo-β-hydroxy-His and l-threo-β-hydroxy-Gln was achieved using Escherichia coli expressing the gene encoding AEP14369 as a whole-cell biocatalyst. Under optimized reaction conditions, 137 mM (23.4 g L-1) l-threo-β-hydroxy-His and 150 mM l-threo-β-hydroxy-Gln (24.3 g L-1) were obtained, indicating that the enzyme is applicable for preparative-scale production. AEP14369, an l-His/l-Gln threo-β-hydroxylase, increases the availability of 2-oxoglutarate-dependent hydroxylase and opens the way for the practical production of β-hydroxy-α-amino acids in the future. The amino acids produced in this study would also contribute to the structural diversification of pharmaceuticals that affect important bioactivities. Importance Owing to an increasing concern for sustainability, enzymatic approaches for producing industrially useful compounds have attracted considerable attention as a powerful complement to chemical synthesis for environment-friendly synthesis. In this study, we developed a bioproduction method for β-hydroxy-α-amino acid synthesis using a newly discovered enzyme. AEP14369 from the moderate thermophilic bacterium Sulfobacillus thermotolerans Y0017 catalyzed the hydroxylation of l-His and l-Gln in a regioselective and stereoselective fashion. Furthermore, we biotechnologically synthesized both l-threo-β-hydroxy-His and l-threo-β-hydroxy-Gln with a titer of over 20 g L-1 through whole-cell bioconversion using recombinant Escherichia coli cells. As β-hydroxy-α-amino acids are important compounds for pharmaceutical development, this achievement would facilitate future sustainable and economical industrial applications.

    DOI PubMed

    Scopus

    1
    Citation
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  • Numerical simulations of seeded batch crystallization demonstrating the effect of stochastic nucleation on crystal product quality

    Joi Unno, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   54 ( 7 ) 380 - 386  2021.07  [Refereed]

    Authorship:Last author

     View Summary

    Numerical simulations of seeded batch cooling crystallization were performed to investigate the effect of stochastic nucleation on crystal quality parameters. In a typical deterministic mathematical model for crystallization, which contains population and mass balance equations, primary and secondary nucleation are regarded as Poisson processes in order to derive a stochastic model. In this study, these stochastic model equations were repeatedly solved to achieve a stochastic simulation, and statistical analysis of the results revealed differences in product quality when the simulations were run under certain conditions. In particular, the statistics, such as the mean and the coefficient of variation, of the product crystal size distribution were found to fluctuate as a result of stochastic primary and secondary nucleation. Further, stochastic primary nucleation was also found to be the source of the differences between the statistics obtained using the deterministic and stochastic simulations when the seed-loading ratio was very low. This difference was attributed to the growth of crystals when the total number of crystals was less than one, as well as the accompanying secondary nucleation, in the standard deterministic simulation. Thus, a novel deterministic model in which secondary nucleation does not occur until the total number of crystals reaches one was used, and the results and statistics were found to agree with those obtained using the stochastic numerical simulation. In addition, a stochastic model ignoring stochastic secondary nucleation omitted to predict the significant statistical fluctuations under certain conditions. Finally, the statistical fluctuations were predicted for several crystallizer scales, and crystallizer scale-up was found to reduce the fluctuations caused by stochastic primary and secondary nucleation.

    DOI

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    1
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  • Nucleation kinetics estimated by using the modified induction time in cooling crystallization and the applicability to the combined process of antisolvent and cooling crystallization

    Takanori Kodera, Masanori Kobari, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   53 ( 11 ) 698 - 707  2020.11  [Refereed]

    Authorship:Last author

     View Summary

    A previously proposed method for estimating antisolvent crystallization kinetics has been successfully applied to cooling crystallization to yield kinetic parameters for simulating the crystallization process. In particular, the primary nucleation kinetics were analyzed using the modified induction time data, essentially as proposed by Kubota. The number density at the detection point, (N/M)det, is an important value in the kinetic analysis but is difficult to estimate experimentally. Therefore, the numerical optimization was used to estimate the value of (N/M)det in the same manner as for antisolvent crystallization. Primary nucleation was detected for both antisolvent and cooling crystallization with a sensitive detection method, visual detection, to reduce the effects of secondary nucleation. As a result, the (N/M)det values for each method are small and almost identical (approximately 200 #/kg-solvent). The secondary nucleation and growth rate parameters for cooling crystallization were also successfully determined by numerical optimization. All the kinetic parameters determined for cooling crystallization were evaluated with experimental data. Consequently, it is confirmed that these rate parameters can simulate trends in concentration as well as the final number mean diameter of the product crystals with acceptable accuracy. Moreover, the crystallization rate parameters determined for both antisolvent and cooling crystallization were validated with simulations and experimental data from combined crystallization, where antisolvent crystallization is followed by cooling crystallization. The simulation and experimental results for the concentration trend and number mean diameter of the produced crystal were in good agreement. The applicability of our estimation method to both antisolvent and cooling crystallization indicates the broad utility of this method for various crystallization process in the pharmaceutical industry.

    DOI

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  • Effect of Anti-Encrustation Additives on Zirconium Molybdate Hydrate

    Risako Abe, Izumi Hirasawa, Yasunori Miyazaki, Masayuki Takeuchi

    Chemical Engineering and Technology   43 ( 6 ) 1059 - 1064  2020.06  [Refereed]

    Authorship:Last author

     View Summary

    Anti-encrustation additives were mainly investigated in nitric acid solution with zirconium (Zr), molybdenum (Mo), and tellurium (Te) to prevent the encrustation of zirconium molybdate hydrate (ZMH). The ZMH generated by reaction crystallization of Mo and Zr as main fission products has a high adhesion property in spent nuclear fuel reprocessing. In addition, it is reported that Te, which is also one of the fission products, precipitates together with ZMH. Encrustation of precipitates containing Te was effectively prevented by adding molybdenum trioxide (MoO3) crystals as an anti-encrustation reagent. The encrustation amount was found to be larger than that under the condition of only Zr and Mo without Te. Consequently, it was suggested that the high adhesion property of Te affected the encrustation amount of ZMH.

    DOI

    Scopus

  • Analysis of Morphological Changes in Monosodium Urate Monohydrate Crystals for Gout Treatment

    Momoko Oda, Izumi Hirasawa, Fukashi Kohori

    Chemical Engineering and Technology   43 ( 6 ) 1087 - 1092  2020.06  [Refereed]

    Authorship:Last author

     View Summary

    Gout is arthritis induced by monosodium urate monohydrate (MSU) crystals. The treatment of gout is mainly a symptomatic treatment, by suppressing the blood uric acid concentration with drugs. Here, the changes in crystal morphology in the process of MSU crystallization were investigated. Experiments were conducted to clarify the mechanisms of nucleation and growth of the MSU crystals, revealing that MSU first precipitated as granular crystals. Thereafter, nucleation and growth of needle-like crystals were observed concomitant with the disappearance of the granular crystals. These results suggest that it is necessary to suppress the nucleation of granular crystals and the change in morphology from granular to needle-like of the MSU crystals that cause gout.

    DOI

    Scopus

    2
    Citation
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  • Effect of Ultrasonic Irradiation on the Probability of Primary Nucleation of L-Arginine Hydrochloride

    Yuki Ike, Izumi Hirasawa

    Chemical Engineering and Technology   43 ( 6 ) 1099 - 1104  2020.06

     View Summary

    Most of the amino acids that are utilized as medical raw materials and food additives show polymorphism. To improve the functionality of amino acid crystals, an effective method of polymorph control is required in the crystallization process. Here, primary nucleation of L-arginine hydrochloride by ultrasonication was investigated. L-Arginine hydrochloride exhibits polymorphism, and it crystallizes into three distinct crystal forms. A cooling crystallization experiment was performed, and nucleation of each polymorph upon ultrasonication was observed. In addition, the nucleation was analyzed using the nucleation probability theory. The results indicate that ultrasonic irradiation would significantly induce the nucleation of a particular polymorph.

    DOI

    Scopus

    2
    Citation
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  • Partial Seeding Policy for Controlling the Crystal Quality in Batch Cooling Crystallization

    Joi Unno, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   43 ( 6 ) 1065 - 1071  2020.06  [Refereed]

    Authorship:Last author

     View Summary

    Partial seeding, in which the nuclei originating from seed crystals grow to yield the product crystals, was simulated and optimized for controlling the batch cooling crystallization process of L-arginine. The product quality was evaluated by the coefficient of variation (CV) of the crystal size distribution. First, the optimum seed amount for partial seeding was estimated by simulation. Then, the simulated values of the optimum seed amount and the resulting local minimum CV were correlated with the seed crystal size and the cooling rate. The correlation can be utilized for estimating the seed amount in the case that the seed crystals are added in a slurry. Finally, these simulated values were compared to the measured ones. Consequently, the optimum seed amount was suggested to be reasonably predicted.

    DOI

    Scopus

    6
    Citation
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  • Parameter Estimation of the Stochastic Primary Nucleation Kinetics by Stochastic Integrals Using Focused-Beam Reflectance Measurements

    Joi Unno, Izumi Hirasawa

    CRYSTALS   10 ( 5 )  2020.05  [Refereed]

    Authorship:Last author

     View Summary

    The kinetic parameters of stochastic primary nucleation were estimated for the batch-cooling crystallization of L-arginine. It is difficult for process analytical tools to detect the first nucleus. In this study, the latent period for the total number of crystals to be increased to a predetermined threshold was repeatedly measured with focused-beam reflectance measurements. Consequently, the latent periods were different in each measurement due to the stochastic behavior of both primary and secondary nucleation. Therefore, at first, the distribution of the latent periods was estimated by a Monte Carlo simulation for some combinations of the kinetic parameters of primary nucleation. In the simulation, stochastic integrals of the population and mass balance equations were solved. Then, the parameters of the distribution of latent periods were estimated and correlated with the kinetic parameters of primary nucleation. The resulting correlation was represented by a mapping. Finally, the parameters of the actual distribution were input into the inverse mapping, and the kinetic parameters were estimated as the outputs. The estimated kinetic parameters were validated using statistical techniques, which implied that the observed distribution function of the latent periods for the thresholds used in the estimation coincided reasonably with the simulated one based on the estimated parameters.

    DOI

    Scopus

    5
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  • Calorimetric and Small-Angle X-ray Scattering Studies on the Memory Effect in the Tetra-n-butylammonium Bromide Semiclathrate Hydrate System

    Hironobu Machida, Takeshi Sugahara, Hiroyasu Masunaga, Izumi Hirasawa

    Journal of Crystal Growth   533   125476-1 - 6  2020.03  [Refereed]

     View Summary

    The solution structures in the tetra-n-butylammonium bromide (TBAB) aqueous solution relate closely with the memory effect. In the present study, the behavior derived from the existence of the residual solution structures after TBAB semiclathrate hydrate (TBAB SCH) decomposition was investigated with two methods. One is a high-precision differential scanning calorimetry. The heat capacity of a TBAB aqueous solution with memory effect was slightly larger than that after the memory effect disappeared. The larger heat capacity implies the existence of solution structures. The other is a small-angle X-ray scattering (SAXS). In the first cooling process, strong scattering derived from rapid crystallization was observed at 263.6 K. In the second cooling process where the TBAB aqueous solution exhibited the memory effect, the scattering intensity gradually increased and became remarkably strong at a temperature (approximately 277 K) higher than 263.6 K. In the second cooling process, the invariant Q, which corresponds to electron density fluctuation, increased gradually until crystallization, whereas, in the first cooling process, the change of the invariant Q was quite small until crystallization. The increase of invariant Q implies the existence of 10–100 nm density fluctuation, which is consistent with the cluster size (10–20 nm) previously observed with electron microscopy in the same system.

    DOI

    Scopus

    4
    Citation
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  • Numerical Evaluation of Melting Point and Fusion Heat for Potassium Acetate Dihydrate as a Latent Heat Storage Material

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   46 ( 2 ) 41 - 48  2020

     View Summary

    To clarify the inevitability of the relationship between the melting point (T-m= 291 K) and the heat of fusion (Delta H-f=135 kJ/kg) of potassium acetate dihydrate, a potential latent heat storage material, a quantitative examination of the relationship was made in terms of the structural formula. First, four pairs of salts comprising Na+ or K+ with the same given anion were investigated, for all of which the degree of hydration and the dehydration transition temperature of the hydrate was known. It was found that the dehydration temperature of the potassium salt was generally 20.50 K lower than that of the sodium salt. It was also found that the dehydration temperature, that is T-m, was lower as the ratio of Stokes radius of the salt ion in aqueous solution to the ion radius in crystal structure decreased. Next, the entropy change Delta S-f (=Delta H-f/T-m) of the hydrate during fusion was expressed as a combination of entropy change Delta S-LHO of water during fusion and the mass fraction Phi(w) of the water of crystallization in the hydrate. With this combination, a simple relational expression between T-m and Delta H-f was derived. Application of this expression to the measured data for 18 different hydrates, it was indicated that the numerical value of Delta H-f could be estimated with a relative standard deviation of +/- 0.212 when the structural formula and the T-m value of a hydrate were both known. Through this, the inevitability of the correspondence between the Delta H-f value and T-m for potassium acetate dihydrate was also confirmed.

    DOI CiNii

  • Properties of Potassium Acetate Dihydrate as a Latent Heat Storage Material

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   46 ( 2 ) 33 - 40  2020

     View Summary

    Hydrated salts are promising latent heat storage materials because of their high heat storage density per unit volume. However, few hydrated salts have melting points in the temperature range suitable for cooling and air conditioning (273-303 K). In this study, the relationship between the temperature and the hydration number of potassium acetate hydrate and its potential applicability as a latent heat storage material were investigated. From direct observation of potassium acetate aqueous solution, the generally accepted crystallization properties of 0.5 and 1.5 hydrated salts were confirmed. It was also suggested that potassium acetate dihydrate would crystallize upon cooling the solution to 229 K. The melting point of the dihydrate was 291 K, and its heat of fusion was 135 kJ/kg. This heat of fusion is intermediate position among those of six other hydrated salts that have melting points within the range of 285. 294 K. Potassium acetate dihydrate thus has comparable potential to those salts for application as a latent heat storage material for cooling and air conditioning.

    DOI CiNii

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    3
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  • Experimental Estimation of Primary and Secondary Nucleation Kinetics of Antisolvent Crystallization As Measured by Induction Time

    Takanori Kodera, Masanori Kobari, Izumi Hirasawa

    Organic Process Research and Development   23 ( 12 ) 2724 - 2732  2019.12

     View Summary

    Methodologies for the estimation of nucleation rate parameters, which are rate constants and orders in antisolvent crystallization, are proposed with the aim of applying to the pharmaceutical industry. Primary and secondary nucleations are clearly distinguished and these rates are defined as power laws of the supersaturation in our antisolvent crystallization model. Primary nucleation rate parameters were experimentally determined using the theoretical equation about the modified induction time in antisolvent crystallization based on the past study reported by Kubota, N. [ J. Cryst. Growth 2010, 312, 548-554 ], in which the induction time is defined as the time when the number density of the crystal reaches a fixed value. It is difficult to estimate the number density at the detection point using an experimental approach. Therefore, a numerical approach was used to determine the number density. The estimated number density at the detection point can determine the secondary nucleation rate parameters. These determined nucleation rate parameters become effective factors for simulating the number mean diameter in antisolvent crystallization and can be applied to the pharmaceutical industry.

    DOI

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  • Modeling and Growth Kinetics of Antisolvent Crystallization Applied to the Pharmaceutical Industry

    Takanori Kodera, Masanori Kobari, Izumi Hirasawa

    Chemical Engineering and Technology   42 ( 7 ) 1458 - 1465  2019.07

     View Summary

    With the aim of simulating the product crystal size, which is one of the important physical properties for active pharmaceutical ingredients, an antisolvent crystallization model is proposed, including only six experimentally determined kinetic parameters to develop a concise model. As a first step, the methodology to assess the growth rate parameters, which are some of the six kinetic parameters, is discussed. An approach for appropriately treating the size distribution data obtained by means of the laser diffraction/scattering method is suggested. The determined growth rate parameters could be used to simulate the crystal size indicating that the simulation by crystallization modeling is a practical application for the pharmaceutical industry.

    DOI

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  • Estimation of Kinetics for Batch Cooling Crystallization by Focused-Beam Reflectance Measurements

    Joi Unno, Hiroki Kawase, Reiya Kaneshige, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   42 ( 7 ) 1428 - 1434  2019.07

     View Summary

    Numerical simulation of the seeded batch cooling crystallization process of active pharmaceutical ingredients was performed. Crystal size distribution was observed by focused-beam reflectance measurements and concentration by simultaneous Fourier transform infrared spectroscopy. First, kinetic parameters were estimated. Nucleation rate coefficient and order were estimated from the linear regression equation between cooling rate and metastable zone width. The remaining parameters were estimated from the evaluation function. Then, the numerical simulation was performed by utilizing the method of moments. Finally, observed data were compared with simulated data. The simulated values of mean mass size corresponded reasonably with the observed ones.

    DOI

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  • Partial Seeding Policy for Controlling Size Distribution of Product Crystal by Batch Cooling Crystallization

    Joi Unno, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   52 ( 6 ) 501 - 507  2019.06

     View Summary

    Simulations were performed for seeded batch cooling crystallization. In industry, partial seeding is often utilized, where a small amount of seed crystal is added to trigger secondary nucleation and grown secondary nuclei are obtained as the product. Partial seeding was investigated by computer simulation in this study. First, the coefficient of variation (CV) of the product crystal size distribution (CSD) was proven to take two local minima, one in the partial seeding range and the other in the range in which the product was mainly composed of seed-grown crystals. The local minimum point in the partial seeding range was considered as an optimum condition for partial seeding. Then, CSDs of grown seed crystals and nuclei were simulated at the optimum seed-loading ratio. As a result, the product was found to be composed mainly of grown secondary nuclei induced by grown seed crystals and grown secondary nuclei themselves. Partial seeding performed at the optimum seed-loading ratio yielded a reasonably good product of unimodal size distribution. Finally, the optimum seed-loading ratio was correlated with the cooling rate and seed crystal size and was found to depend on the cooling rate and more strongly on the seed crystal size. As the cooling rate was decreased, the minimum CV was shown to decrease and the mean size at the optimum seed-loading ratio was shown to increase.

    DOI

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  • Preparation of Dispersed Metal Nanoparticles in the Aqueous Solution of Metal Carboxylate and the Tetra-n-butylammonium Carboxylate

    Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa

    Journal of Crystal Growth   514   14 - 20  2019.05  [Refereed]

     View Summary

    Nano-sized metal particles have been actively investigated. Although the synthesis methods of nano-sized metal particles have been made remarkable progress through many researches, in many cases, heat treatment is required. In order to promote industrial utilization, non-heating, simple and inexpensive synthesis methods are required. In the present study, nano-sized metal particles composed of Ag, Au, Ir, or Pd were prepared in an aqueous solution with a simple and non-heating way. After a noble-metal carboxylate was completely dissolved in the quaternary ammonium carboxylate aqueous solution, nanoparticles composed of the noble metal appeared in the aqueous solution. Since this operation is extremely simple as well as non-heating because the noble-metal carboxylate only dissolves into the quaternary ammonium carboxylate aqueous solution. The nano-sized metal particles were observed by Scanning Electron Microscope (SEM) or Scanning Transmission Electron Microscope (STEM) with the freeze-fracture replica method and characterized with Energy Dispersive X-ray Spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS).

    DOI

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  • Supercooling suppression in the tetrahydrofuran clathrate hydrate formation

    Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa

    CrystEngComm   24 ( 38 ) 6730 - 6738  2022.09

     View Summary

    Generally, supercooling as large as about 25 K is necessary to form tetrahydrofuran clathrate hydrate (THF hydrate). In the present study, we have investigated how the existence of various additives affects the degree of supercooling (ΔT) in the THF hydrate formation without any external stimulus. The addition of either AgO or Ag3PO4 yields the best ΔT suppression, where ΔT was approximately 4 K, much smaller than 25 K. Raman spectra reveal that, in the supercooled THF aqueous solution with AgO before crystallization, the THF molecule forms a coordination bond with AgO, whereas it forms a hydrogen bond with a water molecule in the system without AgO. The oxygen atom of the THF molecules, which is a hydrogen-bonding site, was oriented to a AgO molecule in the aqueous solution. The orientation and the subsequent interruption of the hydrogen bond make it easy to form a hydration shell around the THF molecule. Scanning Transmission Electron Microscopy images by using the freeze-fracture replica method reveal that a cluster, which is the smallest structural unit of a crystal, includes Ag-containing nanoparticles formed from AgO or Ag3PO4, which accelerate the cluster formation. As a result, the addition of AgO or Ag3PO4 effectively diminishes the degree of supercooling in the THF hydrate formation.

    DOI

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  • A Common Property of Melting Point Depression in Inorganic Salt Hydrate Melt Systems

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   45 ( 2 ) 91 - 99  2019

     View Summary

    0 Melt systems of sodium carbonate decahydrate (melting point T-m,T-0 = 304.5 K, latent heat of fusion Delta Hf,0 = 153 kJ/kg, both measured) and of a salt hydrate eutectic E(P-C) (T-m,T-0 = 298 K, Delta H-f,H-0 = 213 kJ/kg, both also measured) consisting of 0.6 mol/mol sodium carbonate decahydrate and 0.4 mol/mol disodium hydrogen phosphate dodecahydrate are attracting attention as potential latent heat storage materials. Changes in the melting point Tm and the latent heat Delta H-f were measured for the two melt systems with readily soluble additives. By using simplified empirical formulae, the abilities of melting point depression a(me) and latent heat reduction b(me) for each additive were quantified. The numerical values of these abilities were different for each additive, but their ratio b(me)/a(me) was almost the same regardless of the kind of additive, showing an eigenvalue of each melt system. In addition, a comparative study was performed of b(me)/a(me) values including those of the calcium chloride hexahydrate system (Watanabe, 2017) and the disodium hydrogen phosphate dodecahydrate system (Watanabe and Hirasawa, 2018b). It was found that, independent of the kind of melt system, the relative degree of melting point depression [1-(T-m/T-m,T-0)] and the relative degree of latent heat reduction [1-(Delta H-f/Delta H-f,(0))], respectively normalized by T-m,T-0 and Delta H-f,H-0, showed an almost constant numerical relationship represented by the following expression.1-(Delta H-f / Delta H-f,H-0) = 21.4 [1-(T-m / T-m,T-0)]

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  • Characteristics of melting point depression in a melt system of disodium hydrogen phosphate dodecahydrate

    Yasuyuki Watanabe, Izumi Hirasawa

    Kagaku Kogaku Ronbunshu   44 ( 6 ) 372 - 378  2018.11

     View Summary

    Technology employing melting point depression can be useful for extending the applicable temperature range of a latent heat storage material. In this study, the melting points T m and latent heats of fusion ΔH f were measured in systems of disodium hydrogen phosphate dodecahydrate (with measured values of T m,0 =308.5 K and ΔH f,0 =227 kJ/kg), which is especially utilized as a medical heat-retention material, with five additives that are readily soluble in the dodecahydrate melt: tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate dihydrate. By using the simplified empirical formula proposed previously expressing the relation between additive concentration and the degree of melting point depression (Watanabe and Hirasawa, 2017) or the degree of latent heat decrease (Watanabe, 2017), the abilities of each additive to depress melting point and decrease latent heat were numerically expressed. These values differed from one additive to another and appeared to be specific to each. However, the numerical relation expressed in the equation below was found to hold almost invariably regardless of the additive(forumala Presented).

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  • Polymorph Control of L-Phenylalanine in Cooling Crystallization by Ultrasonication

    Yuki Ike, Izumi Hirasawa

    Chemical Engineering and Technology   41 ( 6 ) 1093 - 1097  2018.06

     View Summary

    Most of the amino acids that are utilized as medical raw materials and food additives show polymorphism. To improve the physical and chemical properties of the crystals, an effective method for polymorph control is required in the crystallization process. In this study, polymorph control of L-phenylalanine in cooling crystallization by ultrasonication was investigated. L-Phenylalanine crystallizes in anhydrate and monohydrate forms. Without ultrasonication, a mixture of monohydrate and anhydrate forms was obtained. In contrast, the yield of monohydrate was increased by ultrasonication. In addition, ultrasonication shortened the induction time. It was considered that ultrasonic energy could supply the energy required for primary nucleation.

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  • Computing Crystal Size Distribution by Focused-Beam Reflectance Measurement when Aspect Ratio Varies

    Joi Unno, Ryuta Umeda, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   41 ( 6 ) 1147 - 1151  2018.06

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    Chord length distribution (CLD) can be determined by an in-line measuring system with focused-beam reflectance measurement, but it can differ from crystal size distribution (CSD). However, expected values of CLD can be calculated from CSD by statistical methods and vice versa. In this study, a correlation equation between crystal size and aspect ratio during cooling crystallization was obtained and a mapping matrix was calculated based on the correlation equation. Then, the suspension obtained in cooling crystallization was sampled and CSDs were measured by microscopy at the same time that CLDs were measured with FBRM. As a result of error evaluation, transformation of CLD into CSD reduced the errors between CLDs and CSDs except in the early stage of crystallization.

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  • Encrustation Prevention of Zirconium Molybdate Hydrate

    Takahiro Arai, Daiyu Ito, Izumi Hirasawa, Yasunori Miyazaki, Masayuki Takeuchi

    Chemical Engineering and Technology   41 ( 6 ) 1199 - 1204  2018.06  [Refereed]

     View Summary

    In nuclear fuel reprocessing, spent nuclear fuel is dissolved by a nitric acid. It is now known that molybdenum and zirconium in fission products react to form zirconium molybdate hydrate (ZMH). ZMH adheres to the inner surface of reprocessing equipment, which affects the extraction efficiency in the subsequent extraction process. Therefore, a new prevention method of ZMH encrustation is required for stable plant operation. In this study, the encrustation amount of ZMH was investigated. Observing the deposition process, it was clarified that ZMH fine crystals were generated and agglomerated, followed by the rapid deposition. The encrustation amount of ZMH decreased as temperature or initial Mo/Zr mole ratio increased, or as the concentration of a nitric acid was reduced.

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  • Eutectic Composition of a Salt Hydrate Mixture of Sodium Carbonate and Disodium Hydrogen Phosphate

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   44 ( 3 ) 207 - 216  2018

     View Summary

    Based on the idea that eutectic formation is a useful technology for controlling the melting points of latent heat storage materials over a wide temperature range, experimental studies were carried out on the pseudobinary mixtures of sodium carbonate decahydrate and disodium hydrogen phosphate dodecahydrate, both of which are also heat storage materials. From the distribution of melting points of the mixtures of varying composition determined from the heating curve, the phase diagram was developed as a single eutectic type, and the melting point of the eutectic was found to be 298 K. For specifying the eutectic composition, two methods were examined: one by using the empirical formula of the melting point depression, and the other by utilizing the change in the latent heat of fusion. The eutectic composition as a mole fraction of disodium hydrogen phosphate dodecahydrate was estimated to be 0.40 mol/mol by the former method and 0.37 to 0.38 mol/mol by the latter. These values closely match the 0.4mol/mol derived from the hypothesis that the eutectic would be formed by equivalent exchange of dissociated ions in the melt of salt hydrate mixture, proposed by Watanabe and Hirasawa (2018).

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  • Memory effect in tetra-: N -butyl ammonium bromide semiclathrate hydrate reformation: The existence of solution structures after hydrate decomposition

    Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa

    CrystEngComm   20 ( 24 ) 3328 - 3334  2018  [Refereed]

     View Summary

    A large degree of supercooling is necessary to form the tetra-n-butyl ammonium bromide (TBAB) semiclathrate hydrate. One of the effective methods to suppress supercooling is the utilization of a kind of hysteresis called the "memory effect". Generally, the memory effect reduces supercooling and/or the induction period in clathrate hydrate formation. In the present study, we have observed the solution structure of TBAB aqueous solutions in the formation and decomposition processes of TBAB semiclathrate hydrate by scanning electron microscopy (SEM) with the freeze-fracture replica method. The relationship between the memory effect and the solution structures of the TBAB supercooled aqueous solution was elucidated. The memory effect in the TBAB semiclathrate hydrate reformation is derived from the existence of residual clusters of 10-20 nm in the TBAB aqueous solution at 286.2 K, which is 1.0 K higher than the equilibrium decomposition temperature, even after the TBAB semiclathrate hydrate was completely decomposed.

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  • Eutectic formation from melt mixtures of hydrates of nickel and cobalt salts

    Yasuyuki Watanabe, Izumi Hirasawa

    Kagaku Kogaku Ronbunshu   44 ( 1 ) 3 - 11  2018

     View Summary

    Based on the idea that eutectic formation is an useful technology for controlling the melting points of latent heat storage materials over a wide temperature range, precise experimental studies were carried out on the inevitability of eutectic composition of salt hydrate mixtures. Phase diagrams were developed from heating curves of two pseudo-binary systems, Ni(NO3)2·6H2O-CoCl2·6H2O and NiCl2·6H2O-Co(NO3)2·6H2O. The melting points of individual hydrates were 53.5, 53.0, 51.5 and 53.5°C, respectively. In the two binary systems, similar simple eutectic formations were recognized under the same conditions of 30°C and equimolar composition. The crystal compositions in the systems changed depending on the binary mixing ratio. At the same time, new crystal phases that were not attributed to either of original salt hexahydrates were also generated, and the contents of the new phases became maximum at the eutectic points. The two eutectics generated were found to have the same crystal composition as each other as analyzed by X-ray powder diffraction patterns. Consequently, it was concluded that the eutectics were formed through the mutually equivalent exchange of dissociated ions. Further, the inevitability of those compositions was determined as the mixing ratio at which the mutually equivalent exchange might be maintained for all dissociated ions.

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  • Effect of salt addition on supercooling property of erythritol

    Motohiro Suzuki, Hironobu Machida, Hayato Satomi, Izumi Hirasawa

    Kagaku Kogaku Ronbunshu   44 ( 1 ) 12 - 17  2018

     View Summary

    The effect of salt addition on the supercooling properties of erythritol was investigated in an attempt to create a novel sugar alcohol type of latent heat storage material that has high thermal storage density and remains in a supercooled state at room temperature. The mechanism of the effect was also examined. Various cationic and anionic species having different valences were each added to erythritol, and their effects on supercooling properties were evaluated with crystallization temperature and supercooling retention time as indices. The supercooling retention mechanism was also investigated focused on the interaction between erythritol and each additive by NMR (Nuclear Magnetic Resonance) spectroscopy. It was found that erythritol additives containing monovalent anions are effective as supercooling stabilizers, and additives containing divalent anions are effective as supercooling inhibitors. It was also found that cationic species have a smaller influence than anionic species. Additives that include the acetate ion were found to be a capable of maintaining erythritol in a supercooled state at room temperature, and the improvement of supercooling retention was considered to be due to the interaction between the hydroxy group of erythritol and the acetate ion.

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  • Relationship between supercooling stability and solution structure in sodium acetate aqueous solution

    Hironobu Machida, Takeshi Sugahara, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   475   295 - 299  2017.10  [Refereed]

     View Summary

    We have observed the solution structure of the supercooled sodium acetate aqueous solution, especially for the existence of clusters and their crystallization process, by means of Scanning electron microscopy (SEM) with the freeze replica method. Microscopic internal structure of sodium acetate trihydrate crystals mainly constitutes the aggregates of 100-200 nm in diameter, which consists of the clusters of 10-20 nm in diameter. In the case of a supercooled aqueous solution of 293 K, two types of aspect in the vitrified aqueous solution mainly exist: one is the clusters of 10-20 nm in diameter; the other is the smooth zone without any structure. At 263 K, the relationship among clusters of 10-20 nm and their aggregates of 100-200 nm was clearly observed. The aggregates construct the three-dimensional loose networks, which are not fully packed, different from the crystal. (C) 2017 Elsevier B.V. All rights reserved.

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  • The Solubility Characteristics of Aluminum Sulfate in Sulfuric Acid Aqueous Solution in the Presence of Oxalic Acid

    Naoko Imura, Atsushi Sonohara, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   50 ( 7 ) 516 - 520  2017.07  [Refereed]

     View Summary

    The solubility of aluminum sulfate in sulfuric aqueous solution was determined and analyzed thermodynamically. Aluminum sulfate dissolved in sulfuric acid aqueous solution not spontaneously, because the dissolution enthalpy is a positive value. The solubility of aluminum sulfate had a temperature dependency and hardly dissolved with higher concentration of sulfuric acid. On the other hand, aluminum sulfate solubility did not depend on the existence of oxalic acid, which was dissolved to saturation concentration as an additive. Moreover, the solubility curves of aluminum sulfate and oxalic acid were different in the range between 1.5 M and 6 M sulfuric acid aqueous solution at 25 degrees C. Therefore, using the difference of solubility characteristics, aluminum sulfate could be recovered selectively from waste acid containing oxalic acid. An aluminum sulfate crystal generated from the model waste acid, which was 3.5 M sulfuric acid aqueous solution containing 20 g.L-1 oxalic acid, was determined as one of aluminum sulfate hydrate by powder-XRD and its purity was 94%.

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  • Growth Mechanism of Hollow Sodium Chloride Single Crystals Grown from a Mixed Solvent of Cyclohexane and Acetone

    Shiro Kaneko, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   40 ( 7 ) 1276 - 1281  2017.07  [Refereed]

     View Summary

    Recently, hollow sodium chloride crystals have been proposed as potential high-value-added crystals. The crystal growth mechanism of such crystals is elucidated using X-ray diffraction (XRD), optical microscopic imaging, and analysis of both the chloride ions and water content in the mixed solvent of cyclohexane and acetone. A series of experimental conditions, including the stirring time after injecting the aqueous sodium chloride solutions into the mixed solvent and the ratio of cyclohexane and acetone, are evaluated in detail. Based on experimental data, possible growth mechanisms are proposed to explain the formation of hollow sodium chloride crystals.

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  • Polymorph Control of L-ArgHCl on Antisolvent Crystallization by Ultrasonic Irradiation

    Yuki Ike, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   40 ( 7 ) 1318 - 1322  2017.07  [Refereed]

     View Summary

    Amino acids are utilized as medical raw materials and food additives. It is well-known that most of the amino acids show polymorphism. Differences in the crystal structures affect the physical and chemical properties. Therefore, an effective method for polymorph control is required in the crystallization process. Polymorph control of L-arginine hydrochloride (L-ArgHCl) on antisolvent crystallization was achieved by ultrasonic irradiation. L-ArgHCl exhibits polymorphism and crystallizes into three distinct crystal forms. Without irradiation, the metastable form was selectively crystallized. In contrast, the unstable form was selectively crystallized by irradiation. Irradiation after the addition of an antisolvent led to a shorter induction time.

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  • Shape Change and Growth Behavior of Monosodium Urate Monohydrate in a Gout Model

    Chihiro Ozono, Izumi Hirasawa, Fukashi Kohori

    CHEMICAL ENGINEERING & TECHNOLOGY   40 ( 7 ) 1231 - 1234  2017.07  [Refereed]

     View Summary

    Deposition of needle-shaped monosodium urate monohydrate (MSU) crystals in synovial fluid provokes the acute inflammatory response of gout. The mechanism of MSU crystallization was investigated in batch operation under the same pH and Na+ concentration of synovial fluid. It was found that stirring enhanced the aggregation of needle-shaped MSU, and the deposition of MSU was faster and larger in amount. MSU crystals in supersaturated urate solution were detected by dynamic light scattering and UV absorption, suggesting that the urate concentration affected not the crystal growth but nucleation. Since the increase of the number of MSU crystals is assumed to cause a high risk of gout, this result supports the importance of the control of serum urate level as a treatment of gout.

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  • Synthesis of Platinum Nanoparticles by Reductive Crystallization Using Polyethyleneimine

    Hideyuki Nagao, Masumi Ichiji, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   40 ( 7 ) 1242 - 1246  2017.07  [Refereed]

     View Summary

    Sub-10-nm-sized Pt nanoparticles were synthesized by reducing Pt ions with NaBH4, with the addition of polyethyleneimine (PEI) as a protective reagent. Well-dispersed Pt nanoparticles with a narrow size distribution were successfully produced. When lowering the pH of the PEI solution, cubic and tetrahedral nanoparticles were observed, while at a higher pH, only spherical nanoparticles were produced. In addition, by selecting a suitable concentration of PEI, the protective reagent itself can reduce Pt ions to generate Pt nanoparticles with diameters in the range of 12.9-70.7 nm. This shows the potential of one-pot synthesis of Pt nanoparticles by just adding Pt ions and PEI.

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  • Study of polymorphic control in an ethanol-water binary solvent

    Hiroshi Kitano, Takayuki Tanaka, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   469   54 - 58  2017.07  [Refereed]

     View Summary

    Three polymorphs of L-Citrulline crystals, anhydrate (Form alpha, gamma and delta) and pseudo polymorph (dihydrate), were confirmed. In this study, polymorphic control of L-Citrulline was attempted by changing the ethanol concentration in ethanol-water binary solvents. First, each polymorph of L-Citrulline crystals was added to the prepared ethanol-water binary solvents and samples which were obtained chronologically were measured by XRD. Also, the crystal sizes and shapes in transformation were observed by microscope. Then, polymorphs of the crystals after transformation were determined by XRD pattern. As a result, the transformation from dihydrate to anhydrate was observed by adding dihydrate crystals to the ethanol-water binary solvent. Similarly, the transformation from anhydrate to another anhydrate was observed. Especially in the case of adding dihydrate, the existences of all polymorphs were confirmed by adjusting ethanol-water binary solvent. According to the results, it was revealed that polymorphic transformation was affected by the trace amount of water contained in ethanol-water binary solvent. Moreover, transformation from dihydrate to anhydrate was constructed with three phases, dissolution of dihydrate, nucleation and growth of anhydrate. Therefore, the solution-mediated polymorphic transformation was supposed to be a key mechanism for this transformation.

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  • Size control of Au NPs supported by pH operation

    Masumi Ichiji, Hiroko Akiba, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   469   168 - 171  2017.07  [Refereed]

     View Summary

    Au NPs are expected to become useful functional particles, as particle gun used for plant gene transfer and also catalysts. We have studied PSD (particle size distribution) control of Au NPs by reduction crystallization. Previous study found out importance of seeds policy and also feeding profile. In this paper, effect of pH in the reduction crystallization was investigated to clarify the possibility of Au NPs PSD control by pH operation and also their growth process. Au NPs of size range 10-600 nm were obtained in single-jet system using ascorbic acid (AsA) as a reducing agent with adjusting pH of MA. Au NPs are found to grow in the process of nucleation, agglomeration, agglomeration growth and surface growth. Au NPs tend to grow by agglomeration and become larger size in lower pH regions, and to grow only by surface growth and become smaller size in higher pH regions. (C) 2016 Elsevier B.V. All rights reserved.

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  • Particle size distribution control of Pt particles used for particle gun

    M. Ichiji, H. Akiba, H. Nagao, I. Hirasawa

    JOURNAL OF CRYSTAL GROWTH   469   180 - 183  2017.07  [Refereed]

     View Summary

    The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained. (C) 2016 Elsevier B.V. All rights reserved.

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  • Relationship between Degree of Melting Point Depression of Calcium Chloride Hexahydrate Melt and Amount of Additives in the Melt

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   43 ( 2 ) 129 - 137  2017  [Refereed]

     View Summary

    With a view to controlling the melting point and extending the temperature range for practical application of calcium chloride hexahydrate as a latent heat storage material, an attempt was made to derive an empirical equation by which to evaluate quantitatively the degree to which various additives depress its melting point (measured value, 302 K). The change in melting point relative to the amount of additive was measured for each of nine additives, and the ability of each additive to depress melting point was expressed numerically by use of a simple empirical equation. Based on the assumption that the depression of melting point results from the synergistic action of completely dissociated ions in the melt, the ability of each type of ion was quantified, and the values were employed in a simple method to calculate the degree of melting point depression.

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  • Relationship between Degree of Melting Point Depression of Calcium Chloride Hexahydrate Melt and Amount of Additives in the Melt

    Yasuyuki Watanabe, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   43 ( 2 ) 129 - 137  2017  [Refereed]

     View Summary

    With a view to controlling the melting point and extending the temperature range for practical application of calcium chloride hexahydrate as a latent heat storage material, an attempt was made to derive an empirical equation by which to evaluate quantitatively the degree to which various additives depress its melting point (measured value, 302 K). The change in melting point relative to the amount of additive was measured for each of nine additives, and the ability of each additive to depress melting point was expressed numerically by use of a simple empirical equation. Based on the assumption that the depression of melting point results from the synergistic action of completely dissociated ions in the melt, the ability of each type of ion was quantified, and the values were employed in a simple method to calculate the degree of melting point depression.

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    6
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  • Study of polymorphic control in an ethanol-water binary solvent

    Hiroshi Kitano, Takayuki Tanaka, Izumi Hirasawa

       2016.12

  • Particle size distribution control of Pt particles used for particle gun

    M. Ichiji n, H.Akiba, H.Nagao, I.Hirasawa

    Jornal of Crystal Growth    2016.12

  • Purification of uranium products in crystallization system for nuclear fuel reprocessing

    Masayuki Takeuchi, Kimihiko Yano, Atsuhiro Shibata, Yuji Sanbonmatsu, Kazuhito Nakamura, Takahiro Chikazawa, Izumi Hirasawa

    JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY   53 ( 4 ) 521 - 528  2016.04  [Refereed]

     View Summary

    Uranium crystallization system has been developed to establish an advanced aqueous reprocessing for fast breeder reactor (FBR) fuel cycle. In the crystallization system, most part of uranium in dissolved solution of spent FBR-MOX fuels is separated as uranyl nitrate hexahydrate (UNH) crystals by a cooling operation. The targets of U yield and decontamination factor (DF) on the crystallization system are decided from FBR cycle performance and plutonium enrichment management. The DF is lowered by involving liquid and solid impurities on and in the UNH crystals during crystallization. In order to achieve the DF performance (more than 100), we discuss the purification technology of UNH crystals using a Kureha Crystal Purifier (KCP). Results show that more than 90% of uranium in the feed crystals could be recovered as the purified crystals in all test conditions, and the DFs of solid and liquid impurities on the purified UNH crystals are more than 100 under longer residence time of crystals in the column of KCP device. The purification mechanism is mainly due to the repetition of sweating and recrystallization in the column under controlled temperature.

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  • Purification of uranium products in crystallization system for nuclear fuel reprocessing

    Masayuki Takeuchi, Kimihiko Yano, Atsuhiro Shibata, Yuji Sanbonmatsu, Kazuhito Nakamura, Takahiro Chikazawa, Izumi Hirasawa

    JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY   53 ( 4 ) 521 - 528  2016.04  [Refereed]

     View Summary

    Uranium crystallization system has been developed to establish an advanced aqueous reprocessing for fast breeder reactor (FBR) fuel cycle. In the crystallization system, most part of uranium in dissolved solution of spent FBR-MOX fuels is separated as uranyl nitrate hexahydrate (UNH) crystals by a cooling operation. The targets of U yield and decontamination factor (DF) on the crystallization system are decided from FBR cycle performance and plutonium enrichment management. The DF is lowered by involving liquid and solid impurities on and in the UNH crystals during crystallization. In order to achieve the DF performance (more than 100), we discuss the purification technology of UNH crystals using a Kureha Crystal Purifier (KCP). Results show that more than 90% of uranium in the feed crystals could be recovered as the purified crystals in all test conditions, and the DFs of solid and liquid impurities on the purified UNH crystals are more than 100 under longer residence time of crystals in the column of KCP device. The purification mechanism is mainly due to the repetition of sweating and recrystallization in the column under controlled temperature.

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    4
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  • Heterogeneous Precipitation of Gold Nanoparticles on PEI Coated Silica Gel

    Takashi Mikami, Chisato Konno, Yuta Takayasu, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   49 ( 2 ) 186 - 190  2016.02

     View Summary

    Gold nanoparticles were precipitated on the surface of silica gel without mechanical mixing. Polyethylenimine (PEI) which was coated on the surface of silica gel reduced raw materials of hydrogen tetrachloroaurate (III) tetrahydrate (HAuCl4 center dot 4H(2)O). Formation of gold nanoparticles on silica gel was confirmed by using Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray Fluorescence Spectrometer (EDX). In this study, particles size distribution and coverage ratio of gold on silica gel were investigated.

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  • Heterogeneous Precipitation of Gold Nanoparticles on PEI Coated Silica Gel

    Takashi Mikami, Chisato Konno, Yuta Takayasu, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   49 ( 2 ) 186 - 190  2016.02  [Refereed]

     View Summary

    Gold nanoparticles were precipitated on the surface of silica gel without mechanical mixing. Polyethylenimine (PEI) which was coated on the surface of silica gel reduced raw materials of hydrogen tetrachloroaurate (III) tetrahydrate (HAuCl4 center dot 4H(2)O). Formation of gold nanoparticles on silica gel was confirmed by using Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray Fluorescence Spectrometer (EDX). In this study, particles size distribution and coverage ratio of gold on silica gel were investigated.

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  • Heterogeneous Precipitation of Gold Nanoparticles on PEI Coated Silica Gel

    Takashi Mikami, Chisato Konno, Yuta Takayasu, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   49 ( 2 ) 186 - 190  2016.02  [Refereed]

     View Summary

    Gold nanoparticles were precipitated on the surface of silica gel without mechanical mixing. Polyethylenimine (PEI) which was coated on the surface of silica gel reduced raw materials of hydrogen tetrachloroaurate (III) tetrahydrate (HAuCl4 center dot 4H(2)O). Formation of gold nanoparticles on silica gel was confirmed by using Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray Fluorescence Spectrometer (EDX). In this study, particles size distribution and coverage ratio of gold on silica gel were investigated.

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  • Polymorphism, Size and Shape Control of Calcium Carbonate Crystals in the Presence of a Polyelectrolyte

    Yuko Sonobe, Hiroto Watamura, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   38 ( 6 ) 1053 - 1058  2015.06  [Refereed]

     View Summary

    The effects of the presence of a polyelectrolyte on the polymorphism and particle size and shape of calcium carbonate crystals during reactive crystallization were investigated. Crystals were created by the single-jet reaction crystallization method. When polyacrylic acid (PAA) was added, the polymorphism and particle size and shape were different for each molecular weight of PAA and each experimental method. When sodium carboxymethylcellulose was added, the polymorph became different from those made by adding PAA and the particle sizes and shapes were different for each concentration. As a result, it is suggested that the method to achieve supersaturation, such as type of feeding, feed rate, kinds of polyelectrolyte and their concentration, may affect the polymorphism and particle size and shape of calcium carbonate.

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  • Effect of Seeding and pH Conditions on the Size and Shape of Au Nanoparticles in Reduction Crystallization

    Hiroko Akiba, Masumi Ichiji, Hideyuki Nagao, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   38 ( 6 ) 1068 - 1072  2015.06  [Refereed]

     View Summary

    Efficient and simple methods for gene integration into various plants have been studied by many researchers. The particle gun method using fine metal particles is one of the most potent technologies. However, it is difficult to control the particle size distribution and shape of the metal particles and, thus, to design and create adequate particles of suitable quality for the gene-supporting media. Here, reduction crystallization of nanometer- and submicron-sized Au was investigated in order to clarify the effects of the seeding and reaction conditions on the sizes and shapes of Au particles. The seed size has an influence on the surface roughness of the Au nanoparticles. Experiments to form Au particles were also performed using pH-controlled ascorbic acid. The pH has a great influence on the size and shape of nano/submicron Au particles and the mechanism of reduction crystallization.

    DOI

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    5
    Citation
    (Scopus)
  • Solubility Characteristics and Crystallization Behavior of Oxalic Acid in the Presence of Sulfuric Acid

    Naoko Imura, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   38 ( 6 ) 1042 - 1046  2015.06  [Refereed]

     View Summary

    Acidic wastewater from industrial discharge is generally treated by neutralization. Before neutralization or water treatment, selective recovery of valuable compounds is necessary to reduce the environmental impact of this acid waste. As a contribution to the development of a novel acidic wastewater treatment, oxalic acid is set as target material which is found in acid waste from the metalworking industry. Crystallization of oxalic acid in the presence of sulfuric acid has rarely been reported. Since this acid waste also contains aluminum ions, the effect of sulfuric acid and aluminum ions on oxalic acid solubility and crystallization was clarified. As a result, sulfuric acid concentration affected the oxalic acid solubility, but aluminum ions had no influence. Oxalic acid was precipitated in columnar shape by cooling crystallization from sulfuric acid aqueous solution with aluminum ions.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Solubility Characteristics and Crystallization Behavior of Oxalic Acid in the Presence of Sulfuric Acid

    Naoko Imura, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   38 ( 6 ) 1042 - 1046  2015.06

     View Summary

    Acidic wastewater from industrial discharge is generally treated by neutralization. Before neutralization or water treatment, selective recovery of valuable compounds is necessary to reduce the environmental impact of this acid waste. As a contribution to the development of a novel acidic wastewater treatment, oxalic acid is set as target material which is found in acid waste from the metalworking industry. Crystallization of oxalic acid in the presence of sulfuric acid has rarely been reported. Since this acid waste also contains aluminum ions, the effect of sulfuric acid and aluminum ions on oxalic acid solubility and crystallization was clarified. As a result, sulfuric acid concentration affected the oxalic acid solubility, but aluminum ions had no influence. Oxalic acid was precipitated in columnar shape by cooling crystallization from sulfuric acid aqueous solution with aluminum ions.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Effect of Seeding and pH Conditions on the Size and Shape of Au Nanoparticles in Reduction Crystallization

    Hiroko Akiba, Masumi Ichiji, Hideyuki Nagao, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   38 ( 6 ) 1068 - 1072  2015.06  [Refereed]

     View Summary

    Efficient and simple methods for gene integration into various plants have been studied by many researchers. The particle gun method using fine metal particles is one of the most potent technologies. However, it is difficult to control the particle size distribution and shape of the metal particles and, thus, to design and create adequate particles of suitable quality for the gene-supporting media. Here, reduction crystallization of nanometer- and submicron-sized Au was investigated in order to clarify the effects of the seeding and reaction conditions on the sizes and shapes of Au particles. The seed size has an influence on the surface roughness of the Au nanoparticles. Experiments to form Au particles were also performed using pH-controlled ascorbic acid. The pH has a great influence on the size and shape of nano/submicron Au particles and the mechanism of reduction crystallization.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Polymorphism, Size and Shape Control of Calcium Carbonate Crystals in the Presence of a Polyelectrolyte

    Yuko Sonobe, Hiroto Watamura, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   38 ( 6 ) 1053 - 1058  2015.06  [Refereed]

     View Summary

    The effects of the presence of a polyelectrolyte on the polymorphism and particle size and shape of calcium carbonate crystals during reactive crystallization were investigated. Crystals were created by the single-jet reaction crystallization method. When polyacrylic acid (PAA) was added, the polymorphism and particle size and shape were different for each molecular weight of PAA and each experimental method. When sodium carboxymethylcellulose was added, the polymorph became different from those made by adding PAA and the particle sizes and shapes were different for each concentration. As a result, it is suggested that the method to achieve supersaturation, such as type of feeding, feed rate, kinds of polyelectrolyte and their concentration, may affect the polymorphism and particle size and shape of calcium carbonate.

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    11
    Citation
    (Scopus)
  • Aging characteristics of protein precipitates produced by polyelectrolyte precipitation in turbulently agitated reactor

    Woon-Soo Kim, Izumi Hirasawa, Woo-Sik Kim

    Chemical Engineering Science.   57 ( 19 ) 4077 - 4085  2015.05

    Authorship:Last author

  • Effect of Specific Amino Acids on Controlling Crystal Pseudopolymorphism of L-Arginine Hydrochloride

    Takeshi Shimizu, Hiromu Yoshiura, Hiroshi Nagano, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   37 ( 8 ) 1427 - 1430  2014.08  [Refereed]

     View Summary

    The effect of a small amount of amino acid additives on the pseudopolymorphism of L-arginine hydrochloride (LAHCL) in aqueous solution is reported. Results confirm that L-alanine (L-Ala) has a stabilizing effect on the crystals of the anhydrate form of LAHCL at low temperature. Intriguingly, the stabilizing effect was observed even when L-Ala was added after a large amount of LAHCL had formed. In contrast, no stabilizing effect with D-Ala could be stated, suggesting that the stereochemistry of the additives is an important factor. In addition to the stereochemistry, also the length and bulkiness of the alkyl side-chain of the amino acids were found to be significant factors. Based on these results, a mechanism is proposed for stabilization of anhydrate LAHCL crystals by amino acid additives.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Polyacrylic Acid-Assisted Crystallization Phenomena of Carbonate Crystals

    Hiroto Watamura, Yuko Sonobe, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   37 ( 8 ) 1422 - 1426  2014.08  [Refereed]

     View Summary

    The effects of polyacrylic acid (PAA) on the crystallization of carbonates were investigated, revealing a great influence of PAA on the shape, size and polymorph type of the carbonate crystals. Carbonate crystallization was performed through reaction crystallization in a single-jet system. The obtained crystals were measured and characterized by scanning electron microscopy and X-ray diffraction. In lithium carbonate, PAA especially influenced the growth phase, inhibited agglomeration and changed the crystal shape into high-aspect rods. In addition, the degree of the growth inhibition effect was molecular weight dependent and the inhibition effect was also different on each face. In calcium carbonate, an improvement of the monodispersity was observed with miniaturization, under particular conditions. Elongated calcite was found under a slow supersaturation rate. In addition, the molecular weight of PAA affected the polymorph selectivity. Therefore, PAA affected the crystallization phenomena of carbonates, and prospected crystals were obtained by changing the operation conditions.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Polyacrylic Acid-Assisted Crystallization Phenomena of Carbonate Crystals

    Hiroto Watamura, Yuko Sonobe, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   37 ( 8 ) 1422 - 1426  2014.08  [Refereed]

     View Summary

    The effects of polyacrylic acid (PAA) on the crystallization of carbonates were investigated, revealing a great influence of PAA on the shape, size and polymorph type of the carbonate crystals. Carbonate crystallization was performed through reaction crystallization in a single-jet system. The obtained crystals were measured and characterized by scanning electron microscopy and X-ray diffraction. In lithium carbonate, PAA especially influenced the growth phase, inhibited agglomeration and changed the crystal shape into high-aspect rods. In addition, the degree of the growth inhibition effect was molecular weight dependent and the inhibition effect was also different on each face. In calcium carbonate, an improvement of the monodispersity was observed with miniaturization, under particular conditions. Elongated calcite was found under a slow supersaturation rate. In addition, the molecular weight of PAA affected the polymorph selectivity. Therefore, PAA affected the crystallization phenomena of carbonates, and prospected crystals were obtained by changing the operation conditions.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Effect of Specific Amino Acids on Controlling Crystal Pseudopolymorphism of L-Arginine Hydrochloride

    Takeshi Shimizu, Hiromu Yoshiura, Hiroshi Nagano, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   37 ( 8 ) 1427 - 1430  2014.08  [Refereed]

     View Summary

    The effect of a small amount of amino acid additives on the pseudopolymorphism of L-arginine hydrochloride (LAHCL) in aqueous solution is reported. Results confirm that L-alanine (L-Ala) has a stabilizing effect on the crystals of the anhydrate form of LAHCL at low temperature. Intriguingly, the stabilizing effect was observed even when L-Ala was added after a large amount of LAHCL had formed. In contrast, no stabilizing effect with D-Ala could be stated, suggesting that the stereochemistry of the additives is an important factor. In addition to the stereochemistry, also the length and bulkiness of the alkyl side-chain of the amino acids were found to be significant factors. Based on these results, a mechanism is proposed for stabilization of anhydrate LAHCL crystals by amino acid additives.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Effects of detector sensitivity and resolution on induction time reading

    Noriaki Kubota, Masanori Kobari, Izumi Hirasawa

    CRYSTENGCOMM   16 ( 6 ) 1103 - 1112  2014  [Refereed]

     View Summary

    The effects of sensitivity and resolution of a nucleation detector on induction time were mathematically analysed. The induction time was defined here as the time at which the number density of crystals nucleated under isothermal conditions had reached the minimum detectable number density of crystals (N/M)(det). The value of (N/M)(det) depends on the detector used, and therefore can be called the detector sensitivity. Meanwhile, the detector resolution is defined as the minimum detectable crystal size L-d. The equation for induction time t(ind) was derived for a simplified case wherein secondary nucleation and concentration reduction were both neglected. For a more general case where such a simplification cannot be made, the induction time t(ind) was calculated numerically. The sensitivity and resolution had effects on induction time. The induction time increased as the sensitivity decreased (i. e., the value of (N/M)(det) increased). It also increased with a decrease in the resolution (i. e., an increase in the minimum detectable size L-d). The effect of nucleus size L-0 on induction time t(ind) was also analysed. The analysis suggested that the induction time in an actual experiment, where the minimum detectable size L-d would be much larger than the nucleus size L-0, was independent of nucleus size itself but was affected by the resolution L-d. The interfacial energy of a crystal nucleus in solution that is deduced from the widely used plot of ln t(ind) vs. 1/(ln S)(2) (S: supersaturation ratio) was pointed out to be questionable. The effect of agitation rate (or stirrer speed) on induction time was also discussed.

    DOI

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    10
    Citation
    (Scopus)
  • Effects of detector sensitivity and resolution on induction time reading

    Noriaki Kubota, Masanori Kobari, Izumi Hirasawa

    CRYSTENGCOMM   16 ( 6 ) 1103 - 1112  2014  [Refereed]

     View Summary

    The effects of sensitivity and resolution of a nucleation detector on induction time were mathematically analysed. The induction time was defined here as the time at which the number density of crystals nucleated under isothermal conditions had reached the minimum detectable number density of crystals (N/M)(det). The value of (N/M)(det) depends on the detector used, and therefore can be called the detector sensitivity. Meanwhile, the detector resolution is defined as the minimum detectable crystal size L-d. The equation for induction time t(ind) was derived for a simplified case wherein secondary nucleation and concentration reduction were both neglected. For a more general case where such a simplification cannot be made, the induction time t(ind) was calculated numerically. The sensitivity and resolution had effects on induction time. The induction time increased as the sensitivity decreased (i. e., the value of (N/M)(det) increased). It also increased with a decrease in the resolution (i. e., an increase in the minimum detectable size L-d). The effect of nucleus size L-0 on induction time t(ind) was also analysed. The analysis suggested that the induction time in an actual experiment, where the minimum detectable size L-d would be much larger than the nucleus size L-0, was independent of nucleus size itself but was affected by the resolution L-d. The interfacial energy of a crystal nucleus in solution that is deduced from the widely used plot of ln t(ind) vs. 1/(ln S)(2) (S: supersaturation ratio) was pointed out to be questionable. The effect of agitation rate (or stirrer speed) on induction time was also discussed.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • A population balance model for solvent-mediated polymorphic transformation in unseeded solutions

    M. Kobari, N. Kubota, I. Hirasawa

    CRYSTENGCOMM   16 ( 27 ) 6049 - 6058  2014  [Refereed]

     View Summary

    A new population balance model for solvent-mediated polymorphic transformation is presented. The model takes into account the secondary nucleation caused by nuclei grown crystals as well as the primary nucleation. Numerical simulation was performed for crystallization of a hypothetical enantiotropic dimorphic compound in an unseeded solution. In the simulation, particular attention was paid to the effect of secondary nucleation of the stable polymorph on the transformation time. The simulated transformation time decreased with an increase in the secondary nucleation rate of the stable polymorph. Reported experimental data on the effect of stirrer speed were explained by the secondary nucleation-mediated mechanism, in which the secondary nucleation rate is assumed to increase with an increase in stirrer speed. The effect of scale-up on the transformation time was also suggested to be explained by the secondary nucleation-mediated mechanism.

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    11
    Citation
    (Scopus)
  • New insights into additive structure effect on crystal agglomeration of L-valine

    H. Yoshiura, H. Nagano, I. Hirasawa

    Chemical Engineering and Technology   36 ( 12 ) 2023 - 2028  2013.12

     View Summary

    Specific small amounts of amino acids caused agglomeration of L-valine (L-Val) crystals during evaporative crystallization from aqueous solutions. The agglomeration of L-Val occurred only under acidic condition when guest amino acids satisfied several conditions. Only L-form amino acids that have carboxylic acid groups and sufficiently long alkyl chain in the side-chains could induce agglomeration of L-Val. The length of alkyl chain in the side-chains controls the degree of agglomeration. Data indicated only 0.5wt% of L-2-aminoadipic acid, which has a similar chemical structure to L-glutamic acid (L-Glu), produced the large agglomerates &gt
    1000μm. The particle size was ∼500μm when using the same amount of L-Glu. Based on the results from previous tests and this paper, the whole mechanism for the L-Val agglomeration in the presence of specific guest amino acids has been revealed. © 2013 WILEY-VCH Verlag GmbH &amp
    Co. KGaA, Weinheim.

    DOI

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    3
    Citation
    (Scopus)
  • New insights into additive structure effect on crystal agglomeration of L-valine

    H. Yoshiura, H. Nagano, I. Hirasawa

    Chemical Engineering and Technology   36 ( 12 ) 2023 - 2028  2013.12

     View Summary

    Specific small amounts of amino acids caused agglomeration of L-valine (L-Val) crystals during evaporative crystallization from aqueous solutions. The agglomeration of L-Val occurred only under acidic condition when guest amino acids satisfied several conditions. Only L-form amino acids that have carboxylic acid groups and sufficiently long alkyl chain in the side-chains could induce agglomeration of L-Val. The length of alkyl chain in the side-chains controls the degree of agglomeration. Data indicated only 0.5wt% of L-2-aminoadipic acid, which has a similar chemical structure to L-glutamic acid (L-Glu), produced the large agglomerates &gt
    1000μm. The particle size was ∼500μm when using the same amount of L-Glu. Based on the results from previous tests and this paper, the whole mechanism for the L-Val agglomeration in the presence of specific guest amino acids has been revealed. © 2013 WILEY-VCH Verlag GmbH &amp
    Co. KGaA, Weinheim.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • The relationship between crystal morphology and XRD peak intensity on CaSO4 center dot 2H(2)O

    Mikiyasu Inoue, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   380   169 - 175  2013.10  [Refereed]

     View Summary

    Each XRD peak intensity of CaSO4 center dot 2H(2)O crystals changes according to their morphologies. This research clarifies the relationship between XRD peak intensity and morphologies on CaSO4 center dot 2H(2)O crystals synthesized by reaction crystallization with various additives. As a result, as XRD relative intensity of (021) face increases, average longitude and aspect ratio decrease and needle-like or plate-like large crystals transform into granular microcrystals. (C) 2013 The Authors. Published by Elsevier By. All rights reserved.

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    162
    Citation
    (Scopus)
  • 材料・界面

    渡邉 哲, 平沢 泉, 宮本 公明, 塩盛 弘一郎, 清山 史朗, 塩井 章久, 田中 俊輔, 後藤 健彦

    化学工学 = Chemical engineering   77 ( 10 ) 749 - 753  2013.10

    CiNii

  • Kinetic study on polyethylenimine-assisted reactive crystallization of monodisperse strontium sulfate microcrystals

    T. Mikami, I. Hirasawa

    Chemical Engineering and Technology   36 ( 8 ) 1320 - 1326  2013.08

     View Summary

    Double-jet reactive crystallization of SrSO4 was carried out in the presence of polyethylenimine (PEI). A simple kinetic model of primary nucleation as well as crystal growth was investigated under the condition of producing monodisperse microcrystals. Furthermore, surface free energy in the solution of PEI was estimated. PEI addition causes growth inhibition leading to smaller sizes and modifies the Gibbs free energy gap required for occurring nucleation. The effect of polyethylenimine (PEI) addition on nucleation and growth of SrSO4 is determined and a simple kinetic model is proposed. Time-dependent behaviors of crystal size and crystal number are statistically analyzed by a nonlinear least-square program. Kinetic aspects under the condition of obtaining monodisperse crystals are discussed. © 2013 WILEY-VCH Verlag GmbH &amp
    Co. KGaA, Weinheim.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Kinetic study on polyethylenimine-assisted reactive crystallization of monodisperse strontium sulfate microcrystals

    T. Mikami, I.Hirasawa

    Chemical Engineering and Technology   Volume 36, Issue 8   1320 - 1326  2013.08

  • Polyelectrolyte effects on the crystallization phenomena of the lithium carbonate

    Hiroto Watamura, Hironobu Marukawa, Izumi Hirasawa

    Journal of Crystal Growth   373 ( 15 ) 111 - 117  2013.06

     View Summary

    Anionic polyelectrolyte effects on the lithium carbonate crystallization phenomena were investigated. Li2CO3 crystals were obtained by reactive crystallization with seed crystals. Polyelectrolytes were dissolved into the reactive field before the reaction. Obtained crystals were observed with scanning electron microscopy (SEM) and crystal size and agglomeration degree were measured by the SEM images. The results show that Li 2CO3 crystallized different shape and size from absence of polyelectrolyte in those reactive fields. Especially polyacrylic acid (PAA) improved on the agglomeration of the crystals and shaped them high aspect needles. Thus other experimental conditions including PAA molecular weight and concentration, reaction time, supersaturation by Li concentration were investigated in addition. As a result, obtained crystals were not different in each PAA molecular weight reactive fields. Meanwhile PAA concentration has optimum range. Li2CO3 formed less agglomeration and higher aspect around 1 g/l. In the concentration, Li2CO3 did not agglomerate regardless of aging time and Li concentration. Moreover crystals became rectangle shape in higher Li concentration.(020) face intensity of the rectangle shape crystals increased according to XRD pattern. PAA affected the facial growth. These results may provide a method of morphological change and clearly crystallization of Li2CO3. © 2012 Elsevier B.V. All rights reserved.

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    12
    Citation
    (Scopus)
  • Kinetic crystallization separation process of the inositol isomers by controlling metastable zones

    Kaname Konuki, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   373   123 - 127  2013.06  [Refereed]

     View Summary

    D-chiro-inositol (DCI) is prepared by the immobilized enzyme reaction which uses myo-inositol (MI) as the substrate and the conversion rate is about 13%. The aim of this study was to develop a separation method for high purity DCI crystals from a reaction solution including low purity DCI only by the crystallization process. We succeeded in separating DCI crystals of 96% purity by water cooling crystallization, but it was presumed that scale-up was difficult. Although we tried anti-solvent crystallization similar to water cooling crystallization, high purity DCI crystals were not obtained. Therefore, we proposed the crystallization separation process by controlling metastable zones. The purity of a desired compound is controlled by this process, because solid-liquid separation is achieved before crystallization of compound in metastable zone. By the crystallization using this method, the DCI crystals of 97% purity were obtained. Although the yield per batch is about 50%, the actual yield is improved as the last mother liquor returns into the process of the following batch. When this process was repeated, the purity and the yield of DCI were reproduced and the robustness of this process was proved. It is expected that scale-up of this process will be successful, and this purification method could be applicable to similar systems such as separation of isomers and analogs. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

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    4
    Citation
    (Scopus)
  • New Insight into the Additives Structure Effect on Crystal Agglomeration of L- Valine,

    Hiromu Yosahiura, Hiroshi Nagano, Toshiko Kaneko, Izumi Hirasawa

    Journal of Crystal Growth,   373 ( 15 ) 50 - 60  2013.06

  • Kinetic crystallization separation process of the inositol isomers by controlling metastable zones

    Kaname Konuki, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   373 ( 15 ) 123 - 127  2013.06  [Refereed]

     View Summary

    D-chiro-inositol (DCI) is prepared by the immobilized enzyme reaction which uses myo-inositol (MI) as the substrate and the conversion rate is about 13%. The aim of this study was to develop a separation method for high purity DCI crystals from a reaction solution including low purity DCI only by the crystallization process. We succeeded in separating DCI crystals of 96% purity by water cooling crystallization, but it was presumed that scale-up was difficult. Although we tried anti-solvent crystallization similar to water cooling crystallization, high purity DCI crystals were not obtained. Therefore, we proposed the crystallization separation process by controlling metastable zones. The purity of a desired compound is controlled by this process, because solid-liquid separation is achieved before crystallization of compound in metastable zone. By the crystallization using this method, the DCI crystals of 97% purity were obtained. Although the yield per batch is about 50%, the actual yield is improved as the last mother liquor returns into the process of the following batch. When this process was repeated, the purity and the yield of DCI were reproduced and the robustness of this process was proved. It is expected that scale-up of this process will be successful, and this purification method could be applicable to similar systems such as separation of isomers and analogs. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Polyelectrolyte effects on the Crystallization Phenomena of Lithium Carbonate

    H. Watamura, I. Hirasawa

    Journal of Crystal Growth   373 ( 15 ) 111 - 117  2013.06

  • Evaluation of precipitation behavior of zirconium molybdate hydrate

    Liang Zhang, Masayuki Takeuchi, Tsutomu Koizumi, Izumi Hirasawa

    FRONTIERS OF CHEMICAL SCIENCE AND ENGINEERING   7 ( 1 ) 65 - 71  2013.03  [Refereed]

     View Summary

    In the dissolution step of spent nuclear fuel, there is a world-concern problem that zirconium molybdate hydrate precipitates as a byproduct, and accumulates in some reprocessing equipments. In order to prevent this accumulation, we have developed a new method based on the controlled reaction crystallization of zirconium molybdate hydrate (ZMH) in the reprocessing solution, followed by solid liquid separation. In order to measure the particle size of ZMH, batch crystallization experiments were conducted by varying nitric acid concentration and operating temperature. In result, almost all particle sizes scatter around 1 mu m on average, despite the higher concentration of nitric aid and operating temperature, and then small particles grow up as an aggregate sticking to the crystallizer. Moreover, polymorph and color changing were observed by varying the concentration of nitric acid and reaction time. These results suggest that crystal color and adhesiveness are closely related to the particle size of ZMH. And the control of nitric acid concentration and small particle growth would be the useful technique to prevent the ZMH sticking.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Particle size distribution and shape control of Au nanoparticles used for particle gun

    S. Kida, M. Ichiji, J. Watanabe, I. Hirasawa

    Frontiers of Chemical Science and Engineering   7 ( 1 ) 60 - 64  2013.03

     View Summary

    Au nanoparticles are expected for the media to transfer genes into plants. However, the control of particle size distribution (PSD) and shape of Au nanoparticles is too difficult to design and prepare particles with suitable quality for the gene supporting media. Reduction crystallization experiments were performed in aqueous solution in order to clarify the effect of feeding conditions such as feeding profile, feeding rate, and feeding amount on PSD and shape of Au nanoparticles. Ascorbic acid (AsA) was selected as a reducing agent because it is safe for plants. Au particles of 50 nm, 50-200 nm, and 150-400 nm were obtained in batch operation, single-jet, and double-jet, respectively. Moreover, in single-jet and double-jet, the mean size of the obtained Au particles increases with the decrease of feeding rate or the increase of feeding amount. It is concluded that PSD of Au nanoparticles can be controlled in the range of 50-400 nm by changing feeding conditions of AsA and HAuCl4 aqueous solution. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.

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    5
    Citation
    (Scopus)
  • Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by reaction crystallization

    H. Watamura, H. Marukawa, I. Hirasawa

    Frontiers of Chemical Science and Engineering   7 ( 1 ) 55 - 59  2013.03

     View Summary

    Relationship between magnesium ammonium phosphate (MAP) crystal properties and the filtration ability of hollow fiber membrane (HFM) were investigated. Phosphorus recovery process by crystallization has a problem that it produces a large amount of fine crystals. So improvement of the crystallization process by combining with filtration was discussed. MAP crystals were obtained by batch reaction crystallization and the filtration characteristics were investigated. The filtration was evaluated by the specific filtration resistance (αc) on HFM. Filtered slurry was prepared with each suspension density and crystal size distribution. The solution was filtered at constant pressure of 0. 02 MPa and the filtration time on each filtrated volume was recorded. As a result, αc decreases exponentially with suspension density increasing from 0. 25 g/L to 0. 5 g/L and αc decreases moderately with suspension density increasing from 0. 5 g/L to 1. 5 g/L. αc of large crystals decreases exponentially at less suspension density than αc of small crystals does. Also, αc increases as the ratio of the fractured crystals increases. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.

    DOI

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  • Evaluation of precipitation behavior of zirconium molybdate hydrate

    Liang Zhang, Masayuki Takeuchi, Tsutomu Koizumi, Izumi Hirasawa

    FRONTIERS OF CHEMICAL SCIENCE AND ENGINEERING   7 ( 1 ) 65 - 71  2013.03  [Refereed]

     View Summary

    In the dissolution step of spent nuclear fuel, there is a world-concern problem that zirconium molybdate hydrate precipitates as a byproduct, and accumulates in some reprocessing equipments. In order to prevent this accumulation, we have developed a new method based on the controlled reaction crystallization of zirconium molybdate hydrate (ZMH) in the reprocessing solution, followed by solid liquid separation. In order to measure the particle size of ZMH, batch crystallization experiments were conducted by varying nitric acid concentration and operating temperature. In result, almost all particle sizes scatter around 1 mu m on average, despite the higher concentration of nitric aid and operating temperature, and then small particles grow up as an aggregate sticking to the crystallizer. Moreover, polymorph and color changing were observed by varying the concentration of nitric acid and reaction time. These results suggest that crystal color and adhesiveness are closely related to the particle size of ZMH. And the control of nitric acid concentration and small particle growth would be the useful technique to prevent the ZMH sticking.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Creation of Controlled Manganese and Zinc Compounds by Reactive Crystallization

    Yoshiharu Shimizu, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   46 ( 5 ) 342 - 346  2013  [Refereed]

     View Summary

    In this article, manganese and zinc compound formation via reactive crystallization has been summarized. In this process, the metal sulfate solution was reacted with the sodium carbonate solution according to the double-jet method. Some particle properties such as crystal size, shape, agglomeration rate, and metal ion concentration in the effluent have been examined by controlling the pH in the initial reaction field, the concentration of the metal ions in the stock solution, or the flow rate of the solution. The size of formed manganese carbonate particles increases with an increase in the feeding speed and the metal ion concentration in stock solution. This is due to the fact that particle growth is strongly affected by the metal ion supersaturation in the reaction solution. Meanwhile, the manganese carbonate particle recovery rate increases with an increase in the feeding rate and a decrease in the metal ion concentration. The size of zinc oxide particles formed continuously changes with the initial pH. The above experiments indicate that the recovered crystal size and surface roughness, as well as the metal ion recovery rate and monodispersion, are controlled, to some extent, by regulating the reaction conditions.

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    1
    Citation
    (Scopus)
  • Efficient plastid transformation in tobacco using small gold particles (0.07-0.3 mu m)

    Ayako Okuzaki, Shoko Kida, Junpei Watanabe, Izumi Hirasawa, Yutaka Tabei

    PLANT BIOTECHNOLOGY   30 ( 1 ) 65 - 72  2013  [Refereed]

     View Summary

    Plastid transformation methods have been developed for 20 plant species. However, only a few plant species, such as tobacco and lettuce, have been used in applied studies because transformation efficiencies are extremely low in other species. Plastid transformation has been mainly performed by particle bombardment using 0.6-mu m gold particles as microcarriers of the transformation vector. Because the target materials in some plant species are undeveloped proplastids rather than fully developed chloroplasts, optimizing microcarrier size for the target size is a major consideration. In this study, we evaluated the availability of gold particles (0.07, 0.08, 0.1, 0.2, and 0.3 mu m) that were smaller than those used for plastid transformation in previous studies. We obtained stable plastid transformants of tobacco with sufficient efficiency using all the tested small gold particles as the same level as 0.6-mu m gold particles, even the smallest (0.07 mu m). The average number of transformants obtained with 0.3-mu m particles (9.3+/-4.6 per plate) was the highest among the tested gold particles. Because small gold particles were revealed to be sufficient for plastid transformation in a model tobacco plant, it is suggested that choosing appropriate small-sized gold particles which have never been used before will improve plastid transformation in many plant species.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Analytical and numerical study of detector sensitivity and resolution effects on metastable zone width

    Noriaki Kubota, Masanori Kobari, Izumi Hirasawa

    CRYSTENGCOMM   15 ( 11 ) 2091 - 2098  2013  [Refereed]

     View Summary

    The effects of the sensitivity and resolution of a detector on metastable zone width (MSZW) were theoretically studied by using analytical and numerical methods. The detector sensitivity and the detector resolution were defined here as the minimum detectable number density of crystals (N/M)(det) and the minimum detectable size of crystals, respectively. Both the sensitivity and resolution had significant effects on MSZW. The MSZW became larger as the sensitivity was decreased (i.e., the value of (N/M)(det) was increased). It also became larger with a decrease in the resolution (i.e., an increase in the minimum detectable size). The effect of the resolution was less significant than that of the sensitivity. The effect of nucleus size on MSZW is also discussed. The MSZW reading in an actual experiment, where the minimum detectable size is expected to be much larger than the nucleus size, was suggested not to depend on nucleus size.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Mechanism of specific influence of L-Glutamic acid on the shape of L-Valine crystals

    Hiromu Yoshiura, Hiroshi Nagano, Izumi Hirasawa

    Journal of Crystal Growth   363   55 - 60  2013

     View Summary

    The specific interaction between L-valine (L-Val) and L-glutamic acid (L-Glu) in the process of evaporative crystallization from an aqueous solution has been investigated. It was found that only 2.0% (wt/wt) of L-Glu against the total amount of L-Val was required to induce significant agglomeration of L-Val. Interestingly, the agglomeration was only induced under acidic conditions, suggesting that the electrostatic interaction was an effective factor for the agglomeration process. As well as the electrostatic interaction, the length of the amino acid side chain was identified as another important factor. In addition, we confirmed that the incorporation rate of L-Glu into L-Val crystals was different during the nucleation and crystal growth stages. Based on these results, a mechanism has been proposed for the interaction of L-Glu and L-Val during the agglomeration process. © 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Impurities Effect on Carbonate Reactive Crystallization for the Wastewater

    Y. Shimizu, Izumi Hirasawa

    ISRN Chemical Engineering   2013  2013.01

    DOI

  • Kinetic Study on Polyethylenimine-Assisted Reactive Crystallization of Monodisperse Strontium Sulfate Microcrystals

    Takashi Mikami, Izumi Hirasawa

    Chemical Engineering & echnology   36 ( 1 ) 1 - 8  2013.01

  • Deducing primary nucleation parameters from metastable zone width and induction time data determined with simulation

    M. Kobari, N. Kubota, I. Hirasawa

    CRYSTENGCOMM   15 ( 6 ) 1199 - 1209  2013  [Refereed]

     View Summary

    Metastable zone widths (MSZWs) and induction times were determined with numerical simulations on an unseeded aqueous solution. The simulated MSZWs and induction times were significantly affected by secondary nucleation caused by nuclei grown crystals. However, this secondary nucleation-mediated effect on the MSZWs and induction times was negligibly small at high cooling rates and at high supercoolings, respectively. The primary nucleation parameters k(b1) and b1 in the rate expression B-1 = k(b1)(Delta T)(b1), where B-1 is the nucleation rate and Delta T is supercooling, were deduced by applying mathematical Kubota models to the determined MSZWs and induction times, respectively. Correct primary nucleation parameters (i.e., the same values as those input for the simulations) were deduced only under the condition of neglected secondary nucleation. The simulation results suggest that, in actual experiments, the proper primary nucleation parameters b1 and k(b1) can be deduced from the MSZWs and induction times if these were measured under the condition of neglected secondary nucleation. In addition, an experiment with a slow stirrer speed (low secondary nucleation rate) and with a high sensitivity detector (earlier detection of the MSZW and induction time) were recommended for the deduction of correct primary nucleation parameters.

    DOI

    Scopus

    26
    Citation
    (Scopus)
  • Efficient plastid transformation in tobacco using small gold particles (0.07-0.3 mu m)

    Ayako Okuzaki, Shoko Kida, Junpei Watanabe, Izumi Hirasawa, Yutaka Tabei

    PLANT BIOTECHNOLOGY   30 ( 1 ) 65 - 72  2013  [Refereed]

     View Summary

    Plastid transformation methods have been developed for 20 plant species. However, only a few plant species, such as tobacco and lettuce, have been used in applied studies because transformation efficiencies are extremely low in other species. Plastid transformation has been mainly performed by particle bombardment using 0.6-mu m gold particles as microcarriers of the transformation vector. Because the target materials in some plant species are undeveloped proplastids rather than fully developed chloroplasts, optimizing microcarrier size for the target size is a major consideration. In this study, we evaluated the availability of gold particles (0.07, 0.08, 0.1, 0.2, and 0.3 mu m) that were smaller than those used for plastid transformation in previous studies. We obtained stable plastid transformants of tobacco with sufficient efficiency using all the tested small gold particles as the same level as 0.6-mu m gold particles, even the smallest (0.07 mu m). The average number of transformants obtained with 0.3-mu m particles (9.3+/-4.6 per plate) was the highest among the tested gold particles. Because small gold particles were revealed to be sufficient for plastid transformation in a model tobacco plant, it is suggested that choosing appropriate small-sized gold particles which have never been used before will improve plastid transformation in many plant species.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Analytical and numerical study of detector sensitivity and resolution effects on metastable zone width

    Noriaki Kubota, Masanori Kobari, Izumi Hirasawa

    CRYSTENGCOMM   15 ( 11 ) 2091 - 2098  2013  [Refereed]

     View Summary

    The effects of the sensitivity and resolution of a detector on metastable zone width (MSZW) were theoretically studied by using analytical and numerical methods. The detector sensitivity and the detector resolution were defined here as the minimum detectable number density of crystals (N/M)(det) and the minimum detectable size of crystals, respectively. Both the sensitivity and resolution had significant effects on MSZW. The MSZW became larger as the sensitivity was decreased (i.e., the value of (N/M)(det) was increased). It also became larger with a decrease in the resolution (i.e., an increase in the minimum detectable size). The effect of the resolution was less significant than that of the sensitivity. The effect of nucleus size on MSZW is also discussed. The MSZW reading in an actual experiment, where the minimum detectable size is expected to be much larger than the nucleus size, was suggested not to depend on nucleus size.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Creation of Controlled Manganese and Zinc Compounds by Reactive Crystallization

    Yoshiharu Shimizu, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   46 ( 5 ) 342 - 346  2013  [Refereed]

     View Summary

    In this article, manganese and zinc compound formation via reactive crystallization has been summarized. In this process, the metal sulfate solution was reacted with the sodium carbonate solution according to the double-jet method. Some particle properties such as crystal size, shape, agglomeration rate, and metal ion concentration in the effluent have been examined by controlling the pH in the initial reaction field, the concentration of the metal ions in the stock solution, or the flow rate of the solution. The size of formed manganese carbonate particles increases with an increase in the feeding speed and the metal ion concentration in stock solution. This is due to the fact that particle growth is strongly affected by the metal ion supersaturation in the reaction solution. Meanwhile, the manganese carbonate particle recovery rate increases with an increase in the feeding rate and a decrease in the metal ion concentration. The size of zinc oxide particles formed continuously changes with the initial pH. The above experiments indicate that the recovered crystal size and surface roughness, as well as the metal ion recovery rate and monodispersion, are controlled, to some extent, by regulating the reaction conditions.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • The relationship between crystal morphology and XRD peak intensity on CaSO4·2H2O

    Mikiyasu Inoue, Izumi Hirasawa

    Journal of Crystal Growth   380   169 - 175  2013

     View Summary

    Each XRD peak intensity of CaSO4ï \2H2O crystals changes according to their morphologies. This research clarifies the relationship between XRD peak intensity and morphologies on CaSO 4ï \2H2O crystals synthesized by reaction crystallization with various additives. As a result, as XRD relative intensity of (021) face increases, average longitude and aspect ratio decrease and needle-like or plate-like large crystals transform into granular microcrystals. © 2013 The Authors.

    DOI

    Scopus

    162
    Citation
    (Scopus)
  • Effect of Seeding on Metal Ion Recovery from Wastewater by Reactive Crystallization of Metal Carbonates

    Yoshiharu Shimizu, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   35 ( 9 ) 1588 - 1592  2012.09  [Refereed]

     View Summary

    Reactive crystallization for separation and recovery of divalent metal ions from wastewater using a semi-batch crystallizer has been developed. In this process, metal carbonates are produced by reacting metal sulfate solution with sodium carbonate solution. Nickel and copper ions are crystallized under particular initial pH conditions but the product shapes are not regular. Consequently, sphere seeds have been used as nucleus-generating agents and their growth mechanism has been examined. When providing a particular amount of seeds before crystallization, metal substances piled up on the surface of the seeds, maintaining the form sphere, and the production of fines was restricted. The metal removal rate through reactive crystallization was similar to 99.9?% on average. This operation proved to be suitable for application in industrial wastewater treatment and for recycling of metal materials.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Effect of Seeding on Metal Ion Recovery from Wastewater by Reactive Crystallization of Metal Carbonate

    Y. Shimizu, I. Hirasawa

    Chemical Engineering Technology   35 ( 9 ) 1588 - 1592  2012.09

  • Recovery of Ionic Substances from Wastewater by Seeded Reaction Crystallization

    Yoshiharu Shimizu, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   35 ( 6 ) 1051 - 1054  2012.06  [Refereed]

     View Summary

    Crystallization is a suitable process for selective separation of a target ion since ions can be removed and recovered as purified and stable materials. Methods of recovery and recycling of phosphate and fluoride ions have been investigated to determine the optimum crystallization conditions like supersaturation, temperature, pH, impurities, and kind of solvents. As a result, by selecting the optimum crystal operation conditions for each wastewater composition, spherical-shape crystals with desired purity and size are obtained and generation of sludge is minimized.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Effect of Ultrasonic Irradiation on the Crystallization of Sodium Acetate Trihydrate Utilized as Heat Storage Material

    Kiwamu Seo, Shunpei Suzuki, Takuya Kinoshita, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   35 ( 6 ) 1013 - 1016  2012.06  [Refereed]

     View Summary

    The effect of ultrasonic irradiation on nucleation phenomena in the heat storage material CH3COONa center dot 3H2O was investigated by measuring the nucleation probability and induction time. The experimental results show that the concentration of CH3COONa should be operated in the optimum range for CH3COONa center dot 3H2O-selective crystallization. Furthermore, the nucleation probability increased and the induction time decreased with increasing energy input. Consequently, the optimum conditions of ultrasonic irradiation of CH3COONa center dot 3H2O are 53?wt-% CH3COONa, 3.0?W of energy input, and ?T = 1068?K.

    DOI

    Scopus

    29
    Citation
    (Scopus)
  • Recovery of Ionic Substance from the Wastewater By Seeded Reaction

    Y. Shimizu, I. Hirasawa

    Chemical Engineering Technology   Vol.35 ( No.6 ) 1051 - 1054  2012.06

  • Effect of Ultrasonic Irradiation on Primary Nucleation in Heat Storage Material

    K. Seo, M. Sakamoto, Izumi Hirasawa

    Chemical Engineering Technology   Vol 35 ( No.6 ) 1013 - 1016  2012.06

  • Single-Jet Precipitation of Silver Nanocrystals in the Presence of Poly(acrylic) Acid

    Takashi Mikami, Takatoshi Nagahori, Jin Saito, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   35 ( 4 ) 700 - 704  2012.04  [Refereed]

     View Summary

    Precipitation of silver nanocrystals was carried out in a poly(acrylic) acid (PAA) solution by using a single-jet crystallizer. The influence of the feeding rate, the injection position and the PAA dosage on the crystal size distribution (CSD) was clarified. The precipitated silver nanocrystals agglomerate with each other, forming an agglomerated microcrystal. In the presented case, smaller feeding rates caused smaller crystal sizes and narrower CSD widths. PAA, which is a water-soluble polyelectrolyte, successfully inhibited agglomeration and crystal growth, and decreased the crystal size and the CSD width. Thus, this idea may also facilitate the production of other nano-/microcrystalline particles.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Single-Jet Precipitation of Silver Nanocrystals in the Presence of Poly(acrylic) Acid

    Takashi Mikami, Takatoshi Nagahori, Jin Saito, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   35 ( 4 ) 700 - 704  2012.04  [Refereed]

     View Summary

    Precipitation of silver nanocrystals was carried out in a poly(acrylic) acid (PAA) solution by using a single-jet crystallizer. The influence of the feeding rate, the injection position and the PAA dosage on the crystal size distribution (CSD) was clarified. The precipitated silver nanocrystals agglomerate with each other, forming an agglomerated microcrystal. In the presented case, smaller feeding rates caused smaller crystal sizes and narrower CSD widths. PAA, which is a water-soluble polyelectrolyte, successfully inhibited agglomeration and crystal growth, and decreased the crystal size and the CSD width. Thus, this idea may also facilitate the production of other nano-/microcrystalline particles.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Secondary nucleation-mediated effects of stirrer speed and growth rate on induction time for unseeded solution

    M. Kobari, N. Kubota, I. Hirasawa

    CRYSTENGCOMM   14 ( 16 ) 5255 - 5261  2012  [Refereed]

     View Summary

    Simulation of induction time for nucleation was performed under isothermal conditions for unseeded aqueous solutions of different concentrations. The effects of stirrer speed and growth rate on induction time were both explained with the proposed secondary nucleation-mediated mechanism. The effect of stirrer speed N-r was incorporated into the simulation with an empirical relation of k(b2) proportional to N-r(j), where k(b2) is the coefficient in the secondary nucleation rate equation B-2 = k(b2) (Delta T)(b2)mu(3), Delta T is supercooling, j and b2 are empirical constants and mu(3) is the third moment of crystal size distribution. The simulated induction time decreased with an increase in stirrer speed at lower supercoolings, while it remained unchanged at higher supercoolings. Such action of stirrer speed was similar to that observed in the literature data. The growth rate effect was considered to be caused by a faster increase in the secondary nucleation rate via a faster increase in mu(3). The simulated induction time decreased with an increase in crystal growth rate. This type of growth rate effect is completely different from the existing mechanism considering the time needed for invisible nuclei to grow to a detectable size.

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • 超音波を用いた晶析制御の展開

    平沢泉

    ファルマシア   47 ( 11 )  2011.11

  • Computer simulation of metastable zone widt for unseeded potassium sulfate aqueous solution

    Masanori Kobari, Noriaki Kubota, Izumi Hirasawa

    Journal of Crystal Growth   317 ( 1 ) 64 - 69  2011.05

  • Effect of polyethyleneimine addition on crystal size distribution of Au nanocrystals

    Takashi Mikami, Yuta Takayasu, Junpei Watanabe, Izumi Hirasawa

    Journal of Chemical Engineering Technology    2011.05

  • Separation of Solid Impurity by Melt Crystallization of Aluminum Nitrate Nonahydrate

    Mizuki Kumashiro, Takuya Hoshino, Yoshinori Izumi, Yusuke Fujita, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   34 ( 4 ) 525 - 529  2011.04  [Refereed]

     View Summary

    The effect of melt crystallization on inorganic hydrate for purification of crystals containing liquid and solid impurities was investigated. Melt crystallization is generally applied to purify organic crystals. In the case of inorganic crystals, it is cost-ineffective because of the higher melting point. However, some inorganic crystals, i.e., hydrate crystals, can be applied to melt crystallization because of the lower melting point. Hydrate crystals containing impurities were prepared and melt crystallization was carried out to investigate the purification mechanism on inorganic crystals. Liquid impurity in target crystals was removed by sweating and washing with melt. Solid impurity was also separated with melt flow, supported by mixing operations. It was considered that the purification mechanism is differently dependent on the state of impurity.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Influence of Polyethyleneimine Addition on Crystal Size Distribution of Au Nanocrystals

    Takashi Mikami, Yuta Takayasu, Junpei Watanabe, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   34 ( 4 ) 583 - 586  2011.04  [Refereed]

     View Summary

    The influence of polyethyleneimine (PEI) addition on the crystal size distribution (CSD) of Au was investigated. PEI is a water-soluble cationic polyelectrolyte acting as a reducer of AuCl(4)(-) and a stabilizer of precipitated Au nanocrystals. The CSD can be controlled by the PEI dosage, and an increase in PEI dosage decreased both the size and the size distribution width of the obtained Au nanocrystals. The idea of PEI-assisted reductive crystallization of Au may be helpful in the production of nanometals by using a simple batch crystallizer.

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Separation of Solid Impurity by Melt Crystallization of Aluminum Nitrate Nonahydrate

    Mizuki Kumashiro, Takuya Hoshino, Yoshinori Izumi, Yusuke Fujita, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   34 ( 4 ) 525 - 529  2011.04  [Refereed]

     View Summary

    The effect of melt crystallization on inorganic hydrate for purification of crystals containing liquid and solid impurities was investigated. Melt crystallization is generally applied to purify organic crystals. In the case of inorganic crystals, it is cost-ineffective because of the higher melting point. However, some inorganic crystals, i.e., hydrate crystals, can be applied to melt crystallization because of the lower melting point. Hydrate crystals containing impurities were prepared and melt crystallization was carried out to investigate the purification mechanism on inorganic crystals. Liquid impurity in target crystals was removed by sweating and washing with melt. Solid impurity was also separated with melt flow, supported by mixing operations. It was considered that the purification mechanism is differently dependent on the state of impurity.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Removal of Liquid and Solid Impurities from Uranyl Nitrate Hexahydrate Crystalline Particles in Crystal Purification Process

    Masaumi Nakahara, Kazunori Nomura, Tadahiro Washiya, Takahiro Chikazawa, Izumi Hirasawa

    JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY   48 ( 3 ) 322 - 329  2011.03  [Refereed]

     View Summary

    The purification behavior of uranyl nitrate hexahydrate (UNH) was investigated to evaluate the decontamination performance of liquid and solid impurities using a dissolver solution of mixed oxide (MOX) fuel in batch experiments. The UNH crystal recovered from the MOX fuel dissolver solution containing simulated fission products (FPs) was purified by a sweating and melt filtration process. Although the decontamination factors (DFs) of Pu, Cs, and Ba did not change in the sweating process, that of Eu increased with increases in temperature and time. These results indicate that liquid impurities such as Eu were effectively removed by the sweating method, but solid impurities such as Pu, Cs, and Ba were minimally affected in the batch experiments. On the other hand, the DF of Ba increased with 0.45 and 5.0 mu m filters in the melt filtration process. Since Pu and Cs formed as Cs2Pu(NO3)(6) in the course of U crystallization and was accompanied with the UNH crystal, these behaviors were similar to each other. Although the DFs of Pu and Cs did not change with the 5.0 mu m filter, it increased approximately twofold with the 0.45 mu m filter. The particle size of Cs2Pu(NO3)(6) is relatively small and might pass through the 5.0 mu m filter in the melt filtration process. The liquid impurities as Eu remained in the molten UNH crystal with some filters.

    DOI

  • Erratum: Simulation of metastable zone width and induction time for a seeded aqueous solution of potassium sulfate (Journal of Crystal Growth (2010) 312 (2734-2739))

    M. Kobari, N. Kubota, I. Hirasawa

    Journal of Crystal Growth   316 ( 1 ) 201  2011.02  [Refereed]

    DOI

    Scopus

  • Growth and Characterization of Borax Decahydrate by Cooling Crystallization

    Shiro Kaneko, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   44 ( 9 ) 628 - 635  2011  [Refereed]

     View Summary

    The cooling crystallization of borax decahydrate has been investigated for the influence of temperatures on solubility, induction period and yield in order to establish the limits of conditions. Crystal morphology of borax decahydrate was studied by optical microscopy. Characterization of the crystals was performed by X-ray diffraction. The solubility curves were determined within the range of 0 to 25 degrees C. The induction period was extremely short in seeded experiments compared with unseeded experiments. The yield was found to increase with decreasing temperatures. Microscopy observation revealed that as-grown crystals were significantly elongated in a direction parallel to the c-axis of the monoclinic system. The X-ray diffraction analysis indicated that the (002) plane of monoclinic system grew faster than the (120) plane at temperatures of 5 and 9 degrees C. The results indicate that the temperature limit of borax decahydrate crystallization is 9 degrees C.

  • Solvent-Induced Transformation of Myo-Inositol Crystal

    Mizuki Kumashiro, Shunki Saitoh, Azusa Kobayakawa, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   44 ( 3 ) 187 - 190  2011  [Refereed]

     View Summary

    The objective of this study is to investigate the effect of organic solvents on pseudopolymorph transformation kinetics for clarifying the transformation phenomenon. In our previous study, we observed anhydrate and dihydrate crystals of myo-inositol in water and/or an ethanol-water system and transformation phenomena. However, we could not determine the detailed transformation mechanism in organic solvents. Therefore, we attempted adding seed crystals to different alcohol solvents, which resulted in the transformation of seed crystals of a dihydrate into anhydrate crystals. The transformation kinetics increased with a decrease in the alkyl carbon number in the solvents and also with an increase in the ethanol mass fraction. During the transformation process, fine anhydrate crystals were observed on the surface of dihydrate crystals, and the dihydrate crystals were found to dissolve and gradually decrease in size. On the basis of these results, we propose that the hydrophilic nature of organic solvents is a significant factor determining the pseudopolymorph transformation kinetics of myo-inositol. The transformation phenomena proceeded easily upon the addition of dehydrate seed crystals, as if the solvent had the driving force for the crystallization of a stable polymorph. We classified this unique mechanism as a "solvent-induced transformation."

  • Purification of Aluminum Nitrate Nonahydrate by Melt Crystallization

    Mizuki Kumashiro, Yoshinori Izumi, Takuya Hoshino, Yusuke Fujita, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   44 ( 2 ) 105 - 109  2011  [Refereed]

     View Summary

    The objective of our study is to investigate the effect of melt crystallization on inorganic hydrate for purification of crystals including impurity. Melt crystallization is widely applied in the chemical and food industry to purify organic crystals by separating impurities inside the crystals. The target crystals are mainly organic crystals; however, some inorganic crystals are considered for purification by melt crystallization, because of having lower melting point as hydrate crystals. Therefore, we prepared hydrate crystals including impurities and carried out melt crystallization to investigate the purification mechanism on inorganic crystals. Aluminum nitrate nonahydrate was selected as purification target and strontium nitrate was selected as liquid impurity. As solid impurity, we selected barium nitrate. In conclusion, liquid impurity in target crystals was removed by sweating and washing with melt. Moreover, it was considered that the purification mechanism differs depending on the state of the impurity, and melt crystallization is an effective tool for purification the inorganic hydrate crystals.

  • Solvent-Induced Transformation of Myo-Inositol Crystal

    Mizuki Kumashiro, Shunki Saitoh, Azusa Kobayakawa, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   44 ( 3 ) 187 - 190  2011  [Refereed]

     View Summary

    The objective of this study is to investigate the effect of organic solvents on pseudopolymorph transformation kinetics for clarifying the transformation phenomenon. In our previous study, we observed anhydrate and dihydrate crystals of myo-inositol in water and/or an ethanol-water system and transformation phenomena. However, we could not determine the detailed transformation mechanism in organic solvents. Therefore, we attempted adding seed crystals to different alcohol solvents, which resulted in the transformation of seed crystals of a dihydrate into anhydrate crystals. The transformation kinetics increased with a decrease in the alkyl carbon number in the solvents and also with an increase in the ethanol mass fraction. During the transformation process, fine anhydrate crystals were observed on the surface of dihydrate crystals, and the dihydrate crystals were found to dissolve and gradually decrease in size. On the basis of these results, we propose that the hydrophilic nature of organic solvents is a significant factor determining the pseudopolymorph transformation kinetics of myo-inositol. The transformation phenomena proceeded easily upon the addition of dehydrate seed crystals, as if the solvent had the driving force for the crystallization of a stable polymorph. We classified this unique mechanism as a "solvent-induced transformation."

  • Purification of Aluminum Nitrate Nonahydrate by Melt Crystallization

    Mizuki Kumashiro, Yoshinori Izumi, Takuya Hoshino, Yusuke Fujita, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   44 ( 2 ) 105 - 109  2011  [Refereed]

     View Summary

    The objective of our study is to investigate the effect of melt crystallization on inorganic hydrate for purification of crystals including impurity. Melt crystallization is widely applied in the chemical and food industry to purify organic crystals by separating impurities inside the crystals. The target crystals are mainly organic crystals; however, some inorganic crystals are considered for purification by melt crystallization, because of having lower melting point as hydrate crystals. Therefore, we prepared hydrate crystals including impurities and carried out melt crystallization to investigate the purification mechanism on inorganic crystals. Aluminum nitrate nonahydrate was selected as purification target and strontium nitrate was selected as liquid impurity. As solid impurity, we selected barium nitrate. In conclusion, liquid impurity in target crystals was removed by sweating and washing with melt. Moreover, it was considered that the purification mechanism differs depending on the state of the impurity, and melt crystallization is an effective tool for purification the inorganic hydrate crystals.

  • Growth and Characterization of Borax Decahydrate by Cooling Crystallization

    Shiro Kaneko, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   44 ( 9 ) 628 - 635  2011  [Refereed]

     View Summary

    The cooling crystallization of borax decahydrate has been investigated for the influence of temperatures on solubility, induction period and yield in order to establish the limits of conditions. Crystal morphology of borax decahydrate was studied by optical microscopy. Characterization of the crystals was performed by X-ray diffraction. The solubility curves were determined within the range of 0 to 25 degrees C. The induction period was extremely short in seeded experiments compared with unseeded experiments. The yield was found to increase with decreasing temperatures. Microscopy observation revealed that as-grown crystals were significantly elongated in a direction parallel to the c-axis of the monoclinic system. The X-ray diffraction analysis indicated that the (002) plane of monoclinic system grew faster than the (120) plane at temperatures of 5 and 9 degrees C. The results indicate that the temperature limit of borax decahydrate crystallization is 9 degrees C.

  • PEI-assisted preparation of Au nanoparticles via reductive crystallization process

    Takashi Mikami, Yuta Takayasu, Izumi Hirasawa

    CHEMICAL ENGINEERING RESEARCH & DESIGN   88 ( 9A ) 1248 - 1251  2010.09  [Refereed]

     View Summary

    Nano-sized gold particles were prepared in a solution containing polyethylenimine (PEI) utilizing a batch reactor. PEI acts as a reducing agent as well as a stabilizing agent of nanoparticles. The effects of initial concentration of PEI on the mean particle diameter, coefficient of variation (C.V.), growth rate, nucleation rate and the number of nuclei were studied. The particle diameter of gold decreased markedly with increasing initial concentration of PEI, from 3.3 mu m to a minimum value of about 5 nm. The observed decrease of particle diameter was considered to be caused by the growth-inhibiting effect of PEI, which affects the conclusive number of nuclei. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • CSD-controlled reactive crystallization of SrSO4 in the presence of polyethylenimine

    Takashi Mikami, Takahiro Sakuma, Izumi Hirasawa

    CHEMICAL ENGINEERING RESEARCH & DESIGN   88 ( 9A ) 1200 - 1205  2010.09  [Refereed]

     View Summary

    Reactive crystallization of SrSO4 was performed in the presence of polyethylenimine (PEI) using a double-jet crystallizer. PEI dosage suggested important dependence on crystal size distributions (CSDs) leading to obtain micron-sized crystals with mono-dispersed distribution. A plausible role of PEI was considered to be a multiple inhibitor of growth, continuous nucleation and agglomeration. PEI might be an effective polyelectrolyte additive for the production of mono-dispersed fine crystals. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • Effect of ultrasonic irradiation on the selective polymorph control in sulfamerazine

    Masahiro Kurotani, Izumi Hirasawa

    CHEMICAL ENGINEERING RESEARCH & DESIGN   88 ( 9A ) 1272 - 1278  2010.09  [Refereed]

     View Summary

    The selective polymorph control in sulfamerazine (SMZ) using ultrasonic irradiation was investigated. Firstly, the behavior of polymorphs in the absence of ultrasonic irradiation with various degrees of supersaturation was monitored. As a result, only metastable form-I crystallized at the primary nucleation stage and crystal growth of only form-I was recognized. The nucleation rate of stable form-II was very small, and the transformation from form-I to form-II hardly occurred. Therefore, it is easy to obtain form-I without ultrasonic irradiation, as it does not depend on the level of supersaturation. Secondly, the behavior of polymorphs with various degrees of ultrasonic energy and supersaturation was monitored. As a result, only form-I was obtained in the case of small ultrasonic energy. However, in addition to the nucleation of form-I, an unknown form-III and/or the recognized form-II are induced to nucleate under the influence of the ultrasonic energy in the case of large ultrasonic energy. Eventually, all forms changed to form-II within a short period of time. Therefore, polymorph control of SMZ can be achieved easily by supplying an appropriate amount of ultrasonic energy. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • PEI-assisted preparation of Au nanoparticles via reductive crystallization process

    Takashi Mikami, Yuta Takayasu, Izumi Hirasawa

    CHEMICAL ENGINEERING RESEARCH & DESIGN   88 ( 9A ) 1248 - 1251  2010.09  [Refereed]

     View Summary

    Nano-sized gold particles were prepared in a solution containing polyethylenimine (PEI) utilizing a batch reactor. PEI acts as a reducing agent as well as a stabilizing agent of nanoparticles. The effects of initial concentration of PEI on the mean particle diameter, coefficient of variation (C.V.), growth rate, nucleation rate and the number of nuclei were studied. The particle diameter of gold decreased markedly with increasing initial concentration of PEI, from 3.3 mu m to a minimum value of about 5 nm. The observed decrease of particle diameter was considered to be caused by the growth-inhibiting effect of PEI, which affects the conclusive number of nuclei. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • Effect of ultrasonic irradiation on the selective polymorph control in sulfamerazine

    Masahiro Kurotani, Izumi Hirasawa

    CHEMICAL ENGINEERING RESEARCH & DESIGN   88 ( 9A ) 1272 - 1278  2010.09  [Refereed]

     View Summary

    The selective polymorph control in sulfamerazine (SMZ) using ultrasonic irradiation was investigated. Firstly, the behavior of polymorphs in the absence of ultrasonic irradiation with various degrees of supersaturation was monitored. As a result, only metastable form-I crystallized at the primary nucleation stage and crystal growth of only form-I was recognized. The nucleation rate of stable form-II was very small, and the transformation from form-I to form-II hardly occurred. Therefore, it is easy to obtain form-I without ultrasonic irradiation, as it does not depend on the level of supersaturation. Secondly, the behavior of polymorphs with various degrees of ultrasonic energy and supersaturation was monitored. As a result, only form-I was obtained in the case of small ultrasonic energy. However, in addition to the nucleation of form-I, an unknown form-III and/or the recognized form-II are induced to nucleate under the influence of the ultrasonic energy in the case of large ultrasonic energy. Eventually, all forms changed to form-II within a short period of time. Therefore, polymorph control of SMZ can be achieved easily by supplying an appropriate amount of ultrasonic energy. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • CSD-controlled reactive crystallization of SrSO4 in the presence of polyethylenimine

    Takashi Mikami, Takahiro Sakuma, Izumi Hirasawa

    CHEMICAL ENGINEERING RESEARCH & DESIGN   88 ( 9A ) 1200 - 1205  2010.09

     View Summary

    Reactive crystallization of SrSO4 was performed in the presence of polyethylenimine (PEI) using a double-jet crystallizer. PEI dosage suggested important dependence on crystal size distributions (CSDs) leading to obtain micron-sized crystals with mono-dispersed distribution. A plausible role of PEI was considered to be a multiple inhibitor of growth, continuous nucleation and agglomeration. PEI might be an effective polyelectrolyte additive for the production of mono-dispersed fine crystals. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • 理科教育-教師対象の啓発活動 : 中高教諭とケミカルエンジニア交流のための見学・講演会-

    平沢 泉

    化学工学 = Chemical engineering   74 ( 8 ) 430 - 430  2010.08

    CiNii

  • Facile production of mono-dispersed BaSO4 particles via PEI-mediated reactive crystallization process

    Mikami Takashi, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   Vol.43 ( No.8 ) 698 - 703  2010.08

  • Simulation of metastable zone width and induction time for a seeded aqueous solution of potassium sulfate

    M. Kobari, N. Kubota, I Hirasawa

    Journal of Crystal Growth   312 ( 19 ) 2734 - 2738  2010.07

  • 反応晶析プロセスを利用した単分散硫酸塩の製造(その2)

    三上貴司, 平沢 泉

    硫酸と工業   Vol.63 ( 6 ) 83 - 87  2010.06

    CiNii

  • Polyelectrolyte-Assisted Reactive Crystallization of SrSO4 to Obtain Monodispersed Nano/Micro-Particles

    Takashi Mikami, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   33 ( 5 ) 797 - 803  2010.05  [Refereed]

     View Summary

    Micronized SrSO4 crystals having monodispersed/narrow distributions were produced with a controlled double-jet reactive crystallizer. Polyethylenimine (PEI) had the role of a suitable controller of supersaturation and following crystallization phenomena, and then led to agglomeration-less homogeneous crystalline qualities. Especially, the PEI imines seemed to adjust the number of nucleates, and also physical gel networks seemed to contribute to the inhibition of further particulate agglomeration. The current paper mainly demonstrated the influence of PEI addition on the resulting properties, e.g. sizes and size distribution widths. Therefore the polyelectrolyte-assisted technique will develop as a build-up process contributing to provide high-value nano/micro-powders having the desired crystalline qualities.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Quality-Controlled Reactive Crystallization of SrSO4 To Produce High-Valued Chemicals

    Takashi Mikami, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   33 ( 5 ) 775 - 779  2010.05  [Refereed]

     View Summary

    Precipitation of monodispersed SrSO4 particles was carried out in the presence of polyethylenimine (PEI). PEI additions varied some particulate properties, e.g., sizes, shapes, size distribution widths, and agglomeration ratios. The present paper mainly focuses on the influence of PEI dosage on crystal size distributions. PEI-assisted double jet techniques require no difficult controls of feeding rates, therefore, this idea will be applicable to precipitation of other inorganic compounds for the purpose of producing monodispersed nano-/microparticles.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Quality-Controlled Reactive Crystallization of SrSO4 To Produce High-Valued Chemicals

    Takashi Mikami, Izumi Hirasawa

    Chemical Engineering Technology   Vol.33 ( 5 ) 775 - 779  2010.05

  • 反応晶析プロセスを利用した単分散硫酸塩の製造(その1)

    三上貴司, 平沢 泉

    硫酸と工業   Vol.63 ( 6 ) 69 - 75  2010.05

    CiNii

  • Polyethylenimine-Assisted Reactive Crystallization of SrSO4 to Obtain Monodispersed Nano/Micro-Particles

    Mikami T, I. Hirasawa

    Chemical Engineering & Technology   33 ( 5 ) 797 - 803  2010.05

  • Preparation and characterization of dicesium tetravalent plutonium hexanitrate

    Masaumi Nakamura, Kzunori Nomura, Tadahiro Washiya, Takahiro Chikazawa, Izumi Hirasawa

    Journal of Alloys and Compounds   489   659 - 662  2010.04  [Refereed]

  • Influence of Polyethylenimine on Double-Jet Reactive Crystallization Process of Monodisperse BaSO4

    Takashi Mikami, Shota Ikeda, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   43 ( 8 ) 698 - 703  2010

     View Summary

    Micronized BaSO4 particles with a narrow size distribution were produced by using a double-jet reactive crystallizer. Polyethylenimine (PEI) acted as a growth/agglomeration inhibitor at a high PEI dosage, hence the particle size and size distribution width decreased, and BaSO4 crystals with the desired qualities were obtained. Similar results were obtained in previous studies in which of SrSO4 and PbSO4. We believe that our method, which involves the use of PEI, can be employed for the production of various inorganic sulfates in which the particles have a monodisperse size distribution.

  • Effect of Feeding Condition on Crystal Size Distributions of Mono-Dispersed SrSO4 Particles Produced via PEI-Assisted Double-Jet Reactive Crystallization

    Takashi Mikami, Takahiro Sakuma, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   43 ( 3 ) 300 - 307  2010

     View Summary

    Micron-sized SrSO4 particles having mono-dispersed/narrow distributions have been produced with a double-jet semi-batch reactive crystallizer. Slow molar feedings over a short time maintained proper supersaturation levels and result in narrow distributions due to the prevention of agglomeration growth of small primary precipitates. Furthermore, polyethylenimine (PEI) is a suitable growth/agglomeration inhibitor for sulfate precipitation, e. g., SrSO4 and PbSO4, and effectively reduced particle sizes leading to single-micron products. Besides feeding conditions, in the present work, the influence of PEI dosage on crystal size distributions (CSDs) is investigated. The controlled double-jet feeding using a polyelectrolyte additive such as PEI will be a powerful methodology to obtain agglomeration-free uniform micro-powders as a final solid product.

  • Preparation and characterization of dicesium tetravalent plutonium hexanitrate

    Masaumi Nakahara, Kazunori Nomura, Tadahiro Washiya, Takahiro Chikazawa, Izumi Hirasawa

    JOURNAL OF ALLOYS AND COMPOUNDS   489 ( 2 ) 659 - 662  2010.01  [Refereed]

     View Summary

    In experiments on U crystallization in a dissolver solution containing Cs, there is concern that Cs and Pu(IV) nitrate complex are deposited on the UNH crystal in the dissolver solution at the time of the U crystallization. The characteristics of generation of Cs and Pu(IV) nitrate complex with dissolver solution of MOX fuel were examined. This complex was obtained as a precipitate by mixing dissolver solution of MOX fuel and CsNO(3) solution, and was identified as dicesium tetravalent plutonium hexanitrate, Cs(2)Pu(NO(3))(6) by concentration analysis and XRD. The precipitate has a tendency to be generated at high HNO(3) concentrations. Thermal analysis shows that the precipitate is stable below 245 degrees C, and a weight loss of 10.29 +/- 0.23% is observed between 245 and 297 degrees C. This result indicates the decomposition of Cs(2)Pu(NO(3))(6) to Cs(2)PuO(2)(NO(3))(4), With these properties, the UNH crystal should melt at the condition between 60 and 100 degrees C and be separable from the Cs complex by filtration. This suggests a new method of crystal purification allowing higher decontamination of UNH crystal in the U crystallization process. (C) 2009 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Control of CSD Width via PEI-Assisted Reactive Crystallization of Micro-SrSO4 Particles

    Takashi Mikami, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   43 ( 3 ) 308 - 312  2010  [Refereed]

     View Summary

    A controlled double-jet reactive crystallization technique using a PEI (polyethylenimine) additive has been conducted to produce agglomeration-free micro-particles of SrSO4 with narrow and mono-dispersed size distributions. PEI successfully inhibits rapid/continuous nucleation due to a complexation with strontium ions before nucleation occurs, and enables realization of perfect separation of nucleation and growth. Our idea to obtain fine particles with desired size distributions will introduce a new potential for contributing to enhance high-valued material properties.

  • 色材サロン 早稲田大学 平沢研究室

    平沢 泉

    色材   Vol.83 ( No.1 ) 39 - 41  2010.01

  • Control of CSD width via PEI-assisted reactive crystallization of micro-SrSO4 particles

    Takashi Mikami, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   43 ( 3 ) 308 - 312  2010  [Refereed]

     View Summary

    A controlled double-jet reactive crystallization technique using a PEI (polyethylenimine) additive has been conducted to produce agglomeration-free micro-particles of SrSO4 with narrow and mono-dispersed size distributions. PEI successfully inhibits rapid/continuous nucleation due to a complexation with strontium ions before nucleation occurs, and enables realization of perfect separation of nucleation and growth. Our idea to obtain fine particles with desired size distributions will introduce a new potential for contributing to enhance high-valued material properties. © 2010 The Society of Chemical Engineers, Japan.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Effect of Feeding Condition on Crystal Size Distributions of Mono-Dispersed SrSO4 Particles Produced via PEI-Assisted Double-Jet Reactive Crystallization

    Takashi Mikami, Takahiro Sakuma, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   43 ( 3 ) 300 - 307  2010  [Refereed]

     View Summary

    Micron-sized SrSO4 particles having mono-dispersed/narrow distributions have been produced with a double-jet semi-batch reactive crystallizer. Slow molar feedings over a short time maintained proper supersaturation levels and result in narrow distributions due to the prevention of agglomeration growth of small primary precipitates. Furthermore, polyethylenimine (PEI) is a suitable growth/agglomeration inhibitor for sulfate precipitation, e. g., SrSO4 and PbSO4, and effectively reduced particle sizes leading to single-micron products. Besides feeding conditions, in the present work, the influence of PEI dosage on crystal size distributions (CSDs) is investigated. The controlled double-jet feeding using a polyelectrolyte additive such as PEI will be a powerful methodology to obtain agglomeration-free uniform micro-powders as a final solid product.

  • Influence of nitric acid and plutonium concentrations in dissolver solution of mixed oxide fuel on decontamination factors for uranyl nitrate hexahydrate crystal

    M. Nakahara, K. Nomura, T. Washiya, T. Chikazawa, I. Hirasawa

    RADIOCHIMICA ACTA   98 ( 6 ) 315 - 320  2010  [Refereed]

     View Summary

    In order to examine the decontamination behavior of the Pu and fission products (FPs) that contained with the uranyl nitrate hexahydrate (UNH) crystals in the U crystallization process, experiments were carried out using mixed oxide (MOX) fuel dissolver solution. The experiments confirmed that Eu was adequately decontaminated by washing the UNH crystals with a HNO(3) solution. However, Ba crystallized as Ba(NO(3))(2) and the washing was ineffective for the decontamination of Ba. High HNO(3) and Pu concentrations in the mother liquor, the decontamination factor (DF) of Cs was low because Cs precipitated with Pu as Cs(2)Pu(NO(3))(6). The Pu clearly showed a reasonable DF because the amount of Pu in the dissolver solution was higher than that of Cs. Almost all the amount of Pu remains in the mother liquor except the one in the Cs(2)Pu(NO(3))(6) precipitate.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Influence of Polyethylenimine on Double-Jet Reactive Crystallization Process of Monodisperse BaSO4

    Takashi Mikami, Shota Ikeda, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   43 ( 8 ) 698 - 703  2010  [Refereed]

     View Summary

    Micronized BaSO4 particles with a narrow size distribution were produced by using a double-jet reactive crystallizer. Polyethylenimine (PEI) acted as a growth/agglomeration inhibitor at a high PEI dosage, hence the particle size and size distribution width decreased, and BaSO4 crystals with the desired qualities were obtained. Similar results were obtained in previous studies in which of SrSO4 and PbSO4. We believe that our method, which involves the use of PEI, can be employed for the production of various inorganic sulfates in which the particles have a monodisperse size distribution.

  • 化学工学年鑑 晶析

    平沢 泉

    化学工学   73 ( 10 ) 533 - 534  2009.10

  • Effect of ultrasonic irradiation on the behavior of primary nucleation of amino acids in suersaturated solution

    Masahiro Kurotani, tsuko Miyasaka, Satomi Ebihara, Izumi Hirasawa

    Journal of Crystal Growth   311   2714 - 2721  2009.03

  • 高分子電解質を添加剤に用いた金ナノ粒子の還元晶析創製

    三上 貴司, 高安 裕太, 平沢 泉

    化学工学会 研究発表講演要旨集   2009   254 - 254  2009

    DOI CiNii

  • 反応晶析プロセスを利用した硫酸塩微粒子の製造

    三上 貴司, 平沢 泉

    化学工学会 研究発表講演要旨集   2009   297 - 297  2009

    DOI CiNii

  • 反応晶析プロセスを利用した単分散硫酸塩の製造

    三上 貴司, 平沢 泉

    化学工学会 研究発表講演要旨集   2009   434 - 434  2009

    DOI CiNii

  • Application of Ultrasonic Irradiation to Control Crystallization

    Izumi Hirasawa

    Proceedings of International Symposium of Crystal Engineering & Drug Delivery system   1   1 - 13  2009

  • ものづくり、資源、環境そしてアジアの視点から 巻頭言

    平沢 泉

    荏原時報    2009.01

  • A System having a Crystallization Process for Phosphorus Recovery from Methane Fermentation Digested Sludge

    Kazuaki Shimamura, Tateki Kurosawa, Izumi Hirasawa

    KAGAKU KOGAKU RONBUNSHU   35 ( 1 ) 127 - 132  2009  [Refereed]

     View Summary

    Methane fermentation treatment of solids yields a digested sludge containing nitrogen and phosphorus in high concentrations. For the purposes of phosphorus load reduction of the water treatment system, anti-scaling of methane fermentation tanks and their surrounding apparatus, and phosphorus resource recovery, a system for positive crystallization and recovery of magnesium ammonium phosphate (MAP) from the digested sludge was devised. This system consists of a crystallization process, a separation process using the hydrocyclone and a low temperature drying process. The optimum operational conditions for MAP and the MAP drying conditions for a digested sludge containing solids at a concentration of several per cent were clarified, and a pilot-scale plant having a treatment capacity of 2m(3)/h was built and subjected to 16-month demonstration tests.
    For the separation of MAP using the hydrocyclone, it is necessary to suppress nucleation in the crystallization process. Based on the laboratory tests, it was found that MAP nucleation is suppressed and the crystal growth becomes predominant when a good fluidized condition of MAP is maintained in the reactor, the reactor is operated at a low supersaturation degree, and a suitable MAP crystallization loading per charged seed crystal amount is maintained. It was also found that, in the drying process, MAP can maintain its form without transition when the drying temperature is set below 70 degrees C. In the demonstration tests of the series of processes, the PO(4)-P removal efficiency in the crystallization process was above 85%, showing that the reactions proceeded well. Moreover, only about 10% of the reacted phosphorus was nucleated; that is, about 90% of reacted phosphorus grew on the seed crystal surfaces, and as a result, MAP could be separated well from the digested sludge. MAP recovered from the drying process had a moisture content below 0.1%, a purity of 92.6%, and a hazardous metal content below the standard values prescribed by the Fertilizer Regulation Act, and therefore, it could be confirmed that MAP has a high quality as a fertilizer product.

    DOI CiNii

    Scopus

  • Observation of Secondary Nucleation in Drowning-Out Crystallization Using FBRM

    Keigo Hanaki, Izumi Hirasawa

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   42 ( 6 ) 386 - 392  2009  [Refereed]

     View Summary

    The nucleation behavior of an active pharmaceutical ingredient (API) is investigated in semi-batch drowning-out crystallization. A methanol solution of the API was fed in a short period into a well-mixed anti-solvent at low temperature. The effect on nucleation behavior of the amount of seed crystals and concentration of API methanol solution to be fed was investigated using in-line particle monitoring technique (FBRM). Despite the presence of seed crystals in anti-solvent into which the API solution was fed, nucleation took place after an induction period from feeding in some experiments, and it was found that the addition of seed crystals is effective to control the induction period and to enhance nucleation after the induction period. As for feed concentration, at high feed concentration, generation of nuclei during feeding was observed and then a supersaturated slurry of fine particles was obtained; however, at low feed concentration, anti-solvent became clouded locally during feeding and then clear supersaturated solution was obtained. At high feed concentration, it was also observed from time courses of FBRM chord count for several size classes that fine particles generated during feeding grew very slowly during the induction period, and rapid nucleation took place accompanied with agglomeration of fine particles and subsequent dispersion with generating nuclei.

  • 超音波を利用した晶析操作の原理と応用

    宮坂悦子, 平沢 泉

    化学工学   72 ( 11 ) 632 - 635  2008.11

    CiNii

  • Polymorph control of sulfamerazine by ultrasonic irradiation

    Masahiro Kurotani, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   310 ( 21 ) 4576 - 4580  2008.10

     View Summary

    The effect of ultrasonic irradiation on the polymorph control of sulfamerazine (SMZ) in acetonitrile at 21 degrees C was studied. In the primary nucleation stage without ultrasonic irradiation, metastable form-I crystallized primarily from the supersaturated solution. Then, only form-I grew, although slowly, and the SMZ concentration reached the saturation point of form-I. SMZ showed a very low solvent-mediated polymorphic transformation rate owing to the small difference in solubility between its metastable form-I and stable form-II. The transformation from form-I to form-II hardly occurred, even when the suspension of form-I was maintained at 21 degrees C for a few days or weeks. Therefore, it was easier to obtain form-I than form-II by controlling only the degree of supersaturation. On the other hand, form-II could be obtained by supplying a certain amount of ultrasonic energy in the primary nucleation stage. In such cases, the nucleation rate and crystal growth rate were relatively high; the SMZ concentration reached the saturation point of form-II within one day. Furthermore, the solvent-mediated transformation was enhanced by ultrasonic irradiation. The SMZ concentration decreased when periodic ultrasonic irradiation was carried out a few hours after the SMZ concentration reached the saturation point of form-I. Finally, form-I transformed to form-II. Thus, for the production of either form, the polymorph of SMZ can be controlled with or without ultrasonic irradiation. (c) 2008 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    35
    Citation
    (Scopus)
  • 材料界面 晶析

    平沢 泉

    化学工学   72 ( 10 ) 579 - 580  2008.10

    CiNii

  • Crystallization technology to create nanocrystals

    Izumi Hirasawa, Takashi Mikami

    Jouranl of the Japan Society of Color Material   81 ( 5 ) 161 - 164  2008.05

    DOI CiNii

  • 制御された反応晶析場における硫酸ストロンチウム単分散結晶の創製

    三上 貴司, 平沢 泉

    化学工学会 研究発表講演要旨集   2008   557 - 557  2008

    DOI CiNii

  • 難溶解性塩の反応晶析系における添加剤の影響

    三上 貴司, 平沢 泉

    化学工学会 研究発表講演要旨集   2008   697 - 697  2008

    DOI CiNii

  • [依頼講演]MAPの晶析現象を利用した下水からのリン回収プロセスの開発

    島村 和彰, 平沢 泉

    化学工学会 研究発表講演要旨集   2008   920 - 921  2008

    DOI CiNii

  • Recovery of Anion as Resources Based on Crystallization Engineering

    Izumi Hirasawa, Kyoko Ishibashi

    Journal of Material and Mining Japan   124 ( 1 ) 1 - 6  2008.01

     View Summary

    Present state and strategies are summarized on the recovery of anions in the wastewater, based on crystallization engineering. Anion which gives undesirable influence to the environment has been removed by coagulation and precipitation methods to produce a large amount of sludge, requiring wide space for its disposal. Recently steep increase in the price of the resources and deep concern about drying-up of resources have accelerated recovery of ions in the wastewater. Consequently many researches have been done to selectively separate a desirable ion. Crystallization is one of the suitable processes for this purpose, because it can remove and recover ions as the form of purified and stable crystals. In application of crystallization to the wastewater treatment, solid-liquid equilibrium, metastable zone width (MZW), degree of supersaturation, crystallization kinetics (crystal growth, nucleation and so on) and selection of seeds and desirable seed amounts should be given. Examples and strategies on phosphate and fluoride recovery are shown.

    DOI CiNii

  • Development of a process for the recovery of phosphorus resource from digested sludge by crystallization technology

    K. Shimamura, H. Ishikawa, A. Mizuoka, I. Hirasawa

    WATER SCIENCE AND TECHNOLOGY   57 ( 3 ) 451 - 456  2008  [Refereed]

     View Summary

    Removal and recovery of phosphorus from sewage in form of MAP ( magnesium ammonium phosphate) have attracted attention from the viewpoint of eutrophication prevention and phosphorus resource recovery as well as scaling prevention inside digestion tanks. In this work, phosphorus recovery demonstration tests were conducted in a 50m(3)/d facility having a complete mixing type reactor and a liquid cyclone. Digested sludge, having 690 mg/L T-P and 268 mg/L PO4-P, was used as test material. The T-P and PO4-P of treated sludge were 464 mg/ L and 20 mg/ L achieving a T-P recovery efficiency of 33% and a PO4-P crystallization ratio of 93%. The reacted phosphorus did not become fine crystals and the recovered MAP particles were found to be valuable as a fertilizer. A case study in applying this phosphorus recovery process for treatment of sludge from an anaerobic-aerobic process of a 21,000 m(3)/d sewage system, showed that 30% of phosphorus concentration can be reduced in the final effluent, recovering 315 kg/d as MAP.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • 化学工学年鑑2007 材料界面 晶析技術

    平沢 泉

    化学工学   71 ( 10 )  2007.10

  • 晶析技術を利用した下水からのリン回収プロセス

    島村和彰, 石川英之, 平沢 泉

    用水と廃水   49 ( 9 ) 64 - 70  2007.09

  • Design of Constant Supersaturation Cooling Crystallization of a Pharmaceutical: A Simple Approach

    Keigo Hanaki, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   40 ( 1 ) 63 - 71  2007.08

  • 晶析技術を活用した有用元素の回収技術

    平沢 泉

    分離技術   37 ( 3 ) 12 - 17  2007.06

  • 晶析法による有用元素の回収

    平沢 泉

    分離技術   57 ( 3 )  2007.05

  • Preparation of Blue-Flluorescing Chloroapatite Powder in Methanol

    Akio Tanahashi, Izumi Hirasawa

    World Journal of Chemical Engineering   2007 ( 1 ) 35 - 43  2007.05

  • Effects of ultrasonic irradiationon primary nucleation of acetylsalicylic acid in the agitated solution

    Etsuko Miyasaka, Izumi Hirasawa

    World Journal of Chemical Engineering   2007 ( 1 ) 25 - 34  2007.05

  • 晶析技術を用いた嫌気性消化汚泥からのりん資源回収プロセスの開発

    島村和彰, 平沢 泉

    エバラ時報   ( 215 ) 14 - 22  2007.04

    CiNii

  • Use of a seeder reactor to manage crystal growth in the fluidized bed reactor for phosphorus recovery

    Kazuaki Shimamura, Hideyuki Ishikawa, Toshihiro Tanaka, Izumi Hirasawa

    WATER ENVIRONMENT RESEARCH   79 ( 4 ) 406 - 413  2007.04  [Refereed]  [International journal]

     View Summary

    The authors have been engaged in the development of a phosphorus recovery system capable of maintaining high recovery efficiencies, with the chemical cost suppressed. This time, they conducted demonstration tests of a fluidized bed magnesium ammonium phosphate reactor provided with a seeder reactor for the supernatant from anaerobic digestion using a pilot experimental plant with a wastewater treatment capacity of 20 m(3)/d. For the digestion supernatant with a phosphorus concentration of approximately 300 mg/L, the treated water phosphorus concentration was 10 to 25 mg/L, and the phosphorus recovery efficiency was more than 90%. Relative to the chemical cost in the case of magnesium chloride, the chemical cost in the case of magnesium hydroxide is approximately 40%. Thus, with the new system, it was possible to reduce the running cost while maintaining high recovery efficiencies.

    DOI PubMed

    Scopus

    10
    Citation
    (Scopus)
  • 晶析工学を基軸にしたナノ結晶のビルドアップ

    平沢 泉, 三上貴司, 池田将太

    ケミカルエンンジニアリング   52 ( 3 ) 54 - 58  2007.03

  • Development of the Phosphorus Recovery Process for Anaerobic Digested Sludge Using crystallization

    SHIMAMURA Kazuaki, MIZUOKA Asei, ISHIKAWA Hideyuki, HIRASAWA Izumi

    Doboku Gakkai Ronbunshuu G   44   673 - 678  2007

     View Summary

    Removal and recovery of phosphorous from swage in form of MAP (magnesium ammonium phosphate) have attracted attention from the view point of eutrophication prevention, phosphorus resourcerecovery. In this work, we conducted the basic investigations on the phosphorus recovery process for anaerobic digested sludge using crystallization, and the demonstration tests using a pilot scale and full-scale experimenral plant. A total-phosphorus recovery ratio higher than 30% was achieved, and a reacted soluble phosphorus recovery ratio higher than 95% was achieved. A case study in applying this phosphorus recovery process for treatment of sludge from an anaerobic-aerobic process of 21, 000m3/d sewage plant, evidenced that 30% of phosphorus concentration can be reduced in the final effluent and recovering 315kg/d as MAP.

    DOI CiNii

  • 高分子電解質反応場における硫酸バリウム単分散微粒子生成手法に関する考察

    池田 将太, 中江 翼, 三上 貴司, 平沢 泉

    化学工学会 研究発表講演要旨集   2007   97 - 97  2007

    DOI CiNii

  • 熟成過程における硫酸ストロンチウム微粒子特性の挙動について

    三上 貴司, 池田 将太, 平沢 泉

    化学工学会 研究発表講演要旨集   2007   96 - 96  2007

    DOI CiNii

  • 晶析技術を用いた嫌気性消化汚泥中のリン回収システムの検証

    島村和彰, 平沢 泉

    下水道協会誌   43 ( 529 ) 108 - 117  2006.11

    CiNii

  • 資源循環型排水処理の新展開 ー水再生と同時に資源を回収する持続可能プロセスー

    平沢 泉

    平成18年造水技術講演会    2006.11

  • ナノ結晶生成のための戦略

    平沢 泉

    研究情報誌M&E   ( 11 )  2006.11

  • Phosphorus recovery in a fluidized bed crystallization reactor

    Kazuaki Shimamura, Izumi Hirasawa, Hideyuki Ishikawa, Toshihiro Tanaka

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   39 ( 10 ) 1119 - 1127  2006.10  [Refereed]

     View Summary

    A process for recovering phosphorus from wastewater in form of magnesium ammonium phosphate (MAP) crystals using a fluidized bed reactor was investigated. The phosphorus recovery ratio was found to be influenced by the particle size of the MAP crystals, as well as the reaction pH, inlet ammonium and phosphorus concentration. The optimum operation conditions for the fluidized bed reactor to achieve the maximum recovery rate of phosphorus were organized in terms of the supersaturation ratio and reaction pH. The best supersaturation ratio was found to be 3.7. The optimum reaction pH depended on the inlet phosphorus concentration and was found to be 7.9 when the inlet PO4-P was 230 mg.L-1. A continuous treatment of filtrate from digested sludge was performed based on these optimum operation conditions and using a newly proposed fluidized bed system. The fluidized bed system has a seeder, which allowed control of the particle size distribution inside the crystallization tower. A recovery ratio higher than 90% was achieved for a long period of the demonstration test in this new fluidized bed system.

    DOI

    Scopus

    12
    Citation
    (Scopus)
  • Investigation of primary nucleation phenomena of acetylsalicylic acid crystals induced by ultrasonic irradiation - ultrasonic energy needed to activate primary nucleation

    Etsuko Miyasaka, Satomi Ebihara, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   295 ( 1 ) 97 - 101  2006.09  [Refereed]

     View Summary

    The purpose of our study is to clarify ultrasonic primary nucleation phenomena for controlling final product size by adjusting the number of primary nuclei. In our previous study, the effect of ultrasonic irradiation on the number of nuclei was investigated under the same supersaturated condition, as a result two novel phenomena were observed. First, there is a region where ultrasonic irradiation inhibits primary nucleation. Second, a specific amount of energy is needed to activate primary nucleation. From this result, it was expected that the ultrasonic energy needed to activate primary nucleation has a certain relationship to the energy necessary to form a stable nucleus. Therefore, we investigated the following: whether ultrasonic irradiation inhibits and activates primary nucleation at various degrees of supersaturation, whether final crystal size relates to the number of nuclei, and whether the ultrasonic energy needed to activate primary nucleation relates to the energy necessary to form a stable nucleus. First, we found that ultrasonic irradiation inhibits and activates primary nucleation at various supersaturated degrees. Second, we found that final crystal size increases or decreases depending on the number of nuclei. Therefore, it was indicated that ultrasonic energy could yield the desired crystal size by inducing suitable nucleation. Third, we found that the ultrasonic energy needed to activate primary nucleation decreases with a decrease in the energy necessary to form a stable nucleus. From this, we can propose criteria for determining the effect of ultrasonic irradiation on primary nucleation by showing diagrams correlating Delta G(crit) with E-crit. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    51
    Citation
    (Scopus)
  • Effect of ultrasonic irradiation on the nucleation phenomena in Na2HPO4・12H2O melt used as a heat storage material

    Etsuko Miyasaka, Izumi Hirasawa

    Ultrasonics. Sonochemistry   13 ( 4 ) 308 - 312  2006.04  [International journal]

     View Summary

    The effect of ultrasound on nucleation phenomena in the heat storage material Na2HPO4.12H2O was investigated by determining the primary nucleation probability and induction time, and by looking at heat generation phenomena in the initial stage of nucleation. The experimental results show that the primary nucleation probability dramatically increased, and the induction time decreased under the ultrasound irradiation, and in addition, the rate of temperature rise was dependent upon the ultrasonic output. Based on these results and the theoretical relationship between the number of primary nuclei and the heat generation rate, it is proposed that the number of primary nuclei depends upon the ultrasonic output.

    PubMed

  • Strategy to Obtain nm Crystals through Precipitation of Polyelectrolyte

    Izumi Hirasawa, Takashi Mikami

    Chem. Eng. Technol.   29 ( 2 ) 1 - 4  2006.02

  • Strategy to obtain nm size crystals through precipitation in the presence of polyelectrolyte

    Hirasawa, I, T Mikami, A Katayama, T Sakuma

    CHEMICAL ENGINEERING & TECHNOLOGY   29 ( 2 ) 212 - 214  2006.02  [Refereed]

     View Summary

    Crystals of lead sulfate were precipitated in solutions of various polyelectrolyte polymers (acidic, neutral, and basic polymers) using a double-jet crystallizer. Polyetyleneimine (PEI) basic polymer controlled both the nucleation rate and crystal growth rate, and enabled the production of fine monodispersed crystals. The on-line measurement of the variation in the lead concentration indicated that PEI lost its effect when a certain amount of the reactants N-tot was supplied. Interaction between lead ions and PEI was detected by NMR analysis, which suggested that lead ions made some kind of complex with PEI. The values of N-tot correlated well with the weight of PEI in the solution, regardless of the feed flow rate and reactant concentration, as shown in the correlative equation N-tot = k W-0.49. It was suggested that PEI could no longer control the precipitation rate when the amount of reactants supplied exceeded N-tot. Thereafter, rapid nucleation occurred. Precipitation with PEI could be controlled by a certain amount of PEI in a ground solution in order to produce monodispersed fine crystals. These results give an effective idea of how to create various nm size crystals.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • 超音波による核化現象の解明 核化促進に要する照射エネルギーと核形成エネルギーの関係

    宮坂 悦子, 海老原 聡美, 平沢 泉

    化学工学会 研究発表講演要旨集   2006   97 - 97  2006

    DOI CiNii

  • 高分子電解質反応場を利用した硫酸ストロンチウムの単分散微粒子生成

    三上 貴司, 丸山 裕一, 池田 将太, 平沢 泉

    化学工学会 研究発表講演要旨集   2006   83 - 83  2006

    DOI CiNii

  • Effect of ultrasonic irradiation on the number of acetylsalicylic acid crystals produced under the supersaturated condition and the ability of controlling the final crystal size via primary nucleation

    Etsuko Miyasaka, Izumi Hirasawa

    Journal of Crystal. Growth   289   324 - 330  2006.01

  • Investigation of the Range of Fluoride Ion Concentration Applicable to Calcium Fluoride Crystallization

    KANEKO Shiro, HIRASAWA Izumi

    Chemical engineering   31 ( 6 ) 399 - 403  2005.11

     View Summary

    Fluoride ion removal by calcium fluoride crystallization was studied. This study aimed to find the range of fluoride ion concentration which would be applicable to calcium fluoride crystallization. First, batch experiments without a seed crystal were conducted to obtain the relationship between initial fluoride ion concentration and calcium ion concentration where fluoride ion concentration would begin to decrease in the process of calcium fluoride precipitation.<br>Batch experiments using a seed crystal were then conducted under the same conditions as those without a seed crystal to obtain the relationship between initial fluoride ion concentration and calcium ion concentration where fluoride ion concentration would begin to decrease due to crystallization of calcium fluoride on the seed crystal.<br>Supersolubility curves of calcium fluoride were obtained from both sets of experiments. From these, the metastable region of calcium fluoride between the solubility curve and the supersolubility curve was obtained. The range of fluoride ion concentration applicable to calcium fluoride crystallization was found to be less than 3 mmol/l.<br>XRD of the grown calcium fluoride crystals was investigated. The main peaks of the calcium fluoride used in the experiments were found to agree with the literature values.

    DOI CiNii

    Scopus

  • Morphological Control of calcium carbonate in reverse micelle system with anionic surfactant

    Izumi Hirasawa

    Journal of Colloid and Interface 288, 496-502   288 ( 2 ) 496 - 502  2005.08  [International journal]

     View Summary

    The influence of a surfactant over water on the polymorphism and crystal size of calcium carbonate produced by reaction crystallization in microemulsion systems was investigated in a mixing tank reactor. The crystallization was induced by the reaction between two aqueous micelle solutions (Na2CO3-CaCl2) stabilized by anionic surfactants, SDS (sodium dodecyl sulfate) or AOT (sodium bis(2-ethylhexyl) sulfosuccinate). With increasing surfactant ratio to water, the water-in-oil microemulsion was stably developed and the morphology of the calcium carbonate crystallized in the micelles sharply transformed from calcite to vaterite. The influence of SDS on the polymorphism and crystal size of calcium carbonate was much clearer than that of AOT. In addition, with AOT, certain step changes in the morphology and crystal size occurred around a surfactant ratio to water (R=[H2O]/[surfactant]) of 15 due to a two-phase separation of the microemulsion.

    PubMed

  • 高分子凝集抑制剤を用いた反応晶析法による硫酸ストロンチウム結晶の単分散微粒子生成プロセスに関する研究

    佐久間 崇浩, 三上 貴司, 平沢 泉

    化学工学会 研究発表講演要旨集   2005   98 - 98  2005

    DOI CiNii

  • 超音波による核化現象の研究 超音波発振器振動面から晶析槽底面までの距離が及ぼす影響

    宮坂 悦子, 柿本 佳秀, 平沢 泉

    化学工学会 研究発表講演要旨集   2003   798 - 798  2003

    DOI CiNii

  • Effect of supersaturation on crystal size and number of crystals produced in antisolvent crystallization

    Shogo Kaneko, Yasuhiro Yamagami, Heisuke Tochihara, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   35 ( 11 ) 1219 - 1223  2002.11

     View Summary

    The antisolvent crystallization of sodium chloride was carried out in batches to observe crystallization phenomena using ethanol as an antisolvent. To decrease high local supersaturation generated by the addition of antisolvent, the authors have proposed a new idea by choosing high ethanol concentration operational conditions. Obtained crystals seemed to be unagglomerated and monodispersed in the optimum range of ethanol concentration. From the observation of nucleation phenomena, it was considered that nucleation induced by the antisolvent addition occurred due to the local supersaturation generated at the boundary of the starting and feed solutions. On the other hand, crystal growth is considered to proceed by the supersaturation generated by sufficient mixing between the starting and feed solutions. Average crystal size increased with the increase of σR. The number of produced crystals increased with the increase of the starting solution concentration C. The induction period for nucleation tended to decrease with increase of C and σR. Since the number of produced crystals depended on C, nucleation was considered to be influenced by local mixing between the starting and feed solutions.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Changes in crystalline properties of nanosized hydroxyapatite powders prepared by low-temperature reactive crystallization

    Woon-Soo Kim, Woo-Sik Kim, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   35 ( 11 ) 1203 - 1210  2002.11

     View Summary

    In the reactive crystallization of hydroxyapatite (HAP) done with CaCl2, KH2PO4 and NaOH solutions at the reaction temperature of 60°C in a semi-batch reactor, the relationship of the crystalline properties of nanosized HAP powders with the operational conditions was experimentally investigated. The crystallinity of needle-like HAP powders was enhanced with decreasing OH- ion composition and reactants concentration, which corresponded well with the increase in the crystal size, but had nothing to do with the aging of the product suspension. Even though the supersaturation level was predicted not to be influenced by the OH- ion composition, the crystal growth of the HAP powders was striking at low OH- ion composition, thereby resulting in larger HAP with high crystallinity. Comparing the growth orientation of the HAP powders before and after sintering, the crystal growth was preferentially promoted on the face of (002) in the direction of the crystallographic c-axis, especially at low OH- ion composition and reactants concentration during the crystallization, and it was transferred on the (300) face along the a-axis after sintering at 1000°C for 3 h, which seem to be caused by the unbalanced grain coalescing according to the crystallographic axes of HAP.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Effect of supersaturation on crystal size and number of crystals produced in antisolvent crystallization

    S Kaneko, Y Yamagami, H Tochihara, Hirasawa, I

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   35 ( 11 ) 1219 - 1223  2002.11  [Refereed]

     View Summary

    The antisolvent crystallization of sodium chloride was carried out in batches to observe crystallization phenomena using ethanol as an antisolvent. To decrease high local supersaturation generated by the addition of antisolvent, the authors have proposed a new idea by choosing high ethanol concentration operational conditions. Obtained crystals seemed to be unagglomerated and monodispersed in the optimum range of ethanol concentration. From the observation of nucleation phenomena, it was considered that nucleation induced by the antisolvent addition occurred due to the local supersaturation generated at the boundary of the starting and feed solutions. On the other hand, crystal growth is considered to proceed by the supersaturation generated by sufficient mixing between the starting and feed solutions. Average crystal size increased with the increase of a. The number of produced crystals increased with the increase of the starting solution concentration C. The induction period for nucleation tended to decrease with increase of C and a. Since the number of produced crystals depended on C, nucleation was considered to be influenced by local mixing between the starting and feed solutions.

  • Effect of supersaturation on crystal size and number of crystals produced in antisolvent crystallization

    S Kaneko, Y Yamagami, H Tochihara, Hirasawa, I

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   35 ( 11 ) 1219 - 1223  2002.11  [Refereed]

     View Summary

    The antisolvent crystallization of sodium chloride was carried out in batches to observe crystallization phenomena using ethanol as an antisolvent. To decrease high local supersaturation generated by the addition of antisolvent, the authors have proposed a new idea by choosing high ethanol concentration operational conditions. Obtained crystals seemed to be unagglomerated and monodispersed in the optimum range of ethanol concentration. From the observation of nucleation phenomena, it was considered that nucleation induced by the antisolvent addition occurred due to the local supersaturation generated at the boundary of the starting and feed solutions. On the other hand, crystal growth is considered to proceed by the supersaturation generated by sufficient mixing between the starting and feed solutions. Average crystal size increased with the increase of a. The number of produced crystals increased with the increase of the starting solution concentration C. The induction period for nucleation tended to decrease with increase of C and a. Since the number of produced crystals depended on C, nucleation was considered to be influenced by local mixing between the starting and feed solutions.

  • Changes in crystalline properties of nanosized hydroxyapatite powders prepared by low-temperature reactive crystallization

    WS Kim, WS Kim, Hirasawa, I

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   35 ( 11 ) 1203 - 1210  2002.11  [Refereed]

     View Summary

    In the reactive crystallization of hydroxyapatite (HAP) done with CaCl(2), KH(2)PO(4) and NaOH solutions at the reaction temperature of 60degreesC in a semi-batch reactor, the relationship of the crystalline properties of nanosized HAP powders with the operational conditions was experimentally investigated. The crystallinity of needle-like HAP powders was enhanced with decreasing OH(-) ion composition and reactants concentration, which corresponded well with the increase in the crystal size, but had nothing to do with the aging of the product suspension. Even though the supersaturation level was predicted not to be influenced by the OH- ion composition, the crystal growth of the HAP powders was striking at low OH- ion composition, thereby resulting in larger HAP with high crystallinity. Comparing the growth orientation of the HAP powders before and after sintering, the crystal growth was preferentially promoted on the face of (002) in the direction of the crystallographic c-axis, especially at low OH- ion composition and reactants concentration during the crystallization, and it was transferred on the (300) face along the a-axis after sintering at 1000degreesC for 3 h, which seem to be caused by the unbalanced grain coalescing according to the crystallographic axes of HAP.

  • A study on the degradation of endocrine disruptors and dioxins by ozonation and Advanced Oxidation Processes

    S Nakagawa, Y Kenmochi, K Tutumi, T Tanaka, Hirasawa, I

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   35 ( 9 ) 840 - 847  2002.09  [Refereed]

     View Summary

    The effect of O-3 treatment and AOP (Advanced Oxidation Processes) treatment on the decomposition of endocrine disruptors were investigated by using continuous type pilot plant. Reaction kinetic evaluations of these processes were also carried out. In this study, the endocrine disruptors were classified into 2 groups: (1) DXNs: dioxins and (2) EDs: endocrine disruptors other than dioxins. For the case of DXNs decomposition, highly concentrated DXNs in a incinerator washwater were degraded by UV/O-3 combined treatment. Influence of O-3 dosage and forms of DXNs on the reaction rate constant were evaluated. The incinerator washwater was sampled from a scrubber, which was used for the flue gas treatment of a garbage incinerator facility.
    For the case of EDs decomposition, the effect Of O-3 dosage on the reaction rate constant were investigated during O-3 treatment of secondary treated sewage. Also, a comparison was made on the degradability for the above 2 groups. The following results were obtained. (1) The DXNs contained in the incinerator washwater had different decomposition properties depending on the particle size of suspended solid. Above a particle size of 1.0 mum, the reaction rate constant was relatively small and the DXNs were relatively non-degradable. On the other hand, when suspended solid particle size was below 1.0 mum, the reaction rate constant was large and the DXNs were relatively degradable. (2) The amount of decomposed DXNs per consumed O-3 increased with the increase of DXNs concentrations in the influent and higher DXNs decomposition efficiencies were obtained. (3) The reaction rate constant in the EDs decomposition was larger than that in the DXNs decomposition, and the EDs were found to be relatively easy to be decomposed. Once DXNs on the suspended solid particle size larger than 1.0 mum in the incinerator washwater were non-degradable, we found that they should be filtered and concentrated separately prior to the AOP treatment to ensure an efficient treatment.

  • Crystallization phenomena of magnesium ammonium phosphate (MAP) in a fluidized-bed-type crystallizer

    Hirasawa, I, S Kaneko, Y Kanai, S Hosoya, K Okuyama, T Kamahara

    JOURNAL OF CRYSTAL GROWTH   237   2183 - 2187  2002.04  [Refereed]

     View Summary

    In this study, experiments using a fluidized crystallizer with added seed, were performed, to observe the crystal growth and nucleation phenomena of MAP, by changing the degree of supersaturation. The average growth rate of suspended seed crystals correlated relatively well with the degree of supersaturation to obtain the quantitative correlation equation. Also the average crystal growth rate was in good accordance with the crystal growth rate of the small crystals which comprised the seed crystal. This showed that crystal growth was preceeded by the growth of individual crystal is acting as one single seed crystal. But over a certain degree of supersaturation, the surface condition of grown seed crystals was observed to become rough. Concentration of fines was recognized to correlate with the degree of supersaturation, and excess fines were produced over the critical supersaturation, which was the same as when the surface condition of crystals became rough. The critical supersaturation was considered to offer some design criteria for stable operation in the magnesium ammonium phosphate crystallization in the environmental field. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Crystallization phenomena of magnesium ammonium phosphate (MAP) in a fluidized-bed-type crystallizer

    Hirasawa, I, S Kaneko, Y Kanai, S Hosoya, K Okuyama, T Kamahara

    JOURNAL OF CRYSTAL GROWTH   237   2183 - 2187  2002.04  [Refereed]

     View Summary

    In this study, experiments using a fluidized crystallizer with added seed, were performed, to observe the crystal growth and nucleation phenomena of MAP, by changing the degree of supersaturation. The average growth rate of suspended seed crystals correlated relatively well with the degree of supersaturation to obtain the quantitative correlation equation. Also the average crystal growth rate was in good accordance with the crystal growth rate of the small crystals which comprised the seed crystal. This showed that crystal growth was preceeded by the growth of individual crystal is acting as one single seed crystal. But over a certain degree of supersaturation, the surface condition of grown seed crystals was observed to become rough. Concentration of fines was recognized to correlate with the degree of supersaturation, and excess fines were produced over the critical supersaturation, which was the same as when the surface condition of crystals became rough. The critical supersaturation was considered to offer some design criteria for stable operation in the magnesium ammonium phosphate crystallization in the environmental field. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Application of Reduction Crystallization to the Treatment of Electroless Nickel Plating Wastewater : The Effect of Specific Surface Area of Seed Crystals on the Reaction Behavior

    HORIKAWA Ken, HIRASAWA Izumi

    Jitsumu Hyomen Gijutsu   53 ( 3 ) 203 - 207  2002.03

     View Summary

    In this study, Ni2+ removal from electroless nickel plating wastewater (A. co., Ltd.) by reduction crystallization was investigated, to make clear the effect of seeds specific surface area on the Ni2+ removal characteristics. Although the main reaction in this research is the same as the one in electroless nickel plating, the authors have proposed reduction crystallization in which wastewater from electroless nickel plating contacts with suspended nickel powder, to remove and recover Ni2+. The results could be obtained on the relationship between the pH change profile and recovery efficiency in the reaction process, in which nickel powders having various specific surface area were used as seeds. Experimental results were discussed, considering surface conditions of grown nickel and the behavior of produced fines. With a constant 10% NaOH solution feed rate, the pH profile changed in the process of Ni2+ reduction, by changing the specific surface area of seeds, which means that Ni2+ removal efficiency was affected by the specific surface area of seeds. When constant pH7 was maintained, higher removal efficiency (0.99; Ni2+ concentration in the treated water 2.5×10-2g·dm-3) could be obtained, although the specific surface area of Ni seed powder varied. Specific surface of seeds, based on the roughness of seed crystal, was suggested to be an effective factor on the Ni metal coating behavior on the seed surface and also the phenomena of fines production in the process of Ni deposition.

    DOI CiNii

  • Modification of crystal growth mechanism of yttrium oxalate in metastable solution

    MH Sung, JS Kim, WS Kim, Hirasawa, I, WS Kim

    JOURNAL OF CRYSTAL GROWTH   235 ( 1-4 ) 529 - 540  2002.02

     View Summary

    In the seeded crystallization of yttrium oxalate from a metastable supersaturated solution, the growth mechanism was observed to become modified by variations in agitation and additive concentration. From the desupersaturation curve, the crystal growth rate was estimated and described using a power law of supersaturation (R-T = k(gDelta)C(p))Without an additive in the metastable solution, the overall growth rate coefficient, K-g, increased with an increase in the agitation speed while the growth rate order, p, was almost independent of the agitation speed. When the additive sodium tripolyphosphate was used to inhibit crystal growth, the desupersaturation in the solution was substantially retarded and the growth rate order varied up to about 2.5 with an increase in the additive concentration. Using a two-step growth model, the kinetic parameter dependencies of the crystal growth of yttrium oxalate, such as the mass transfer coefficient, surface integration order, and surface integration coefficient, were estimated in relation to the agitation speed and additive concentration. The mass transfer coefficient increased with an increase in the agitation, whereas the surface integration coefficient was independent of the agitation speed. However, as the additive concentration in the solution increased, the surface integration coefficient was reduced while the mass transfer coefficient remained almost invariant. The change in the rate-determining step by the additive was examined using an effectiveness factor. It was shown that the effect of the additive on the surface integration followed a Langmuir type isotherm. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Modification of crystal growth mechanism of yttrium oxalate in metastable solution

    MH Sung, JS Kim, WS Kim, Hirasawa, I, WS Kim

    JOURNAL OF CRYSTAL GROWTH   235 ( 1-4 ) 529 - 540  2002.02

     View Summary

    In the seeded crystallization of yttrium oxalate from a metastable supersaturated solution, the growth mechanism was observed to become modified by variations in agitation and additive concentration. From the desupersaturation curve, the crystal growth rate was estimated and described using a power law of supersaturation (R-T = k(gDelta)C(p))Without an additive in the metastable solution, the overall growth rate coefficient, K-g, increased with an increase in the agitation speed while the growth rate order, p, was almost independent of the agitation speed. When the additive sodium tripolyphosphate was used to inhibit crystal growth, the desupersaturation in the solution was substantially retarded and the growth rate order varied up to about 2.5 with an increase in the additive concentration. Using a two-step growth model, the kinetic parameter dependencies of the crystal growth of yttrium oxalate, such as the mass transfer coefficient, surface integration order, and surface integration coefficient, were estimated in relation to the agitation speed and additive concentration. The mass transfer coefficient increased with an increase in the agitation, whereas the surface integration coefficient was independent of the agitation speed. However, as the additive concentration in the solution increased, the surface integration coefficient was reduced while the mass transfer coefficient remained almost invariant. The change in the rate-determining step by the additive was examined using an effectiveness factor. It was shown that the effect of the additive on the surface integration followed a Langmuir type isotherm. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Modification of crystal growth mechanism of yttrium oxalate in metastable solution

    MH Sung, JS Kim, WS Kim, Hirasawa, I, WS Kim

    JOURNAL OF CRYSTAL GROWTH   235 ( 1-4 ) 529 - 540  2002.02  [Refereed]

     View Summary

    In the seeded crystallization of yttrium oxalate from a metastable supersaturated solution, the growth mechanism was observed to become modified by variations in agitation and additive concentration. From the desupersaturation curve, the crystal growth rate was estimated and described using a power law of supersaturation (R-T = k(gDelta)C(p))Without an additive in the metastable solution, the overall growth rate coefficient, K-g, increased with an increase in the agitation speed while the growth rate order, p, was almost independent of the agitation speed. When the additive sodium tripolyphosphate was used to inhibit crystal growth, the desupersaturation in the solution was substantially retarded and the growth rate order varied up to about 2.5 with an increase in the additive concentration. Using a two-step growth model, the kinetic parameter dependencies of the crystal growth of yttrium oxalate, such as the mass transfer coefficient, surface integration order, and surface integration coefficient, were estimated in relation to the agitation speed and additive concentration. The mass transfer coefficient increased with an increase in the agitation, whereas the surface integration coefficient was independent of the agitation speed. However, as the additive concentration in the solution increased, the surface integration coefficient was reduced while the mass transfer coefficient remained almost invariant. The change in the rate-determining step by the additive was examined using an effectiveness factor. It was shown that the effect of the additive on the surface integration followed a Langmuir type isotherm. (C) 2002 Elsevier Science B.V. All rights reserved.

  • A study on the degradation of endocrine disruptors and dioxins by ozonation and advanced oxidation processes

    Sota Nakagawa, Yukio Kenmochi, Kaori Tutumi, Toshihiro Tanaka, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   35 ( 9 ) 840 - 847  2002

     View Summary

    The effect of O3 treatment and AOP (Advanced Oxidation Processes) treatment on the decomposition of endocrine disrupters were investigated by using continuous type pilot plant. Reaction kinetic evaluations of these processes were also carried out. In this study, the endocrine disrupters were classified into 2 groups: (1) DXNs: dioxins and (2) EDs: endocrine disrupters other than dioxins. For the case of DXNs decomposition, highly concentrated DXNs in a incinerator washwater were degraded by UV/O3 combined treatment. Influence of O3 dosage and forms of DXNs on the reaction rate constant were evaluated. The incinerator washwater was sampled from a scrubber, which was used for the flue gas treatment of a garbage incinerator facility. For the case of EDs decomposition, the effect of O3 dosage on the reaction rate constant were investigated during O3 treatment of secondary treated sewage. Also, a comparison was made on the degradability for the above 2 groups. The following results were obtained. (1) The DXNs contained in the incinerator washwater had different decomposition properties depending on the particle size of suspended solid. Above a particle size of 1.0 μm, the reaction rate constant was relatively small and the DXNs were relatively non-degradable. On the other hand, when suspended solid particle size was below 1.0 μm, the reaction rate constant was large and the DXNs were relatively degradable. (2) The amount of decomposed DXNs per consumed O3 increased with the increase of DXNs concentrations in the influent and higher DXNs decomposition efficiencies were obtained. (3) The reaction rate constant in the EDs decomposition was larger than that in the DXNs decomposition, and the EDs were found to be relatively easy to be decomposed. Once DXNs on the suspended solid particle size larger than 1.0 μm in the incinerator washwater were non-degradable, we found that they should be filtered and concentrated separately prior to the AOP treatment to ensure an efficient treatment. Copyright ©2002 The Society of Chemical Engineers.

    DOI

    Scopus

    14
    Citation
    (Scopus)
  • A study on the degradation of endocrine disruptors and dioxins by ozonation and advanced oxidation processes

    Sota Nakagawa, Yukio Kenmochi, Kaori Tutumi, Toshihiro Tanaka, Izumi Hirasawa

    Journal of Chemical Engineering of Japan   35 ( 9 ) 840 - 847  2002

     View Summary

    The effect of O3 treatment and AOP (Advanced Oxidation Processes) treatment on the decomposition of endocrine disrupters were investigated by using continuous type pilot plant. Reaction kinetic evaluations of these processes were also carried out. In this study, the endocrine disrupters were classified into 2 groups: (1) DXNs: dioxins and (2) EDs: endocrine disrupters other than dioxins. For the case of DXNs decomposition, highly concentrated DXNs in a incinerator washwater were degraded by UV/O3 combined treatment. Influence of O3 dosage and forms of DXNs on the reaction rate constant were evaluated. The incinerator washwater was sampled from a scrubber, which was used for the flue gas treatment of a garbage incinerator facility. For the case of EDs decomposition, the effect of O3 dosage on the reaction rate constant were investigated during O3 treatment of secondary treated sewage. Also, a comparison was made on the degradability for the above 2 groups. The following results were obtained. (1) The DXNs contained in the incinerator washwater had different decomposition properties depending on the particle size of suspended solid. Above a particle size of 1.0 μm, the reaction rate constant was relatively small and the DXNs were relatively non-degradable. On the other hand, when suspended solid particle size was below 1.0 μm, the reaction rate constant was large and the DXNs were relatively degradable. (2) The amount of decomposed DXNs per consumed O3 increased with the increase of DXNs concentrations in the influent and higher DXNs decomposition efficiencies were obtained. (3) The reaction rate constant in the EDs decomposition was larger than that in the DXNs decomposition, and the EDs were found to be relatively easy to be decomposed. Once DXNs on the suspended solid particle size larger than 1.0 μm in the incinerator washwater were non-degradable, we found that they should be filtered and concentrated separately prior to the AOP treatment to ensure an efficient treatment. Copyright ©2002 The Society of Chemical Engineers.

    DOI

    Scopus

    14
    Citation
    (Scopus)
  • Prediction of Lysozyme Separation by Polyelectrolyte Precipitation in Mechanically Agitated MSMPR Reactor

    KIM Woon-Soo, KIM Hyun-Seok, HIRASAWA Izumi, KIM Woo-Sik

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   34 ( 10 ) 1259 - 1266  2001.10

     View Summary

    In lysozyme precipitation by polyacrylic acid (PAA) with different molecular weights, the lysozyme separation was predicted using Smoluchowski's collision theory and the micromixing limitation model, plus the model predictions were compared with the experimental data from an MSMPR reactor. Since, in Smoluchowski's theory, ideal mixing was assumed in the solution, the lysozyme separation was only predicted to depend on the PAA properties, such as the PAA dosage and its molecular weights. However, in the micromixing limitation model, the lysozyme separation was represented as being affected by the operational conditions, including the mean residence time and the mixing intensity, in addition to the PAA properties. The difference between the lysozyme separations predicted by each model significantly increased at short residence time and low agitation speed. When compared with the experimental data obtained with various PAA properties and operational conditions, the degree of the lysozyme separation predicted by the micromixing limitation model was found to be in better consistency with the experimental data than that done by Smoluchowski's theory because the operational conditions as well as the PAA properties were included in describing the lysozyme-PAA combination in the reactor.

    DOI CiNii

    Scopus

    1
    Citation
    (Scopus)
  • Combination Mechanism of Lysozyme with Polyacrylic Acid at Equilibrium in Polyelectrolyte Precipitation

    KIM WOON-Soo, KIM HYUN-Seok, HIRASAWA Izumi, KIM Woo-Sik

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   34 ( 10 ) 1244 - 1250  2001.10

     View Summary

    In polyelectrolyte precipitation of lysozyme, the combination mechanism between lysozyme and polyacrylic acid (PAA) at various experimental conditions was investigated from the stoichiometric coefficient at equilibrium in a batch reactor. At the underdosed condition of PAA to lysozyme, the lysozyme-PAA combination was performed by the electric charge neutralization and polymer bridging between lysozyme and PAA. As the PAA dosage decreased and its molecular weight increased, the bridging effect of PAA became more significant in the lysozyme-PAA combination because the more lysozyme was captured by the polymer bridging of PAA. The stoichiometric coefficient of the lysozyme-PAA combination, which was estimated from the lysozyme separation, was affected by both the PAA dosage and its molecular weight, but the effect of agitation was not observed. The linear equations were derived from the relationship between the stoichiometric coefficient and the dosage at three different PAA molecular weights of 2.0 × 103, 4.5 × 105 and 4.0 × 106, and well consistent with the experimental data.

    DOI CiNii

    Scopus

    3
    Citation
    (Scopus)
  • A present Study of Wastewater treatment of Electroless Nickel Plating

    Izumi Hirasawa

    Surface Technology   52/1,62-63 ( 1 ) 62 - 63  2001.01

    Authorship:Last author

    DOI CiNii

  • 特集II.第8回国際塩シンポジウム(Salt 2000) : 研究発表会の概要 : 晶析

    平沢 泉, 長谷川 正巳

    日本海水学会誌   54 ( 6 ) 442 - 444  2000.12

    DOI CiNii

  • Removal and Recovery of Nickel Ion from Wastewater of Electroless Plating by Reduction Crystallization

    Ken Horikawa, Izumi Hirasawa

    Korean Journal of Chemical Engineering   17 ( 6 ) 629 - 632  2000

     View Summary

    Wastewater treatment after electroless nickel plating runs has been known to be difficult and this has been a subject of worldwide concern. Discarding wastewater of electroless nickel plating into sea was prohibited under the London Dumping Treaty since 1996. We have studied on recovering nickel from wastewater by reduction crystallization. In this study, the characteristics of nickel ion removal and recovery were investigated in the process of reduction crystallization using a laboratory scale batch crystallizer (500 ml), in order to propose a new process for wastewater treatment from nickel plating. In the reduction crystallization, which can use hypophosphite ion as a reducing agent for nickel ion in the wastewater, nickel ion could be recovered as a form of nickel metal by seeding nickel powder having large specific surface area.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Removal and Recovery of Nickel Ion from Wastewater of Electroless Plating by Reduction Crystallization

    Ken Horikawa, Izumi Hirasawa

    Korean Journal of Chemical Engineering   17 ( 6 ) 629 - 632  2000

     View Summary

    Wastewater treatment after electroless nickel plating runs has been known to be difficult and this has been a subject of worldwide concern. Discarding wastewater of electroless nickel plating into sea was prohibited under the London Dumping Treaty since 1996. We have studied on recovering nickel from wastewater by reduction crystallization. In this study, the characteristics of nickel ion removal and recovery were investigated in the process of reduction crystallization using a laboratory scale batch crystallizer (500 ml), in order to propose a new process for wastewater treatment from nickel plating. In the reduction crystallization, which can use hypophosphite ion as a reducing agent for nickel ion in the wastewater, nickel ion could be recovered as a form of nickel metal by seeding nickel powder having large specific surface area.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Secondary nucleation rate by growing crystals and oscillation phenomena in sodium borate decahydrate crystal suspension

    Hirasawa, I

    KAGAKU KOGAKU RONBUNSHU   25 ( 4 ) 549 - 553  1999.07  [Refereed]

     View Summary

    Crystal growth experiments were performed in a suspension system of sodium borate decahydrate crystals, to observe the surface status of crystals in the process of their growth, and to obtain the correlative equation of the factors ( degree of supercooling, linear velocity in the crystallizer and revolution rate of the agitator) affecting secondary nucleation rate. It is also made clear that the average secondary nucleation rate based on the operation time is affected by the surface status of the growing crystals, and its rate osccillates against the operation time. This oscillation phenomena are discussed, based on the qualitative model of two series processes consisted of a diffuison stage and a surface reaction stage.

  • Trends of Crystallization Process

    HIRASAWA Izumi

    Bulletin of the Society of Sea Water Science, Japan   53 ( 3 ) 142 - 147  1999.06

    DOI CiNii

  • Circumstances of International Symposium on Industrial Crystallization

    HIRASAWA Izumi

    Bulletin of the Society of Sea Water Science, Japan   53 ( 3 ) 132 - 135  1999.06

    DOI CiNii

  • タンデム質量分析法による金属表面保護剤中の界面活性剤の同定

    Izumi Hirasawa

    分析化学   48/8,797-801 ( 28 ) 30 - 33  1999.03  [Refereed]

    Authorship:Last author

    CiNii

  • Structural analysis of metal-surface protect surfactants by tandem mass spectrometry

    Hisashi Kambe, Toshimichi Shibue, Izumi Hirasawa

    Bunseki Kagaku   48 ( 8 ) 797  1999

     View Summary

    The applicability of tandem mass spectrometry to the quality analysis of metal-surface protect surfactants without any pretreatment or purification of the sample solution was investigated. Three typical spectra were constructed and verified by FAB CID-MS/MS using sodium n-dodecylsulfate (anionic surfactant), tetradecyl dimethylbenzylammonium chloride (cationic surfactant) and heptaethylene glycol mono-n-dodecyl ether (nonionic surfactant) as a model. The FAB CID-MS/MS spectra of metal-surface protect surfactants provided useful structural information that analyte surfactants have a polyoxyethylene structure, which has been identified as a nonionic surfactant. The authors concluded that FAB CID-MS/MS will be a good analytical method for direct quality analysis without any pretreatment or purification of the metal-surface protect surfactant for industrial use.

    DOI

    Scopus

  • Nucleation and growth phenomena in producing monodispersed lead sulfate particles by reactive crystallization

    Izumi Hirasawa, Daisuke Katou, Ken Toyokura, Kenji Muraoka

    KAGAKU KOGAKU RONBUNSHU   21 ( 3 ) 495 - 501  1995  [Refereed]

     View Summary

    In this study, lead sulfate particles were produced in a batch crystallizer, by feeding lead nitrate and sodium sulfate solutions (concentration : 0.025-0.4 mol/l) continuously to the vicinity of an agitator rotating at 400 rpm from individual feed pipes. The batch crystallizer contained a solution of Pb 10-2 mol/l, gelatin 5 wt% and acetic acid 3.48 mol/l. In the crystallization process, crystals were sampled over time to measure crystal size distribution based on number, and to observe the shape and surface condition of crystals. From the results of experiments, it was shown that the position, where the nucleation phenomenon was detected in the equipment, changed for a feed concentration 0.4-0.5 mol/l. This phenomenon was considered with respect to the supersaturation ratio in the equipment. Moreover, in the range of experimental conditions, where relatively monodispersed fine particles were produced, it was observed that crystals of unstable state were fromed in the beginning of the reaction, but after that they were transformed to a stable rhombic shape. The stable crystals were considered to grow while consuming all the reactant components in the equipment. Also, an experimental equation was presented showing that formation rate of nuclei to become product crystal was proportional to the fifth power of the feed supersaturation ratio. © 1995, The Society of Chemical Engineers, Japan. All rights reserved.

    DOI

    Scopus

  • ペレット法による高硬度原水の軟化処理に関する基礎的研究

    平沢 泉

    廃棄物学会論文誌   3 ( 3 ) 61 - 65  1992.03

    Authorship:Last author

     View Summary

    Sanitary landfill leachate softening processes have been developed for scaling problems. Calcium carbonate crystallization characteristics were studied by using the apparatus of fluidizedbed type reactor, with the existence of seeds (blast furnace slag) . Caustic soda and sodium hydrogencarbonates were used for softening. The concentration of calcium in synthetic leachate was adjusted from 1.2 to 14.1 mol⋅ m-3. The crystallization proceeded rapidly. At the first sampling point (0.1 m), the concentration of calcium had already been reduced from its influent value to effluent value. The calcium removal rate reached was 48%-60%. The turbidity of effluent was under 30, and its pH value was 7.6 8.0. The contents of the fluidized-bed are thoroughly mixed. This reaction can be described by the following equation :<BR>Co-C=Ko⋅C⋅θ<BR>where Co: influent of Ca2+ [mol⋅m-3] C: effluent of Ca2+ [mol⋅ m-3] θ: retention time [h]<BR>Ko: reaction rate constant [h-1]

    DOI CiNii

  • Controlled double-jet precipitation of sparingly soluble salts. A method for the preparation of high added value materials

    Jiří Stávek, Milan Šípek, Izumi Hirasawa, Ken Toyokura

    Chemistry of Materials   4 ( 3 ) 545 - 555  1992

     View Summary

    In recent years considerable attention is given to the development of methods for the preparation of microcrystals with a narrow crystal size distribution (CSD). One promising technique, been developed for the preparation of silver halides crystals, is controlled double-jet precipitation (CDJP). In the CDJP the cation and anion solutions are added simultaneously through separate input lines to a stirred solution oi a lyophihc polymer. The formation and growth of monodisperse microcrystals in the bulk of crystallizer and the nucleation of unstable nuclei or primary particles formed near jets occur simultaneously during the whole run. The monodisperse particles are prepared if these unstable nuclei or primary particles continuously disappear from the system by controlled Ostwald ripening or controlled agglomeration, and the matter serves as a source for the growth of constant number of stable particles. The objective of this contribution is to survey this unique precipitation technique while the concept of CDJP can be used in general for the precipitation of various sparingly soluble salts.

    DOI

    Scopus

    57
    Citation
    (Scopus)
  • 水処理分野における晶析

    平沢 泉

    化学工学   55/4   202 - 203  1991.04

    Authorship:Lead author

  • Effect of Collisions between the impeller blade and the crystals on the secondary nucleation rate of the potash-Alum System

    Ken Toyokura, Izumi Hirasawa

    International chemical Engineering   vol.21 ( 2 ) 269 - 275  1981.02

  • 接触脱リン法による下水中のリン除去に関する研究Ⅱ

    平沢 泉

    下水道協会誌   18/204 ( 204 ) 12 - 21  1981

    CiNii

  • Effect of Collision by Agitation of Impeller on Secondary Nucleation Rate of K-Alum

    Ken Toyokura, Makoto Uchiyama, Masaki Kawai, Izumi Hirasawa

    Kagaku Kogaku Ronbunshu   5 ( 6 ) 596 - 600  1979

     View Summary

    Effect of collision by agitation of impeller on secondary nucleation rate of K-Alum was studied in the range of nucleation rate increasing with impeller rotational speed. Fluidized bed of seed crystal with a paddle-type impeller was used as the crystallizer, and the height of seed bed was adjusted to be the same as the width of the impeller to allow for seed crystals to be directly agitated by the impeller. The total number of secondary nuclei generated was observed by direct counting under a microscope. Secondary nucleation rates are correlated with supersaturation, and these powers of supersaturation are in the range 1.3-1.6, depending upon impeller rotational speed and impeller diameter. These values of 1.3-1.6 are smaller than the power of 3.3 obtained by fluidized seeds and by seeds of the minimum size to be able to produce secondary nuclei, and are almost identical with that for crystal growth rate. This result is discussed in terms of the damaged surface repairing model reported by Larson et al. New equation of secondary nucleation rate by impeller agitation is derived by improving the semi-theoterical model of secondary nucleation rate in a stirred tank reported by de Jong et al., and experimental data obtained in this study are correlated by that equation. © 1979, The Society of Chemical Engineers, Japan. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • 攪拌槽内における最小粒径種晶によるカリミョバンの二次核発生速度

    平沢 泉

    Journal of Chemial Engineering Japan   10/1

  • 微小核を含む過飽和溶液中における板状晶ホウ砂の成長速度

    平沢 泉

    Proc. of 4th World Congress of Chem. Engr.   10

  • 半回分晶析装置内のNaClの二次核発生速度及び成長速度

    平沢 泉

    第7回国際塩会議  

  • 難溶性ヒドロキシアパタイトの晶析に関する研究

    平沢 泉

    旭硝子財団助成研究成果報告   115-118

  • 接触脱リン法による下水中のリン除去に関する研究Ⅲ

    平沢 泉

    下水道協会誌   18/205

  • 接触脱リン法による下水中のリン除去に関する研究Ⅰ

    平沢 泉

      18/203

  • リン酸カルシウムの晶析現象を利用したリン除去プロセスの開発-炭酸物質の影響-

    平沢 泉

    11th Symposium on Ind. Crystallization  

  • ベンゼンーシクロヘキサン融液からのベンゼン結晶の純度

    平沢 泉

    Proc. of 4th World Congress of Chem. Engr.   10

  • ドロキシアパタイトの反応晶析における核化と成長現象

    平沢 泉

    晶析シンポジウム   93-97

  • コントロールダブルジェット法による硫酸鉛の生成

    平沢 泉

    Proc. of 4th World Congress of Chem. Engr.   10

  • コントロール・ダブルジェット法 高付加価値製品の製造法として

    平沢 泉

    Chemistry and Materials   4,545-555

  • カリ明バン系の2次核発生速度に対する攪拌翼の衝突の影響

    平沢 泉

    化工論文集   5/6

▼display all

Books and Other Publications

  • 晶析工学

    久保田, 徳昭, 平沢, 泉, 小針, 昌則

    東京電機大学出版局  2016.10 ISBN: 9784501630102

  • Advances in Organic Crystal Chemistry

    Izumi Hirasawa

    Springer  2015.09

  • 最近の化学工学 晶析 国際会議における晶析工学の展開

    平沢 泉

    化学工学会  2014.12

  • ゲルテクノロジーハンドブック 高分子電解質集合体を反応場とするナノ結晶の創製

    平沢 泉

    エヌ・ティー・エス  2014.10

  • 分離技術シリーズ 分離技術への超音波の応用展開 晶析分野への超音波技術の適用

    平沢 泉

    分離技術会  2014.10

  • 分離技術のシーズとライセンス技術の実用化 晶析工学を基盤にした希望結晶の創製のための自在核化

    平沢 泉

    分離技術会  2014.10

  • 分散・塗布・乾燥の基礎と応用 乾燥中の固体析出 高分子電解質共存下における微結晶生成

    平沢 泉, 分担執筆

    株式会社 テクノシステム  2014.03

  • 化学便覧 応用化学編 分離と精製 晶析

    平沢 泉

    丸善  2014.01

  • 化学工学便覧 その他の晶析操作と設計

    平沢 泉

    丸善  2012.09

  • リサイクル・廃棄物事典 晶析技術による排水中の有価物イオン回収、廃溶剤の回収・資源化に向けての提言

    平沢 泉

    産業調査会  2011.11

  • 工業排水・廃材からの資源回収技術

    分担執筆

    シーエムシー出版  2010.08 ISBN: 9784781302614

  • 分離技術ハンドブック 環境保全プロセス

    平沢 泉, 分担執筆

    分離技術会  2009.12

  • 分離プロセス工学の基礎

    分担執筆

    朝倉書店  2009.03

  • 実用製造プロセス物性集覧 ー環境分野ー

    平沢 泉

    分離技術会  2008.02

  • 新版工業晶析操作 微粒子の晶析化技術

    平沢 泉

    分離技術会  2007.01

  • 溶剤リサイクルハンドブック

    平沢 泉

    溶剤リサイクル工業会  2006.11

  • Fluidized-Bed Process for Phosphate Removal by Calcium Phosphate Crystallization

    A. C. S. Books Symposium Series 

  • Continuous crystallization operation and crystal size distribution

    Saikin no Kagaku Kougaku 

  • Handbook of Separation and Purification Technology

    Marcel Dekkar 

  • Phosphate Recovery by Reactive Crystallization of Magnesium Ammonium phosplate : Application to Wastewater

    ACS Symposium Series 667 Separation and Purification by Crystallization 

  • Crystallization Technology Handbook chater 7 Melt Crystallization

    A. Mersmawn Ed. Macel Dekkar 

  • リン酸カルシウムの晶析現象を利用した流動層脱リンプロセス

    平沢 泉

    A. C. S. Books 

  • 連続晶析操作と粒径分布

    平沢 泉

    最近の化学工学 

  • 分離精製技術ハンドブック(共著)

    平沢 泉

    丸善 

  • リン酸マグネシウムアンモニウムの反応晶析法によるリン酸イオンの回収:排水への適用

    ACSシンポジウムシリーズ667 晶析法による分離と高純度化 

  • 晶析技術ハンドブック 7章 融液晶析

  • 晶析工学ハンドブック13章第2版

    マッセルデッカー 

▼display all

Misc

  • 2-1-3 Crystallization of cold storage material by dynamic stimulation

    MACHIDA Hironobu, SUGAHARA Takeshi, HIRASAWA Izumi

    Proceedings of the Annual Conference of The Japan Institute of Energy   31   12 - 13  2022.07

     View Summary

    A large degree of supercooling is necessary to form the tetra-n-butylammonium bromide (TBAB) semiclathrate hydrate. Developing an effective method to suppress supercooling is essential to use semiclathrate hydrates as potential thermal storage media. We have already reported the relationship between the memory effect and the solution structures in the TBAB semiclathrate hydrate reformation, based on the scanning electron microscopic observation. In this presentation, we report a dynamic stimulation method as a means of supercooling suppression. We would like to discuss the relationship between the conditions of dynamic stimulation and crystallization.

    DOI

  • Numerical Comparison between Phase Change Temperatures of Latent Heat Storage Material Na2HPO4 Aqueous Solutions Measured by Thermal Cycling and Phase Diagram Values for the Na2HPO4–H2O System

    Watanabe Yasuyuki, Hirasawa Izumi

    KAGAKU KOGAKU RONBUNSHU   48 ( 2 ) 62 - 69  2022.03

     View Summary

    Disodium hydrogen phosphate dodecahydrate is a latent heat storage material that is expected to be applied to in-door air conditioning and floor heating, but the heptahydrate is stable at above the melting point of the dodecahydrate and can therefore crystallize and accumulate in the melt of the dodecahydrate during a long-term thermal cycle of heat storage and heat release, thereby reducing the latent heat of storage material. To avoid such phase segregation, an excess amount of water is generally added relative to the liquidus line of the heptahydrate on the phase diagram, but this has the drawback of reducing the latent heat. In addition, it is extremely difficult to predict the transient behavior of phase transition of the heptahydrate during heat storage and heat release by means of the phase diagram in the equilibrium system. In this study, to make clear the correspondence between the phase transition behavior of the material and the phase diagram, thermal cycle tests in the temperature range of 243‒353 K were performed on aqueous solutions of 24.7‒52.9 wt% disodium hydrogen phosphate, and phase change behaviors were observed from the obtained cooling and heating curves. Three crystal phases were identified, namely, a eutectic mixture of dodecahydrate and water, do-decahydrate, and heptahydrate, and their melting points were in agreement with the phase diagram. However, the po-sitions of the liquidus lines of dodecahydrate and heptahydrate were different from the phase diagram, indicating that they were on the higher concentration side.

    DOI J-GLOBAL

  • Te存在下におけるZMH種晶添加によるスケーリング抑制効果の検討

    諏江霞純, 平沢泉, 竹内正行, 宮崎康典

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • L-アルギニンを用いた電流印加による晶析挙動変化の検討

    岡田哲, 平沢泉, 小堀深

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • 尿路結石形成プロセスにおけるCaC2O4結晶形態へのクエン酸およびマグネシウムの影響

    奥田真仁, 平沢泉, 小堀深

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • TBAB hydrate蓄冷材における過冷却緩和手法の検討

    森口太智, 平沢泉, 町田博宣

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • 炭酸ガス固定を牽引する難溶性炭酸塩の反応晶析技術

    平沢泉

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • 潜熱蓄熱材Na2HPO4・12H2O用発核剤特性の共通性

    渡邉裕之, 平沢泉

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • グルタミン酸吸着によるヒドロキシアパタイトの成長制御

    山崎結華, 平沢泉, 小堀深

    化学工学会年会研究発表講演要旨集(CD-ROM)   87th  2022

    J-GLOBAL

  • 2-1-3 Crystallization of cold storage material by dynamic stimulation

    町田博宣, 菅原武, 平沢泉

    日本エネルギー学会大会講演要旨集(Web)   31  2022

    J-GLOBAL

  • 婦人科悪性腫瘍の傍大動脈リンパ節郭清術におけるEnhanced Recovery After Surgery management (ERAS)の有効性—Effectiveness of Enhanced Recovery After Surgery management for women undergoing paraaortic lymphadenectomy in gynecologic cancer

    泉 顕治, 町田 弘子, 矢坂 美和, 飯田 哲士, 池田 仁惠, 信田 政子, 吉田 浩, 平澤 猛, 三上 幹男

    日本婦人科腫瘍学会雑誌 = The journal of the Japan Society of Gynecologic Oncology   39 ( 2 ) 515 - 522  2021.04

    CiNii

  • 今月の主題 早期胃癌内視鏡治療・適応のUPDATE 主題症例 前庭部の亜全周性早期胃癌に対するESD後,狭窄と変形により通過障害を認めて外科手術を要した1例

    泉本 裕文, 由雄 敏之, 並河 健, 渡海 義隆, 吉水 祥一, 堀内 裕介, 石山 晃世志, 平澤 俊明, 土田 知宏, 藤崎 順子

    胃と腸   56 ( 1 ) 114 - 119  2021.01

    DOI

  • 晶析技術の持続可能な開発目標

    平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   52nd  2021

    J-GLOBAL

  • TBAB hydrate蓄冷材における過冷却緩和手法の開発

    森口太智, 平沢泉, 町田博宜

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   52nd  2021

    J-GLOBAL

  • マイクロタッピングによる核化促進機構の数値解析

    渡邉裕之, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   52nd  2021

    J-GLOBAL

  • 界面活性剤を用いた疎水性アミノ酸に対する新規晶析手法の検討

    中村優斗, 平沢泉, 小堀深

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   52nd  2021

    J-GLOBAL

  • Effects of Bezafibrate on Carbon Tetrachloride and T0901317-Induced Nonalcoholic Steatohepatitis Model

    Kawasaki Yukiko, Otsu Shoko, Noda Yuri, Imaizumi Takahito, Matsushita Hisami, Endo Katsumi, Hirasawa Yasushi

    Proceedings for Annual Meeting of The Japanese Pharmacological Society   94   3-P2-31  2021

     View Summary

    To date, we have established a non-alcoholic steatohepatitis (NASH) model by feeding rats and mice a choline-deficient amino acid diet or a high-fat diet. However, it has been pointed out that it takes a long time to prepare the model and that the extrapolation to humans is low. Therefore, we confirmed the reproducibility of the NASH model, which develops in a short period of time, by referring to the method of Ohkohchi et al., and whether bezafibrate is effective for this model.

    C57BL/6J mice were fed a high-fat diet (60 kcal% fat, HF) for 4 weeks. The NASH model was constructed by administering carbon tetrachloride twice a week from 2 weeks after the start of HF loading and T0901317 during the last 5 days of HF loading. Bezafibrate was administered orally for 4 weeks from the start of HF loading. On the last day of HF loading, blood was collected and the liver was removed, and an insulin resistance test was performed. Serum AST, ALT, and TG levels and the amount of hydroxyproline in the liver were measured, and the liver was examined histopathologically.

    Administration of carbon tetrachloride and T0901317 during a 4-week high-fat loading induced hepatic steatosis and fibrosis, confirming the reproducibility of the NASH model. Bezafibrate inhibited hepatic steatosis and fibrosis, and showed efficacy against NASH.

    DOI CiNii

  • Evaluation of cognitive function in diabetic germ-free mice

    Kobayashi Hiroyuki, Murasawa Hiroyasu, Pawlak Akiko, Katayama Kazutaka, Kishigai Daisuke, Shimato Saki, Sugiyama Miki, Okuyama Masae, Imaizumi Takahito, Shimato Nozomu, Nonomura Hiroko, Nishiyama Ryusei, Mizuki Takuji, Hirasawa Yasushi

    Proceedings for Annual Meeting of The Japanese Pharmacological Society   94   2-P1-12  2021

     View Summary

    It is widely known that diabetes is a risk factor for dementia. It has been reported that the cognitive function is impaired in the streptozotocin (STZ)-induced diabetic mouse model. Recently, it has also been reported that alteration of the intestinal flora is a risk factor for dementia. However, effects of alteration of the intestinal flora due to dementia on the cognitive function have not been adequately assessed. One of the reasons is that germ-free mice, which have no intestinal flora, need to be housed in a germ-free environment. Therefore, it is difficult to subject to behavioral tests in a germ-free environment to assess the cognitive function.

    In the present study, the cognitive function was assessed by a novel object recognition test in a germ-free environment using germ-free mice (C57B6N) in the control group treated with physiological saline and in the STZ group in which diabetes was induced by STZ administration.

    In the STZ group, the rate of exploration time to the novel object in the retention trial was significantly lower than in the control group.

    In conclusion, STZ-induced diabetic mouse model in a germ-free environment indicated impairment of cognitive function in the novel object recognition test performed in a germ-free environment.

    DOI CiNii

  • 超音波照射を利用した結晶多形制御の展開

    ヒラサワ イズミ

      51 ( 4 ) 228 - 234  2021

    CiNii J-GLOBAL

  • リゾチームを用いた膜晶析法における透過流束と膜面濃度の推算

    植田紗綾, 平沢泉, 小堀深

    化学工学会年会研究発表講演要旨集(CD-ROM)   86th  2021

    J-GLOBAL

  • 結晶添加が及ぼすZMH結晶の壁面付着抑制効果の検討

    諏江霞純, 平沢泉

    化学工学会大会(Web)   2021  2021

    J-GLOBAL

  • 反応晶析を用いた塩化銀微結晶の作製

    佐野亮介, 平沢泉

    化学工学会大会(Web)   2021  2021

    J-GLOBAL

  • 高分子電解質反応場を利用した還元晶析法による銀ナノ粒子の創製

    青木優真, 平沢泉

    化学工学会大会(Web)   2021  2021

    J-GLOBAL

  • シュウ酸銀添加によるTBAB hydrate過冷却緩和

    平沢泉, 森口太智, 町田博宣

    化学工学会年会研究発表講演要旨集(CD-ROM)   86th  2021

    J-GLOBAL

  • 収束ビーム反射測定法を用いた医薬品結晶の破砕及び凝集の数理モデル化

    海野城衣, 真崎郁茉, 平沢泉

    化学工学会年会研究発表講演要旨集(CD-ROM)   86th  2021

    J-GLOBAL

  • 結晶添加によるZMH結晶の壁面付着抑制法の検討と評価

    諏江霞純, 平沢泉, 竹内正行, 宮崎康典

    化学工学会年会研究発表講演要旨集(CD-ROM)   86th  2021

    J-GLOBAL

  • エネルギー分野に貢献する晶析工学

    平沢泉

    化学工学会年会研究発表講演要旨集(CD-ROM)   86th  2021

    J-GLOBAL

  • Establishment of chronic obstructive pulmonary disease model using intratracheal mist spray

    Kawasaki Yukiko, Sugiura Takahiro, Imaizumi Takahito, Nagatsu Yukari, Hirasawa Yasushi

    Proceedings for Annual Meeting of The Japanese Pharmacological Society   93   3-P-308  2020

     View Summary

    When chronic obstructive pulmonary disease (COPD) develops, it is difficult to completely recover. The number of patients dying of COPD is increasing year by year. Researches on degenerative medicines of pulmonary diseases, including evaluation with animal models, are being advanced. A spray, which had been used for intratracheal administration, is currently unavailable. Therefore, we aimed to establish a COPD mouse model using a new intratracheal spray.

    Using KN-34700 Natsume Aerosol Sprayers, elastase was administered intratracheally to male C57BL/6J mice at 10 weeks of age. LPS was administered intratracheally 3 weeks after the elastase administration. Bronchoalveolar lavage fluid was collected 3 days after the LPS administration. Respiratory function was measured 3, 6, and 12 weeks after the elastase administration. The lungs were isolated 3, 6, and 12 weeks after the elastase administration and examined histopathologically.

    Pulmonary emphysema was confirmed to have developed 3 weeks after the elastase administration. BALF and respiratory function are being analyzed.

    DOI CiNii

  • ZMHの付着に温度変化が及ぼす影響

    諏江霞純, 竹内正行, 宮崎康典, 平沢泉

    化学工学会年会研究発表講演要旨集(CD-ROM)   85th  2020

    J-GLOBAL

  • シュウ酸によるランタン結晶回収方法の検討

    中島啓貴, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • L-グルタミン酸の多形制御

    小西あかり, 池勇樹, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • 超音波照射によるL-アルギニン塩酸塩の核化確率の制御

    池勇樹, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • 沈殿から反応晶析に焦点を当てた戦略

    平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • 確率論的核化が種晶添加回分晶析の製品品質に及ぼす影響に関する数値シミュレーション

    海野城衣, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • 衝撃核化におよぼす操作因子の影響

    渡邉裕之, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • ZMHの付着に温度変化が及ぼす影響

    諏江霞純, 竹内正行, 宮崎康典, 平沢泉

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   51st  2020

    J-GLOBAL

  • Crystallization Kinetic Analysis for Antisolvent and Cooling Crystallization, and Challenges in Application for API Process Development

    小寺孝憲, 小寺孝憲, 小針昌則, 平沢泉

    日本プロセス化学会ウィンターシンポジウム講演要旨集(Web)   2020  2020

    J-GLOBAL

  • 工業応用を志向した貧溶媒および冷却晶析における晶析速度解析

    コデラ タカノリ, コバリ マサノリ, ヒラサワ イズミ

      50 ( 6 ) 347 - 353  2020

    CiNii J-GLOBAL

  • 埋込み領域選択可能な暗号化画像のための可逆情報埋込み法—A Reversible Data Hiding Method for Both Plain and Encrypted Images

    井澤 佑介, 平澤 凌一, 今泉 祥子, 貴家 仁志

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報   119 ( 335 ) 29 - 34  2019.12

    CiNii

  • 2-5-3 Various Behavior Derived from Solution Structures in TBAB Aqueous Solution

    SUGAHARA Takeshi, MACHIDA Hironobu, HIRASAWA Izumi

    Proceedings of the Annual Conference of The Japan Institute of Energy   28   64 - 65  2019.07

     View Summary

    A large degree of supercooling is necessary to form the tetra-n-butylammonium bromide (TBAB) semiclathrate hydrate. Developing an effective method to suppress supercooling is essential to use semiclathrate hydrates as potential thermal storage media. One of the methods is the memory effect, which is a kind of temperature hysteresis. We have already reported the relationship between the memory effect and the solution structures in the TBAB semiclathrate hydrate reformation, based on the scanning electron microscopic observation. In this presentation, we indicate some phenomena that would be derived from the existence of the solution structure. We would like to discuss the thermal stability of the solution structures.

    DOI CiNii

  • Renoprotective mechanism analysis of agmatine on ischemic acute kidney injury with high coverage expression profiling

    Sugiura Takahiro, Sugiyama Miki, Imaizumi Takahito, Hirasawa Yasushi

    Proceedings for Annual Meeting of The Japanese Pharmacological Society   92   2-P-126  2019

     View Summary

    Acute kidney injury (AKI) represents a major clinical problem with high mortality in kidney transplantation and nephron-sparing surgery. The ischemic AKI model by the interception of the bloodstream is the superior model that can evaluate an efficacy evaluation and condition of a patient elucidation in a short term for AKI without the therapeutic drug. We reported that agmatine has the preventive effect on ischemic AKI. But we do not find the detailed mechanism about the renoprotective effect of agmatine. Therefore, we examined the detailed renoprotective mechanism of agmatine with the high coverage expression profiling (HiCEP). Male Crl:CD1 mice's right kidney was removed. After a 2-week, to induce ischemic AKI, the left renal artery and vein were occluded with a clamp for 50 min. Agmatine was injected 5 min before the ischemia. At 6 h after reperfusion, we excised the left kidney and detected the gene change with HiCEP. As a result, we obtained the gene changes of TRXR, synbindin, ADAMTS1 and PEA15.

    DOI CiNii

  • 2-4-3 Memory effect in supercooled aqueous solution of TBAB

    MACHIDA Hironobu, MASUNAGA Hiroyasu, SUGAHARA Takeshi, HIRASAWA Izumi

    Proceedings of the Annual Conference of The Japan Institute of Energy   27   50 - 51  2018.08

     View Summary

    Clathrate hydrate of tetra-n-butylammonium bromide (TBAB) is expected as a cold storage material for air conditioning, but supercooling is a problem. For visualization of the supercooling phenomenon, both the microstructure of TBAB clathrate hydrate and TBAB aqueous solution were observed by freeze fracture replica method. In the decomposition and formation processes, the generation and disappearance of the clusters were found to be explained as a significant step for the phase change. In addition, the relationship between thermal behavior, solution structure, and hysteresis phenomenon (so-called memory effect) was investigated and it was found that the memory effect can be explained by cluster generation. Further, as a cross check, structure evaluation in TBAB aqueous solution was carried out by X-ray scattering method and mutual complementary results were obtained.

    DOI CiNii

  • Teイオン添加によるZMH析出・付着抑制効果の検討

    下端健吾, 平沢泉, 宮崎康典, 竹内正行

    化学工学会秋季大会研究発表講演要旨集(CD-ROM)   50th  2018

    J-GLOBAL

  • 三酸化モリブデン半水和物結晶の懸濁液添加によるZMH付着抑制効果の検討

    阿部りさこ, 平沢泉, 竹内正行, 宮崎康典

    化学工学会大会(Web)   2018  2018

    J-GLOBAL

  • 反応晶析法によるZr-Te析出物組成に関する検討

    下端健吾, 荒井貴大, 伊藤大雄, 平沢泉, 竹内正行, 宮崎康典

    化学工学会年会研究発表講演要旨集(CD-ROM)   82nd  2017

    J-GLOBAL

  • MoO3結晶添加によるZMH壁面付着抑制

    下端健吾, 伊藤大雄, 平沢泉, 宮崎康典, 竹内正行

    化学工学会大会(Web)   2017  2017

    J-GLOBAL

  • 関東支部の活動と戦略

    平沢 泉

    化学工学 = Chemical engineering   74 ( 2 ) 88 - 88  2010.02

    CiNii

  • 材料・界面

    長尾 大輔, 平沢 泉, 安原 賢, 山村 方人, 塩盛 弘一郎, 清山 史朗, 塩井 章久, 三宅 義和, 後藤 健彦, 清田 佳美

    化学工学 = Chemical engineering   73 ( 10 ) 533 - 537  2009.10

    CiNii

  • 関東支部の活動と戦略

    平沢 泉

    化学工学 = CHEMICAL ENGINEERING OF JAPAN   71 ( 11 ) 782 - 782  2007.11

    CiNii

  • 晶析技術

    平沢 泉

    化学工学 = CHEMICAL ENGINEERING OF JAPAN   71 ( 10 ) 707 - 708  2007.10

    CiNii

  • Development of phosphate recovery process for sewage using crystallization

    Journal of water and waste   49 ( 9 ) 782 - 788  2007.09

    CiNii

  • 晶析工学を基軸にしたナノ結晶のビルドアップ

    平沢 泉, 三上 貴司, 池田 将太

    ケミカルエンジニヤリング   52 ( 3 ) 222 - 226  2007.03

    CiNii

  • How Could We Contribute to the Society of Sea Water Science Japan?

    HIRASAWA Izumi

      60 ( 4 ) 222 - 222  2006.08

    CiNii

  • Present State of Water Pollution in the Stagnant Sea Area and Future Problems

    HIRASAWA Izumi

    Bulletin of the Society of Sea Water Science, Japan   60 ( 4 ) 224 - 228  2006.08

     View Summary

    Environmental Strategy in the stagnant sea has focused on the regulation of total emission in COD, N and P, especially in the wastewater, for 25 years. In spite of significant reduction of COD, flowing to the sea area, the attainment rate for the Environmental Standard has not improved yet, to become almost constant rate. This fact is considered to be caused by non-point source of COD, N and P, such as the internal load from the sediments in the sea, the load from the not regulated industry, agriculture, and fishery field and also the rainfall-caused load from the combined sewer system and so on. We will have the 6thregulation of total emission in COD, N and P. In this paper, present state of water pollution in the stagnant sea area and future problems are discussed, to present a future strategy in the 21stcentury.

    DOI CiNii

  • The Mission and Dignity of the S.C.E.J. : From a Viewpoint of Region, Science Education and Asia

    HIRASAWA Izumi

      70 ( 7 ) 323 - 323  2006.07

    CiNii

  • 実用化が進展するソノ晶析プロセス--超音波を用いた晶析プロセスの展開

    宮坂 悦子, 平沢 泉

    ケミカルエンジニヤリング   50 ( 12 ) 957 - 962  2005.12

    CiNii

  • Preface

    HIRASAWA Izumi

      58 ( 5 ) 447 - 447  2004.10

    CiNii

  • 金属資源のリサイクル--晶析工学からのアプローチ (特集 リサイクルテクノロジーの進展)

    平沢 泉

    ケミカルエンジニヤリング   49 ( 10 ) 763 - 768  2004.10

    CiNii

  • Effect of Supersaturation on Crystallization Phenomena in Antisolvent Crystallization of Sodium Chloride

    KANEKO Shogo, YAMAGAMI Yasuhiro, TOCHIHARA Heisuke, HIRASAWA Izumi

    Bulletin of the Society of Sea Water Science,Japan   57 ( 1 ) 22 - 26  2003.02

    CiNii

  • Learning from Biocrystallization : Crystallization Technology as a Fixation Method for Resources from the Sea

    HIRASAWA Izumi

    Bulletin of the Society of Sea Water Science,Japan   55 ( 5 ) 289 - 296  2001.10

    CiNii

  • The Antisolvent Crystallization Phenomena of Sodium Chloride under the Existence of Potassium Chloride Impurities

    KANEKO Shogo, YAMAGAMI Yasuhiro, HIRASAWA Izumi

    Bulletin of the Society of Sea Water Science,Japan   55 ( 2 ) 91 - 96  2001.04

    CiNii

  • 高純度塩化ナトリウム結晶の創製--貧溶媒添加法によるKCl存在化のNaClの晶析現象

    平沢 泉, 金子 正吾, 山上 泰弘

    財団法人ソルト・サイエンス研究財団助成研究報告集   1999   13 - 23  2001.03

    CiNii

  • 貧溶媒添加法における新規な過飽和度概念に基づく結晶の創製

    平沢 泉, 金子 正吾, 山上 泰弘

    助成研究報告集   2001   127 - 136  2001

    CiNii

  • Formation of Calcium Carbonate by Reaction Crystallization

    HIRASAWA Izumi

    Journal of the Society of Inorganic Materials,Japan   7 ( 287 ) 307 - 312  2000.07

    CiNii

  • セッションCR 晶析 (特集 第5回日韓合同分離技術シンポジウム)

    大嶋 寛, 平沢 泉

    分離技術   30 ( 1 ) 18 - 20  2000.02

    CiNii

  • 潜熱蓄熱プロセスと静止融液系の核化現象

    平沢 泉, 高井 正和, 垣内 博行

    分離技術   29 ( 3 ) 176 - 178  1999.06

    CiNii

  • 国際会議「工業晶析の総括と21世紀への展望」報告

    平沢 泉

    分離技術   29 ( 1 ) 37 - 41  1999.02

    CiNii

  • 晶析装置

    平沢 泉, 三木 秀雄

    化学工学   61 ( 8 ) 595 - 598  1997.08

    CiNii

  • EPAデ-タベ-スの利用およびそのアクセス方法について

    平沢 泉

    ケミカルエンジニヤリング   42 ( 1 ) 82 - 85  1997.01

    CiNii

  • 文献一覧「晶析」編(1995年)

    平沢 泉

    分離技術   26 ( 6 ) 394 - 396  1996.11

    CiNii

  • [9616]高濃度硝酸イオン含有排水の有効利用

    平沢 泉

    化学工学   60 ( 6 ) 407 - 407  1996.06

    CiNii

  • 物質循環のための工業晶析

    平沢 泉

    化学工学   59 ( 7 ) 500 - 503  1995.07

    CiNii

  • 水処理技術分野における晶析 (晶析<特集>) -- (特殊晶析技術)

    平沢 泉

    化学工学   55 ( 4 ) p292 - 293  1991.04

    CiNii

  • 流動床式脱リン法におけるリン酸カルシウムの結晶成長

    平沢泉

    化学工学シンポジウムシリーズ18     146 - 150  1988

    CiNii

  • 接触脱リン法による水中のリン除去

    岩井 信行, 平沢 泉

    工業用水   ( 320 ) p13 - 18  1985.05

    CiNii

  • 接触脱リン法による廃水の高度処理 (′82に期待される実用研究<特集>)

    平沢 泉, 嶋田 和夫

    ケミカルエンジニヤリング   27 ( 3 ) p190 - 195  1982.03

    CiNii

  • リン酸カルシウムの晶析現象を利用した液中のリン酸塩の除去

    平沢 泉, 嶋田 和夫

    化学工学   45 ( 11 ) p718 - 720  1981.11

    CiNii

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Industrial Property Rights

  • 蓄熱材組成物、蓄熱装置及び蓄熱方法

    特許第6590607号

    鈴木 基啓, 町田 博宣, 竹口 伸介, 椎 健太郎, 平沢 泉, 森岡 想

    Patent

    J-GLOBAL

  • 電動車両

    特許第6215809号

    久保 和樹, 町田 清仁, 田中 信行, 泉 純太, 平沢 崇彦, 栗原 史好, 岡嶋 大介, 多田 貴志

    Patent

    J-GLOBAL

  • 蓄電システム

    特許第6123737号

    西 勇二, 田邉 千済, 田中 宏昌, 海谷 裕之, 平沢 崇彦, 泉 純太

    Patent

    J-GLOBAL

  • 蓄熱材組成物および蓄熱材組成物を用いる方法

    鈴木 基啓, 平沢 泉

    Patent

    J-GLOBAL

  • 自己集積型金属錯体結晶の製造方法

    5403505

    平沢 泉, 神代 瑞希, 水上 耕平

    Patent

    J-GLOBAL

  • 過冷却防止剤、蓄熱方法及び蓄熱システム

    内山 洋平, 鈴木 基啓, 平沢 泉

    Patent

    J-GLOBAL

  • タンパク質の結晶化方法

    平沢 泉, 佐々木 俊輔, 島 有紀

    Patent

  • 非イオン界面活性剤の回収方法

    高橋 裕和, 平沢 泉, 佐々木 俊輔

    Patent

  • 単分散微粒子の製造方法

    平沢 泉, 片山 晃男, 郡山 日出人, 樹下 菜穂

    Patent

  • リン及びアンモニア含有排水の処理方法

    特許第3122602号

    萩野 隆生, 平沢 泉

    Patent

    J-GLOBAL

  • 液中のリン除去方法

    南 武, 鈴木 義明, 平沢 泉, 中村 弘志

    Patent

    J-GLOBAL

  • 有機性汚水の処理方法

    南 武, 鈴木 義明, 平沢 泉, 中村 弘志

    Patent

    J-GLOBAL

▼display all

Works

  • Strategy on improving contamination of the stagnant water area

    2008.10
    -
    2009.03

  • Investigation on B,N,F removal method

    2008.09
    -
    2009.03

  • Investigation for Environmental Impact

    2008.03
    -
     

  • Investigation for Advanced Solvent Recycle System

    2008.03
    -
     

  • Investigation on Creation of Sophisticated Solbent Recycle System

    2007.03
    -
     

  • Investigation Report on Removal Technology of Toxic trace Metal Ion in the Water Environment

    2007.03
    -
     

  • Investigation on Strategies to Create Environment od Stagnant Sea Area

    2006.03
    -
     

  • Survey on Researches and Technologies Relating Massive Co2 Fixation by Ca ad Mg ion in Sea Water

    1994
    -
     

  • Study on Formation of Sparingly Soluble Carbonate as CO2 Fixation technology

    1993
    -
     

  • Guideline for wastewater treatment technology -measure for nitrogen removal (in inorganic pigment manufacturing)

    1991
    -
     

  • Guideline for wastewater treatment technology -measure for nitrogen removal- (in organic pigment manufacturing)

    1991
    -
     

  • Investigation on the research trend in the important field of the earth environment

    1991
    -
     

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Other

  • Crystals grow and breeds nuclei. Crystal exists between inanimate and animate things. New theory is needed to combine fundamentals and real engineering theory.

Awards

  • SCEJ Fellow

    2019.03   SCEJ   SCEJ Fellow

  • Outstanding Paper Award 2016

    2018.09   Society of Chemical Engineers Japan  

  • JCEJ Reviewing Contribution Award

    2017.03   Society of Chemical Engineers Japan  

    Winner: Izumi Hirasawa

  • Distinguished Speaker Award

    2014.12  

  • SCEJ Cintribution Award

    2012.03  

  • ICSST09 Contribution Award

    2009.11  

  • SCEJ Kantoh Branch prize of a merit

    2005.08  

  • ICSST05 Contribution Award

    2005.08  

  • Excellent Technology Prize/ SSPEJ

    2005.06  

  • Poster Prize ( Soc. of Separation Engineers Japan)

    2004.06  

  • Poster Prize ( Soc. of Separation Engineers Japan)

    2000.11  

  • Excellent Technology Prize( Soc. of Chemical Engr. Japan)

    2000.03  

  • Excellent Paper Award (Sewage Works Japan)

    1982.04  

▼display all

Research Projects

  • Development of heat recovery process by using laten heat storage materials

    Project Year :

    2010
    -
     
     

  • CSD and Crystallinity Control of Oranic Crystals by Cooling Crystallization

    Project Year :

    2010
    -
     
     

  • Triggering nucleation of the supercooled melt

    Project Year :

    2009
    -
    2010
     

  • Crystallization control of ultra-high specific surface area materials

    Project Year :

    2008
    -
    2010
     

  • Develoment of Heat Storage Process using Latent Heat Storage Material

    Project Year :

    2008
    -
    2010
     

  • Develoment of Ultrasonic Probe for Sonocrystallization

    Project Year :

    2009
    -
     
     

  • Nucleation Control of Amino Acid Crystals

    Project Year :

    2009
    -
     
     

  • Fundamental Study on nano size metal creation

    Project Year :

    2009
    -
     
     

  • Separation and Purification Process by Crustallization

    Project Year :

    2009
    -
     
     

  • Simulayion and Prediction of Crystallization Process

    Project Year :

    2009
    -
     
     

  • Design of Waste Recycling System

    Project Year :

    2009
    -
     
     

  • Separation and purification of solid impurity included in the process of crystallization

    Project Year :

    2009
    -
     
     

  • Particle Size Control and Creation Process of Au Nano Particles Utilized as Plant Transformation

    Project Year :

    2009
    -
     
     

  • Development of a new heat storage material

    Project Year :

    2008
    -
    2009
     

  • Development of heat storage system with saving energy

    Project Year :

    2008
    -
    2009
     

  • Pseudoolymorh control in heating process

    Project Year :

    2008
    -
    2009
     

  • Establishment of a New Nuclear Fuel Recycle by Crystallization

    Project Year :

    2006
    -
    2009
     

  • Study on Treatment of wastewater containing Fluoride ion by crystallization method

    Project Year :

    2000
    -
    2009
     

  • Creation of organometallic crystals by reaction crystallization

    Project Year :

    2008
    -
     
     

  • Development of sono Crystallization process

    Project Year :

    2008
    -
     
     

  • Development of water business in Asia

    Project Year :

    2008
    -
     
     

  • Develoment of Sonocrystallization Process

    Project Year :

    2008
    -
     
     

  • Recovery of sparingly soluble rare matal compound by reaction crystallization

    Project Year :

    2007
    -
    2008
     

  • Reaction crystallization treatment of fluoride containing wastewater by using membrane

    Project Year :

    2006
    -
    2008
     

  • Study on Selective Crystallization of a Desirable Polymorph

    Project Year :

    2006
    -
    2008
     

  • Selective Crystallization and Purification of Functional Saccharide

    Project Year :

    2006
    -
    2008
     

  • Development of Crysatal Covered with Heterocrystals

    Project Year :

    2006
    -
    2008
     

  • Next Fuel Cycle: R&amp;D on Purification Technology of Crystallization

    Project Year :

    2006
    -
    2008
     

  • Study on transformation of amoorphous API

    Project Year :

    2006
    -
    2008
     

  • Study on Selective Crystallization of MI

    Project Year :

    2005
    -
    2008
     

  • Pharmaceutical Crystallization by Drawing-out

    Project Year :

    2003
    -
    2008
     

  • Kinetics of Inorganic Nano Crystals by Reaction Crystallization

    Project Year :

    2007
    -
     
     

  • Mechanism of thin film formation on the solid surface

    Project Year :

    2006
    -
    2007
     

  • Study on purification of waste acid by melt crystallization

    Project Year :

    2006
    -
    2007
     

  • Development of Inorganic DDS drug

    Project Year :

    2006
    -
    2007
     

  • Creation of Fine Crystals by Wet Milling Method

    Project Year :

    2005
    -
    2007
     

  • Study on Removal and Recovery of Phosphate ion applied to separated water from sludge treatment

    Project Year :

    1998
    -
    2007
     

  • Recovery and purification of Uranium by crystallization

    Project Year :

    2006
    -
     
     

  • Creation of nm Size Phosphor by Reaction Crystallization

    Project Year :

    2000
    -
    2006
     

  • Study on Crystallization Control by Ultrasonic Irradiation

    Project Year :

    2003
    -
    2005
     

  • Production of nm Calcite by Reaction Crystallization

    Project Year :

    2003
    -
    2004
     

  • 環境触媒プロセスの開発

    文部科学省 

    Project Year :

    2000
    -
    2004
     

  • 微生物機能を利用した資源循環型水環境プロセスの構築

    文部科学省 

    Project Year :

    1999
    -
    2003
     

  • Study on Recovery of Ni metal from wastewater of plating bath by reduction Crystallization

    Project Year :

    1999
    -
    2002
     

  • Prccipitation phenomena of calcite and research for apparatus and operational conditions

    Project Year :

    1995
    -
    1996
     

     View Summary

    Calcium carbonate precipitated by the reaction between calcium chloride solution and sodium carbonate solution was studied. In this reaction calcium carbonate intermediate was came out in the initial reaction step, and then transformed to mixture of calcite and vaterite in the reacting solution, and transformation of intermediate was focused in this study. Sodium chloride crystal was added to reacting slurry in which intermediate was coexisted, calcite was precipitated dominantly. Crystal size and precipitated number of calcite was affected by the crystal size of added sodium chloride crystal and crystal growth rate of calcite was obtained in the reacting slurry which intermediate was coexisted. On the other hand, calcite precipitated dominantly by reaction between calcium chloride solution and sodium bicarbonate solution. In this reaction, precipitated number of calcite was correlated with the amount of sodium bicarbonate and it was considered that transformation of intermediate to calcite was promoted by decomposition of bicarbonate ions.In the case of double jet reactive crystallization method wihch is applied for precipitation of silver halide industry, precipitated calcium carbonate was mixture of calcite and vaterite and it was not found the operational conditions which calcite precipitated dominantly. Therefore nucleating agent were considered to be necessary in this system.Crystallization phenomena of calcite in the stationary solution was studied. It was found that mixture of calcite and vaterite was precipitated within the range of average supersaturation which was calculate by the values of pH from 100 to 250. But the calcite was precipitated in the range of average supersaturation under 50 or over 280

  • Separation and purification of optically active substancc by crystallization

    Project Year :

    1995
    -
    1996
     

     View Summary

    Experimental study of aqueous solution of DL-Mandelic acid was carried out to observe solubility data less than 30 percent of L-Mandelic acid against DL-acid by the cooling method under atmospheric pressure. And the solubility curve for the range was more than 30 percent of L-Mandelic acid also observed by high pressure crystallization. From this observed data, a new effective optical resolution process was proposed as a combination between evaporation and high pressure crystallization. And optical resolution of L-SCMC (S-Carboxymethyl-L-Cysteine) from DL-SCMC solution was studied at isoelectric point and supersaturated solution in which L-SCMC seed grew without nucleation of D-SCMC nuclei, was discussed. Crystal growth rate of a single crystal of L-SCMC was observed in aqueous solution of DL-SCMC with 5 and 10 wt% of NaCl for the range of supersaturation of 0.1-0.25 [g/100ml]. From these test's results, crystal growth rate of L-SCMC was affected by concentration D-SCMC "S_D" factor in the solution and disturb factor alpha which was defined by the ratio of supersaturation of L-SCMC to S_D, was proposed. On the other hand, concentration of only L-SCMC in the solution decreased by growth of L-SCMC seed which was added into supersaturated solution, for an initial period of operation just after L-SCMC seed was added, but when the operation continued for a long while, concentration of D-SCMC also started to decrease. This phenomenon was confirmed to come from nucleation of D-SCMC nuclei on the surface of L-SCMC aeed. Then, this nucleation was studied, and waiting time for two-dimensional nucleation of D-SCMC turned out to be affected by supersaturation of the solution and suspension density of crystal in the solution. Operational condition on which only L-SCMC crystal grows, was found out from this data. And crystal growth rate of L-SCMC seed was also observed by evaporatting crystallization and the data was compared with data obtained by cooling crystallization.

  • Separation and purification of optically active substancc by crystallization

    Project Year :

    1995
    -
    1996
     

     View Summary

    Experimental study of aqueous solution of DL-Mandelic acid was carried out to observe solubility data less than 30 percent of L-Mandelic acid against DL-acid by the cooling method under atmospheric pressure. And the solubility curve for the range was more than 30 percent of L-Mandelic acid also observed by high pressure crystallization. From this observed data, a new effective optical resolution process was proposed as a combination between evaporation and high pressure crystallization. And optical resolution of L-SCMC (S-Carboxymethyl-L-Cysteine) from DL-SCMC solution was studied at isoelectric point and supersaturated solution in which L-SCMC seed grew without nucleation of D-SCMC nuclei, was discussed. Crystal growth rate of a single crystal of L-SCMC was observed in aqueous solution of DL-SCMC with 5 and 10 wt% of NaCl for the range of supersaturation of 0.1-0.25 [g/100ml]. From these test's results, crystal growth rate of L-SCMC was affected by concentration D-SCMC "S_D" factor in the solution and disturb factor alpha which was defined by the ratio of supersaturation of L-SCMC to S_D, was proposed. On the other hand, concentration of only L-SCMC in the solution decreased by growth of L-SCMC seed which was added into supersaturated solution, for an initial period of operation just after L-SCMC seed was added, but when the operation continued for a long while, concentration of D-SCMC also started to decrease. This phenomenon was confirmed to come from nucleation of D-SCMC nuclei on the surface of L-SCMC aeed. Then, this nucleation was studied, and waiting time for two-dimensional nucleation of D-SCMC turned out to be affected by supersaturation of the solution and suspension density of crystal in the solution. Operational condition on which only L-SCMC crystal grows, was found out from this data. And crystal growth rate of L-SCMC seed was also observed by evaporatting crystallization and the data was compared with data obtained by cooling crystallization.

  • Prccipitation phenomena of calcite and research for apparatus and operational conditions

    Project Year :

    1995
    -
    1996
     

     View Summary

    Calcium carbonate precipitated by the reaction between calcium chloride solution and sodium carbonate solution was studied. In this reaction calcium carbonate intermediate was came out in the initial reaction step, and then transformed to mixture of calcite and vaterite in the reacting solution, and transformation of intermediate was focused in this study. Sodium chloride crystal was added to reacting slurry in which intermediate was coexisted, calcite was precipitated dominantly. Crystal size and precipitated number of calcite was affected by the crystal size of added sodium chloride crystal and crystal growth rate of calcite was obtained in the reacting slurry which intermediate was coexisted. On the other hand, calcite precipitated dominantly by reaction between calcium chloride solution and sodium bicarbonate solution. In this reaction, precipitated number of calcite was correlated with the amount of sodium bicarbonate and it was considered that transformation of intermediate to calcite was promoted by decomposition of bicarbonate ions.
    In the case of double jet reactive crystallization method wihch is applied for precipitation of silver halide industry, precipitated calcium carbonate was mixture of calcite and vaterite and it was not found the operational conditions which calcite precipitated dominantly. Therefore nucleating agent were considered to be necessary in this system.
    Crystallization phenomena of calcite in the stationary solution was studied. It was found that mixture of calcite and vaterite was precipitated within the range of average supersaturation which was calculate by the values of pH from 100 to 250. But the calcite was precipitated in the range of average supersaturation under 50 or over 280.

  • Study on Sparingly-Soluble Carbonete Crystallization as Technology for CO_2 Fixation

     View Summary

    Reactive crystallization tests were done batch-wisely, to examine the effect of l-aspartic acid and l-glycine on the crystallization rate. From the results, effect of them was recognized not to be significant in comparison to the effect of crystallization operation factors. Then studies on reactive crystallization were carried out to obtain the effect of supersaturation, the rate of its formation, temperature and mixing on the shape of calcium carbonate crystals. Based on the results of above studies, direct mixing of calcium salt and carbonate sollution was applied to calcium carbonate crystallization under normal temperature and pressure, to recognize that solid sodium chloride addition was effective to form calciteselectively, althogh vaterite crystallized much without its addition. And also method of addition, reactant concentration affected crystal shape and size distribution. Consequently new phenomena that unstale microfines were transformed selectively to calcite by dissolution of sodium chloride surface, was found, and growth rate of calcite was obtained. This study could be located as a germic reserach, and it will contribute not only to the new process development of carbon dioxide flxation by calcium carbonate crystallization

  • Study on generation of new crystal substances and design of crystallizer, crystallizing operation under high utilization of resource, less consumption of energy and out of pollution

     View Summary

    Industrial crystallization is an operation of precipitation of solid from liquid phase as crystal and evaluated by utilization of energy generated (or absorbed) by transformation of phase, properties of obtained crystal and/or remained liquid after separation of crystal. The recent trend of development of technology is expected to be done in harmony with the circumstances of high utilization of resource, less consumption of energy and out of environmental pollution, and in chemical industry, development of production technology of new faculty substances is hoped under low cost. Crystal is characterized by pure solid of stable property for high faculty and industrial crystallization suitable to production of these substances was discussed on contribution to establishment of new technologies in a chemical industry in 21 century.On these back grounds, this study team decided to investigate what is an industrial crystallization contributed for development of the chemical industry in 21 century, what research projects are required for new development on industrial crystallization, how about are the present technology and research on industrial crystallization, and the report was made from research results obtained and surveyed by members and from the planning projects, through six subgroups classified by fundamentals, new topics, design and control of crystallizers and operations. Then the following conclusions were summarized : Design theories of crystallizers and operations for production of a chemical commodity are proposed for desired size and amount of a product and applied satisfactorily for industrial purposes. And new crystallizing technology for production of high purity and new faculty crystal and for control of operating supersaturation by utilization of transformation of polymorphology are introduced.From these investigations, industrial crystallization is regarded as a effective technology for development of chemical industries, and largely contributes to development of chemical, pharmaceutical, food and other industries especially to prevention of pollution

  • Study on phosphate and Ammonium Removal using Magnesium Ammonium Phosphate Crystallization

     View Summary

    Development of Ammonium and Phosphate ions removal process has been needed for removing them from wastewater exhausted in the process of sludge treatment, considering the concept of sludge treatment base in the metropolitan urban cite. In this research, basic investigation was done on the relation between crystallization characteristics and removability. Batch experiments were done to verify the crystallization characteristics of MAP (characteristics of water quality and operational conditions to crystallize MAP selectively), and selective crystallization conditions (temperature, pH,Mg/P molar ratio and NH4/P molar ratio) was obtained. Based on the results above, batch reactive crystallization experiments were performed, to investigate relation between the process of Magnesium and Phosphate removal and crystallization of MAP,and to clarify operational pH and Mg/P molar ratio for obtaining optimum removal efficiency and consider MAP crystallization based on nucleation and crystal growth phenomena, by measuring the dynamic change of crystal size and its shape through SEM.And also Alcohol addition method was investigated, to make clear the effect of alcohol on the solid-liquid equilibrium. Addition of alcohol lowered the solubility product.Process of MAP crystallization was considered to consist of reaction of ions, diffusion and surface integration stpes, and it was recognized that integration step determined the rate, when desirable product size was needed. Consequently design method on the material balance and crystallization rate was proposed, considering relation between crystallization rate and design method of the crystallizer

  • Development of fusion process in combination with membrane and crystallization

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Presentations

  • Development of PCM Heat Storage Process by using Inducing Nucleation with Ulyrasonic Irradiation

    SSPEJ Annual Meeting 2011 

    Presentation date: 3011.06

  • Recovery of suvstance from wastewater by crytsallization

    CHEMCON2914 

    Presentation date: 2014.12

  • Crystallization to create nano crystals in liquid phase

    SCEJ Niigata Meeting 

    Presentation date: 2014.11

  • Development of PAT for crystallization process in the international symposium

    RXE Forum 2014 

    Presentation date: 2014.07

  • Removal and recovery from acid waste containing metal ion and organic acid by crystallization

    ACTS2914CGOM11 

    Presentation date: 2014.06

  • Ultrasonic induced nucleation of aminoacids

    BIWIC 2013 

    Presentation date: 2013.09

  • Efficient Imprivement Method of Carbonates Crystallization Phenomena

    WCCE9 

    Presentation date: 2013.06

  • Crystallization environment to vuild up nanoparticles

    BIWIC2012 

    Presentation date: 2012.09

  • Solvent induced transition of Myo-Inositol

    HIW 2012 

    Presentation date: 2012.09

  • Contribution of crystallization to the various fields

    Kongju National Univ. Summer Seminar 

    Presentation date: 2012.09

  • Crystallization environment to create nanometer particles

    Asian Crystallization Technology Symposium 2012 

    Presentation date: 2012.05

  • Wastewater treatment based ion recovery by crystallization

    Japan -China International Workshop of Chemistry on Wastewater Treatment 

    Presentation date: 2012.05

  • Effect of Ultrasonic Irradiation on the Selective Crystallization of Organic Substances

    ICMAT2011 International Conference of Materials for Advanced Technologies 

    Presentation date: 2011.07

  • Nucleation control of Pharmaceutical substance by Using a New Crystallization Environment,

    Japan Wochen an der MLU 2011 

    Presentation date: 2011.06

  • Recovery of Anion in the Wastewater as Resources Based on Crystallization Technology

    The Sixth Foint China Japan Chemical Engineering Symposium 

    Presentation date: 2011.06

  • Utilization of Phosphate Recovery Process Using the method for Creating Crystals

    Second Workshop for Phosphate Recovery as Resources 

    Presentation date: 2011.06

  • Crystallization in the polyelectrolyte environment

    SCEJ autumn meeting 

    Presentation date: 2010.09

  • Creation of Mondispersed Nanoparticles by Reaction Crystallization in the Polyelectrolyte Environment

    NCCG-39 

    Presentation date: 2009.11

  • Crystallization Engineering Contributing to Creation of Highly Functional Materials

    SCEJ Autim Meeting 

    Presentation date: 2009.09

  • Creation of Nanocrystals in the Polyelectrolyte Environment

    SCEJ Yonezawa Regional Meeting 

    Presentation date: 2009.08

  • Polymorh and pseudopolymorph transformation of organic crystals

    PXE Forum 2009 Japan 

    Presentation date: 2009.07

  • Induction of primary nucleation of supercooled PCM by ultrasonic irradiation

    Annual meeting of SSPEJ 2009 

    Presentation date: 2009.06

  • New Develoment of Creating Crystals- Pharmaceutical and Food

    Lecture Meeting on Hot Talks 

    Presentation date: 2009.05

  • Application of ultrasonic irradiation to control crystallization

    International Forum of Crystallization Engineering &amp; DDS 2009 

    Presentation date: 2009.04

  • Crystallization Engineering Contributing to Production

    Annual Meeting of SCEJ 

    Presentation date: 2009.03

▼display all

Specific Research

  • 難溶解性有機物結晶のナノサイズ化

    2016  

     View Summary

    研究成果を、2016年9月、ドイツ/マグデブルグで開催されたBIWIC2016、2017年3月 化学工学会第82年会にて学会発表した。

  • 晶析工学による金属ナノ粒子粒径制御

    2013  

     View Summary

    ナノサイズ領域の金属粒子創製法として、過飽和度制御で還元晶析を行う手法を提案し、原料供給速度、溶液内環境(pH、種結晶量)が還元晶析過程いおける核化、成長に及ぼす影響を解明し、希望の形状、粒径分布を有するナノ金属懸濁液を得るための最適操作条件を確立した。従来、単分散ナノ金属を創製する手法として、塩基性高分子電解質であるPEIを用いることを提案したが、100nm-400nmの粒子を制御することができず、原料供給速度、溶液内環境(pH、種結晶量)を最適条件にすることで、100nm-400nmの粒子を、自在に生成することが可能になり、粒径分布幅も狭くすることを達成できた。これにより、簡易に金および白金の粒子を還元晶析生成する手法およに戦略を提案できた。当研究室の成果を評価した農林省農業生物資源研究所より、葉緑体への遺伝子導入用担体として、所定粒径の金ナノ粒子の調整を依頼され、要望のものが作成でき、植物形質転換用粒子し、適用しすぐれた導入効率を達成した。未発達なプロプラスチドへの形質転換効率の向上を将来的な目的とし、従来使用されている金粒子よりも微小なサイズの金粒子を作成し、葉緑体形質転換法へ利用可能であるかを検討した。まず、微小金粒子の作成はシングルジェット法で行い、溶媒にはアスコルビン酸溶液を用いる条件を検討した。その結果、平均粒径0.067±0.016 ミクロンメータ (最大粒径0.119 &#61549;ミクロンメータ, 最少粒径0.032 &#61549;ミクロンメータ)の金粒子(以降、微小金粒子と記載)を作出することができた。次に、微小粒子によるタバコの葉緑体形質転換実験を行った。その際、0.6 ミクロンメータの金粒子(BioRad社)をコントロールとした。導入ベクターには選抜マーカー遺伝子であるaadAおよびGFPを発現するpNtagを作成して用いた。1プレートにつきタバコ葉片(5 mm角)を約50個並べ、pNtagを2&#61472;&#61549;g塗布した金粒子を2回導入した後、スペクチノマイシン500 mgL-1を含む再分化培地において選抜を行った。2プレートへの遺伝子導入を1実験とし、3反復実験を行った。微小金粒子をヘリウムガス圧1,100 psiで導入したところ、1実験平均3.3±1.2個体の葉緑体形質転換体が得られ、1,350 psiの条件では2.3±0.9個体得られた(表1)。0.6ミクロンメータの金粒子においては1実験平均4.7±3.4個体であった(表1)。これより、微小金粒子を用いた場合においても0.6ミクロンメータの金粒子と効率に有意差がなく葉緑体形質転換体が作出できることがわかり、これまで困難と思われたプロプラスチドへの遺伝子導入へ利用できる可能性が示された。今後、微小金粒子の作成条件のさらなる改良、遺伝子導入条件の最適化を行うことで、これまで技術が確立されていない植物種における葉緑体形質転換系の確立が期待できる。粒子の表面状態も、pHや熟成状態で制御できるめどができ、さらなる精密制御の道が開けた。

  • 反応晶析工学による金属ナノ粒子の形状制御

    2012  

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     本申請の課題では、金属イオン(金および白金)を対象に、還元剤の存在下に還元晶析を行い、希望の粒径および粒径分布を有する金属ナノ粒子を積み上げるための最適な原料供給制御手法を明らかにする。回分反応晶析法により、還元剤の存在下に、原料供給条件(原料注入速度、注入量、注入時間を工夫することにより、金や白金の微粒子粒径制御(50-400nm)に成功した。微小金粒子の作成はシングルジェット法で行い,溶媒にはアスコルビン酸溶液を用いる条件を検討した.その結果,0.3 μm以下の平均粒径を持つ金粒子を段階的に作成することに成功した. 次に,作出した平均粒径約0.08, 0.1, 0.2および0.3 μm金粒子を用いて葉緑体形質転換への利用が可能であるか検討するため,モデル植物であるタバコを材料として遺伝子導入を行った.その際,粒径0.6&#61472;&#61549;mとして販売されている金粒子(BioRad社)をコントロールとして用いた.葉緑体形質転換ベクターには,選抜マーカー遺伝子であるaadAおよびGFPを発現するpNtag (Okuzaki and Tabei, in press) を用い,各粒径の金粒子に塗布してそれぞれ4プレートに導入した.スペクチノマイシン選抜を行い,1シャーレあたりに得られた葉緑体形質転換体の作出効率を比較した.その結果,粒径0.3 μm以下の全ての粒径を用いた場合において,葉緑体形質転換効率が粒径0.6μmの結果を上回った.最も効率が高かったのは粒径0.3 μmを用いた場合で,1シャーレあたり約9個体の葉緑体形質転換体が得られ,0.6&#61472;&#61549;mと比べて形質転換効率が約2倍となった.以上の結果より,本研究で作出した微小金粒子を利用することで,プロプラスチドへの遺伝子導入効率の向上や,まだ葉緑体形質転換技術が確立されていない植物種における葉緑体形質転換系の開発が期待される.植物形質転換は、(独)農業生物資源研 田部井、奥崎氏との共同研究により推進した。この成果は、国際誌Plant Biotechnology に採択された。

  • 高分子凝集抑制剤を使用した難溶性塩の超微粒子生成プロセスの確立

    2004  

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    ナノ結晶の用途開発が進展しつつあり、希望の品質を有するナノ結晶を効率的に生産することが求められる。そのための一つの戦略として、高分子電解質の存在下で、反応晶析を行う手法を提案している。ここでは、硫酸鉛の反応晶析系を対象に、結晶の生成過程を動的に追跡し、特に塩基性ポリマーであるポリエチレンイミン(PEI)と鉛イオンの相互作用や、高分子による生成結晶の保護作用が、単分散ナノ結晶の創製に寄与することを、核化、成長挙動に基づいて検討した。ダブルジェット半回分反応晶析実験装置を用いて、PEIの存在下に、硫酸鉛の反応晶析を行った。 PEIの存在下、反応晶析をした過程での鉛イオンの濃度変化は、ある時間まで若干の上昇傾向を示すが、その後、急速に濃度低下していた。この濃度が低下する時間は、目視における核化の待ち時間とほぼ一致していた。一方、PEIを添加しない場合は、反応原料を供給した時点から、濃度低下することを見いだした。このことから、鉛イオンは、溶液中に自由に存在するのではなく、PEIの表面に弱い結合で保持され、このことが核化を大幅に遅延させていることが考えられた。鉛イオンが、PEIのイミン基に錯体結合していることは、NMRスペクトルの結果により示唆された。このように、PEIを反応晶析過程で存在させることにより、見かけ上、準安定域の幅を大幅に広げ、このことが大量の瞬時の核化につながり、ナノ結晶の創製に寄与したと考える。また、イミン基のサイトでの核化、成長が、ナノ結晶同士の凝集を抑制していることも示唆された。PEIの添加量 (W) が一定の条件下では、濃度が急激に低下する点(屈曲点と呼ぶ)は、供給流量、供給原料の濃度、過剰に添加した鉛モル数によらず、核発生までに装置内に存在する鉛の総モル数(Ntot) は、ほぼ一定の値となった。このように、Ntotは、PEIの添加量でほぼ一義的に決まり、屈曲点、つまり核発生数は、PEIの添加量で制御できることになる。

  • 潜熱蓄熱材の一次核生成に及ぼす超音波の影響

    1999  

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     申請者は、特定課題(研究課題番号99A-176)の助成を受け、潜熱蓄熱材の一次核発生に及ぼす超音波の影響について、研究を行った。潜熱蓄熱材は、夜間の余剰エネルギー、未利用の熱源を、回収する材料として、注目されている。しかしながら、この材料を融点以下に冷却しても、融液が過冷却状態で、安定化し、結晶が生成せず、熱の放出過程が不安定になる。このような状況を解消するために、核発生を促進する発核剤の研究がなされているが、蓄熱容量が大きな材料では、しばしば発核剤がなく、蓄熱剤としても適用が見送られていた。そこで、申請者は、発核を促進される手段として、超音波の適用を提案し、リン酸1水素2ナトリウム・12水和物を対象に、超音波照射が、核発生に及ぼす影響について検討した。実験は、恒温槽に浸漬した超音波センサー付き回分晶析槽を用いて行い、所定の過冷却度に調整した融液に、20kHZの超音波を照射強度を変化させて照射し、核化・成長の過程を観察するとともに、核発生のための待ち時間、初期の発熱速度を実測し、超音波照射の核生成に及ぼす影響を解析した。この結果、超音波を照射した場合、融点36℃で、100%の発核確率で、一次核生成が生起し、超音波照射無しでは、発核のために17-23℃の過冷却度を要し、発核確率も分布を持った。また、核発生のための待ち時間は、超音波出力と反比例の関係となることを見いだすとともに、核化に必要な最小照射強度が存在することを明らかにした。さらに、初期の発熱過程について解析し、初期の発熱速度が、一次核の発生速度と比例する概念を導出し、照射強度により一次核発生速度が制御できることを提示した。本研究により、リン酸1水素2ナトリウム・12水和物を蓄熱材に用いた場合、超音波照射により、過冷却度0℃で、核化させることが可能となり、照射強度により、発熱過程も制御できるという新規な知見を見いだした。

  • 排水からのジクロロメタン除去・回収プロセスに関する研究

    1997  

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    溶剤としてジクロロメタンを使用する実験室の排水を想定し、模擬排水を対象に除去回収実験を行った。排水濃度0.3-100mg/lの範囲の所定濃度の排水を、通水速度120m/dayで、充填塔(充填物テラレット)の上部より通液し、塔底部より、空気を、ガス液比を変化させて、流し、液中のジクロロエタンの除去(放散)特性を調査した。いずれの濃度レベルにおいての、ガス液比が、3000倍を越えると、排水の基準値0.2mg/lを満足した。同時に、充填物の高さが1mを越えると、液の偏流がおこり、除去効率を高めるには、充填物1mごとに、液分散版を設ける必要があることを明らかにした。以上より、排水と空気を接触させることにより、ジクロロエタンを放散除去できること、および、そのような放散塔を設計するための因子を明らかにした。しかしながら、この方式では、ジクロロエタンを大気中に放散させることになるので、放散塔より流出する空気を活性炭吸着塔で処理する実験を行った。活性炭層に排ガスを空間速度5-501/hの間の所定の値に設定し流通させ、排ガス中の濃度を測定したところ、空間速度301/hより低い条件下では、ジクロロエタンは不検出であった。破過曲線を、各実験で求め、活性炭の吸着容量は、200mg/g-活性炭となり、これより、所定条件下における再生頻度を算出した。上記の結果より、放散塔と活性炭吸着塔からなら、ジクロロエタン除去プロセスを提案し、各工程の設計因子を明らかにした。研究成果の発表1999年3月(予定) 水質汚濁研究あるいは産業環境管理協会誌

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