2022/11/26 更新

写真a

ヒラサワ イズミ
平沢 泉
Scopus 論文情報  
論文数: 0  Citation: 0  h-index: 11

Citation Countは当該年に発表した論文の被引用数

所属
理工学術院 先進理工学部
職名
教授

他学部・他研究科等兼任情報

  • 理工学術院   大学院先進理工学研究科

学内研究所・附属機関兼任歴

  • 2020年
    -
    2022年

    理工学術院総合研究所   兼任研究員

学歴

  •  
    -
    1978年

    早稲田大学   理工学研究科   応用化学  

  •  
    -
    1976年

    早稲田大学   理工学部   応用化学科  

学位

  • 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

▼全件表示

経歴

  • 2013年
    -
     

    早稲田大学   環境保全センター   所長

  • 2013年
    -
     

    早稲田大学   環境保全センター   所長

  • 1995年
    -
    1996年

    , 2004-2006 、2009-2011中央環境対策審議会 委員

  • 1995年
    -
     

    早稲田大学 教授

  • 1989年
    -
    1994年

    早稲田大学 助教授

  • 1978年
    -
    1989年

    荏原インフィルコ荏原総研 主任研究員

▼全件表示

所属学協会

  •  
     
     

    分離技術会

  •  
     
     

    アメリカ化学工学会

  •  
     
     

    日本化学会

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    水環境学会

  •  
     
     

    日本結晶成長学会

  •  
     
     

    化学工学会

  •  
     
     

    海水学会

  •  
     
     

    化学工学会

  •  
     
     

    海水学会

  •  
     
     

    化学工学会

  •  
     
     

    化学工学会

  •  
     
     

    ヨーロッパ化学工学連合

  •  
     
     

    日本原子力学会

▼全件表示

 

研究分野

  • 反応工学、プロセスシステム工学

研究キーワード

  • 晶析,排水処理,蓄熱、化学工学一般、環境保全、分離・精製・検出法

論文

  • 潜熱蓄熱材Na2HPO4·12H2O融液の相分離現象の観察とその発生機構に関する考察

    渡邉 裕之, 平沢 泉

    化学工学論文集   48 ( 4 ) 152 - 160  2022年

     概要を見る

    リン酸水素二ナトリウム12水塩は室内の空調や床暖房,特に医療用途への適用が期待される潜熱蓄熱材であるが,それとは結晶水の数が異なる7水塩は12水塩の融点より高い温度で安定に存在しうるので,長期にわたる蓄熱・放熱の繰返しにおいて12水塩の融液中に晶析して蓄積し,潜熱量の減少を引き起こす.本研究ではこのような相分離の発生を抑制するため,12水塩に熱サイクルを加えたときの融解凝固挙動を詳細に観察した.その結果,相分離の発生は潜熱量の減少のみならず核化温度の低下をもたらすことが明らかになった.この7水塩の晶析による相分離の発生は,7水塩の溶解過程における拡散速度の低下に起因しているとみられ,たとえば蓄熱装置に撹拌機構を設けるなど,融液中に形成されるNa2HPO4成分の濃度分極を解消すれば7水塩の液相線は実質的に消滅し,相分離の発生を防止できることが示唆された.

    DOI

    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年

     概要を見る

    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年12月

     概要を見る

    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

    3
    被引用数
    (Scopus)
  • 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年08月  [査読有り]  [国際誌]

    担当区分:最終著者

     概要を見る

    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
    被引用数
    (Scopus)
  • 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年07月  [査読有り]

    担当区分:最終著者

     概要を見る

    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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  • 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年11月  [査読有り]

    担当区分:最終著者

     概要を見る

    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

    Scopus

  • 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年06月  [査読有り]

    担当区分:最終著者

     概要を見る

    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年06月  [査読有り]

    担当区分:最終著者

     概要を見る

    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
    被引用数
    (Scopus)
  • 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年06月

     概要を見る

    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
    被引用数
    (Scopus)
  • Partial Seeding Policy for Controlling the Crystal Quality in Batch Cooling Crystallization

    Joi Unno, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   43 ( 6 ) 1065 - 1071  2020年06月  [査読有り]

    担当区分:最終著者

     概要を見る

    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

    4
    被引用数
    (Scopus)
  • Parameter Estimation of the Stochastic Primary Nucleation Kinetics by Stochastic Integrals Using Focused-Beam Reflectance Measurements

    Joi Unno, Izumi Hirasawa

    CRYSTALS   10 ( 5 )  2020年05月  [査読有り]

    担当区分:最終著者

     概要を見る

    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

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    4
    被引用数
    (Scopus)
  • 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年03月  [査読有り]

    DOI

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    2
    被引用数
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  • 潜熱蓄熱材酢酸カリウム2水塩の融点と潜熱量の数値評価

    渡邉 裕之, 平沢 泉

    化学工学論文集   46 ( 2 ) 41 - 48  2020年

     概要を見る

    潜熱蓄熱材として利用が期待される酢酸カリウム2水塩の融点Tm=291 Kと潜熱量ΔHf=135 kJ/kgとの関係の必然性を明らかにするため,その化学構造式に着目し,両者の関係について定量的検討を試みた.まず,同一の陰イオンを有し陽イオンがNa+とK+である化合物同士で,水和塩の結晶水の数とその脱水転移温度とが明らかな組合せ4組を検討した.その結果,総じてその脱水転移温度はナトリウム塩に対しカリウム塩の方が20–50 K程度低くなることがわかった.また,結晶中のイオン半径に対する水溶液中のストークス半径の比が小さいほど,脱水転移温度,いわゆるTmが低くなる傾向を指摘した.次に,水和塩が融解するときのエントロピー変化量ΔSf(=ΔHf/Tm)を水単体の融解エントロピー変化量ΔSf,HOと水和塩中の結晶水の重量分率Φwとで関係づけ,これに基づきTmとΔHfとの関係を記述する簡便な関係式を導出した.この式を実測値(水和塩計18種)を用いて検証した結果,水和塩の化学構造式とそのTm値が決定されれば,±0.212の相対標準偏差でΔHf値を推算できることを明らかにした.またこれにより,酢酸カリウム2水塩のTmに対するΔHfの数値の必然性が確認された.

    DOI CiNii

  • 酢酸カリウム2水塩の潜熱蓄熱材特性

    渡邉 裕之, 平沢 泉

    化学工学論文集   46 ( 2 ) 33 - 40  2020年

     概要を見る

    水和塩系の化合物は単位体積当たりの蓄熱密度が高いことから,潜熱蓄熱材として期待されている.しかし,冷房空調用に適した温度範囲273–303 Kに融点を有するものは少なく,選択の範囲が限られていた.このため,新たな潜熱蓄熱材候補となりうる水和塩の探査を目的として,本研究では酢酸カリウムの水和物について温度と水和数との関係を検討し,潜熱蓄熱材としての可能性を調べた.まず,酢酸カリウム水溶液の直接観察の結果,一般に知られる0.5および1.5水塩の晶析特性を確認した.また,冷却温度を229 Kまで低下することによって酢酸カリウム2水塩が晶析することが示唆された.晶析した2水塩の融点は291 Kで,潜熱量は135 kJ/kgであった.この潜熱量の数値は,水和塩系で285–294 Kの範囲内に融点を有する他の冷房空調用途の候補素材6種のうちのほぼ中間的な位置にあり,それらと遜色がないことがわかった.

    DOI CiNii

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    3
    被引用数
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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年12月

     概要を見る

    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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    6
    被引用数
    (Scopus)
  • 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年07月

     概要を見る

    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

    Scopus

    8
    被引用数
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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年07月

     概要を見る

    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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    4
    被引用数
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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年06月

     概要を見る

    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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    3
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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年05月  [査読有り]

    DOI

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    5
    被引用数
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  • 無機水和塩系融液の融点降下特性における共通性

    渡邉 裕之, 平沢 泉

    化学工学論文集   45 ( 2 ) 91 - 99  2019年

     概要を見る

    潜熱蓄熱材として利用が期待される炭酸ナトリウム10水塩(融点Tm,0=304.5 K, 潜熱量ΔHf,0=153 kJ/kg, ともに実測値)および炭酸ナトリウム10水塩0.6 mol/molとリン酸水素二ナトリウム12水塩0.4 mol/molとの水和塩共晶(E(P–C);融点Tm,0=298 K, 潜熱量ΔHf,0=213 kJ/kg, ともに実測値)の2種水和塩系に対し,その融液に溶解可能な添加物を混合した系について,融点Tmおよび潜熱量ΔHfの変化を測定した.簡易的な実験式を用い,各添加物の融点降下能力ameおよび潜熱量低下能力bmeを数値化した.これら能力の数値は添加物ごとに異なったが,能力比率bme/ameは添加物の種類によらずほぼ同じ数値となって,水和塩系それぞれの固有値を示した.さらに,前報(Watanabe, 2017)およびその続報(Watanabe and Hirasawa, 2018b)で得られた塩化カルシウム6水塩系およびリン酸水素二ナトリウム12水塩系の各bme/ame値もあわせて比較検討した結果,水和塩単体のTm,0およびΔHf,0でそれぞれ規格化した相対融点降下度[1−(Tm/Tm,0)]と相対潜熱量低下度[1−(ΔHf/ΔHf,0)]との間には,水和塩系の種類に依存しない下式で表されるほぼ一定の数値関係が成立することがわかった.

    <img align="middle" src="./Graphics/abst-math31.png"/>

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  • リン酸水素二ナトリウム12水塩系融液の融点降下特性

    渡邉 裕之, 平沢 泉

    化学工学論文集   44 ( 6 ) 372 - 378  2018年11月

     概要を見る

    融点降下法による潜熱蓄熱材の適用温度範囲の拡大をねらい,特に医療用保温材などに利用されるリン酸水素二ナトリウム12水塩(融点Tm,0=308.5 K, 潜熱量ΔHf,0=227 kJ/kg, ともに実測値)の融液に溶解可能な添加物5種(リン酸三カリウム,リン酸水素二カリウム,リン酸二水素カリウム,リン酸二水素アンモニウムおよびリン酸二水素ナトリウム2水塩)を混合した系について,融点Tmおよび潜熱量ΔHfの変化を測定した.さらに前報(Watanabe and Hirasawa, 2017; Watanabe, 2017)で提案した,添加物濃度と融点降下度および潜熱量低下度との関係を記述する簡易的な実験式を用い,各添加物の融点降下能力および潜熱量低下能力を数値化した.これら能力の数値は添加物ごとに異なり,それぞれ固有値を示した.これに対し,融点降下度と潜熱量低下度との間には,添加物の種類に依存しない下式で表されるほぼ一定の数値関係が成立することがわかった.

    <img align="middle" src="./Graphics/abst-math1.png"/>

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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年06月

     概要を見る

    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年06月

     概要を見る

    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年06月  [査読有り]

     概要を見る

    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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    2
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  • 炭酸ナトリウム–リン酸水素二ナトリウム系水和塩混合物の共晶組成

    渡邉 裕之, 平沢 泉

    化学工学論文集   44 ( 3 ) 207 - 216  2018年

     概要を見る

    共晶法は,潜熱蓄熱材の融点を調整してその適用温度範囲を広げる有効な手法の一つである.ともに水和塩系蓄熱材である炭酸ナトリウム10水塩とリン酸水素二ナトリウム12水塩との混合によって生成する共晶の組成を明らかにするため,両水和塩混合系の擬二成分相図を作成した.加熱曲線によって決定された各混合組成における融点の分布から,相図は単純共晶型で,共晶の融点は298 Kであった.共晶組成を特定する手法として,融点降下の実験式を利用する方法と融解潜熱量の変化を利用する方法とをそれぞれ試みた.その結果,前者の手法ではリン酸水素二ナトリウム12水塩の混合モル分率として共晶組成が0.40 mol/mol, また後者では0.37–0.38 mol/molと見積もられた.この数値は,Watanabe and Hirasawa(2018)による混合水和塩の融液中における解離イオンの等価的交換によって共晶が形成するとする仮説から計算される数値0.4 mol/molとよく一致した.

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    6
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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年  [査読有り]

     概要を見る

    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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    18
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  • ニッケル・コバルト水和塩混合融液からの共晶形成

    渡邉 裕之, 平沢 泉

    化学工学論文集   44 ( 1 ) 3 - 11  2018年

     概要を見る

    共晶法は,潜熱蓄熱材の融点を調整してその適用温度範囲を広げる有効な手法の一つである.水和塩混合系における共晶組成の必然性を明らかにするため,硝酸ニッケル6水塩–塩化コバルト6水塩ならびに塩化ニッケル6水塩–硝酸コバルト6水塩の二成分混合系2種について擬二成分相図を作成した.加熱曲線から決定された各水和塩の融点は,それぞれ順に53.5, 53, 51.5そして53.5°Cであった.また両相図とも単純共晶型で,等モル混合で生成した共晶の融点は共に同じ30°Cであった.混合系の結晶組成は混合比率に対応して変化したが,混合前の当初6水塩には帰属されない新たな結晶相も晶析し,その比率は共晶組成において最大となった.生成した各共晶の粉末X線回折パターンは一致しており,両者は同一結晶組成にあることがわかった.解離イオンの等価的交換による共晶形成機構が提案された.また,すべての解離イオンに対して対イオンが相互に等価的数量関係を維持し得る混合比率が,共晶組成であることが示唆された.

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  • エリスリトールの過冷却特性に対する塩添加の影響

    鈴木 基啓, 町田 博宣, 里見 颯斗, 平沢 泉

    化学工学論文集   44 ( 1 ) 12 - 17  2018年

     概要を見る

    本研究では,エリスリトールの過冷却特性に対する塩添加の影響について検討を行うことにより,高い蓄熱密度を有し,かつ,室温環境下においても過冷却を保持し得る新規な糖アルコール系の潜熱蓄熱材を創出し,その過冷却保持のメカニズムを明らかにした.具体的には,エリスリトールの添加剤として,カチオン種,アニオン種とその価数の異なる塩について,各々の添加量をパラメータに,結晶化開始温度,過冷却保持時間の評価を行うとともに,エリスリトールと添加剤との相互作用に着目して,核磁気共鳴(NMR)装置を用いて過冷却保持のメカニズム検討を行った.その結果,エリスリトールの添加剤として,1価のアニオンを含む塩は,過冷却保持,2価のアニオンを含む塩は,過冷却抑制に有効であり,カチオン種の影響は,アニオン種と比較して小さいことが明らかとなった.また,室温環境下において,エリスリトールの過冷却を保持するための添加剤として,アニオンとして酢酸イオンを含む塩を抽出し,結晶化開始温度の低下,および過冷却保持の長時間化は,エリスリトールのヒドロキシ基と酢酸イオンの相互作用に起因すると推察した.

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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年10月  [査読有り]

     概要を見る

    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年07月  [査読有り]

     概要を見る

    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年07月  [査読有り]

     概要を見る

    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年07月  [査読有り]

     概要を見る

    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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    14
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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年07月  [査読有り]

     概要を見る

    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

    Nagao, Hideyuki, Ichiji, Masumi, Hirasawa, Izumi

    Chemical Engineering and Technology   40 ( 7 ) 1242 - 1246  2017年07月  [査読有り]

     概要を見る

    © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Sub-10-nm-sized Pt nanoparticles were synthesized by reducing Pt ions with NaBH 4 , 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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    21
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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年07月  [査読有り]

     概要を見る

    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年07月  [査読有り]

     概要を見る

    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年07月  [査読有り]

     概要を見る

    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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  • 塩化カルシウム6水塩の融点降下度と添加物混合量との関係

    渡邉 裕之, 平沢 泉

    化学工学論文集   43 ( 2 ) 129 - 137  2017年  [査読有り]

     概要を見る

    <p>本研究は,潜熱蓄熱材として利用される塩化カルシウム6水塩(融点302 K, 実測値)の融点調整手法に関するものである.塩化カルシウム6水塩融液に溶解可能な物質を添加すると,融液の融点はその添加量に応じて降下するので,潜熱蓄熱材としての適用可能な温度範囲を広げることが期待される.しかし,この融点降下度は添加物の種類によって異なり,一般に知られる希薄な電解質水溶液系における融点降下に関する理論式からでは予測ができない.そこで,本報では添加物の融点降下能力を定量的に評価するための実験式の導出を試みた.塩化カルシウム6水塩融液に溶解する添加物9種について,それぞれの添加量に対する融点の変化を実測し,添加物の融点降下能力を簡易的な実験式を用いて数値化した.さらに,この融点降下能力が融液中で完全解離した添加物イオンによる相乗的な作用と仮定して,各解離イオンの融点降下能力を定量化し,これらの数値を用いて融点降下度を算出する簡易的な方法を提案した.</p>

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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年  [査読有り]

     概要を見る

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

    Hiroshi Kitano, Takayuki Tanaka, Izumi Hirasawa

       2016年12月

  • 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年12月

  • 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年04月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    4
    被引用数
    (Scopus)
  • 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年04月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    4
    被引用数
    (Scopus)
  • 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年02月

     概要を見る

    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.

    DOI CiNii

    Scopus

    2
    被引用数
    (Scopus)
  • 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年02月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    2
    被引用数
    (Scopus)
  • Heterogeneous precipitation of gold particles on silica gel

    Takashi MIKAMI, Chisato KONNO, Yuta TAKAYASU, Izumi HIRASAWA

    Journal of Chemical Engoneers of Japn   49 ( 2 ) 186 - 190  2016年02月  [査読有り]

    DOI

    Scopus

    2
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    11
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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
    被引用数
    (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年06月

     概要を見る

    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
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    11
    被引用数
    (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年05月

    担当区分:最終著者

  • 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年08月  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Polyacrylic Acid-Assisted Crystallization Phenomena of Carbonate Crystals

    Hiroto Watamura, Yuko Sonobe, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   37 ( 8 ) 1422 - 1426  2014年08月  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Polyacrylic Acid-Assisted Crystallization Phenomena of Carbonate Crystals

    Hiroto Watamura, Yuko Sonobe, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   37 ( 8 ) 1422 - 1426  2014年08月  [査読有り]

     概要を見る

    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
    被引用数
    (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年08月  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Effects of detector sensitivity and resolution on induction time reading

    Noriaki Kubota, Masanori Kobari, Izumi Hirasawa

    CRYSTENGCOMM   16 ( 6 ) 1103 - 1112  2014年  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Effects of detector sensitivity and resolution on induction time reading

    Noriaki Kubota, Masanori Kobari, Izumi Hirasawa

    CRYSTENGCOMM   16 ( 6 ) 1103 - 1112  2014年  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • A population balance model fot solvent-mediated polymオrphic transformation in unseeded solution

    M. Kobari, N. Kubota, I. Hirasawa

    CrystEngComm   16 ( 27 ) 6049 - 6058  2014年  [査読有り]

    DOI

    Scopus

    11
    被引用数
    (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年12月

     概要を見る

    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
    被引用数
    (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年12月

     概要を見る

    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
    被引用数
    (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年10月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    154
    被引用数
    (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年10月

    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年08月

     概要を見る

    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
    被引用数
    (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年08月

  • 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年06月

     概要を見る

    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.

    DOI

    Scopus

    12
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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
    被引用数
    (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年06月

  • 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年06月  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Polyelectrolyte effects on the Crystallization Phenomena of Lithium Carbonate

    H. Watamura, I. Hirasawa

    Journal of Crystal Growth   373 ( 15 ) 111 - 117  2013年06月

  • 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年03月  [査読有り]

     概要を見る

    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
    被引用数
    (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年03月

     概要を見る

    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.

    DOI

    Scopus

    5
    被引用数
    (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年03月

     概要を見る

    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

    Scopus

  • 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年03月  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年

     概要を見る

    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
    被引用数
    (Scopus)
  • Impurities Effect on Carbonate Reactive Crystallization for the Wastewater

    Y. Shimizu, Izumi Hirasawa

    ISRN Chemical Engineering   2013  2013年01月

    DOI

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

    Takashi Mikami, Izumi Hirasawa

    Chemical Engineering &amp; echnology   36 ( 1 ) 1 - 8  2013年01月

  • 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年  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Efficient plastid transformation in tobacco using small gold particles (0.07&#8211;0.3μm)

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

    Plant Biotechnology   30 ( 1 ) 65 - 72  2013年  [査読有り]

    DOI

    Scopus

    10
    被引用数
    (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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年

     概要を見る

    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

    154
    被引用数
    (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年09月  [査読有り]

     概要を見る

    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
    被引用数
    (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年09月

  • Recovery of Ionic Substances from Wastewater by Seeded Reaction Crystallization

    Yoshiharu Shimizu, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   35 ( 6 ) 1051 - 1054  2012年06月  [査読有り]

     概要を見る

    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
    被引用数
    (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年06月  [査読有り]

     概要を見る

    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

    28
    被引用数
    (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年06月

  • 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年06月

  • 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年04月  [査読有り]

     概要を見る

    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
    被引用数
    (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年04月  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • 超音波を用いた晶析制御の展開(最前線,<特集>クリスタルエンジニアリング)

    平沢 泉

    ファルマシア   47 ( 11 ) 1024 - 1027  2011年11月

    DOI CiNii

  • 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年11月

  • 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年05月

  • 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年05月

  • 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年04月  [査読有り]

     概要を見る

    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
    被引用数
    (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年04月  [査読有り]

     概要を見る

    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
    被引用数
    (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年04月  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Removal of liquid and solid impurities from uranyl nitrate hexahydrate crystalline particles in crystal purification process

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

    Journal of Nuclear Science and Technology   48 ( 3 ) 322 - 329  2011年03月  [査読有り]

    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年02月  [査読有り]

    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年  [査読有り]

     概要を見る

    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年  [査読有り]

     概要を見る

    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年  [査読有り]

     概要を見る

    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年  [査読有り]

     概要を見る

    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年  [査読有り]

     概要を見る

    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年  [査読有り]

     概要を見る

    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年09月  [査読有り]

     概要を見る

    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

    22
    被引用数
    (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年09月  [査読有り]

     概要を見る

    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
    被引用数
    (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年09月  [査読有り]

     概要を見る

    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
    被引用数
    (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年09月  [査読有り]

     概要を見る

    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

    22
    被引用数
    (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年09月  [査読有り]

     概要を見る

    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
    被引用数
    (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年09月

     概要を見る

    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
    被引用数
    (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年08月

    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年08月

  • 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年07月

  • 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年06月

    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年05月  [査読有り]

     概要を見る

    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
    被引用数
    (Scopus)
  • Quality-Controlled Reactive Crystallization of SrSO4 To Produce High-Valued Chemicals

    Takashi Mikami, Izumi Hirasawa

    CHEMICAL ENGINEERING & TECHNOLOGY   33 ( 5 ) 775 - 779  2010年05月  [査読有り]

     概要を見る

    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
    被引用数
    (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年05月

  • 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年05月

    CiNii

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

    Mikami T, I. Hirasawa

    Chemical Engineering &amp; Technology   33 ( 5 ) 797 - 803  2010年05月

  • 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年04月  [査読有り]

  • 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年

     概要を見る

    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年

     概要を見る

    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年01月  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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年01月

  • 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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年  [査読有り]

     概要を見る

    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年10月

  • 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年03月

  • 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年

    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年

    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年

    DOI CiNii

  • Application of Ultrasonic Irradiation to Control Crystallization

    Izumi Hirasawa

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

  • 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年01月

  • メタン発酵液からのリン回収プロセスにおける晶析操作

    島村 和彰, 黒澤 建樹, 平沢 泉

    化学工学論文集   35 ( 1 ) 127 - 132  2009年  [査読有り]

     概要を見る

    固形物のメタン発酵処理では,窒素,リンを高濃度に含む消化液が発生する.筆者等は,水処理系のリン負荷低減,メタン発酵槽内部やその周辺機器のスケール防止,リン資源の回収を目的として,消化液からリン酸マグネシウムアンモニウム(MAP)を積極的に析出させて回収するプロセスを考案した.プロセスは,晶析工程,液体サイクロンによる分離工程,洗浄工程,低温乾燥工程からなる.本報では,固形物濃度が数%含まれる消化液を対象としたMAPの最適な晶析操作条件と乾燥条件を把握すると共に,処理量2 m3/hの実規模スケールの装置を作製し,16か月に渡り実証試験を行った結果を報告する.<br>MAPを液体サイクロンで分離するために,晶析工程では核発生を抑制する必要がある.ラボ実験より,リアクタ内のMAPの流動状態を良好に保つこと,低過飽和度で操作すること,種晶充填量あたりのMAP晶析速度を適切に保つことで,MAPの核化が抑制され,結晶成長が優先的となることを見出した.また,乾燥工程では,乾燥温度を70&deg;C以下にすることでMAPは転移することなく現状の形態を維持できることが明らかとなった.一連のプロセスの実証試験において,晶析工程でのPO4&ndash;P除去率は85%以上であり,良好に反応を行うことができた.また,反応したリンのうち,核化した割合は約10%であり,反応したリンの約90%は種晶表面で成長したので,良好に消化液からMAPを分離することができた.乾燥工程から回収したMAPの含水率は0.1%以下,MAPの純度は92.6%,有害金属の含有量は肥料取締り法で定める基準値以下であったことから,MAPの肥料製品としての高い品質を保っていることが確認できた.

    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年  [査読有り]

     概要を見る

    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年11月

    CiNii

  • Polymorph control of sulfamerazine by ultrasonic irradiation

    Masahiro Kurotani, Izumi Hirasawa

    JOURNAL OF CRYSTAL GROWTH   310 ( 21 ) 4576 - 4580  2008年10月

     概要を見る

    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

    34
    被引用数
    (Scopus)
  • 材料界面 晶析

    平沢 泉

    化学工学   72 ( 10 ) 579 - 580  2008年10月

    CiNii

  • Crystallization technology to create nanocrystals

    Izumi Hirasawa, Takashi Mikami

    Jouranl of the Japan Society of Color Material   81 ( 5 ) 161 - 164  2008年05月

    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年

    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年

    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年

    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年01月

     概要を見る

    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年  [査読有り]

     概要を見る

    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
    被引用数
    (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年10月

  • 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年09月

  • 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年08月

  • 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年06月

  • 晶析法による有用元素の回収

    平沢 泉

    分離技術   57 ( 3 )  2007年05月

  • Preparation of Blue-Flluorescing Chloroapatite Powder in Methanol

    Akio Tanahashi, Izumi Hirasawa

    World Journal of Chemical Engineering   2007 ( 1 ) 35 - 43  2007年05月

  • 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年05月

  • 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年04月

    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年04月  [査読有り]  [国際誌]

     概要を見る

    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
    被引用数
    (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年03月

  • 晶析技術を用いた下水汚泥からのリン資源回収プロセスの開発

    島村 和彰, 水岡 亜聖, 石川 英之, 平沢 泉

    環境工学研究論文集   44   673 - 678  2007年

     概要を見る

    下水放流水のリン濃度低減、リン資源回収の観点からリンを除去・回収する方法として、リン酸マグネシウムアンモニウム (MAP) の形態で回収するMAP法がある。筆者らは、消化汚泥に直接マグネシウムを添加してMAPを晶析・分離回収するプロセスを開発した。本プロセスについて、基本的な晶析操作条件の検討、パイロットスケールの実証試験、実機スケールの実証試験を行ったところ、消化汚泥の全リンの30%以上、結晶化したリンの95%以上に相当する量を回収することができた。また、このプロセスを処理量21, 000m3/dの嫌気性消化槽を有する下水処理場に設置した場合、放流水のリン濃度の30%以上を低減可能であること、315kg/dのMAPを回収可能であることを示した。更に、消化槽内のスケール抑制の可能性を見出した。

    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年

    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年

    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年11月

    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年11月

  • ナノ結晶生成のための戦略

    平沢 泉

    研究情報誌M&amp;E   ( 11 )  2006年11月

  • 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年10月  [査読有り]

     概要を見る

    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
    被引用数
    (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年09月  [査読有り]

     概要を見る

    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

    50
    被引用数
    (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年04月  [国際誌]

    PubMed

  • Strategy to Obtain nm Crystals through Precipitation of Polyelectrolyte

    Izumi Hirasawa, Takashi Mikami

    Chem. Eng. Technol.   29 ( 2 ) 1 - 4  2006年02月

  • 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年02月  [査読有り]

     概要を見る

    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
    被引用数
    (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年

    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年

    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年01月

  • フッ化カルシウム晶析法に適用可能なフッ素イオン濃度範囲の検討

    金子 四郎, 平沢 泉

    化学工学論文集   31 ( 6 ) 399 - 403  2005年11月

     概要を見る

    フッ素イオンを晶析法により分離除去する方法において,晶析に適用できるフッ素イオン濃度とカルシウムイオン濃度の範囲を検討した.まず,種晶を添加しない実験で,初期フッ素イオン濃度とカルシウムイオン濃度を変えて,撹拌後のフッ素イオン濃度を検討して,フッ素イオンがカルシウムイオンと反応してフッ化カルシウムの沈殿を生成してフッ素イオン濃度が低下しはじめるときの初期フッ素イオン濃度とカルシウムイオン濃度の関係を求めた.次に,種晶を添加した実験を,種晶を添加しない実験と同一条件で行って,フッ素イオンがカルシウムイオンと反応してフッ化カルシウム結晶を種晶上に析出してフッ素イオン濃度が低下しはじめるときの初期フッ素イオン濃度とカルシウムイオン濃度の関係を求めた.この両者の実験結果から,フッ化カルシウムの過溶解度線を作成して,溶解度線と過溶解度線の間の準安定域を明らかにした.この結果から,晶析可能なフッ素イオン濃度は,3 mmol/l以下であることがわかった.<br>実験後のフッ化カルシウム結晶のXRDを測定した.その測定結果から,実験後のフッ化カルシウム結晶のメインピーク値が文献値と一致し,フッ化カルシウムであることが確認できた.

    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年08月  [国際誌]

    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年

    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年

    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年11月

     概要を見る

    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
    被引用数
    (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年11月

     概要を見る

    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
    被引用数
    (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年11月  [査読有り]

     概要を見る

    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年11月  [査読有り]

     概要を見る

    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年11月  [査読有り]

     概要を見る

    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年09月  [査読有り]

     概要を見る

    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年04月  [査読有り]

     概要を見る

    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年04月  [査読有り]

     概要を見る

    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.

  • 無電解ニッケルめっき老化液処理への還元晶析法の適用 : 反応挙動に対する種晶比表面積の影響

    堀川 健, 平沢 泉

    表面技術 = The journal of the Surface Finishing Society of Japan   53 ( 3 ) 203 - 207  2002年03月

     概要を見る

    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

  • 還元晶析法による無電解ニッケルめっき老化液からのNiイオン除去・回収技術

    堀川 健, 平沢 泉

    CREATIVE   ( 345-52 )  2002年03月

  • 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年02月

     概要を見る

    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年02月

     概要を見る

    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年02月  [査読有り]

     概要を見る

    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年

     概要を見る

    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

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    14
    被引用数
    (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年

     概要を見る

    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

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    14
    被引用数
    (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年10月

     概要を見る

    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
    被引用数
    (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年10月

     概要を見る

    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
    被引用数
    (Scopus)
  • A present Study of Wastewater treatment of Electroless Nickel Plating

    平沢 泉

    Surface Technology   52/1,62-63 ( 1 ) 62 - 63  2001年01月

    担当区分:最終著者

    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年12月

    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年

     概要を見る

    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

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    26
    被引用数
    (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年

     概要を見る

    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

    26
    被引用数
    (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年07月  [査読有り]

     概要を見る

    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.

  • 晶析プロセスの動向

    平沢 泉

    日本海水学会誌   53 ( 3 ) 142 - 147  1999年06月

    DOI CiNii

  • 開催の経緯

    平沢 泉

    日本海水学会誌   53 ( 3 ) 132 - 135  1999年06月

    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

    平沢 泉

    分析化学   48/8,797-801  1999年03月  [査読有り]

    担当区分:最終著者

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

    Hisashi Kambe, Toshimichi Shibue, Izumi Hirasawa

    Bunseki Kagaku   48 ( 8 ) 797  1999年

     概要を見る

    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年  [査読有り]

     概要を見る

    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年03月

    担当区分:最終著者

     概要を見る

    最近, 一般廃棄物最終処分場で浸出水中のカルシウムが問題となっている。本研究ではカルシウムイオン濃度1.2から14.1mol・m-3までの原水の軟化処理を種晶に高炉スラグを用いたペレット流動床法により行った。軟化処理の薬剤には水酸化ナトリウムと炭酸水素ナトリウムを用いた。晶析反応は即時に完結し, 最初のサンプリング位置 (0.1m) でカルシウム濃度は装置出口濃度まで低下した。<BR>カルシウムイオンの除去率は49%から60%であった。処理水の濁度は30度以下で, pHは7.6から8.0の範囲であった。流動層内は完全混合とみなせたので, 次の簡易特性モデル式を適用することができた。<BR>Co-C=Ko・C・θ<BR>Co: 原水カルシウムイオン濃度 [mol・m-3] C: 処理水カルシウムイオン濃度 [mol・m-3]<BR>θ: 滞留時間 [h] Ko: カルシウムイオン除去速度定数 [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年

     概要を見る

    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

    56
    被引用数
    (Scopus)
  • 水処理分野における晶析

    平沢 泉

    化学工学   55/4   202 - 203  1991年04月

    担当区分:筆頭著者

  • 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年02月

  • 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年

     概要を見る

    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

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    3
    被引用数
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  • 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Ⅱ

    平沢 泉

    下水道協会誌   18/204

  • 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

▼全件表示

書籍等出版物

  • 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年10月 ISBN: 9784501630102

  • 有機結晶化学の進歩

    平沢 泉

    Springer  2015年09月

  • 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年12月

  • 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年10月

  • 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年10月

  • 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年10月

  • 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年03月

  • 化学便覧 応用化学編 分離と精製 晶析

    平沢 泉

    丸善  2014年01月

  • 化学工学便覧 その他の晶析操作と設計

    平沢 泉

    丸善  2012年09月

  • 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年11月

  • 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年08月 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年12月

  • 分離プロセス工学の基礎

    分担執筆

    朝倉書店  2009年03月

  • 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年02月

  • 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年01月

  • 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年11月

  • 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 

▼全件表示

Misc

▼全件表示

産業財産権

  • 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

    特許権

    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

    特許権

    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

    特許権

    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

    特許権

    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

    特許権

    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

    特許権

    J-GLOBAL

  • タンパク質の結晶化方法

    平沢 泉, 佐々木 俊輔, 島 有紀

    特許権

  • 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

    特許権

  • 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

    特許権

  • 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

    特許権

    J-GLOBAL

  • 液中のリン除去方法

    南 武, 鈴木 義明, 平沢 泉, 中村 弘志

    特許権

    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

    特許権

    J-GLOBAL

▼全件表示

Works(作品等)

  • 閉鎖性水域対策の戦略

    2008年10月
    -
    2009年03月

  • BNF暫定フォローアップ調査

    2008年09月
    -
    2009年03月

  • 環境負荷対策調査

    2008年03月
    -
     

  • 高度溶剤リサイクルシステムの形成に関する調査

    2008年03月
    -
     

  • 高度溶剤リサイクルシステムの形成に関する調査

    2007年03月
    -
     

  • 河川、沿岸、生活廃水に含まれる微量有害金属の除去技術に関する技術調査報告書

    2007年03月
    -
     

  • 閉鎖性海域環境対策に関わる調査研究

    2006年03月
    -
     

  • 海水中のCa及びMgイオンを利用した大量CO2の処理に関する研究技術面調査研究報告書

    1994年
    -
     

  • CO2固定技術としての難溶性炭酸塩の生成に関する研究

    1993年
    -
     

  • 排水処理技術指導書 窒素排水処理対策(無機顔料製造業,黄鉛顔料)

    1991年
    -
     

  • 排水処理技術指導書 窒素排水処理対策(有機顔料製造業・銅フタロシアニン系顔料)

    1991年
    -
     

  • 地球環境関連研究の重点分野の動向調査

    1991年
    -
     

▼全件表示

その他

  • 結晶は、成長し、かつ核化する。無生物と生物の間に結晶があり、まさに結晶は生きている。基礎理論と実際の工学理論を埋める新規な概念を提出したい。

受賞

  • 化学工学会 フェロー

    2019年03月   化学工学会   化学工学会 フェロー  

  • JSCEJ 優秀論文賞

    2018年09月   化学工学会  

  • 2016年度論文審査貢献賞

    2017年03月   化学工学会  

    受賞者: 平沢 泉

  • インド化学工学会 優秀発表賞

    2014年12月  

  • 化学工学会 功労賞

    2012年03月  

  • 国際分離技術会議2009貢献賞

    2009年11月  

  • 化学工学会関東支部功労賞

    2005年08月  

  • 国際分離技術会議2005貢献賞

    2005年08月  

  • 分離技術会 技術賞

    2005年06月  

  • ポスター賞(分離技術会)

    2004年06月  

  • ポスター賞(分離技術会)

    2000年11月  

  • 技術賞(化学工学会)

    2000年03月  

  • 優秀論文賞(下水道協会)

    1982年04月  

▼全件表示

共同研究・競争的資金等の研究課題

  • 潜熱蓄熱材を用いた熱回収システム開発

    研究期間:

    2010年
    -
     
     

  • 冷却操作による有機物結晶の粒子径、結晶化度制御

    研究期間:

    2010年
    -
     
     

  • 過冷却融液の核化誘導

    研究期間:

    2009年
    -
    2010年
     

  • 超高比表面積材料の結晶化制御

    研究期間:

    2008年
    -
    2010年
     

  • 過冷却蓄熱剤を用いた蓄熱プロセスの開発

    研究期間:

    2008年
    -
    2010年
     

  • ソノ晶析のための超音波プローブの開発

    研究期間:

    2009年
    -
     
     

  • アミノ酸結晶の核化制御

    研究期間:

    2009年
    -
     
     

  • ナノ金属創製に関する基礎研究

    研究期間:

    2009年
    -
     
     

  • 晶析法による不純物の分離プロセス

    研究期間:

    2009年
    -
     
     

  • 晶析過程の予測シミュレーション

    研究期間:

    2009年
    -
     
     

  • 廃棄物循環システムの設計

    研究期間:

    2009年
    -
     
     

  • 晶析工程で取り込まれた固体系不純物の分離精製

    研究期間:

    2009年
    -
     
     

  • 植物形質転換用金ナノ粒子の粒子径制御と生成プロセス

    研究期間:

    2009年
    -
     
     

  • 新規潜熱蓄熱材の開発

    研究期間:

    2008年
    -
    2009年
     

  • 省エネ蓄熱システム開発

    研究期間:

    2008年
    -
    2009年
     

  • 加温化擬多形制御

    研究期間:

    2008年
    -
    2009年
     

  • 晶析法による新規核燃料リサイクルの構築

    研究期間:

    2006年
    -
    2009年
     

  • 晶析法によるフッ素含有排水の処理に関する研究

    研究期間:

    2000年
    -
    2009年
     

  • 反応晶析法による有機金属結晶の創製

    研究期間:

    2008年
    -
     
     

  • 超音波晶析プロセスの開発

    研究期間:

    2008年
    -
     
     

  • アジアにおける水ビジネス開発

    研究期間:

    2008年
    -
     
     

  • 超音波晶析プロセスの開発

    研究期間:

    2008年
    -
     
     

  • 反応晶析法による貴金属難溶解性結晶の回収

    研究期間:

    2007年
    -
    2008年
     

  • 膜を利用したフッ素含有排水の反応晶析処理

    研究期間:

    2006年
    -
    2008年
     

  • 医薬品多形の選択的晶析に関する研究

    研究期間:

    2006年
    -
    2008年
     

  • 機能性糖類の選択的晶析および高純度化

    研究期間:

    2006年
    -
    2008年
     

  • 異種結晶被覆型結晶の開発

    研究期間:

    2006年
    -
    2008年
     

  • 次世代核燃料サイクル 晶析工程における結晶精製技術に関する研究開発

    研究期間:

    2006年
    -
    2008年
     

  • 非晶質医薬品の転移に関する研究

    研究期間:

    2006年
    -
    2008年
     

  • 所望糖類の選択晶析に関する研究

    研究期間:

    2005年
    -
    2008年
     

  • 貧溶媒添加晶析法による医薬品の晶析

    研究期間:

    2003年
    -
    2008年
     

  • 反応晶析法により無機ナノ結晶の生成過程

    研究期間:

    2007年
    -
     
     

  • 固体表面への薄膜生成機構

    研究期間:

    2006年
    -
    2007年
     

  • 精製晶析法による廃酸の高純度化に関する研究

    研究期間:

    2006年
    -
    2007年
     

  • 無機DDS製剤の開発

    研究期間:

    2006年
    -
    2007年
     

  • 湿式ミル法による微結晶の創製

    研究期間:

    2005年
    -
    2007年
     

  • 汚泥分離水を対象としたリン酸イオンの除去・回収に関する研究

    研究期間:

    1998年
    -
    2007年
     

  • 晶析法によるウランの回収と高純度化

    研究期間:

    2006年
    -
     
     

  • 反応晶析法によるナノ蛍光体結晶の創製

    研究期間:

    2000年
    -
    2006年
     

  • 超音波による晶析制御に関する研究

    研究期間:

    2003年
    -
    2005年
     

  • 反応晶析法によるnmカルサイトの生産

    研究期間:

    2003年
    -
    2004年
     

  • 環境触媒プロセスの開発

    文部科学省 

    研究期間:

    2000年
    -
    2004年
     

  • 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 

    研究期間:

    1999年
    -
    2003年
     

  • 還元晶析法によるニッケルメッキ排水からのNi金属の回収に関する研究

    研究期間:

    1999年
    -
    2002年
     

  • カルサイト結晶の生成現象と生成装置・操作の研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(一般研究(B))

    研究期間:

    1995年
    -
    1996年
     

     概要を見る

    本研究では、溶液反応によって機能性物質としての所望粒径の微粒子を生成するプロセス設計法開発のための基礎研究を、難溶性微粒子の生成現象としてCaCl_2とNa_2CO_3の両溶液の液液反応による炭酸カルシウムの生成を対象に行った。この反応ではまず中間体微粒子が生成し、それがカルサイト、バテライト等に転移することに着目し、中間体が存在するスラリー中にNaCl結晶あるいは他の無機塩結晶を添加することにより、操作条件によって中間体からカルサイトが優先的に生成することを見出し、中間体存在下でのカルサイトの成長現象の検討を行った。ここで生成するカルサイトの粒径及び結晶個数は原料濃度や添加する結晶量及びその粒径の影響を受けており、それらの相関式を提出した。また、Na_2CO_3の代わりにNaHCO_3とCaCl_2の反応においてもカルサイトが優先的に生成する条件を見出した。この系において生成するカルサイトは粒径の分布幅が広く、それはNaHCO_3の分解過程がカルサイトの生成を促進しているためと考えた。ここで生成するカルサイトは、NaHCO_3の反応量に影響を受けており、それらの相関式を提出した。しかし、ダブルジェット晶析法を用いた場合、カルサイトとバテライトの混合物が生成し、カルサイトを選択的に生成する条件を見出すことができなかった。これらの攪拌系に対し冷却された静止溶液中での炭酸カルシウムの晶析現象について検討を行った。初期濃度が0.02M〜0.1MのNa_2CO_3/CaCl_2水溶液を313Kに保った四口フラスコ内に仕込み30S攪拌混合し懸濁液を箱型晶析装置の平板面上(293K)に0.05〜0.2g滴下し、経時変化を測定した。その結果、懸濁溶液のpHは徐々に減少し、Na_2CO_3及びCaCl_2の初濃度が0.1mol/lでは静止後約1.5min経過後にほぼ一定となった。pHの変化より算出した平均過飽和度が100〜250の条件下ではアラゴナイト、バテライトが多く生成したが、50以下または、280以上ではカルサイトの生成割合が、高くなることを明らかにした

  • 晶析法による光学活性物質の分離・精製法

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(A))

    研究期間:

    1995年
    -
    1996年
     

     概要を見る

    本研究では、DL-マンデル酸系及びDL-SCMC(S-Carboxymethyl-DL-Cysteine)系をモデル系として、優先晶析法によるD体及びL体の選択的分割プロセス開発のための基礎研究とプロセスの提案を行った。マンデル酸系においては、L体組成が(L+D)に対し30〜70%の範囲の分割に関しては圧力晶析法と蒸発法との組み合わせプロセスを検討し、またL体組成が30%以下の範囲に関しては、その303Kにおける溶解度曲線を測定し、それらの組み合わせによる効果的分割法を提案した。
    一方、DL-SCMC系からのL体の分割については等電点近傍に着目して、D体の核発生のない範囲におけるL体種晶の成長条件を検討し、操作過飽和度0.1〜0.25[g/100ml]の5wt%及び10wt%NaCl添加DL-SCMC溶液内でのL体単一結晶上の成長速度を実測した。その結果、成長速度は共存するD体量の影響を受けるという結果が得られ、D体濃度S_Dの結晶成長速度に対する影響として、ΔC_L/S_D=αなる成長阻害因子を考えた。これより、ΔC_L・αを結晶成長速度に寄与する過飽和度ΔC_rとして、結晶成長速度dL_a/dθとΔC_rの相関を得た。一方、晶析操作時の溶液濃度変化は、ラセミ過飽和溶液にL体種晶を添加すると、L体の成長に従って初めL体濃度のみが減少するが、ある時間経過すると、D体の濃度も低下した。これは、L体種晶表面上にD体の結晶核が発生し、それが成長するためであることを確認した。そこで、L体種晶表面上へのD体の核化現象について研究を行い、二次元核化の待ち時間が過飽和度、結晶懸濁密度の影響を受けることを明らかにして、L体のみが安定に成長する操作条件を見出した。また、蒸発晶析法の実験も行い、冷却法で得られたデータとの比較検討も行った。これらより蒸発操作を加味した晶析法による光学分割プロセスを提出した。

  • 晶析法による光学活性物質の分離・精製法

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(A))

    研究期間:

    1995年
    -
    1996年
     

     概要を見る

    本研究では、DL-マンデル酸系及びDL-SCMC(S-Carboxymethyl-DL-Cysteine)系をモデル系として、優先晶析法によるD体及びL体の選択的分割プロセス開発のための基礎研究とプロセスの提案を行った。マンデル酸系においては、L体組成が(L+D)に対し30〜70%の範囲の分割に関しては圧力晶析法と蒸発法との組み合わせプロセスを検討し、またL体組成が30%以下の範囲に関しては、その303Kにおける溶解度曲線を測定し、それらの組み合わせによる効果的分割法を提案した。
    一方、DL-SCMC系からのL体の分割については等電点近傍に着目して、D体の核発生のない範囲におけるL体種晶の成長条件を検討し、操作過飽和度0.1〜0.25[g/100ml]の5wt%及び10wt%NaCl添加DL-SCMC溶液内でのL体単一結晶上の成長速度を実測した。その結果、成長速度は共存するD体量の影響を受けるという結果が得られ、D体濃度S_Dの結晶成長速度に対する影響として、ΔC_L/S_D=αなる成長阻害因子を考えた。これより、ΔC_L・αを結晶成長速度に寄与する過飽和度ΔC_rとして、結晶成長速度dL_a/dθとΔC_rの相関を得た。一方、晶析操作時の溶液濃度変化は、ラセミ過飽和溶液にL体種晶を添加すると、L体の成長に従って初めL体濃度のみが減少するが、ある時間経過すると、D体の濃度も低下した。これは、L体種晶表面上にD体の結晶核が発生し、それが成長するためであることを確認した。そこで、L体種晶表面上へのD体の核化現象について研究を行い、二次元核化の待ち時間が過飽和度、結晶懸濁密度の影響を受けることを明らかにして、L体のみが安定に成長する操作条件を見出した。また、蒸発晶析法の実験も行い、冷却法で得られたデータとの比較検討も行った。これらより蒸発操作を加味した晶析法による光学分割プロセスを提出した。

  • カルサイト結晶の生成現象と生成装置・操作の研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(一般研究(B))

    研究期間:

    1995年
    -
    1996年
     

     概要を見る

    本研究では、溶液反応によって機能性物質としての所望粒径の微粒子を生成するプロセス設計法開発のための基礎研究を、難溶性微粒子の生成現象としてCaCl_2とNa_2CO_3の両溶液の液液反応による炭酸カルシウムの生成を対象に行った。この反応ではまず中間体微粒子が生成し、それがカルサイト、バテライト等に転移することに着目し、中間体が存在するスラリー中にNaCl結晶あるいは他の無機塩結晶を添加することにより、操作条件によって中間体からカルサイトが優先的に生成することを見出し、中間体存在下でのカルサイトの成長現象の検討を行った。ここで生成するカルサイトの粒径及び結晶個数は原料濃度や添加する結晶量及びその粒径の影響を受けており、それらの相関式を提出した。また、Na_2CO_3の代わりにNaHCO_3とCaCl_2の反応においてもカルサイトが優先的に生成する条件を見出した。この系において生成するカルサイトは粒径の分布幅が広く、それはNaHCO_3の分解過程がカルサイトの生成を促進しているためと考えた。ここで生成するカルサイトは、NaHCO_3の反応量に影響を受けており、それらの相関式を提出した。しかし、ダブルジェット晶析法を用いた場合、カルサイトとバテライトの混合物が生成し、カルサイトを選択的に生成する条件を見出すことができなかった。これらの攪拌系に対し冷却された静止溶液中での炭酸カルシウムの晶析現象について検討を行った。初期濃度が0.02M〜0.1MのNa_2CO_3/CaCl_2水溶液を313Kに保った四口フラスコ内に仕込み30S攪拌混合し懸濁液を箱型晶析装置の平板面上(293K)に0.05〜0.2g滴下し、経時変化を測定した。その結果、懸濁溶液のpHは徐々に減少し、Na_2CO_3及びCaCl_2の初濃度が0.1mol/lでは静止後約1.5min経過後にほぼ一定となった。pHの変化より算出した平均過飽和度が100〜250の条件下ではアラゴナイト、バテライトが多く生成したが、50以下または、280以上ではカルサイトの生成割合が、高くなることを明らかにした。

  • CO_2固定技術としての難溶性炭酸塩の生成に関する研究

     概要を見る

    平成3年度の炭酸カルシウムの反応品析及びバイオクリスタリゼーションに関する文献調査、アミノ酸存在下における回分反応品析実験の結果をふまえて、まずダブルジェット反応品析装置を用いた未回分式実験を常温・常圧下で行ない、この反応品析過程における結晶形態及び粒径分布に及ぼす濃度(過飽和度)と品析時間の影響について検討した。これより、温度0.3mol/l以上の条件では、一部にアルサイトの生成が認められるが、大部分はバテライト型となり、また粒径分布の経時的堆積より、バテライトの成長過程は粒径の依存性があること、及び粒径が増大すると二次核発生による小粒径側のピークが認められた。そこで、常温、常圧下でカルサイトの均一微粒子を選択的に品析せせるべく、反応液を直接混合することにより多量の不安定機が存在している状態で、少なくとも6〜10分以内にNacl固体粒子を添加することにより、本実験範囲でカルサイトの均一微粒子が得られた。Naclの添加とカルサイトの生成結品個数の関係を相関すると、濃度に依らずNacl添加量のみの影響を受けること、添加により急速にカルサイトが生成され、その粒径分布は添加時間の影響をうけないことから、カルサイトの選択品析は、添加した固体粒子の負、あるいはその溶解過程が寄与するという新しい事実を見出した。また、粒径と個数の関係を物質収支に基づいたモデルより提出し、所等粒径の結品を得るための設計式を提出した。以上の研究成果に基づいて、排ガス中のCO_2を固定するそ一のプロセスを、海水中からの製塩工程及び排ガス又は吸収処理工程とを有機的に結合することになり提出した。本研究は、CO_2を難活性炭酸塩結晶の型で回収するとともに、得られた結晶が高品位のものとなる可能性を見出すとともに、結晶多形を生ずる系において、安定形を効果的に生成すると共の新しい工程品析操作を創出する新展開をきりひらいた、まさに萌芽的研究である

  • 省資・エネルギー・環境技術としての新結晶物質の生成と装置・操作の設計に関する研究

     概要を見る

    晶析は主として液層より固相を結晶として生成する現象を利用する操作で、そこで工学的に評価される対象は、結晶が生成するときに発生(あるいは吸収)する相変換エネルギー利用のための制御に関する基礎現象、生成する結晶そのものの特性及び結晶を生成して残る液相組成に関する現象など広範である。特に最近の技術開発に関する動向としては、エネルギー環境と資源の有効利用との調和のうえで新しい機能物質を生産する技術を開発するニーズが高まっている。結晶は高純度で高機能特性を安定に維持できる固相であり、このような物質を効率よく生産できる技術を提案し確立することは21世紀の化学工業の発展に貢献するものであることを本研究チームの幹事分担者と討議して、活動方針を決定した。そこで各研究分担者に対して、“調査研究の方向として21世紀の化学工業に貢献する晶析技術とは何か?そこで必要とされる晶析研究テーマは何か?これらの技術・研究の現状と課題は何か?"についてのアンケート調査を行い、各分担者からの研究実績と現在検討している研究計画に基づいた回答を得た。これに基づき、工学基礎から装置・操作の設計とその制御に関する6つのサブテーマについての調査研究を行った。その結果、製品結晶粒径と生産量に基づく晶析装置の設計理論はほぼ確立しており、工業晶析装置・操作の設計は可能になっていることを明らかにし、さらに高純度で新機能を持つ結晶の生成に対する研究の状況を整理した。また新しい操作法としては、結晶多形を利用した操作過飽和度の制御法を提案し、微粒子の生成を含めた新しい晶析技術の可能性も示すことができた。この成果は単に化学工業のみでなく、医薬品・食品工業など広い分野に波及すると考えられる。特に環境対策技術への効果ははかり知ることができない

  • リン酸マグネシウムアンモニウムの晶析現象を利用したリン及び窒素の除去に関する研究

     概要を見る

    大都市において汚泥を集中処理する構想、いわゆる汚泥処理基地構想を想定し、汚泥処理の過程で排出される汚泥返流水中のアンモニア、およびリン酸イオンの除去方法の開発が求められている。本研究では、MAP(リン酸マグネシウムアンモニウム6水塩)の晶析現象を利用した排水中の窒素・リン除去プロセスの開発を目的として、その晶析特性と除去特性の関連について、基礎的検討を行った。まず、MAP結晶の晶析特性(対象結晶を支配的に晶析させる排水の水質特性・操作条件)を明らかにするために、回分晶析実験を試み、選択的生成条件(温度、pH、Mg/Pモル比、NH4/Pモル比)を見いだした。この結果に基づいて、回分晶析実験を試み、Mgイオンおよびリン酸イオンの除去過程とMAPの晶析過程の関連について検討し、最適除去率を得るためのpH範囲、Mg/Pモル比を明らかにするとともに、その条件下での、MAP結晶の生成過程をSEM観察による形状、および粒径の測定などにより、核化・成長現象に基づいて考察した。同時に、MAPの固液平衡関係で、決定される液中のアンモニア、リン酸イオンの濃度を低減するための、アルコール添加法についても検討し、溶解度積を1/2に低下できることを明らかにした。MAPの生成過程を考慮し、晶析速度と装置設計法の関連について考察した結果、液側の物質収支、晶析速度に基づいた連続装置の設計手法を提出できた

  • 膜分離と晶析の融合プロセス開発

▼全件表示

講演・口頭発表等

  • 超音波照射による核化誘導を用いた潜熱蓄熱プロセスの開発、

    分離技術会年会2011  

    発表年月: 3011年06月

  • 晶析法による排水からの物質回収

    インド化学工学会議2014  

    発表年月: 2014年12月

  • 液相系においてナノ結晶を創製するための晶析工学的手法

    化学工学会 新潟大会  

    発表年月: 2014年11月

  • 国際会議に見る晶析プロセスにおけるPATの展開

    RXE フォーラム 2014  

    発表年月: 2014年07月

  • 晶析法による金属イオンおよび有機酸含有廃棄物からの除去回収

    アジア晶析技術会議2014・第11回有機結晶成長会議  

    発表年月: 2014年06月

  • アミノ酸の超音波誘導核化

    工業晶析ワークショップ2013  

    発表年月: 2013年09月

  • 炭酸塩晶析現象の効果的改善手法

    第9回世界化学工学会議  

    発表年月: 2013年06月

  • ナノ粒子を積み上げるための晶析環境

    ブレーメン国際工業晶析会議2012  

    発表年月: 2012年09月

  • Myo-イノシトールの溶媒誘発転移

    Hanbat 国際航業晶析および医薬品会議  

    発表年月: 2012年09月

  • さまざまな分野に貢献する晶析技術

    公州大学夏季セミナー  

    発表年月: 2012年09月

  • ナノ結晶を創るための晶析環境

    アジア晶析技術国際会議2012  

    発表年月: 2012年05月

  • 晶析法によるイオン回収を基盤にした排水処理

    日中排水処理技術に関する化学ワークショップ  

    発表年月: 2012年05月

  • 超音波照射が有機化合物の選択晶析に及ぼす影響

    ICMAT 2011  

    発表年月: 2011年07月

  • 新しい晶析環境場を用いた医薬品有機物の核化制御

    MLUにおける日本週間2011  

    発表年月: 2011年06月

  • 晶析技術を基盤とした排水中アニオンの資源回収

    第6回日中化工シンポジウム  

    発表年月: 2011年06月

  • 結晶を創製する手法を駆使したリン回収技術の実用化

    リン回収・資源化 第2回ワークショップ  

    発表年月: 2011年06月

  • 高分子電解質環境場における晶析過程

    化学工学会 秋季大会  

    発表年月: 2010年09月

  • 高分子電解質環境場における反応晶析法による単分散微粒子の創製

    第39回結晶成長学会  

    発表年月: 2009年11月

  • 高度材料創成に貢献する晶析工学

    化学工学会 秋季大会  

    発表年月: 2009年09月

  • 高分子電解質環境場におけるナノ結晶創製

    化学工学会 米沢大会  

    発表年月: 2009年08月

  • 有機物結晶の多形擬多形転移過程

    日本PXEフォーラム2009  

    発表年月: 2009年07月

  • 超音波照射による潜熱蓄熱材の過冷却融液の核化誘導

    分離技術会2009  

    発表年月: 2009年06月

  • 結晶創りの新展開ー医薬品・食品分野における結晶創りの新潮流

    ホットな話題の講演会  

    発表年月: 2009年05月

  • 晶析制御のための超音波照射の適用

    国際晶析工学ドラッグデリバリー会議  

    発表年月: 2009年04月

  • ものづくりに貢献する晶析工学

    化学工学会 年会  

    発表年月: 2009年03月

▼全件表示

学内研究費(特定課題)

  • 難溶解性有機物結晶のナノサイズ化

    2016年  

     概要を見る

    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年  

     概要を見る

    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年  

     概要を見る

     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年  

     概要を見る

    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年  

     概要を見る

     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年  

     概要を見る

    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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