論文 - 寺坂　宏一

ウルトラファインバブル水の国際輸送

田中俊也, 成瀬祐里, 寺坂宏一, 藤岡沙都子, 山本陽子, 野口雄介, 山崎京香, 庄村拓也, 原田駿

混相流 35 （ 1 ） 185 - 196 2021年

Ultrafine Bubbles

K. Terasaka, K. Yasui, W. Kanematsu, N. Aya

Jenny Stanford Publishing 2021年

ISSN  979- 981-487-7596

加減圧の繰り返し操作による水中からのウルトラファインバブル生成

山崎京香,　寺坂宏一,　藤岡沙都子

混相流 （日本混相流学会）  34 （ 4 ） 532 - 540 2020年12月

研究論文（学術雑誌）, 共著

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Hydrodynamic and mass transfer correlation in a microbubble aerated stirred tank reactor

Matthes S., Thomas B., Ohde D., Hoffmann M., Bubenheim P., Liese A., Tanaka S., Terasaka K., Schlueter M.

Journal of Chemical Engineering of Japan （Journal of Chemical Engineering of Japan）  53 （ 10 ） 577 - 584 2020年10月

ISSN  Print ISSN : 0021-9592

　概要を見る

© 2020 The Society of Chemical Engineers, Japan Many chemical and biocatalytic reactions are consuming gaseous species like oxygen, provided by the mass transfer across interfaces of multiphase contact apparatuses. For biocatalytic reactions a macroscopic aeration can lead to reduced enzyme activity by foaming and shear forces and for fast chemical reactions in multiphase flows, the mass transfer limitation is often the bottleneck for a process optimization. The present study investigates the use of bubbles with diameters less than 100 µm for aeration of a 3 L lab scale stirred tank reactor. For demineralized water and a solution of glucose and bovine serum albumin (BSA) as biocatalytic model protein solution, two different membrane spargers with a mean pore size of 1 µm and 2 µm are investigated. Determining the influence of the energy input on the hydrodynamics of the system, endoscopic measurements of bubble size distributions are carried out. The mass transfer performance of the two spargers is analyzed by measurements of the oxygen kla value for varying gas flow rates. As a result microbubble aeration shows a significant higher mass transfer performance compared to an open tube aeration saving 60% of the gaseous phase by reaching the same kla values. Besides high specific interfacial areas and long residance times, the Laplace pressure inside the bubble is identified as an enhancing force for mass transfer at microscale.

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加圧容器からのスプレー噴射による酸素ウルトラファインバブル水の製造

山崎京香,　寺坂宏一,　藤岡沙都子

混相流 （日本混相流学会）  34 （ 3 ） 436 - 443 2020年09月

研究論文（学術雑誌）, 共著

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Generation and Long-Term Stability of Ultrafine Bubbles in Water

Tanaka S., Terasaka K., Fujioka S.

Chemie-Ingenieur-Technik （Chemie-Ingenieur-Technik）  93 （ 1-2 ） 168 - 179 2020年

ISSN  0009286X

　概要を見る

© 2020 Wiley-VCH GmbH This study investigated submicron-sized bubbles, more precisely ultrafine bubbles (UFBs). The number concentration, size, and scattered light intensity of UFBs were measured by particle tracking analysis (PTA). The results showed that storage temperature had a significant effect, whereas the storage containers had little effect on the long-term stability of UFBs. It was found that the second-order aggregation rate equation could predict the stability of UFBs; however, there were some differences from the theory at high storage temperatures. The features of the PTA were also discussed in detail.

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Dissolution and Shrinking of a Single Microbubble in Stationary Liquid with Surfactants

Fujioka S., Mizuno K., Terasaka K.

Chemie-Ingenieur-Technik （Chemie-Ingenieur-Technik）  93 （ 1-2 ） 216 - 222 2020年

ISSN  0009286X

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© 2020 Wiley-VCH GmbH For a variety of applications of microbubbles, it is necessary to clarify the dissolution dynamics and the lifetime of a microbubble. Although various models have been proposed, predicting the dissolution rate of a microbubble in a static fluid with a surfactant is still difficult. In this study, dissolution behavior was predicted with taking into account the mass transfer inhibition effect due to a surfactant at the bubble surface. The shrinking behavior of an oxygen microbubble was observed with several surfactants and the experimental results were in good agreement with model predictions.

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Concentration and dilution of ultrafine bubbles in water

Tanaka S., Naruse Y., Terasaka K., Fujioka S.

Colloids and Interfaces （Colloids and Interfaces）  4 （ 4 ）  2020年

　概要を見る

Submicron-sized bubbles are now officially called ultrafine bubbles (UFBs) by the international standard. The concentration of UFBs is generally low (<109 particles/mL; <0.001 vol%) compared to other colloidal dispersions. To overcome this practical problem, we concentrated UFBs in ultrapure water prepared by a commercial UFB generator and quantified the effect of rotary evaporation of the dispersion media on the stability of UFBs. The UFB dispersions were characterized by a particle tracking analysis (PTA) instrument. The experimental results showed that the UFBs can be diluted and concentrated without changing the size distribution and there was little or no loss of UFBs. By using a rotary evaporator, UFB dispersions were about 30-fold concentrated and the resultant number concentration reached over 3 × 1010 particles/mL. Increasing the concentration of UFBs allowed for satisfactory dynamic light scattering (DLS) measurements. The differences among the three algorithms for analyzing the raw data, i.e., autocorrelation function, obtained by DLS are discussed, along with the characteristics of the particle size distribution derived from each algorithm.

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Fine Bubble-based CO<inf>2</inf> Capture Mediated by Triethanolamine Coupled to Whole Cell Biotransformation

Ohde D., Thomas B., Matthes S., Percin Z., Engelmann C., Bubenheim P., Terasaka K., Schlüter M., Liese A.

Chemie-Ingenieur-Technik （Chemie-Ingenieur-Technik）  91 （ 12 ） 1822 - 1826 2019年12月

ISSN  0009286X

　概要を見る

© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Carbon capture technology can be set up in combination with biocatalysis to utilize the bound CO2 as substrate in the Kolbe-Schmitt like enzymatic reaction. The exemplary whole cell biotransformation of catechol to 2,3-dihydroxybenzoic acid in a triethanolamine-mediated multiphase system shows increased equilibrium conversion. Apart from the beneficial thermodynamics, the inherent fluid properties of triethanolamine is enabling easy application of CO2 fine bubbles as highly efficient gassing method to minimize the CO2 demand and CO2 emissions.

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Absorption of carbon dioxide at high temperature with molten alkali carbonate using bubble column reactor

金井由悟, 寺坂 宏一, 藤岡 沙都子, 福永 健一郎

Journal of Chemical Engineering of Japan （Journal of Chemical Engineering of Japan）  52 （ 1 ） 31 - 40 2019年

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  00219592

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© 2019 The Society of Chemical Engineers, Japan The purpose of this study is to examine the possibility of establishing a novel CO 2 absorption process with molten alkali carbonate using a bubble column reactor. In our previous study, a hot CO 2 recovery process using Li 4 SiO 4 suspended in molten Li 2 CO 3 -K 2 CO 3 was developed. In the process, molten alkali carbonate itself showed great potential for CO 2 absorption at high temperature. If a hot CO 2 absorption process were established using only molten alkali carbonate, it could make the system simpler and the operating temperature range could be extended without the limitation of reaction temperature of solid absorbent. In the study, molten Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 and its eutectic mixture were selected as CO 2 absorbent. A bubble column was chosen as the device for gas absorption at high temperature. First, the CO 2 absorption performance of each single molten alkali carbonate was investigated. The result showed that the molten Li 2 CO 3 had a great ability to absorb CO 2 at high temperature. Li 2 O was thought to be produced by decomposition of Li 2 CO 3 during the melting and purging process and a reaction of CO 2 with Li 2 O occurred during the absorption process. Further, the CO 2 absorption performance of eutectic mixture increased exponentially with increasing the ratio of Li 2 CO 3 in composition. Second, the possibility of establishing a CO 2 absorption process using molten Li 2 CO 3 was examined. The overall CO 2 absorption process in the bubble column was investigated and the experimental results showed that the mass transfer of CO 2 into molten Li 2 CO 3 was the rate-controlling step. The operational conditions of the bubble column were optimized. The superficial gas velocity was an important operational parameter that affected both the CO 2 absorption rate and total amount of CO 2 finally absorbed in the bubble column. The operating temperature also greatly affected the amount of absorbed CO 2 .

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Fine bubble based CO2 capture mediated by triethanolamine coupled to whole cell biotransformation

Andreas Liese, Michael Schlueter, Koichi Terasaka

Chemie Ingenieur Technik  2019年

研究論文（学術雑誌）, 共著

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Synthesis, kinetic study, and reaction mechanism of Li<inf>4</inf>SiO<inf>4</inf> with CO<inf>2</inf> in a slurry bubble column reactor

Kanai Y., Terasaka K., Fujioka S.

Chemical Engineering Communications （Chemical Engineering Communications）  207 （ 5 ） 598 - 611 2019年

ISSN  00986445

　概要を見る

© 2019, © 2019 Taylor & Francis Group, LLC. This study was performed to investigate the synthesis, kinetic and reaction mechanism of Li 4 SiO 4 with CO 2 in a slurry bubble column reactor. The Li 4 SiO 4 powder sample was prepared via a solid-state reaction. The sample was characterized via X-ray diffraction (XRD) analysis and verified as a single phase. The median diameter of the sample was measured using the laser diffraction and scattering method as about 20 μm. The synthesized sample was suspended in binary molten carbonate of Li 2 CO 3 –K 2 CO 3 having a molar ratio of 38:62. The experimental results show that Li 4 SiO 4 in the slurry bubble column absorbed approximately a stoichiometric amount of CO 2 . The kinetic study shows that the CO 2 reaction behavior on the Li 4 SiO 4 surface was fitted to a double exponential model and the limiting step of the reaction was lithium diffusion. The mass transfer coefficient of CO 2 and rate constant of reaction with Li 4 SiO 4 were studied to understand the overall absorption mechanism in the reactor. The resistance for the direct reaction of CO 2 on the Li 4 SiO 4 was much smaller than the resistance for the mass transfer of CO 2 to the Li 4 SiO 4 . We can conclude that the direct contact of CO 2 with Li 4 SiO 4 was the main path for the reaction.

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Mass transfer from freely rising microbubbles in aqueous solutions of surfactant or salt

Tanaka S., Kastens S., Fujioka S., Schlüter M., Terasaka K.

Chemical Engineering Journal （Chemical Engineering Journal）  387 2019年

ISSN  13858947

　概要を見る

© 2019 Elsevier B.V. Microbubbles are used in many applications. One of the major advantages of using microbubbles is to improve the mass transfer of gases to the bulk phase. In this study, mass transfer from single microbubbles that rise in ultrapure water and aqueous solutions of surfactants (SDS, Pluronic F68) or salt (NaCl) was investigated. The rising and dissolution behaviors of single air microbubbles were observed using a high-speed imaging technique by which the rising velocity, U B , and the mass transfer coefficient, k L , were optically evaluated. We found that the rising velocity of microbubbles obeys Stokes’ law, indicating that the surface of the microbubbles used in this study is immobile, despite their rising in ultrapure water. The obtained mass transfer coefficients were in good agreement with those predicted by Ranz and Marshall's correlation for the Sherwood number, Sh. Using the two correlations for U B and Sh, a theoretical model that describes the mass transfer from a microbubble was constructed. The proposed model can predict the dissolution of single microbubbles rising in ultrapure water and aqueous solutions with an accuracy of ±10% in terms of dissolution time.

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ファインバブルテクノロジーの発展と展望

寺坂 宏一

粉体技術 （一般社団法人日本粉体工業技術協会）  10 （ 11 ） 44 - 48 2018年11月

研究論文（学術雑誌）, 単著,  ISSN  1883-3292

ファインバブルを用いた洗浄・浄化に関する研究

#H秦隆志, 西内悠祐,　田中克也,　岡本祐里子,　榊原靖,　寺坂宏一

混相流 （日本混相流学会）  32 （ 1 ） 4 - 11 2018年

研究論文（学術雑誌）, 共著

超音波刺激によるウルトラファインバブルからマイクロバブルへの変化

寺坂 宏一

日本ソノケミストリー 11 （ 1 ） 1 - 8 2017年03月

The Establishment of Experimental Method to Observe Bubble Formation in High Temperature Molten Salt System and Estimation of Generated Bubble Size

Y. Kanai, K. Terasaka, S. Fujioka and K. Suzukawa J. Chem. Eng. Japan, Vol.50(2), pp.86-93 (2017)

J. Chem. Eng. Japan （J. Chem. Eng. Japan）  50 （ 2 ） 86 - 93 2017年02月

研究論文（学術雑誌）, 共著,  ISSN  0021-9592

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水平摺動するノズルからの微細気泡生成

村上大次郎寺坂宏一,　藤岡沙都子

混相流 （日本混相流学会）  31 （ 4 ） 422 - 426 2017年

研究論文（学術雑誌）, 共著

水中を収縮しつつ浮上する単一マイクロバブルからの物質移動

岩切扶樹寺坂宏一,　藤岡沙都子,　シュルーター　ミヒャエル,　カステンス　スヴェン,　田中俊也

混相流 （日本混相流学会）  30 （ 5 ） 529 - 535 2017年

研究論文（学術雑誌）, 共著

ファインバブルの現状と将来展望

寺坂 宏一

混相流 （日本混相流学会）  30 （ 1 ） 1 - 2 2016年03月

研究論文（学術雑誌）, 単著