Faculty Profiles - YASUDA, Keiji

Papers - YASUDA, Keiji

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ハイブリッド型超音波反応器による有害物質の分解と除去 Invited

安田啓司

超音波TECHNO Vol. 29 ( 6 ) page： 32-36 2017.12

Dependence of Cavitation, Chemical Effect, and Mechanical Effect Thresholds on Ultrasonic Frequency Reviewed Open Access

T. Nguyen, Y. Asakura, S. Koda and K. Yasuda

Ultrasonics Sonochemistry Vol. 39 page： 301 - 306 2017.11

Production of Liposome from Sphingomyelin by Ultrasonic Device under Supercritical Carbon Dioxide Reviewed

C. Uemori, T. Katsube, S. Machmudah, Wahyudiono, H. Kanda, K. Yasuda and M. Goto

Asian Journal of Applied Sciences Vol. 5 ( 5 ) page： 1042-1048 2017.10

Removal of Silicic Acid in Geothermal Water by a Combination of Ultrasonication and Silica Gel Seed

Nguyen Tam Thanh, Takahashi Yuta, Asakura Yoshiyuki, Yasuda Keiji

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol. 50 ( 7 ) page： 542 - 547 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：The Society of Chemical Engineers, Japan

A combination of ultrasonication and silica gel seed was studied as a silica scale prevention method in geothermal water. The effects of ultrasonic frequency, initial monosilicic acid concentration, pH, concentration, particle diameter and pore size of the silica gel on the removal ratio of silicic acid were examined. For comparison, stirring without and with silica gel, and ultrasonication with the addition of hydrogen peroxide or t-butanol were performed. Ultrasonication enhances the removal of silicic acid by silica gel seed. Ultrasonication at 500 kHz was more effective for the removal of silicic acid than ultrasonication at 28 kHz and stirring. The removal ratio of silicic acid increased with an increase in silica gel concentration. The small seed particle diameter of 60 µm and large seed pore size of 7 nm performed well in the removal of silicic acid. When the initial concentration of monosilicic acid was 1.1 g/L and the silica gel concentration was 1.5 g/L, the removal ratio of silicic acid was highest at pH 6 because the reaction between polymer and polymer is dominant. However, in the case of an initial monosilicic acid concentration of 0.5 g/L, the removal ratio was highest at pH 9 because reaction between polymer and monomer is dominant. The polymerization rate of monosilicic acid was increased by the addition of hydrogen peroxide due to a higher formation rate of hydroxide radicals. In contrast, the addition of t-butanol lowered the polymerization rate of monosilicic acid because the hydroxide radicals were scavenged. The frequency switching from 500 kHz to 28 kHz at 90 min for each ultrasonication enhanced the removal ratio of silicic acid.

DOI： 10.1252/jcej.16we262

Web of Science

Scopus

CiNii Research

Effect of Ultrasonic Cavitation on Measurement of Sound Pressure Using Hydrophone Reviewed

T. T. Nguyen, Y. Asakura, N. Okada, S. Koda and K. Yasuda

T. T. Nguyen, Y. Takahashi, Y. Asakura, N. Okada, S. Koda, K. Yasuda Vol. 56 ( 7 ) page： 07JE061-07JE065 2017.7

A05 Development of sonochemical reactor using ultrafine bubble

Matsushima Hodaka, Asakura Yoshiyuki, Yasuda Keiji

Proceedings of the Annual Meeting of the Japan Society of Sonochemistry Vol. 26 ( 0 ) page： 11 - 12 2017

Language：Japanese Publisher：Japan Society of Sonochemistry

Development of sonochemical reactor with high efficiency is necessary to put sonochemical process into practical use. With the intention to supply nuclei of cavitation bubble and increase cavitation amount, ultrafine bubble (UFB) whose diameter was lower than 1 μm was generated in the reactor. The reactor consisted of two vessels. One vessel contained a 488 kHz transducer to generate sonochemical reaction. Another vessel contained a 22 kHz transducer and boiling stone to generate UFB. Two vessels were connected by liquid pump and tubes. Sample was 0.1 M KI aqueous solution which was prepared using ultrapure water or high-density UFB water. High-density UFB water was produced by pressurized dissolution method. I3- production amount for high-density UFB water was higher than that for ultrapure water. However, UFB number in high-density UFB water rapidly reduced by ultrasound at 488 kHz. Many UFB generated by ultrasound at 22 kHz and boiling stone in ultrapure water. Ultrafine bubble sonoreactor with 488 kHz, 22 kHz and boiling stone showed additional increase in I3- production amount.

DOI： 10.20577/pamjss.26.0_11

CiNii Research

P17 Effect of ultrasound condition on generation and reduction of ultrafine bubble

Asakura Yoshiyuki, Matsushima Hodaka, Yasuda Keiji

Proceedings of the Annual Meeting of the Japan Society of Sonochemistry Vol. 26 ( 0 ) page： 53 - 54 2017

Language：Japanese Publisher：Japan Society of Sonochemistry

Bubbles of less than 1 μm in diameter are called ultrafine bubbles (UFB). When ultrasound
was irradiated to ultrapure water in a vessel, the change of number density of UFB with irradiation time was
investigated in ultrasonic frequency at 22, 43, 129, 488 kHz and 1 MHz. The number density of UFB
exponentially increased with irradiation time. The number density of UFB increased with decreasing
frequency. The mean and mode diameters of UFB after ultrasonic irradiation for 5 minutes to ultrapure water
were 100 - 120 nm and 90 - 100 nm, respectively. Furthermore, when ultrasound was irradiated to water
containing high-concentration UFB, the change of number density of UFB with irradiation time was
investigated. The number density of UFB decreased exponentially with irradiation time. The number density
of UFB decreased with increasing frequency. Therefore, it was clear that generation and reduction of UFB
occurred simultaneously by ultrasonic irradiation to water.

DOI： 10.20577/pamjss.26.0_53

CiNii Research

P05 Synthesis of gold nanoparticles using ultrasound and ultrafine bubbles

Sato Tomofumi, Yasuda Keiji, Asakura Yoshiyuki

Proceedings of the Annual Meeting of the Japan Society of Sonochemistry Vol. 26 ( 0 ) page： 29 - 30 2017

Language：Japanese Publisher：Japan Society of Sonochemistry

Gold nanoparticles possess the size- and shape-dependent catalytic and optical properties. Synthesis by ultrasonic cavitation needs no surfactant and reductive agents. Ultrafine bubble (UFB) which is smaller than 1 μm in diameter has high charge on the surface and long residence time. In this study, we investigated how UFB effect the synthesis of gold nanoparticles by ultrasound. Sample was 0.1 mM HAuCl4 solution. Ultrasonic frequency and temperature were 500 kHz and 283 K, respectively. By addition of UFB, nucleus generation time was shorten, diameter of gold nanoparticles decreased and diameter distribution of spherical particles became narrow. As the UFB density became higher, dimeter of gold nanoparticles became smaller. It is thought that UFB enhances cavitation generation and UFB attached on nanoparticles prevents aggregation of nanoparticles. As the UFB density increased, fraction of plate particles decreases. This is because formation rate of plate particles is slower than that of sphere particles.

DOI： 10.20577/pamjss.26.0_29

CiNii Research

超音波反応器の開発とソノプロセスの応用 Invited

安田啓司

Vol. 23 ( 383 ) page： 236-242 2016.7

Simulation of the Formation and Characteristics of Ultrasonic Fountain Reviewed

Z. Xu, K. Yasuda, X-J. Liu

Ultrasonics Sonochemistry Vol. 32 page： 241-246 2016.3

ファインバブルの資源・環境分野への活用 Invited

安田啓司

混相流 Vol. 30 ( 1 ) page： 37-44 2016.3

Quantitative Calculation of Reaction Performance in Sonochemical Reactor by Bubble Dynamics Reviewed

Z. Xu, K. Yasuda and X-J. Liu

Chinese Physics B Vol. 24 ( 10 ) page： 1043011-1043017 2015.8

Dispersion and Coalescence of Oil Droplets by Ultrasound and Application for Solvent Extraction of Gallium Reviewed

K. Yasuda, T. T. Nguyen, R. Okura, S. Nakayama, J. Jin and Y. Asakura

Japanese Journal of Applied Physics Vol. 54 ( 7S1 ) page： 07HE031-07HE035 2015.5

Characteristics of Ultrasonic Atomization and Alcohol Separation Invited

Bulletin of the Japan Society of Sonochemistry Vol. 9 ( 1 ) page： 17-22 2015.3

Separation of Oil Droplets from Oil-in-water Emulsion Using a Microbubble Generator Reviewed

K. Yasuda and K. Haneda

Journal of Chemical Engineering of Japan Vol. 48 ( 3 ) page： 175-180 2015.3

Methane Hydrate Formation by Using Finebubbles and Tetrahydrofuran Invited

Keiji Yasuda

J. Jpn. Inst. Energy Vol. 93 ( 11 ) page： 1031-1037 2014.11

Influence of Orifice Shape on Reaction Rate by Hydrodynamic Cavitation Reviewed

K. Yasuda, T. Kaji and Z. Xu

Applied Mechanics and Materials Vol. 625 page： 718-721 2014.8

Separation Characteristics of Alcohol from Aqueous Solution by Ultrasonic Atomization Reviewed

K. Yasuda, M. Mochida, Y. Asakura and S. Koda

Ultrasonics Sonochemistry Vol. 21 ( 6 ) page： 2026-2031 2014.7

地熱水中ケイ酸重合に及ぼす超音波の影響

安田啓司, 高橋優太

超音波TECHNO Vol. 26 ( 4 ) page： 46-49 2014.7

Effect of Ultrasonic Irradiation on Behavior of Silica Polymerization in Geothermal Water Reviewed

K. Yasuda, Y. Takahashi and Y. Asakura

Japanese Journal of Applied Physics Vol. 53 ( 7S ) page： 07KE081-07KE083 2014.6

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Papers - YASUDA, Keiji