Faculty Profiles - YASUDA, Keiji

Papers - YASUDA, Keiji

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超音波とウルトラファインバブルを活用した金ナノ粒子合成 Invited

安田啓司

化学工学 Vol. 85 ( 4 ) page： 232 - 235 2021.4

Sonochemical Green Technology Using Active Bubbles: Degradation of Organic Substances in Water Invited Reviewed

Yasuda Keiji

Current Opinion in Green and Sustainable Chemistry Vol. 27 page： 100411 2021.2

ウルトラファインバブルの安定性 Invited

安田啓司

化学工学 Vol. 54 ( 12 ) page： 644 2020.12

Effect of Ultrafine Bubbles on Ethanol Enrichment Using Ultrasonic Atomization Reviewed

Yasuda Keiji, Yumi Nohara, Asakura Yoshiyuki

Japanese Journal of Applied Physics Vol. 59 ( SK ) page： SKKD09 2020.7

Size-controlled Synthesis of Gold Nanoparticles by Ultrafine Bubbles and Pulsed Ultrasound Reviewed

Yasuda Keiji, Tomofumi Sato, Asakura Yoshiyuki

Chemical Engineering Science Vol. 217 page： 115527 2020.5

2P4-5 Effect of Frequency on Ultrasonic Degassing

Asakura Yoshiyuki, Yasuda Keiji

Proceedings of Symposium on Ultrasonic Electronics Vol. 40 ( 0 ) page： n/a 2019.11

Responses to the comment on the paper "Generation and reduction of bulk nanobubbles by ultrasonic irradiation"

Yasuda, K; Matsushima, H; Asakura, Y

CHEMICAL ENGINEERING SCIENCE Vol. 207 page： 1366 - 1367 2019.11

超音波霧化濃縮における液滴中のアルコール濃度 Invited

安田啓司

超音波TECHNO Vol. 67 ( 8 ) page： 350 - 353 2019.10

超音波を利用した水中の汚染物質分解と有価物質分離 Invited

安田啓司

化学と教育 Vol. 67 ( 8 ) page： 350 - 353 2019.8

Effect of Venturi Tube Shape on Reaction Performance by Hydrodynamic Cavitation

Yasuda Keiji, Ako Daisuke

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol. 52 ( 3 ) page： 280 - 282 2019.3

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

The effect of venturi tube shape on reaction rate by hydrodynamic cavitation was investigated. The apparatus mainly composed of the venturi tube, a liquid pump, a tank, a pipe arrangement, and a heat exchanger. The upstream and downstream pressures of the venturi tube were measured. The sample was an aqueous solution containing potassium iodine and chloroform. The generation rate of triiodide ion increased with increasing upstream pressure. This is because liquid velocity at the venturi tube is high and the amount of cavitation bubbles increases. When the throat diameter of the venturi tube was 2.5 mm, the generation rate of triiodide ion reached a maximum value. As the throat diameter of the venturi tube became smaller, the generation rate of triiodide ion per pass of venturi tube increased and the pass number of venturi tube decreased. Both low cavitation number and large pass number are important for high reaction performance.

DOI： 10.1252/jcej.18we183

Web of Science

Scopus

CiNii Research

Generation and Reduction of Bulk Nanobubbles by UIltrasonic Irradiation Reviewed

Yasuda Keiji, Matsushima Hodaka, Asakura Yoshiyuki

Chemical Engineering Science Vol. 195 page： 455 - 461 2019.2

ファインバブルによるオゾン反応の促進 Invited

安田啓司

エレクトロニクスコミュニケーション Vol. 34 page： 9 - 12 2019.1

A06 Size control by pulsed ultrasound and ultrafine bubbles on sonochemical synthesis of gold nanoparticles

Sato Tomofumi, Yasuda Keiji, Asakura Yoshiyuki

Proceedings of the Annual Meeting of the Japan Society of Sonochemistry Vol. 27 ( 0 ) page： 11 - 12 2018.11

Language：Japanese Publisher：Japan Society of Sonochemistry

Gold nanoparticles have electronic, magnetic and optical characteristics depending on their sizes and shapes. Ultrasonic irradiation to an aqueous solution of gold salt is able to synthesize gold nanoparticles without surfactants and reducers. Previous our study, the diameter of gold nanoparticles decreased and diameter distribution became narrow by the addition of ultrafine bubbles (UFB). In this study, we investigated effect of gas kind in UFB and pulsed ultrasound irradiation. The mean diameter of particles with Air-, Ar-, N2-, and O2-UFB are 24.7, 49.4, 73.0, and 43.1 nm, respectively. The standard deviation of particles with Air-, Ar-, N2-, and O2-UFB are 8.0, 13.5, 21.2, and 7.7 nm. This is because maximum temperature of cavitation for air is high, and many kinds of reducers (such as, nitrous acid and hydrogen peroxide) are generated since air contain Ar, N2 and O2. Compared with continuous wave, it is clear that pulse ultrasound reduces particle size.

DOI： 10.20577/pamjss.27.0_11

CiNii Research

P07 Factor that influences of sonochemical efficiency

Matsushima Hodaka, Asakura Yoshiyuki, Yasuda Keiji

Proceedings of the Annual Meeting of the Japan Society of Sonochemistry Vol. 27 ( 0 ) page： 37 - 38 2018.11

Language：Japanese Publisher：Japan Society of Sonochemistry

Intensification of sonochemical reaction is necessary to put sonochemical process into industrial
application. To evaluate the rate of sonochemical reaction, we choose sonochemical efficiency because this method has high quantitative performance, do not use hazardous chemical material, and is simple to operate. In this study, factor that influence of sonochemical efficiency is investigated. A Langevin and disc type transducers were used at 129 and 488 kHz, respectively. A circulating water bath was connected to the annular section of the vessel to maintain the sample temperature at 298 ± 1 K. Sample was aqueous solution of 0.1 M potassium iodide and volume was 100 ml. At 488 kHz, sonochemical efficiency increased with ultrasonic power until 5 W after that becomes constant. This is because sonochemical reaction fields are not enough to spread in the reactor. On the other hand, at 129 kHz, as ultrasonic power becomes higher, sonochemical efficiency increased until 1 W after that decreased. The sonochemical efficiency at 1 W is 1.5 times higher than that at 500 kHz.

DOI： 10.20577/pamjss.27.0_37

CiNii Research

P02 High-speed synthesis of nanographene with ultrasound and in-liquid plasma

Hasegawa Kenta, Nakada Ryo, Kano Hiroyuki, Kondo Hiroki, Hori Masaru, Yasuda Keiji

Proceedings of the Annual Meeting of the Japan Society of Sonochemistry Vol. 27 ( 0 ) page： 27 - 28 2018.11

Language：Japanese Publisher：Japan Society of Sonochemistry

Nanographenes are synthesized from alcohols by in-liquid plasma with ultrahigh rate. When carbon number in an alcohol molecule is high, synthesis rates increase but the crystalline nature of nanographene decreases. To eliminate trade-off between synthesis rates and crystal nature of nanographenes, ultrasound was irradiated to alcohols under in-liquid plasma. Samples were ethanol, 2-propanol, and 1-hexanol. Ultrasonic frequency was 500 kHz and power was 7.5 W. After nanographene synthesis, suspended solids were filtered using 0.45-μm-pore-size filters and treated with 30% hydrogen peroxide solution. Treated nanographene was analyzed by Raman scattering spectroscopy. Sample color was changed from transparent to black by in-liquid plasma and black area spread under ultrasound. The synthesis rate for all alcohol increased by ultrasound. In the case of 1-hexanol, crystal nature of nanographene was improved due to ultrasonic cavitation.

DOI： 10.20577/pamjss.27.0_27

CiNii Research

資源利用・環境浄化のためのファインバブルの活用 Invited

安田啓司

ファインケミカル Vol. 47 ( 10 ) page： 5-12 2018.10

ファインバブルによる廃水処理性能の向上 Invited

安田啓司

ペトロテック Vol. 41 ( 6 ) page： 432-436 2018.6

Measurement of distribution of broadband noise and sound pressures in sonochemical reactor Open Access

Yasuda, K; Nguyen, TT; Asakura, Y

ULTRASONICS SONOCHEMISTRY Vol. 43 page： 23 - 28 2018.5

Language：English Publisher：Ultrasonics Sonochemistry

Cross-sectional area distribution of broadband noise in a sonochemical reactor was measured to estimate reaction fields. A needle-type hydrophone scanned the sonochemical reactor in horizontal and vertical directions at one-millimeter interval. To show an absolute value of broadband noise, average of broadband sound pressure was defined. The distribution of sound pressures at the fundamental and second harmonic frequencies were also measured. In the case of driving frequency at 130 kHz, sonochemical reaction fields were observed in several ellipse shapes. The reaction fields in upper part of the reactor was high because cavitation bubbles moved upper part due to radiation force. The sound pressure distribution at the fundamental frequency showed existence of standing wave and reaction fields were weak at pressure antinode because cavitation bubbles were repelled by primary Bjerknes force. The sound pressure distribution at the second harmonic frequency indicated that the pattern of bubbles distribution resembled to that of reaction fields closely. In the case at 43 kHz, distributions of reaction fields and sound pressures were complex due to coupled vibration. The reaction fields were relatively weak in areas which had very high sound pressures at the fundamental frequency.

DOI： 10.1016/j.ultsonch.2017.12.051

Production of β-carotene nanoemulsions with the emulsification-evaporation technique using supercritical CO2 and improvement of its efficiency by Z-isomerization pre-treatment Reviewed

M. Ono, M. Honda, Wahyudiono, K. Yasuda, H. Kanda and M. Goto

The Journal of Supercritical Fluids Vol. 138 page： 124-131 2018.4

Measurement of Distribution of Broadband Noise and Sound Pressures in Sonochemical Reactor Reviewed

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

Ultrasonics Sonochemistry Vol. 43 page： 23-28 2017.12

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Papers - YASUDA, Keiji