著者

刈谷 未来 山脇 直也 奥村 勇人 赤松 重則 西内 悠祐 秦 隆志

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 27 (ISSN:24241512)

巻号頁・発行日

pp.47-48, 2018-11-19 (Released:2022-09-20)

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In this study, for the evaluation of ultrafine bubbles (UFB) which is important in fine bubble research, a method to use hydroxyl (OH) radicals or luminescence phenomenon (sonoluminescence) generated by the collapse of UFB when applying ultrasonic wave to UFB as an indicator was verified. Electron spin resonance method and potassium iodide (KI) method were used for the evaluation of OH radicals, and photomultiplier tubes were used for the evaluation by sonoluminescence. OH radicals by the collapse of UFB were observed from the result of OH radical measurement by ESR. And, even in the KI method which is a simple OH radical evaluation, it was shown that the same evaluation can be made from the difference in absorbance when ozone is used for the inclusion gas. On the other hand, in the sonoluminescence measurement, it was confirmed that the luminescence intensity in water to which inorganic particles of the same amount as that of UFB was added was smaller than in the case of UFB water.

著者

朝倉 俊博

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 7 (ISSN:24241512)

巻号頁・発行日

pp.1, 1998 (Released:2017-07-18)

著者

大常 雄基 安田 啓司 朝倉 義幸

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 25 (ISSN:24241512)

巻号頁・発行日

pp.39-40, 2016 (Released:2017-07-21)

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To investigate generation of ultrasonic cavitation in gel, sodium polyacrylate swollen in potassium iodide solution was used as a sample. After ultrasonic irradiation at 500 kHz, absorbance and viscosity of sample were measured. The absorbance and viscosity changes are originated from oxidation reaction of potassium iodide and decrease in the degree of polymerization of sodium polyacrylate, respectively. The absorbance started to increase after several minutes irradiation. On the other hand, viscosity decreases immediately after irradiation. This is because polymer is degraded due to shear stress of ultrasonic propagation in addition to cavitation. After sample viscosity fully decreased, it is able to generate ultrasonic cavitation and chemical reaction occurs. As sample temperature became lower, the viscosity decreased and the absorbance increased. To use this sample, detection of cavitation generation in gel is possible.

著者

竹村 洸亮 安田 啓司 朝倉 義幸

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 (ISSN:24241512)

巻号頁・発行日

pp.41-42, 2016 (Released:2017-07-21)

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Ethanol and organic material mixed aqueous solution were atomized using ultrasonic irradiation at 2.4 MHz. Atomized liquid was collected by refrigeration of liquid nitrogen. The concentrations in collected liquid and mist were experimentally investigated. Malic acid, lactic acid (organic acid), 1-propanol, methanol (alcohol), methyl ethyl ketone, diethyl ketone (ketone) were used as organic material. The ethanol concentration in collected liquid was little affected by addition of organic materials. Organic acid in ethanol aqueous solution was not separated. On the other hand, alcohol and ketone concentrations in collected liquid were higher than those in sample. The 1-propanol concentration in collected liquid was lower than that in mist. This is because it is difficult to collect nano-sized droplets which contain highly condensed alcohol.

著者

東海 旭宏 水越 克彰 興津 健二 堀 史説 西村 芳実 岩瀬 彰宏

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 (ISSN:24241512)

巻号頁・発行日

pp.43-44, 2016 (Released:2017-07-21)

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We synthesized graphene-Pd nanocomposites in one-pot by ultrasound, radiation and liquid phase plasma. Graphene dispersion containing Pd ions and 2-propanol was irradiated with ultrasound (200 kHz, 200 W) for 30 min and with gamma-ray (̴1 MeV) and electron beam (̴6 MeV). In radiochemical synthesis, the absorbed dose was 10 kGy. In these processes, the reduction of Pd ions and oxidation of graphene occurred simultaneously in one-pot. In the liquid plasma method, Pd nanoparticles generated directly from the electrodes were deposited onto carbonyl modified graphene. Based on the results, the formation mechanism of the nanocomposites was discussed.

著者

田口 君彦 松岡 辰郎 香田 忍

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集

巻号頁・発行日

vol.15, pp.63-64, 2006

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The mechanism of ultrasonic degradation is still obscure, but it is well accepted that cavitation bubbles are mainly responsible for the degradation. The intense shear field generated by the collapse of the cavitation bubbles induces chain scission. Most of investigations on ultrasonic degradation have been carried out at low ultrasonic frequency around 20kHz. In this work, the ultrasonic degradation of methyl cellulose in aqueous solution was studied at two frequencies (20kHz and 500kHz) at the constant calorimetric power (20W) and temperature (25℃). The time variation of the average molecular weights and the molecular distribution were determined by Gel Permeation Chromatography (GPC). The mass average molecular weights (M_w) decreases with sonication time. The large lowering of M_w was observed at the frequency 500kHz. The degradation rate was suppressed by the addition of t-BuOH which act as a radical scavenger. The ultrasonic degradation rate coefficient k_d was estimated and compared with the results of other water-soluble polymers. The order of k_d value were PEO > Dextran 〓 Pullulan > MC. We will discuss on the frequency effects on the ultrasonic degradation.

著者

安井 久一 辻内 亨 Judy Lee 小塚 晃透 砥綿 篤哉

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 18 (ISSN:24241512)

巻号頁・発行日

pp.97-98, 2009-10-23 (Released:2017-07-18)

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Ashokkumar et al. [J. Am. Chem. Soc. 129, 2250 (2007)] reported that the intensity of the broad-band noise in acoustic cavitation noise from a low concentration surfactant (SDS) solution is much weaker than that from pure water. In the present study, numerical simulations of acoustic cavitation noise have been performed in order to study the mechanism of the much weaker broad-band noise from aqueous surfactant solution. The results of the numerical simulations have indicated that bubbles are shape stable in a low concentration aqueous surfactant solution due to smaller ambient radius of bubbles than that in pure water. It results in the much weaker broad-band noise because there is much less temporal fluctuation in the number of bubbles which is the origin of the broad-band noise. In other words, in a low concentration surfactant solution stable cavitation dominates, while in pure water transient cavitation dominates. Transient cavitation causes the temporal fluctuations in the number of bubbles resulting in the intense broad-band noise.

著者

渡邊 美香 熊野 史一 高橋 晋 伊藤 幸雄

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演論文集 18 (ISSN:24241512)

巻号頁・発行日

pp.95-96, 2009-10-23 (Released:2017-07-18)

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The hot spots that high pressures and temperatures generate during the bubble collapse process, especially in acoustic cavitation, directly related to the physical and chemical reactions, hi this study, to investigate the possibility of realization for the sake production process, we investigate the MB effects on the composition of sake. The fragrance ingredient in sake is affected by the activities of the hot spot and/or shock waves, resulting in the decompositions and the synthsis of the fragrance ingredient. The ethyl acetate and the ethyl caproate activated to are decreasing by hydrolysis, while the isoamyl acetate is activated by increasing in the dehydration. There are many point which must be clarified, i.e., the oxidation of isoamyl alcohol by affecting the dissolved gas in the solutions.

著者

福壽 快斗 朝倉 義幸 香田 忍

出版者

日本ソノケミストリー学会

雑誌

ソノケミストリー討論会講演要旨集

巻号頁・発行日

no.22, pp.39-40, 2013-10-25

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We have re-examined the frequency dependence of the cavitation threshold for air-saturated water and organic solvents. Cavitation threshold was estimated by observation of generation of cavitation from the results of the polymer degradation effect and acoustic spectrum. We used direct irradiation type and indirect irradiation type ultrasonic reactor in this experiment. All experiments were performed in the driving power 0.5〜50W, fluid volume 50mL, the driving frequency 20kHz〜5MHz. Cavitation threshold which is calculated from the results of the polymer degradation was larger than the cavitation threshold, which is calculated from the acoustic spectrum measurement. Regardless of solvents, in the frequency range below 45kHz, cavitation threshold decreased with increasing the frequency. Further, in the frequency range above 45kHz, cavitation threshold gradually increased with increasing the frequency.