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Optimization of Ultrasonic Irradiation as an Advanced Oxidation Technology

Hua, Inez and Hoffmann, Michael R. (1997) Optimization of Ultrasonic Irradiation as an Advanced Oxidation Technology. Environmental Science and Technology, 31 (8). pp. 2237-2243. ISSN 0013-936X. doi:10.1021/es960717f.

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The optimization of ultrasonic irradiation as an advanced oxidation technology can be achieved by adjusting the ultrasonic frequency and saturating gas during sonolysis. The sonolytic production of hydrogen peroxide (H_2O_2) and hydroxyl radical (•OH) has been investigated at the ultrasonic frequencies of 20, 40, 80, and 500 kHz, respectively, in the presence of four different saturating gases (i.e., Kr, Ar, He, O_2) at each frequency. H_2O_2 was measured with a KI dosimeter, and the formation of •OH was monitored by trapping with terephthalic acid. Both the applied frequency and the physicochemical properties of the saturating gases influ ence the sonochemical rates of production of •OH and H_2O_2. At 20 kHz, the rate contants for the production of H_2O_2 vary over an order of magnitude as a function of the nature of the dissolved gas (0.0508 and 1.31 μM min^(-1)). Similar trends are observed for the production of •OH at the same frequencies and under an identical set of saturating gases. The highest rates of production of H_2O_2 (pH 7, 2.94 μM min^(-1)) and •OH (pH 11, 0.391 μM min^(-1)) are observed during sonolysis of Kr-saturated solutions at 500 kHz. Sonolysis of He-saturated solutions at 20 kHz results in the lowest rates of production of H_2O_2 (0.0508 μM min^(-1)) and •OH (0.0310 μM min^(-1)). Decreasing differences among the saturating gases at higher frequencies are attributed to changes in bubble dynamics and thermodynamics as the resonant bubble radius decreases from 177 μm at 20 kHz to 7 μm at 500 kHz.

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Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 1997 American Chemical Society. Received for review August 19, 1996. Revised manuscript received March 24, 1997. Accepted March 31, 1997. The authors are grateful to the Electric Power Research Institute (EPRI contract RP8003-36) and to the Department of Defenses Advanced Research Project Agency's University Research Initiative (ARPA Grant NAV5HFMNN0101492J1901) for their generous financial support.
Funding AgencyGrant Number
Electric Power Research Institute (EPRI)RP8003-36
Office of Naval Research (ONR)NAV 5 HFMN N0001492J1901
Advanced Research Projects Agency (ARPA)UNSPECIFIED
Issue or Number:8
Record Number:CaltechAUTHORS:20150814-081851553
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Official Citation:Optimization of Ultrasonic Irradiation as an Advanced Oxidation Technology Inez Hua and Michael R. Hoffmann Environmental Science & Technology 1997 31 (8), 2237-2243 DOI: 10.1021/es960717f
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59518
Deposited By: Ruth Sustaita
Deposited On:14 Aug 2015 16:47
Last Modified:10 Nov 2021 22:21

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