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Kinetics and Mechanism of the Sonolytic Degradation of CCl_4: Intermediates and Byproducts

Hua, Inez and Hoffmann, Michael R. (1996) Kinetics and Mechanism of the Sonolytic Degradation of CCl_4: Intermediates and Byproducts. Environmental Science and Technology, 30 (3). pp. 864-871. ISSN 0013-936X. doi:10.1021/es9502942.

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The sonolytic degradation of aqueous carbon tetrachloride is investigated at a sound frequency of 20 kHz and 135 W (112.5 W cm^(-2)) of power. The observed first-order degradation rate constant in an Ar-saturated solution is 3.3 × 10^(-3) s^(-1) when the initial CCl_4 concentration, [CCl_4]_i, is 1.95 × 10^(-4) mol L^(-1) and increases slightly to 3.9 × 10^(-3) s^(-1) when [CCl_4]_i = 1.95 × 10^(-5) mol L^(-1). Low concentrations (10^(-8)−10^(-7) mol L^(-1)) of the organic byproducts, hexachloroethane and tetrachloroethylene, are detected, as well as the inorganic products chloride ion and hypochlorous acid. The chlorine mass balance after sonolysis is determined to be >70%. The reactive intermediate, dichlorocarbene, is identified and quantified by means of trapping with 2,3-dimethyl-2-butene. The presence of ozone in the sonicated solution does not significantly effect the rate of degradation of carbon tetrachloride; however, O_3 inhibits the accumulation of hexachloroethane and tetrachloroethylene. Ultrasonic irradiation of an aqueous mixture of p-nitrophenol (p-NP) and carbon tetrachloride results in the acceleration of the sonochemical degradation of p-NP. The sonolytic rate of degradation of p-NP appears to be enhanced by the presence of hypochlorous acid, which results from the sonolysis of CCl_4.

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Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 1996 American Chemical Society. Received for review May 1, 1995. Accepted September 14, 1995. Publication Date (Web): February 26, 1996. The authors thank Wonyong Choi for help with the carbene trapping experiments. Financial support from the Advanced Research Projects Agency, ARPA, (Grant NAV5 HFMN N0001492J1901), the Office of Naval Research, ONR, and the Electric Power Institute, EPRI (Grant RP 8003-37) is gratefully acknowledged.
Funding AgencyGrant Number
Advanced Research Projects Agency (ARPA)UNSPECIFIED
Office of Naval Research (ONR)NAV5 HFMN N0001492J1901
Electric Power Research Institute (EPRI)RP 8003-37
Issue or Number:3
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Official Citation:Kinetics and Mechanism of the Sonolytic Degradation of CCl4:  Intermediates and Byproducts Inez Hua and Michael R. Hoffmann Environmental Science & Technology 1996 30 (3), 864-871 DOI: 10.1021/es9502942
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59366
Deposited By: Ruth Sustaita
Deposited On:11 Aug 2015 16:22
Last Modified:10 Nov 2021 22:19

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