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Chemical mechanism of inorganic oxidants in the TiO_2/UV process: increased rates of degradation of chlorinated hydrocarbons

Martin, Scot T. and Lee, Albert T. and Hoffmann, Michael R. (1995) Chemical mechanism of inorganic oxidants in the TiO_2/UV process: increased rates of degradation of chlorinated hydrocarbons. Environmental Science and Technology, 29 (10). pp. 2567-2573. ISSN 0013-936X. https://resolver.caltech.edu/CaltechAUTHORS:20150810-083411329

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Abstract

Particulate suspensions of TiO_2 irradiated with UV light at wavelengths shorter than 385 nm catalyze the autooxidation of chlorinated hydrocarbons such as 4-chlorophenol (4-CP). The addition of oxyanion oxidants such as CIO_2^-, CIO_3^-, IO_4^-, S_2O_8^(2-), and BrO_3^- increases the rate of photodegradation of 4-CP in the following order: CIO_2^- > IO_4^- > BrO_3^- > CIO_3^-. In the absence of TiO_2, CIO_3^- shows no photoreactivity toward 4-CP, while HSO_5^- and MnO_4^- exhibit rapid thermal reactivity with 4-CP. BrO_3^- appears to increase photoreactivity by scavenging conduction-band electrons and reducing charge-carrier recombination. With CIO_3^- as an oxidant, the degradation of 4-CP appears to follow three concurrent pathways. Kinetic equations for the rate of degradation of 4-CP as a function of [4-CP], [CIO_3^-], and [O_2] and of the light intensity are derived from a proposed mechanism.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/es00010a017DOIArticle
http://pubs.acs.org/doi/abs/10.1021/es00010a017PublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0002-0432-6564
Additional Information:© 1995 American Chemical Society. Received for review February 7, 1995. Revised manuscript received June 1, 1995. Accepted July 6, 1995. We are grateful to ARPA and ONR {NAV 5 HFMN N0001492J1901} for financial support. Drs. Ira Skurnick and Harold Gund provided generous support and encouragement. S. T .M. is supported by a National Defense Science and Engineering Graduate Fellowship. A.T.L. is the recipient of a Summer Undergraduate Research Fellowship from Caltech. Wonyong Choi, Peter Green, Nicole Peill, and Janet Kesselman provided valuable support and stimulating discussion.
Funders:
Funding AgencyGrant Number
Advanced Research Projects Agency (ARPA)UNSPECIFIED
Office of Naval Research (ONR)NAV 5 HFMN N0001492J1901
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
Issue or Number:10
Record Number:CaltechAUTHORS:20150810-083411329
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150810-083411329
Official Citation:Chemical mechanism of inorganic oxidants in the TiO2/UV process: increased rates of degradation of chlorinated hydrocarbons Scot T. Martin, Albert T. Lee, and Michael R. Hoffmann Environmental Science & Technology 1995 29 (10), 2567-2573 DOI: 10.1021/es00010a017
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59332
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:10 Aug 2015 18:23
Last Modified:03 Oct 2019 08:45

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