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Photo-Induced Electron Transfers to CCl_4 and its Degradation Mechanism on TiO_2 Particles

Choi, W. and Hoffmann, M. R. (1995) Photo-Induced Electron Transfers to CCl_4 and its Degradation Mechanism on TiO_2 Particles. Abstracts of Papers of the American Chemical Society, 209 . 200-ENVR. ISSN 0065-7727.

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The photoreductive degradation of CCl_4 in TiO_2 particulate suspensions in the presence of a variety of organic electron donors (alcohols, carboxylic acids, and benzene derivatives) has been examined. CHCl_3, C_2Cl_4, and C_2Cl_6 are detected as intermediates during photolysis. The rate of CCl_4 dechlorination can be enhanced significantly when alcohols and organic acids are used as electron donors. Kinetic isotope effects and structure-reactivity relationships show that hydrogen-abstraction by hydroxyl radicals plays an important role in the hole-scavenging mechanism. The pH of the TiO_2 suspension influences the rate of CCl_4 reduction either by altering the electrostatic interactions of electron donors on the TiO_2 surface or by changing the reduction potential of the conduction band electron in a Nernstian fashion. Since dissolved oxygen is shown to be nonessential for the complete mineralization of CCl_4, a mechanism, which involves dichlorocarbene formation through a two-electron transfer, is proposed.

Item Type:Article
Hoffmann, M. R.0000-0001-6495-1946
Additional Information:© 1995 American Chemical Society.
Record Number:CaltechAUTHORS:20151215-093807476
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62923
Deposited By: Tony Diaz
Deposited On:15 Dec 2015 18:01
Last Modified:03 Mar 2020 13:01

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