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Title: Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on TiO[sub 2] surfaces en route to mineralization. A combined photocatalytic and radiation chemical study. [gamma radiolysis]

Abstract

The oxidative degradation of chlorinated ethanes proceeds practically via the same mechanism in [gamma]-radiolysis and photocatalysis at TiO[sub 2] surfaces, respectively. C-centered radicals generated via hydroxyl radical induced C-H bond cleavage and peroxyl radicals derived therefrom after oxygen addition are the key radical intermediates in these processes. The main molecular products identified and isolated in both the [gamma]-radiolytic and photocatalytic experiments are organic (mostly chlorinated) acids, HCl, and CO[sub 2]. Other products formed in minor yields are aldehydes and HCOOH. Photocatalytic degradation of these product acids and nonionic substrates leads eventually to complete mineralization. The results strongly suggest that the photocatalytic degradation is initiated by an oxidation of the chlorinated compounds through TiO[sub 2]-surface-adsorbed hydroxyl radicals. Only some acids, like trichloroacetic acid and oxalic acid, seem to be oxidized primarily by valence band holes via a photo-Kolbe process. Several rate constants are reported on the oxidation of chlorinated ethanes and acids by free and surface-adsorbed hydroxyl radicals and on the overall photocatalytic degradation of the chlorinated compounds. The paper also includes a discussion of the material balance. The study demonstrates the value of radiation chemical investigations for the understanding of the details in the photocatalytic mineralization process of halogenated organicmore » compounds.« less

Authors:
; ;  [1]
  1. Hahn-Meitner Inst., Berlin (Germany)
Publication Date:
OSTI Identifier:
6923506
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry; (United States)
Additional Journal Information:
Journal Volume: 95:24; Journal ID: ISSN 0022-3654
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; CHLORINATED ALIPHATIC HYDROCARBONS; PHOTOCHEMICAL REACTIONS; RADIOLYSIS; ALKYL RADICALS; CATALYSIS; CHEMICAL REACTION KINETICS; EXPERIMENTAL DATA; GAMMA RADIATION; HYDROXYL RADICALS; MINERALIZATION; ORGANIC ACIDS; OXIDATION; PEROXY RADICALS; REACTION INTERMEDIATES; SUPPORTS; TITANIUM OXIDES; CHALCOGENIDES; CHEMICAL RADIATION EFFECTS; CHEMICAL REACTIONS; DATA; DECOMPOSITION; ELECTROMAGNETIC RADIATION; HALOGENATED ALIPHATIC HYDROCARBONS; INFORMATION; IONIZING RADIATIONS; KINETICS; MECHANICAL STRUCTURES; NUMERICAL DATA; ORGANIC CHLORINE COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; RADIATION EFFECTS; RADIATIONS; RADICALS; REACTION KINETICS; TITANIUM COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; 400500* - Photochemistry; 400600 - Radiation Chemistry

Citation Formats

Mao, Yun, Schoeneich, C, and Asmus, K D. Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on TiO[sub 2] surfaces en route to mineralization. A combined photocatalytic and radiation chemical study. [gamma radiolysis]. United States: N. p., 1991. Web. doi:10.1021/j100177a085.
Mao, Yun, Schoeneich, C, & Asmus, K D. Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on TiO[sub 2] surfaces en route to mineralization. A combined photocatalytic and radiation chemical study. [gamma radiolysis]. United States. https://doi.org/10.1021/j100177a085
Mao, Yun, Schoeneich, C, and Asmus, K D. 1991. "Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on TiO[sub 2] surfaces en route to mineralization. A combined photocatalytic and radiation chemical study. [gamma radiolysis]". United States. https://doi.org/10.1021/j100177a085.
@article{osti_6923506,
title = {Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on TiO[sub 2] surfaces en route to mineralization. A combined photocatalytic and radiation chemical study. [gamma radiolysis]},
author = {Mao, Yun and Schoeneich, C and Asmus, K D},
abstractNote = {The oxidative degradation of chlorinated ethanes proceeds practically via the same mechanism in [gamma]-radiolysis and photocatalysis at TiO[sub 2] surfaces, respectively. C-centered radicals generated via hydroxyl radical induced C-H bond cleavage and peroxyl radicals derived therefrom after oxygen addition are the key radical intermediates in these processes. The main molecular products identified and isolated in both the [gamma]-radiolytic and photocatalytic experiments are organic (mostly chlorinated) acids, HCl, and CO[sub 2]. Other products formed in minor yields are aldehydes and HCOOH. Photocatalytic degradation of these product acids and nonionic substrates leads eventually to complete mineralization. The results strongly suggest that the photocatalytic degradation is initiated by an oxidation of the chlorinated compounds through TiO[sub 2]-surface-adsorbed hydroxyl radicals. Only some acids, like trichloroacetic acid and oxalic acid, seem to be oxidized primarily by valence band holes via a photo-Kolbe process. Several rate constants are reported on the oxidation of chlorinated ethanes and acids by free and surface-adsorbed hydroxyl radicals and on the overall photocatalytic degradation of the chlorinated compounds. The paper also includes a discussion of the material balance. The study demonstrates the value of radiation chemical investigations for the understanding of the details in the photocatalytic mineralization process of halogenated organic compounds.},
doi = {10.1021/j100177a085},
url = {https://www.osti.gov/biblio/6923506}, journal = {Journal of Physical Chemistry; (United States)},
issn = {0022-3654},
number = ,
volume = 95:24,
place = {United States},
year = {Thu Nov 28 00:00:00 EST 1991},
month = {Thu Nov 28 00:00:00 EST 1991}
}