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Title: Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(O) particles

Abstract

Pathways and kinetics through which chlorinated ethylenes and their daughter products react with Fe(O) particles were investigated through batch experiments. Substantial intra- and interspecies inhibitory effects were observed, requiring the use of a modified Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model in which species compete for a limited number of reactive sites at the particle-water interface. Results indicate that reductive {beta}-elimination accounts for 87% of tetrachloroethylene (PCE), 97% of trichloroethylene (TCE), 94% of cis-dichloroethylene (cis-DCE), and 99% of trans-dichloroethylene (Trans-DCE) reaction. Reaction of 1,1-DCE gives rise to ethylene, consistent with a reductive {alpha}-elimination pathway. For the highly reactive chloro- and dichloro-acetylene intermediates produced from the reductive elimination of TCE and PCE, 100% and 76% of the reaction, respectively, occur via hydrogenolysis to lessen chlorinated acetylenes. The branching ratios for reactions of PCE or TCE (and their daughter products) with iron particles are therefore such that production of vinyl chloride is largely circumvented. Reactivity of the chlorinated ethylenes decreases markedly with increasing halogenation, counter to the trend that might be anticipated if the rate-limiting step were to involve dissociative electron transfer. The authors propose that the reaction of vinyl halides proceeds via a di-{sigma}-bonded surface-bound intermediate. The reactivity trends and pathways observed in thismore » work explain why lesser-chlorinated ethylenes have only been reported as minor products in prior laboratory and field studies of PCE and TCE reaction with Fe(O).« less

Authors:
;
Publication Date:
Research Org.:
Johns Hopkins Univ., Baltimore, MD (US)
OSTI Identifier:
20080522
Resource Type:
Journal Article
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 34; Journal Issue: 9; Other Information: PBD: 1 May 2000; Journal ID: ISSN 0013-936X
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CHLORINATED ALIPHATIC HYDROCARBONS; REMEDIAL ACTION; L CODES; IRON; CHEMICAL REACTION KINETICS; CONTAINMENT SYSTEMS

Citation Formats

Arnold, W.A., and Roberts, A.L. Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(O) particles. United States: N. p., 2000. Web. doi:10.1021/es990884q.
Arnold, W.A., & Roberts, A.L. Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(O) particles. United States. doi:10.1021/es990884q.
Arnold, W.A., and Roberts, A.L. Mon . "Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(O) particles". United States. doi:10.1021/es990884q.
@article{osti_20080522,
title = {Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(O) particles},
author = {Arnold, W.A. and Roberts, A.L.},
abstractNote = {Pathways and kinetics through which chlorinated ethylenes and their daughter products react with Fe(O) particles were investigated through batch experiments. Substantial intra- and interspecies inhibitory effects were observed, requiring the use of a modified Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model in which species compete for a limited number of reactive sites at the particle-water interface. Results indicate that reductive {beta}-elimination accounts for 87% of tetrachloroethylene (PCE), 97% of trichloroethylene (TCE), 94% of cis-dichloroethylene (cis-DCE), and 99% of trans-dichloroethylene (Trans-DCE) reaction. Reaction of 1,1-DCE gives rise to ethylene, consistent with a reductive {alpha}-elimination pathway. For the highly reactive chloro- and dichloro-acetylene intermediates produced from the reductive elimination of TCE and PCE, 100% and 76% of the reaction, respectively, occur via hydrogenolysis to lessen chlorinated acetylenes. The branching ratios for reactions of PCE or TCE (and their daughter products) with iron particles are therefore such that production of vinyl chloride is largely circumvented. Reactivity of the chlorinated ethylenes decreases markedly with increasing halogenation, counter to the trend that might be anticipated if the rate-limiting step were to involve dissociative electron transfer. The authors propose that the reaction of vinyl halides proceeds via a di-{sigma}-bonded surface-bound intermediate. The reactivity trends and pathways observed in this work explain why lesser-chlorinated ethylenes have only been reported as minor products in prior laboratory and field studies of PCE and TCE reaction with Fe(O).},
doi = {10.1021/es990884q},
journal = {Environmental Science and Technology},
issn = {0013-936X},
number = 9,
volume = 34,
place = {United States},
year = {2000},
month = {5}
}