Abiotic Reductive Dechlorination of Chlorinated Ethylenes by Iron-Bearing Soil Minerals. 1. Pyrite and Magnetite

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Abiotic reductive dechlorination of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), cisdichloroethylene (cis-DCE), and vinyl chloride (VC)) by pyrite and magnetite was characterized in a batch reactor system. Dechlorination kinetics was adequately described by a modified Langmuir-Hinshelwood model that includes the effect of a decreasing reductive capacity of soil mineral. The kinetic rate constant for the reductive dechlorination of target organics at reactive sites of soil minerals was in the range of 0.185 ((0.023) to 1.71 ((0.06) day-1. The calculated specific reductive capacity of soil minerals for target organics was in the range of 0.33 ((0.02) to 2.26 ((0.06) íM/g and sorption coefficient was in the range of 0.187 ((0.006) to 0.7 ((0.022) mM-1. Surface areanormalized pseudo-first-order initial rate constants for target organics by pyrite were found to be 23.5 to 40.3 times greater than those by magnetite. Target organics were mainly transformed to acetylene and small amount of chlorinated intermediates, which suggests that â-elimination was the main dechlorination pathway. The dechlorination of VC followed a hydrogenolysis pathway to produce ethylene and ethane. The addition of Fe(II) increased the dechlorination rate ofcis-DCE and VC in magnetite suspension by nearly a factor of 10. The results obtained in this research provide basic knowledge to better predict the fate of chlorinated ethylenes and to understand the potential of abiotic processes in natural attenuation.
Publisher
American Chemical Society
Issue Date
2002-12-01
Keywords

Abiotic reductive dechlorination; Chlorinated ethylene; Soil mineral; Pyrite; Magnetite

Citation

ENVIRONMENTAL SCIENCE & TECHNOLOGY, v.36, no.23, pp.5147-5154

ISSN
0013-936X
DOI
10.1021/es025836b
URI
http://hdl.handle.net/10203/7260
Appears in Collection
CE-Journal Papers(저널논문)

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