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Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Reduction of trichloroethylene by outer-sphere electron-transfer agents
Angela D Follett1, Kristopher McNeill
1Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Journal of the American Chemical Society
|January 20, 2005
Summary
Investigating trichloroethylene (TCE) reduction reveals that outer-sphere electron transfer is not the primary mechanism for vitamin B12. The cis- to trans-dichloroethylene ratio serves as a key indicator for TCE reduction pathways.
Area of Science:
- Environmental Chemistry
- Organic Chemistry
- Biochemistry
Background:
- Trichloroethylene (TCE) is a common environmental pollutant.
- Understanding TCE reduction mechanisms is crucial for remediation strategies.
- Vitamin B12 is known to catalyze reductive dehalogenation.
Purpose of the Study:
- To investigate the mechanism of TCE reduction using outer-sphere electron-transfer agents.
- To compare the TCE reduction pathway mediated by outer-sphere reductants with that of vitamin B12.
- To determine if outer-sphere electron transfer is the major pathway for vitamin B12-mediated TCE reduction.
Main Methods:
- Utilized a series of well-characterized outer-sphere electron-transfer agents.
- Analyzed the final product ratios of cis-dichloroethylene (cDCE) to trans-dichloroethylene (tDCE).
- Compared product ratios from outer-sphere reductants to those obtained with vitamin B12.
Main Results:
- Outer-sphere electron-transfer agents yielded specific [cDCE]:[tDCE] ratios.
- The [cDCE]:[tDCE] ratio for vitamin B12 differed significantly from those of outer-sphere reductants.
- Kinetic data support a two-step reduction mechanism involving vinyl radicals and vinyl anions for outer-sphere reductants.
Conclusions:
- Outer-sphere electron transfer is unlikely to be the major pathway for TCE reduction by vitamin B12.
- The [cDCE]:[tDCE] product ratio can serve as a diagnostic tool to elucidate TCE reduction mechanisms.
- Results provide kinetic support for a two-step reduction mechanism involving vinyl radicals and anions in TCE reduction by outer-sphere agents.
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