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USE OF CARBON STABLE ISOTOPE FOR THE DECHLORINATION OF TRICHLOROETHYLENE ON GRANULAR-GRAPHITE PACKED ELECTRODES (PRESENTATION)
Citation:
FANG, J. AND S. R. AL-ABED. USE OF CARBON STABLE ISOTOPE FOR THE DECHLORINATION OF TRICHLOROETHYLENE ON GRANULAR-GRAPHITE PACKED ELECTRODES (PRESENTATION). Presented at International Conference on Energy, Environment, and Disasters (INCEED 05), Charlotte, NC, July 24 - 30, 2005.
Impact/Purpose:
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Description:
Trichloroethylene (TCE) is widely used as a solvent in metal processing and electronic manufacturing industries, but waste and spilled TCE often results in blocks of non-aqueous liquid in vadose and saturated zones which become continuous contamination sources for groundwater. Electrochemical remediation has advantages over other technologies which have limitations in effectiveness and economics. Among materials used for electrodes, granular graphite obviously has big advantages. However, remediation using graphite electrode complicates the technology due to TCE adsorption by the graphite and side reactions on the carbon electrode surfaces. The complications also include less recovery of chlorine and carbon and the production of possible carcinogen chloromethane which is not commonly seen in TCE dechlorination pathways. The purpose of the paper is to use carbon stable 13C isotope TCE to study the dechlorination process at granular-graphite packed cathodes. The objectives are i) to use a conventional GC/MS in analyzing 13C isotope TCE and the chlorinated hydrocarbon products and ii) to investigate the formation of chloromethane in the TCE dechlorination on granular graphite. Dichloroethene isomers (DCEs) are the chlorinated products of dechlorination in which the cis-DCE is the major one, and acetylene, ethylene, and ethane are the hydrocarbon products. Chloromethane was observed in high amounts during TCE dechlorination in ammonium acetate but was not seen during dechlorination in potassium nitrate. The investigation confirmed that chloromethane is not a direct product of TCE dechlorination at the granular graphite cathode and that it is formed in acetate electrolyte due to the oxidation of the chloride, the major product of TCE dechlorination.