Use of carbon stable isotope to investigate chloromethane formation in the electrolytic dechlorination of trichloroethylene

• Published in: Journal of hazardous materials 2007-03, Vol.141 (3), p.729-735
• Main Authors: Fang, Yuanxiang, Al-Abed, Souhail R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbon Isotopes - chemistry; Carbon stable isotope; Chlorine - chemistry; Electrodes; Electrolysis; Electrolytic dechlorination; Ethylene Dichlorides - analysis; Ethylene Dichlorides - chemistry; Exact sciences and technology; Gas Chromatography-Mass Spectrometry; Graphite; Methyl Chloride - analysis; Methyl Chloride - chemistry; Pollution; Trichloroethylene (TCE); Trichloroethylene - analysis; Trichloroethylene - chemistry
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2006.07.036

Carbon stable isotope trichloroethylene ( 13C TCE) was used to investigate the formation of chloromethane (CM) during the electrolytic dechlorination of trichloroethylene (TCE) at a granular-graphite packed cathode. A method was developed to use a conventional GC/MS to analyze and quantify regular and 13C TCE and their dechlorination products. The concentration of a 13C compound can be calculated, based on the concentration of its regular counterpart, from the response ratio of two fragments of different mass per charge values from the compounds in a sample and two characteristic MS spectrum ratios: one is the response ratio of the two fragments of the regular compound, and the other is the response ratio of the corresponding fragments of the regular and 13C compounds at the same concentrations. The method was used to analyze the regular and 13C compounds observed in an experiment of dechlorination in an ammonium acetate solution that contained both regular TCE and 13C TCE. Results of analysis confirmed that CM was not a direct product of TCE dechlorination at the granular graphite cathode that cis-DCE was an intermediate product of TCE dechlorination, and that 1,1-DCE was not a dechlorination product.