Modeling the Electrolytic Dechlorination of Trichloroethylene in a Granular Graphite-Packed Reactor
- 1 June 2007
- journal article
- research article
- Published by Mary Ann Liebert Inc in Environmental Engineering Science
- Vol. 24 (5), 581-594
- https://doi.org/10.1089/ees.2006.0181
Abstract
A comprehensive reactor model was developed for the electrolytic dechlorination of trichloroethylene (TCE) at a granular-graphite cathode. The reactor model describes the dynamic processes of TCE dechlorination and adsorption, and the formation and dechlorination of all the major dechlorination products in an open reactor system with three phases: the solution, the graphite, and the headspace. The dynamic processes were affected by adsorption on the granular graphite, by dilution of the headspace by the outgoing stream of gas generated in the electrolytic reactor, and by kinetic reactions of dechlorination and formation of products. Major dechlorination pathways include: (1) TCE hydrogenolysis to cis- and transdichloroethene (DCE), which are then reduced to acetylene; (2) TCE hydrogenolysis to 1,1-DCE, which is reduced further to ethylene; and (3) the indirect reduction from TCE to ethane. Values for the kinetic rate constants were obtained by fitting the reactor model to the measured concentrations of TCE, cis-DCE, t-DCE, chloride, and chloromethane (a byproduct of chloride reaction) in the solution, and to the measured concentrations of acetylene and ethylene in the headspace in the experiments of TCE dechlorination at three voltages. These values suggest that the rate of adsorption was most likely enhanced by the electrolysis, that the actual amount adsorbed depended on the change of TCE concentration in the solution, and that TCE hydrogenolysis and indirect reduction of TCE (direct conversion) to ethane were the major routes for TCE dechlorination at the granular-graphite cathode.Keywords
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