Pathways and Kinetics of Chlorinated Ethylene and Chlorinated Acetylene Reaction with Fe(0) Particles

Abstract

Pathways and kinetics through which chlorinated ethylenes and their daughter products react with Fe(0) particles were investigated through batch experiments. Substantial intra- and interspecies inhibitory effects were observed, requiring the use of a modified Langmuir−Hinshelwood−Hougen−Watson (LHHW) kinetic model in which species compete for a limited number of reactive sites at the particle−water interface. Results indicate that reductive β-elimination accounts for 87% of tetrachloroethylene (PCE), 97% of trichloroethylene (TCE), 94% of cis-dichloroethylene (cis-DCE), and 99% of trans-dichloroethylene (trans-DCE) reaction. Reaction of 1,1-DCE gives rise to ethylene, consistent with a reductive α-elimination pathway. For the highly reactive chloro- and dichloroacetylene intermediates produced from the reductive elimination of TCE and PCE, 100% and 76% of the reaction, respectively, occur via hydrogenolysis to lesser chlorinated acetylenes. The branching ratios for reactions of PCE or TCE (and their daugh...