Reductive dehalogenation of trichloroethylene: Kinetic models and experimental verification

This paper develops a generalized kinetic model for two-phase systems involving reactions in one phase with product partitioning into a second phase, and applies it to the reductive dehalogenation of trichloroethylene using two systems. The generalized approach can be used for a variety of catalyst choices, including zero-valent metals. With vitamin B₁₂, the model includes specific reaction pathways for the reductive dehalogenation of TCE combined with the partitioning of reactants, intermediates, and products between the gas and liquid phases. The model has been used to study the effect of various parameters on the process effectiveness, which otherwise are very difficult to conceive through experimental analysis. In the case of zero-headspace system with zero-valent iron, sorption effects are included to incorporate the partitioning onto the solid surface. A new parameter, 'fractional active site concentration' is introduced to incorporate the differences in reactive and nonreactive sites on the iron surface, which affects the degradation performance. The generalized model has important implications for kinetic modeling, monitoring of VOCs and their degradation products, and design and selection of remediation technologies for such materials. The model predictions have been verified with our experimental data and the results from the literature.