Interphase mass transfer during chemical oxidation of TCE DNAPL in an aqueous system

The chemical oxidation of trichloroethene dense non-aqueous phase liquid by permanganate was studied in an aqueous system using micro-reaction/extraction vessels in a novel approach. Experiments were conducted at ambient temperature ( approximately 20 degrees C) under static and mixed conditions to evaluate the rate of TCE(DNAPL) dissolution as a function of permanganate concentration. Chemical oxidation by permanganate was shown to increase the rate of TCE(DNAPL) dissolution under static conditions and decrease the rate of dissolution under mixed conditions. The apparent inconsistency in results appears to result from the local deposition of a film at the DNAPL interface composed of manganese oxide solids as discovered through visual observation with the aid of a Goniometer. Data from interfacial deposition experiments suggest that the film formed rapidly and reached maturation within approximately 2 h with little or no growth occurring thereafter. A conceptual model of the reaction and mass transfer processes occurring at the DNAPL interface was proposed based on the experimental results.