Reductive Dechlorination of Chlorinated Solvents on Zerovalent Iron Surfaces

Abstract

Optimal design of zerovalent iron-based permeable reactive barriers requires a complete understanding of dechlorination kinetics and mechanism. The effect of other ambient constituents, which may retard or enhance the dechlorination processes, should be considered. Literature has revealed that reduction of chlorinated compounds occurs on the iron surface and the reaction rate is limited by surface processes, rather than transport processes. Adsorption onto the surface can take place on both reactive sites that are responsible for the reductive dechlorination, and nonreactive sites that only sequester the contaminants. This chapter explores a model based on the assumptions that adsorption equilibrium on the two types of surface sites is always maintained, but the reduction rate is directly proportional to the amount sorbed onto reactive sites only. Numerical solutions are obtained to illustrate the effect of coadsorbates on the adsorption and reduction of chlorinated compounds under this mechanistic framework.