Reduction of 1,2-dibromoethane in the presence of zero-valent iron

The degradation reaction of 1,2-dibromoethane (ethylene dibromide or EDB) i n water was studied in the presence of zero-valent iron (acid-cleaned, cast iron) in well-mixed batch aqueous systems. The observed products were ethy lene and bromide ions. Carbon and bromine mass recoveries of >95% were obta ined. Bromoethane and vinyl bromide were not observed. The reduction rates of bromoethane and vinyl bromide with iron indicate that they should have b een observed if they were significant reaction intermediates for EDB. The r esults indicate that reductive beta-elimination may be the dominant reactio n pathway. Reaction kinetics are rapid and pseudo-first order. The activati on energy was determined to be 50 kJ/mol, indicating that the reaction rate may not be aqueous phase diffusion controlled but rather controlled by the chemical reaction rate on the iron surface. Metallic iron may be a suitabl e treatment approach for EDB-contaminated groundwater in above-ground, as w ell as in situ applications, due to rapid kinetics and nontoxic products.