A METHOD FOR THE RAPID DECHLORINATION OF LOW-MOLECULAR-WEIGHT CHLORINATED HYDROCARBONS IN WATER

1,1,2-Trichloroethylene (TCE), 1,1-dichloroethylene, cis and trans-1,2 -dichloroethylene and tetrachloroethylene (PCE), at concentrations of 20 ppm in aqueous solutions were rapidly hydrodechlorinated to ethane (in a few minutes), on the surface of palladized iron in batch experim ents that were performed in closed vials. No intermediate reaction pro ducts such as 1,1-dichloroethylene, 1,2-dichloroethylenes and vinyl ch loride were detected at concentrations >1 ppm either in the headspace or in solution. The chloromethanes, CCl4, CHCl3, and CH2Cl2, were also dechlorinated to methane on palladized iron; the CCl4 was dechlorinat ed in a few minutes, the CHCl3, in less than an hour and the CH2Cl2, i n 4-5 h. These results indicate that an above-ground treatment method can be designed for the treatment of groundwater contaminated with low molecular weight chlorinated hydrocarbons.