Abstract
Polychlorinated ethanes and methanes were reductively dechlorinated using iron powder E-200 (supplied by Dowa Iron Powder Co., Ltd.) in the aqueous layer. Time courses of their concentrations were observed and the intermediates and final degradation products were determined quantitatively. The degradation reaction of these compounds showed a pseudo-first-order rate process and the rate constants were calculated. Tetrachloroethanes and tetrachloromethane were easily degraded in the aqueous layer, but dichloroethanes, chloroethane, dichloromethane and chloromethane were only slightly degraded. The rate constants and the reaction products of polychlorinated ethane isomers, that is, 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane, or 1,1,1-trichloroethane and 1,1,2-trichloroethane, were significantly different from each other. This denotes that the main degradation pathways of these compounds are different. The possibility of using iron powder for the remediation of soil and groundwater contaminated with chlorinated organic compounds is discussed.
