Dechlorination of Trichloroethene in Aqueous Solution Using Fe⁰

Abstract

Flow-through column tests were conducted to investigate the products of degradation of aqueous trichloroethene (TCE) in contact with granular iron metal. The results indicated the degradation process to be pseudo-first-order and the rate constant to be relatively insensitive to the initial concentration of TCE over the range from about 1.3 to 61 mg/L. The principal degradation product was ethene, followed by ethane with substantially smaller amounts of other C1−C4 hydrocarbons. About 3.0−3.5% of the initial TCE appeared as chlorinated degradation products, including the three dichloroethene isomers and vinyl chloride. Although the chloride mass balance was generally between 98 and 102%, a maximum of 73% of the carbon could be accounted for in the identified products. Based on the low concentrations of chlorinated degradation products in the solution phase, it is proposed that most of the TCE remains sorbed to the iron surface until complete dechlorination is achieved.