We report the effective hydrodechlorination of various chloroaromatic contaminants (phenoxy herbicides 2,4-D and 2,4,5-T, chlorinated biphenyls and naphthalene) in aqueous media by electrocatalytic reduction at Pd-loaded carbon felt at room temperature. The selective removal of chlorine from the environmentally resistant organochlorine pollutants could be readily achieved (1) at room temperature and (2) directly in aqueous media. No highly active reducing chemicals were required for such a treatment. The use of carbon felt of high surface area as a solution-permeable cathode offered high adsorption capacity for chloroaromatics whereas supported palladium provided the system with highly reactive reducing species supposed to be the surface-bound hydride generated upon reductive decomposition of water. The facilitating effect of bulky tetraalkylammonium cations of a supporting electrolyte on substrate conversion and product recovery is discussed. Reaction mechanism for hydrodechlorination of chloroaromatics in aqueous media and scheme for activation of Pd-loaded carbon felt by electrolytic pre-treatment are proposed.
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