Catalytic dechlorination of 2, 2'', 3, 4, 4'', 5, 5''- heptachlorobiphenyl in soil by Pd/Fe
钯/铁双金属对土壤中2,2′,3,4,4′,5,5′-七氯联苯的催化脱氯研究

Dechlorination of 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl in soil was studied by using Pd/Fe bimetallic catalytic reduction. 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl can be dechlorinated effectively by Pd/Fe bimetal. It was found that the removal efficiency of 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl in soil could reach 54% after 5 days of reaction with 1 g of Pd/Fe (Pd loading 0.05%) and at an initial pH of 5.6. Several important experiment parameters involved in this process were also studied, including Pd loading, initial soil pH, the reaction time, the amount of Pd/Fe used and 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl initial concentration. The results showed that higher Pd loading, higher dosage of Pd/Fe, lower initial concentration of 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl and weak acid condition were beneficial to the catalytic dechlorination of 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl. The degradation of 2, 2', 3, 4, 4', 5, 5'- heptachlorobiphenyl, catalyzed by Pd/Fe, followed first-order kinetics, and the rate constant was 0.014 2/h, the half life was 49 h. In addition, two possible mechanisms of the dechlorination reaction were proposed and discussed.