Dechlorination of endocrine disrupting chemicals using Mg 0/ZnCl 2 bimetallic system

Abstract

In the present study, Mg 0/ZnCl 2 bimetallic system was evaluated for its efficiency to dechlorinate endosulfan and lindane in aqueous phase. Presence of acetone in the reaction mixture played an important role by increasing the solubilities of both pesticides and thereby accelerating its mass transfer. Water acetone ratio of 2:1 and 1:1 (v/v) was found optimum for the dechlorination of endosulfan and lindane respectively. Presence of H+ ions in the reaction mixture (50 μl ml(-1) of glacial acetic acid) accelerated the degradation efficiency of 30 ppm initial concentration of endosulfan (96% removal) and lindane (98% removal) at Mg 0/ZnCl 2 dose of 5/1 mg ml(-1) within 30 min of reaction. Dechlorination kinetics for endosulfan and lindane (10, 30 and 50 ppm initial concentration of each pesticide) with varying Mg 0/ZnCl 2 doses and the time course profiles of each pesticide were well fitted into the first order dechlorination reaction. The optimum observed rate constant (k(obs)') values for endosulfan (0.2168, 0.1209 and 0.1614 min(-1) for 10, 30 and 50 ppm initial concentration respectively) and lindane (0.1746, 0.1968 and 0.2253 min(-1) for 10, 30 and 50 ppm initial concentration respectively) dechlorination were obtained when the reactions were conducted with doses of 7.5/1 mg ml(-1) and 5/1 mg ml(-1) Mg 0/ZnCl 2 respectively. Endosulfan and lindane were completely dechlorinated into their hydrocarbon skeletons namely, Bicyclo [2,2,1] hepta 2-5 diene and Benzene respectively as revealed by GCMS analysis.