Reductive transformation of endosulfan in aqueous phase using magnesium-palladium bimetallic systems: a comparative...

The efficiencies of reductive transformation of endosulfan by bimetallic systems consisting of zerovalent magnesium (Mg(0)) as the electron donor and three forms of palladium as the catalyst (Pd(0)-alumina, Pd(0)-carbon and Pd-K(2)PdCl(6)) were compared in this investigation. Results revealed that both Pd(0)-alumina and Pd(0)-carbon were able to remove 90 and 93% of 10 mg L(-1) of endosulfan, respectively in 30 min with the concomitant accumulation of trace concentrations of partially chlorinated compounds in the reaction medium. Removal of endosulfan followed first-order kinetics and the rate constant (k(obs)) value was computed to be 0.2 min(-1) for both Pd(0)-alumina and Pd(0)-carbon. Pd(0)-carbon was relatively more stable and reusable in comparison to Pd(0)-alumina. More than 99% of 10 mg L(-1) endosulfan was converted to hydrocarbon end product by Pd-K(2)PdCl(6) system within 6 min of reaction. The formation of hydrocarbon end product suggested desulfurization and complete dechlorination of endosulfan. The efficiencies of removal of α and β endosulfan isomers were nearly the same in reaction media containing acetone or Tween 80 as the pesticide solubilizing agents. Results obtained in this study suggest the possibility of developing a reactor containing immobilized palladium for the treatment of water contaminated with endosulfan.