Endosulfan and lindane degradation using ozonation.

The fact that ozone is a very powerful oxidizing agent (E0 = +2.07 V) was harnessed to degrade endosulfan and lindane in the present study. An ozone dosage of 57 mg min(-1) was found to be optimal for the degradation of both endosulfan (89%) and lindane (43%). The pH of the reaction mixtures play a profound role on the extent of degradation and it was observed that alkaline conditions favours the generation of hydroxyl radicals and thus a pH of 10 was chosen as the optimum for endosulfan degradation as the degradation efficiency was found to be 93%. A pH value of 12 was chosen as the optimum for lindane degradation as the degradation efficiency was observed to be 82%. Kinetics of degradation was performed and the set of data was fitted into first-order kinetics of the reaction for both endosulfan and lindane. The observed rate constants (k(obs')) for 5, 7.5 and 10 ppm initial endosulfan concentrations were 0.0274, 0.0273 and 0.0161 min(-1), respectively. While for initial lindane concentrations of 5, 7.5 and 10 ppm, the observed rate constants were 0.0243, 0.0333 and 0.056 min(-1), respectively. Gas chromatography mass spectroscopy analysis revealed that endosulfan was degraded into methyl cyclohexane and o-xylene which disappeared as reaction proceeded and lindane was degraded to 1-hexene indicating the ring fission mechanism.