34-Leaching Characteristics of Endosulfan Contaminated Indian Soils and Possible Immobilization Techniques

Abstract

Leaching characteristics of endosulfan from four types of commonly available Indian soils namely clayey soil, red soil, sandy soil and composted soil were estimated by adsorption and desorption batch studies. The maximum adsorption capacity (qm ) was estimated from Langmuir and Freundlich isotherms. The adsorption of alpha and beta endosulfan followed Langmuir isotherm better than Freundlich isotherm. The clayey soil adsorbed 0.4480 (mg/g of soil) of alpha isomer and 0.2186 (mg/g of soil) of beta isomer. But, it reduced to 0.3876 mg/g, 0.2186 mg/g and 0.1083 mg/g of soil of alpha endosulfan and 0.2018 mg/g, 0.1966 mg/g and 0.0942 mg/g of soil of beta endosulfan in composted soil, red soil and sandy soil respectively. Results showed that endosulfan molecules have more affinity towards the clayey soil than other soils. Also, it was observed that the organic matter increased the adsorption of both alpha and beta endosulfan. Desorption studies were conducted with distilled water and it was estimated that 40, 61, 65 and 84 % of the adsorbed endosulfan was desorbed from clayey soil, composted soil, red soil and sandy soil respectively. The sorption studies indicate that the immobilization of endosulfan in soils can be achieved by increasing the organic matter, clay and silt content.