Reductive dehalogenation of endosulfan by cast iron: Kinetics, pathways and modeling

•High Carbon Iron Filings (HCIF) were successful in dehalogenating endosulfan.•Endosulfan adsorbed substantially to High Carbon Iron Filings (HCIF).•Aqueous phase endosulfan underwent reduction.•The process of simultaneous sorption/desorption/reduction could be modelled.•Reduction of endosulfan by HCIF resulted in less halogenated products.

Cast iron has been a material of choice for in-situ remediation of groundwater. In this study interaction of endosulfan with High Carbon Iron Filings (HCIF) was studied in batch reactors. Decline in total concentration (Ct) could be related to aqueous concentration (Ca) by equation dCt/dt = k1.M.Can, where reaction rate constant (k1) and order (n) were found to be 1.246 × 10−4 L g−1 iron h−1 and 1.47, respectively. Partitioning of endosulfan to HCIF could be explained by Freundlich isotherm. The process of simultaneous reductive dehalogenation and adsorption/desorption was successfully modelled. The reductive dehalogenation of endosulfan resulted in by-products identified as [(3a, alpha,7beta,7a alpha,8s)-4,5,6,7,8 Pentachloro 3a,4,7,7a-tetrahydro] (C9H3Cl5O3) and Benzofuran,4,5,7-trichloro-2,3-dihydro-2-methyl (C9H7Cl3O).