Peach-nut Shells-An Effective and Low Cost Adsorbent forthe Removal of Endosulfan from Aqueous Solutions

Abstract

In the present studies the adsorption efficiency of peach nut shells for the removal of endosulfan from aqueous solutions has been investigated. The adsorption of endosulfan has been studied as a function of contact time, concentration and temperature. Maximum adsorption (95 ± 1%) was achieved for 0.24 × 10⁻⁴ mol dm⁻³ of endosulfan solution, using 0.1 g of adsorbent in 20 ml of solution for 30 min agitation time at pH 6. The Freundlich and Langmuir isotherms fit the equilibrium data satisfactory and their constants, adsorption intensity 1/n (0.36), multilayer adsorption capacity Cm 6.5 ± 0.26 mmol g⁻¹, and monolayer adsorption capacity Q 0.27 ± 0.03 mmol g⁻¹, have been evaluated. Thermodynamics parameters namely change in enthalpy ΔH, Gibbs free energy ΔG and entropy ΔS, were calculated. The negative values of ΔG and positive value of ΔH indicate that the adsorption process is spontaneous and endothermic in nature and positive value of entropy ΔS confirms the possibility of the favorable adsorption. The developed adsorption method has been employed to surface water samples.