Removal of Chlorothalonil from water by a bentonite treated chemically

Abstract

The adsorption of Chlorothalonil fungicide from aqueous solution onto raw and activated bentonite samples was investigated as a function of parameters such as pH, contact time, and temperature. The acid activation of natural bentonite was performed by treatment with hydrochloric solution of different concentrations. The high adsorption capacity of chlorothalonil was obtained by activated bentonite at 323 K in the range of pH 3-4 for 60 min of contact time. It was be 32.01 and 42.88 mg/g for raw and bentonite activated by 1N hydrochloric acid, respectively. The Langmuir and Freundlich adsorption models were applied to describe the related isotherms. Freundlich equation has shown the best fitting with the experimental data. The pseudo-first order and pseudo-second order kinetic models were used to describe the kinetic data. The changes of enthalpy, entropy and Gibbs free energy of adsorption process were determined. The results indicated that the adsorption of chlorothalonil occurs spontaneously as an endothermic process.