Simultaneous Removal of Pesticides from Water by Rice Husk Ash: Batch and Column Studies

Abstract

The present study evaluated rice husk ash (RHA) as an adsorbent for simultaneous removal of a mixture of seven different pesticides (alachlor, metolachlor, chlorpyriphos, fipronil, α‐endosulfan, β‐endosulfan, and p,p′ ‐DDT) and two metabolites ( p,p′ ‐DDE and endosulfan sulfate) from water. The adsorbent RHA was prepared in the laboratory and characterized by techniques such as X‐ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy/energy‐dispersive X‐ray spectrometry. Adsorption kinetics were well described by the pseudo‐second‐order kinetic model. The Freundlich isotherm model fitted the equilibrium data better than the Langmuir model, and the maximum sorption capacity varied from 0.078 to 0.166 mg/g. The column elution studies showed that 10 L of mixed pesticide‐contaminated water (0.05 mg/L) can be treated with only 10 g of RHA at a removal efficiency of 90%. The results implied that RHA can be used as a low‐cost, easily available, and efficient adsorbent for the simultaneous removal of pesticides from contaminated water.