Kinetic and thermodynamic study of the adsorption of As(III) from aqueous solutions by naturally occurring and modified montmorillonites

Abstract

Adsorption of As(III) from aqueous solutions using naturally occurring and modified Algerian montmorillonites was investigated as a function of contact time, pH and temperature. Kinetic studies reveal that uptake of As(III) ions is rapid within the first 3 hours and it slows down thereafter. Equilibrium studies show that As(III) shows the highest affinity towards Acidic-montmorillonite even at very low concentration of arsenic. A pseudo-second-order chemical reaction model was obtained for As(III). Adsorption isotherms of As(III) fitted the Langmuir and Freundlich isotherm models well. From the thermodynamic parameters, it is concluded that adsorption is exothermic, spontaneous and favorable. The results suggest that M1, M2 and Acidic-M2 could be used as effective filtering materials for removal of arsenic from water.