Equilibrium and kinetic studies of the adsorption of Cr(III) ions onto amberlite XAD-8 impregnated with di-(2-ethylhexyl) phosphoric acid (DEHPA)

Abstract

The adsorption performance of Amberlite XAD-8 impregnated with di(2-ethylhexyl) phosphoric acid (DEHPA) in the process of Cr(III) ion removal from aqueous solutions was examined. The equilibrium adsorption data were well described by the Langmuir model. The values of the dimensional separation factor, R L, indicated favourable adsorption. The maximum adsorption capacity of the DEHPA-impregnated XAD-8 material was 5.64 mg Cr(III) ion/g. The kinetics of the adsorption process were best described by the pseudo-second-order kinetic equation. The variation in the extent of adsorption with temperature was used to evaluate the thermodynamic parameters for the process. The values of ΔH 0 and ΔG 0 obtained showed that the adsorption process was endothermic and spontaneous. The adsorption activation energy also showed that the process was endothermic.