Removal of Copper(II) Ion from Aqueous Solution by Adsorption on Iron Oxide and Kaolin

Abstract

The effect of various physiochemical parameters on kinetics and equilibrium adsorption of Cu(II) metal ion from its aqueous solution by iron oxide and kaolin have been investigated using batch adsorption experiment. The results show that the amount of adsorption of Cu(II) metal ion increases with initial metal ion concentration, contact time, solution pH but decreases with the amount of adsorbent. The kinetic experimental results show that the adsorption of Cu(II) on oxide as well as on kaolin is a two-step process: a rapid adsorption of metal ions to the external surface is followed by possible slow intraparticle diffusion in the interior of the particles which has been confirmed by intra-particle diffusion model. Higher linear regression correlation coefficients (R $^2$ ) among fitted pseudo-first-order, pseudo-second-order and intra-particle diffusion model suggest that adsorption of copper metal ion on iron oxide as well as on kaolin follow pseudo-second-order kinetics and various kinetic parameters have been calculated. Langmuir and Freundlich models are used to describe the adsorption of copper metal ion on iron oxide and kaolin within specified metal ion concentration range. The value of separation factor, R $_L$ from Langmuir equation and rate of biosorption, 'n' from Freundlich model also gives an indication of favourable adsorption.