Adsorption of Cu2+ and Ni2+ on iron oxide and kaolin and its importance on Ni2+ transport in porous media

Adsorption of divalent heavy metal ions on iron oxide and kaolin is important to determine the transport and ultimate fate of ions in underground water and soil. In this study, kinetics and equilibrium adsorption of Cu2+ and Ni2+ metal ions from their aqueous solutions on iron oxide, kaolin and sand have been investigated. Batch adsorption studies show that Cu2+ and Ni2+ adsorb more strongly on the colloidal fines, iron oxide and kaolin than on the sand material. It is shown that the adsorption of Cu2+ and Ni2+ is a function of system pH, and solid adsorbent concentration. The equilibrium data follow the most widely used nonlinear Freundlich isotherm equilibrium model which has the general form of X=KF Cn. It is found that ‘n’ is strongly dependent on the nature of the adsorbent and virtually independent of conditions such as pH. The other parameter, ‘KF’ strongly depends on the pH of the solution. Finally, predictions of contaminant transport of Ni2+ due to the presence of colloidal fines, kaolin based on batch adsorption value has been compared with measured data using sand-kaolin packed beds.