Adsorption kinetics and isotherms for the removal of nickel ions from aqueous solutions by an ion-exchange resin: application of two and three parameter isotherm models

The capacity of a strong cation-exchange resin for removal of nickel from aqueous solutions was investigated under different conditions such as contact time, initial nickel ion concentration, stirring speeds, solution pH, and resin dose. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, Temkin, Elovich, Fowler-Guggenheim, Kiselev, Hill-de Boer, Jovanovic, Hill, and Koble-Corrigan isotherms. Correlation coefficients indicated the following order to fit isotherms: Langmuir > Koble-Corrigan > Freundlich > Hill > Jovanovic > Temkin > Hill-de Boer > Fowler-Guggenheim > Kiselev > Elovich. On the basis of the lowest values of the four error functions studied, Hill model provided the best correlation for the experimental data. The kinetic data were analyzed using pseudo-first-order, pseudo-second-order, and Elovich model. Intra-particle diffusion model and the liquid film diffusion model were used to investigate the adsorption mechanism. Kinetic studies showed that the adsorption of Ni2+ ions onto ion-exchange resin followed Elovich kinetic model, and indicates that the intra-particle diffusion controls the rate of adsorption. Furthermore, separation factors and distribution coefficients of nickel were calculated.