Kinetic and equilibrium studies of chromium (VI) metal ions adsorption using Amberlite IRA-420 anions exchanger

A fundamental investigation of the removal of chromium (VI) ions (HCrO4– and Cr2O72–) from aqueous solutions by Amberlite IRA-420 anions exchanger particles (AMB) was conducted under batch conditions. The kinetic and equilibrium results obtained for chromium (VI) ions sorption with different initial concentrations onto AMB were analyzed. Kinetic modeling analysis with three different types of kinetic sorption models (pseudo-first-order, pseudo-second-order, and simple Elovich models) was applied to simulate the chromium (VI) ions sorption data. The analysis of the kinetic data indicated that the sorption was a second-order process. An ion-exchange mechanism may have existed in the chromium (VI) ions sorption process with AMB. The chromium (VI) ions uptake by AMB was quantitatively evaluated with equilibrium sorption isotherms. The experimental data of the removal equilibrium were correlated with the Langmuir, Dubinin–Radushkevich (D–R), Freundlich, and Harkins-Jura isotherm models, and the applicability of these isotherm equations to the sorption systems was compared by the correlation coefficients. Moreover, diffusion mechanism of chromium (VI) ions was described by different adsorption diffusion models. The diffusion equations inside particulate of Dumwald–Wagner and intraparticle models were used to calculate the diffusion rate. The actual rate-controlling step involved in the chromium (VI) ions sorption process was determined by further analysis of the sorption data by the kinetic expression given by Boyd.