Adsorption kinetics of chromium (VI) onto an anion exchange fiber containing polyamine

An anion exchange fiber containing polyamine functional group was synthesized by chemical modification using polyacrylonitrile fiber as the raw material. The adsorption behavior of Cr(VI) using the self-made fiber was studied. Within the observed temperature and concentration range, equilibrium data for the adsorption of Cr(VI) from aqueous solutions by the fiber were obtained and correlated with Langmuir-type and Freundlich-type isotherm equations. The adsorption is shown to be a favorable type and the polyamine functional group has a strong affinity for Cr(VI). We mainly studied the adsorption kinetics of Cr(VI) onto the self-made fiber and fitted the kinetic data to the Lagergren first-order equation, the pseudo second-order equation, the modified pseudo first-order equation, and the intra-particle diffusion model. The respective characteristic rate constants were calculated and analyzed. Results show that the adsorption process is fast and that it reaches equilibrium at about 20 min. The experimental data for the adsorption systems fit well to a pseudo second-order equation and chemical adsorption is the main adsorption process. The fiber can be regenerated and repeatedly used for the adsorption of Cr(VI).