Preparation and characterization of porous chitosan-tripolyphosphate beads for copper(II) ion adsorption

Porous chitosan-tripolyphosphate beads, prepared by the ionotropic crosslinking and freeze-drying, were used for the adsorption of Cu(II) ion from aqueous solution. Batch studies, investigating bead adsorption capacity and adsorption isotherm for the Cu(II) ion, indicated that the Cu(II) ion adsorption equilibrium correlated well with Langmuir isotherm model. The maximum capacity for the adsorption of Cu(II) ion onto porous chitosan-tripolyphosphate beads, deduced from the use of the Langmuir isotherm equation, was 208.3 mg/g. The kinetics data were analyzed by pseudo-first, pseudo-second order kinetic, and intraparticle diffusion models. The experimental data fitted the pseudo-second order kinetic model well, indicating that chemical sorption is the rate-limiting step. The negative Gibbs free energy of adsorption indicated a spontaneous adsorption, while the positive enthalpy change indicated an endothermic adsorption process. This study explored the adsorption of Cu(II) ion onto porous chitosan-tripolyphosphate beads, and used SEM/EDS, TGA, and XRD to examine the properties of adsorbent. The use of porous chitosan-tripolyphosphate beads to adsorb Cu(II) ion produced better and faster results than were obtained for nonporous chitosan-tripolyphosphate beads. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013