Facile synthesis of cross linked-chitosan-grafted-polyaniline composite and its Cr(VI) uptake studies

In the present investigation, the removal of Cr(VI) ions from aqueous solution using cross linked-chitosan-grafted-polyaniline composite (CCGP) was compared with that of chitosan-grafted-polyaniline (CGP) composite. The composites were characterized using FTIR, SEM-EDX, XRD, DSC, and TGA techniques. Batch equilibrium method was used for the optimization of various equilibrium parameters such as pH, contact time, dosage and initial Cr(VI) ion concentration. The removal efficiency by CCGP composite was found to be higher compared to CGP composite in all the studied conditions. The adsorption process was well described by Freundlich isotherm model for both the composites. The maximum adsorption capacity of CGP and CCGP composite for Cr(VI) ions was 165.6. mg/g and 179.2 mg/g at 303 K. Thermodynamic parameters for the adsorption system were calculated and concluded that the nature of sorption was spontaneous and endothermic in nature. The Cr(VI) adsorption kinetic process was well described by pseudo-second-order kinetic model and the sorption process was being controlled by intraparticle diffusion pattern. Desorption and regeneration experiments of CGP and CCGP composites were performed and reused for more than two consecutive cycles.