Preparation of conductive polymer nano-composite with chitosan and its application in the removal of hexavalent chromium

The conductive polymer, polyaniline (PANI) and its grafting with chitosan (chitosan-grafted polyaniline, CS-g-PANI), were synthesized and analyzed by means of FTIR, TGA, TEM and XRD. The two resins were subjected for the adsorption of hexavalent chromium from aqueous solutions. The factors affecting the adsorption processes were tested, such as pH, time, temperature, and the initial concentrations of chromium. Also, both kinetics and equilibrium isotherm models were studied. The results indicated that the optimum conditions for the preparation of poly aniline are: APS to aniline ratio is 1.5, the HCL concentration is 2.5 M, the reaction time is 1.5 h and the optimum ratio for the preparation of CS-g-PANI is 1.2. It was also found that the prepared nanoparticles of PANI may reach a size of 23–32 nm and the CS-g-PANI is 26-37 nm. The adsorption of chromium VI by the two resins were found to follow Langmuire’s isotherm with maximum adsorption capacity of 526 mg/g for PANI and 370 mg/g for CS-g-PANI at 60 oC. The adsorption mechanism was found to follow the second order model for the two resins.