Study on adsorption of cadmium and chromium ions from the aqueous solution by response surface methodology with chitosan

Response surface methodology was used to investigate the adsorption rate of Cd2+ and Cr6+ions onto chitosan in the aqueous solution. The effect of chitosan amount, initial concentration of heavy metal ions, pH range and adsorption time were investigated to optimize the treatment of Cd2+ and Cr6+ions. This process was analyzed using Box-Behnken Design in RSM. Chitosan loading of 26g/L, initial concentration of Cd2+ ion was 319mg/L, pH of 6 and adsorption time of 117min had been found to be the optimum conditions for the maximum removal ratio of Cd2+ ion in 93. 62% batch mode;Chitosan loading of 4g/L, initial concentration of Cr6+ion was 61mg/L, pH of 1 and adsorption time of 360min had been found to be the optimum conditions for the maximum removal ratio of Cr6+ion in 99. 27% batch mode. Under the above conditions, the Cd2+ and Cr6+ions uptake was attained to be circa 12. 46 and 10. 55mg/g. The Infrared spectroscopy was used to analysis that —CH3group played a important role in binding Cd2+ ion and —OH, —CH, —NH and —C—O groups play important roles in binding Cr6+ion in chitosan.