[Characterization of cross-linked quaternary chitosan salt and its adsorption of perchlorate from water]

Cross-linked quaternary chitosan salt was prepared and used to adsorb perchlorate from water. Parameters of cross-linking agent, temperature and pH were investigated to optimize the reaction conditions. The adsorption and regeneration ability of the adsorbent were also conducted. Quaternary chitosan salt could be fixed by cross-linking with glutaraldehyde using ethanol as dispersant. The optimal glutaraldehyde dosage and temperature were 6.82% and 45 degrees C, respectively. The cross-linked reaction was independent of pH with the range from 3 to 12. Quaternary chitosan salt was cross-linked mainly through the reaction between the methyl groups of ammonium on quaternary chitosan salt and the -C=O groups on glutaraldehyde. The optimal pH(zpc) of the adsorbent was about 10.6. The adsorbent showed high efficiency for perchlorate removal, and the adsorption capacity varied from 12.321 mg/g to 117.819 mg/g with the ClO4(-) concentration range from 5 mg/L to 200 mg/L. The spent adsorbents could be effectively regenerated by NaCl brine with the concentration more than 0.3%. The results suggest that the cross-linked chitosan quaternary ammonium salt would be a promising method for perchlorate removal from water.