[Removal of lead from aqueous solutions by complexation-ultrafiltration with chitosan].

Polyethersulphone (PES) membrane was chosen and chitosan was used as complexing agent to remove lead ions by complexation-ultrafiltration. Effects of solution pH, Pb2+/chitosan ratio, ionic strength and Ca2+ on the rejection coefficient of lead were investigated. The effect of concentration time on lead rejection coefficient and membrane flux was also studied. The value of pH was found to be the key parameter in the process of complexation-ultrafiltration. The rejection coefficient of lead goes high to over 99% at pH 6.0 with the Pb2+/chitosan ratio 0.25. The increase of ionic strength and Ca2+ is not beneficial to the lead removal by complexation-ultrafiltration. The chitosan-metal complex was acidified and then the chitosan was regenerated by diafiltration. The regenerated chitosan was used to remove Pb2+ by complexation-ultrafiltration, and the rejection coefficient of lead was found to be 96.2%, which shows no significant difference with that obtained on the fresh chitosan. Results showed that complexation-ultrafiltration can effectively remove lead from aqueous solutions and chitosan can be effectively regenerated.