Copper Sorption of Crosslinked Chitosan Resin Modified by L-Lysine

Chitosan is known to have good complexing ability. The NH2 groups on the chitosan chains are involved in specific interactions with metals. Many papers in recent years areconcerned with the recovery of heavy metals from various waste waters with chitosan [1]. Metal cations can be absorbedby chelation on amine groups of chitosan in neutral solutions [2]. However, physical or chemical modification of chitosan has been frequently conducted to develop its applications. It iswell known that crosslinking enhance resistance of chitosan against acids, alkaline solutions and other chemicals [3]. Llysineis a natural amino acid, with pKa values at 8.95 and 10.53, respectively. Thus the amino groups of lysine residue together with the amino groups of the chitosan make the sorbent to be a type of modified cation exchanger In this work, novel crosslinked chitosan resin modified by Llysineas prepared through the reaction between formaldehyde, chitosan and L-lysine. The structure of the modified crosslinked chitosan was confirmed by FTIRspectroscopy, thermogravimetric analysis (TGA), and swelling experiments. Sorption experiments were performedby varying pH, different initial L-lysine, and copper concentrations, as well as contact time for optimization. The maximum sorption of the sorbent for Cu(II) was found to be about 200 mg/g at pH 7.