Synthesis of Crosslinked Chitosan with Epichlorohydrin Possessing Two Novel Polymeric Ligands and Its Use in Metal Removal

One of the major applications of chitosan and its derivatives is based on its ability to bind strongly toxic metal ions. In this work, two novel polymeric ligands were synthesized to investigate the adsorption properties of Cu(II), Pb(II), Zn(II) and Ni(II) ions in an aqueous solution. To prevent the reaction between as the C-2 amine group of chitosan and ECH, the C-2 amine group was protected N-benzylidene chitosan (CTB). After the reaction with ECH to give N-benzaldehyde crosslinked chitosan (CCTB), the Schiff base was removed in a dilute ethanol hydrochloride solution to obtain CCTS which has free amine group. CCTS-ECH was synthesized by the reaction of CCTS and ECH. Then, CCTS-ECH was reacted with (2-hydroxyphenylimino)methylbenzene-1,4-diol (HBD) and N,N'-bis(2,5-dihydroxybenzylidene)-1,4-diaminobenzene (DHDB) to give ligands CCTS-ECH-HBD and CCTS-ECH-DHDB. The batch experiments showed that two novel polymeric ligands can be effectively used to remove Cu(II) from water.