Synthesis and characterization of aminated copolymers of polyacrylonitrilegraft- chitosan and their application for the removal of heavy metals from aqueous solution

Abstract

Aminated copolymers of polyacrylonitrile-graft-chitosan (APANCS) were synthesized via the reaction of copolymers of polyacrylonitrile-graft-chitosan (PANg- CS) with diethylenetriamine in solution. Specifically, copolymers of PAN-g-CS have been obtained via a graft polymerization method using acrylonitrile (AN), chitosan (CS) and a free-radical initiating process with ceric ammonium nitrate (CAN) as initiator under air presence. Superficial structure of these copolymers was modified using amination reactions to introduce amine groups on its polymeric matrix. This polymer (APANCS) was applied in the removal of Pb2+, Cd2+ and Zn2+ ions in aqueous solutions. Samples of PAN-g-CS and APANCS were characterized by FT-IR spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, TGA, DSC and gravimetric analyses. Results of this study suggest that the amine groups of the structure of chitosan are involved in the grafting process onto the polymeric matrix of polyacrylonitrile. On the other hand, the adsorption capacities for heavy metal removal of this polymer were significantly improved using the chemical modification with amination reactions. Specifically, this polymeric material showed a maximum adsorption of 12.93, 2.27 and 2.10 mg/g at pH 5 for the removal of Pb2+, Cd2+ and Zn2+ ions, respectively.