CHEMICAL MODIFICATION OF CHITOSAN BY GRAFTING TECHNIQUE

Abstract

Graft Copolymerization of Glycidyl methacrylate (GMA), Methacrylic acid (MAA), Itaconic acid (IA) and 2-vinyl pyrrolidone (VP) onto Chitosan was carried out using potassium persulphate as an initiator. The effect of the reaction variables such as; monomer concentration, Initiator Concentration, Time and Temperature on the extent of grafting was studied systematically.

Values for the grafting percentages up to 770 %, 286 %, 68% and 67 % for Chitosan-g-PGMA, Chitosan-g-PMAA, Chitosan-g-PIA and Chitosan-g-PVP, respectively, were reached. The graft copolymers are characterized by FT-IR Spectroscopy, Scanning electron microscope (SEM), Thermogravimetric analysis and solubility test. It was observed that the solubility of Chitosan in organic acids was reduced after grafting. Moreover, a reproducible high swelling capacity of Chitosan-g-PMAA, Chitosan-g-PIA and Chitosan-g-PVP in distilled water as well as in buffer solutions at pH 4 and pH 10 was observed.

The swelling at equilibrium is highly dependent on the copolymer composition and pH. Chitosan-g-PGMA didn't swell due to the hydrophobic nature of PGMA chains. The adsorption of Cu2+ and Ni2+ ions in buffer solution onto Chitosan-graft ...r copolymers was examined. The results showed that the adsorption of Cu 2 is greater than N1•2+1• ons.

The results of the adsorption of the dye indicate that the adsorption of the dye is higher in Chitosan-graft-copolymers in comparison with Chitosan and the adsorption is higher with basic dye than with acidic one.