Microwave synthesized chitosan-graft-poly(methylmethacrylate): An efficient Zn2+ ion binder

Microwave promoted grafting of methylmethacrylate on to the chitosan has been optimized. Chitosan-graft-poly(methylmethacrylate) (Ch-g-PMMA) could be synthesized with 160% grafting using 80% MW power in 2 min at (MMA) 0.17 M, (Chitosan) 0.1 g/25 ml. While for the same concentration of the methylmethacrylate and the chitosan, 105% grafting was observed when K2S2O8/ascorbic acid redox initiator used in presence of Ag+ (catalyst) and atmospheric oxygen (co-catalyst) at 35±0.2 °C. K2S2O8/ascorbic acid redox system is for the first time used for grafting methylmethacrylate on to the chitosan. The representative graft copolymer was characterized by Fourier transform-infrared, thermo gravimetric analysis and X-ray diffraction measurement, taking chitosan as reference. The effect of reaction variables as monomer/chitosan concentration, microwave power and exposure time on the graft co-polymerization was studied. A probable mechanism for grafting under microwave heating has been proposed. Viscosity of the grafted chitosan solutions and water/saline retention for the grafted chitosans were determined and compared with that of the chitosan. The microwave synthesized graft copolymer was found to have efficient adsorption ability for Zn2+ ions in aqueous solution. Effect of pH and Zn2+ concentration on adsorption was also studied.