Graft copolymerization of N-vinyl-2-pyrrolidone onto chitosan: Synthesis, characterization and study of physicochemical properties

The optimum conditions for maximum grafting have been determined by varying the concentrations of N-vinyl-2-pyrrolidone, hydrogen ion, potassium bromate, silver nitrate, chitosan along with time and temperature. The grafting ratio increased on increasing N-vinyl-2-pyrrolidone concentration and reaches maximum value at 20 × 10−2 mol dm−3. Similarly, the concentration of hydrogen ion increases, the grafting parameters increase and attain maximum value at 1.8 × 10−2 mol dm−3. The grafting parameters increase continuously on increasing the concentration of potassium bromate from 2 × 10−3 mol dm−3 to 10 × 10−3 mol dm−3. On increasing silver nitrate concentration from 0.4 × 10−2 to 3.6 × 10−2 mol dm−3, grafting ratio is found to be maximum at 2.8 × 10−2 mol dm−3. The grafting parameters decrease continuously on increasing the concentration of chitosan. An attempt has been made to study some of the physicochemical properties in terms of swelling, metal ion sorption and flocculation. The chitosan and chitosan-g-N-vinyl-2-pyrrolidone were characterized by infrared spectroscopy and thermogravimetric analysis.