Modification of alginate by grafting of N-vinyl-2-pyrrolidone and studies of physicochemical properties in terms of swelling capacity, metal-ion uptake and flocculation

The optimum conditions for grafting of N-vinyl-2-pyrrolidone onto alginate initiated by potassium peroxymonosulphate/glycolic acid redox initiator have been determined by varying the concentration of N-vinyl-2-pyrrolidone, hydrogen ion, potassium peroxymonosulphate, glycolic acid, alginate along with time and temperature. Experimental results show that maximum grafting has been obtained at 0.1 g dm(-3) concentration of alginate and 16 x 10(-2) mol dm(-3) concentration of N-vinyl-2-pyrrolidone. It has been observed that grafting ratio, add on, conversion and efficiency increase up to 5.0 x 10(-3) mol dm(-3) of hydrogen ion, 2.8 x 10(-3) mol dm(-3) of glycolic acid, 12 x 10(-3) mol dm(-3) of potassium peroxymonosulphate and 40 degrees C of temperature. A physicochemical phenomenon in terms of swelling, metal-ion uptake and flocculation has also been studied and it has been found that graft copolymer shows enhancement in these properties than pure alginate. Both, grafted and ungrafted samples have been characterized by FTIR-Spectroscopy and thermogravimetric analysis. (C) 2010 Elsevier Ltd. All rights reserved.