Study on the synthesis, characterization, and sorption of some metal ions on gelatin- and acrylamide-based hydrogels

Graft copolymers and networks of gelatin were synthesized with three acrylamides (acrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid, and N-iso-propylacrylamide) by using a redox initiator system consisting of ammonium peroxysulfate-ferrous ammonium sulfate in either the absence or the presence of a crosslinker (N,N-methylene bisacrylamide) at two temperatures. Characterization of synthesized polymers was studied by FTIR and thermal studies to investigate evidence of grafting or interpenetrating network formation and to investigate the effect of reaction conditions and crosslinker concentration on the properties of synthesized polymers. Detailed investigation into water-uptake properties of these hydrogels was carried out as a function of time, temperature, and pH. The inherent properties of the monomer incorporated onto gelatin collectively act as determinant of the water-absorption behavior of the hydrogels. Sorption of Fe+2, Cr+6, and Cu+2 ions from their aqueous solutions was also studied on select hydrogels, where it was observed that metal ions are sorbed by effective partitioning between hydrogels and solution phase and apart from the nature of metal ions, and structural aspects of hydrogels also determine the quantum of metal ion uptake. (C) 2003 Wiley Periodicals, Inc.