Separation of heavy metal ions by complexation on poly (N-vinyl imidazole) hydrogels

Poly (N-vinyl imidazole) (PVIm) hydrogels were prepared by gamma-irradiating binary mixtures of N-vinyl imidazole-water in a Co-60-gamma source having 4.5 kGy/h dose rate. These hydrogels were characterized with gravimetric and spectrophotometric studies. Hydrogels with equilibrium swelling ratio of 600% in distilled water were used in the metal ion adsorption studies. The effects of pH, equilibration time, and initial metal ion concentration were considered in batch equilibrium study on the chelation of Cu2+, Co2+, Cd2+, and Pb2+ ions. Maximum metal ion adsorption were observed at pH=6.0. It has also been observed that the amount of adsorbed metal ions decreased at lower pHs because of protonation of PVIm ring.