SINGLE AND DOUBLE IMPRINTED POLYMER FOR SELECTIVE RECOGNITION OF Cd(II) IONS IN AQUEOUS MEDIA

In this paper, we have reported the synthesis of a new single and double-imprinted polymeric material for the separation of Cd(II) ions in aqueous solutions. Chitosan has choosen as the Cd(II) metal complexing big polymer for single and double imprinted polymers. In the synthesis of single imprinted polymer, Cd(II)-complexed chitosan has crosslinked by epichlorohydrin. In the synthesis of double imprinted polymer, Cd(II)-complexed chitosan was reacted with 3-mercaptopropyl-trimethoxysilane. Then, the polymeric beads have crosslinked with tetraethoxysilane (TEOS). The imprinted cadmium ions have removed from the polymeric matrix by 0.1M HNO3 (to prepare Cd(II) templates). Optimum pH for rebinding of Cd(II) on the single and double-imprinted polymers was 7.0. Equilibrium binding time and sorbent capacity have been found as 120 and 60 min, 342 and 172 mg g-1 for single and double imprinted polymers, respectively. In selectivity studies, it has been found that double imprinted results in increased affinity of the material toward Cd(II) ion over other competitor metal ions with the same charge. The prepared single and double-imprinted polymers have repeatedly used and regenerated for thirty times without a significant decrease in polymer binding affinities.