Selective Solid-Phase Extraction of Cd(II) Using Double Imprinting Strategy

Molecular imprinting technology is a strategy for producing chemically selective binding sites, which recognize a particular molecule, in a macroporous polymer matrix. Molecular recognition-based separation techniques have received much attention in various fields because of their high selectivity for target molecules. In this study, we have used a molecular imprinting approach to achieve specific metal binding utilizing 3- aminopropyltrimethoxysilane (APTS) as a metal-complexing ligand. In the first step, APTS has complexed with Cd(II) ions and then reacted with 3-mercaptopropyl-trimethoxysilane. Then, polymeric particles have crosslinked with tetraethoxysilane (TEOS). The imprinted Cd(II) ion has removed from the polymeric matrix by 0.1 M HNO3. Double-imprinted particles have characterized by Fourier Transform Infrared (FTIR). Maximum binding capacity, optimum pH, and equilibrium binding time have found as 548 mg g-1, pH 6.0, and 45 min, respectively. In selectivity study, it has found that imprinting results in increased affinity of the material toward Cd(II) ion over other competitor metal ions with the same charge. It was established that double- imprinted polymers can be used repeatedly without a considerable adsorption capacity loss.