Fabrication and binding characterization of ion imprinted polymers for highly selective Co2+ ions in an aqueous medium

A new sorbent material for cobalt ion extraction was synthesized using molecular imprinting technology for determination of cobalt ions in an aqueous medium. Two types of imprinted polymers were synthesized using different functional monomers (methacrylic acid and 4-vinylpyridine) in the presence of dipicolinic acid for complex forming with cobalt ion. The imprinted polymers were cross-linked by ethylene glycol dimethacrylate via bulk polymerization procedure. Simultaneously, the non-imprinted polymers were prepared as controlled samples. The effects of sample dosage and time taken were investigated through an adsorption isotherm study. The affinity of Co2+ ions for the imprinted polymer based on methacrylic acid monomer was stronger than 4-vinylpyridine monomer as proven by higher adsorption capacity and increased selectivity toward Co2+ ions over the competing metal ions. Therefore, the coordinate mode of cobalt-dipicolinic acid, along with the functionality of monomers, led to the production of highly selective recognition toward the cobalt ions. This synergistic effect seems logical as each component contributed to the overall imprinting process. The adsorption isotherm experiment indicated that the Freundlich isotherm model yields a better fit toward the equilibrium adsorption data, while the Pseudo-second-order equation is the appropriate model describing the kinetic sorption behavior of the polymers.