Zn2+-imprinted porous polymer beads: Synthesis, structure, and selective adsorption behavior for template ion

Zn2+-imprinted polymer was synthesized in porous spherical forms via a self-assembled complex between 2,2′-bipyridyl/4-vinylpyridine complexant/functional monomer and Zn2+ template ion. Diameters of particles ranged from 250 to 550 μm to enlarge the surface area and thus enhance the adsorption capacity. The presence/absence of the template ion in the preparation of the imprinted polymer was confirmed by EDX spectroscopy, and the physical structure of the particles was investigated using ESEM and BET analysis. The particle and the pore size were controlled by the cross-linker/monomer feed ratio. The adsorption capacity of the imprinted polymers was 210.61 μmol g−1 for Zn2+, while those for Cu2+, Ni2+, and Pb2+, were 37.92 μmol g−1, 33.02 μmol g−1, and 9.70 μmol g−1, respectively. This big discrepancy of the adsorption capacities illustrates the excellent separation selectivity of the imprinted polymers. The adsorption capacity decreased significantly at pH below 4.5, as the polymers are easily protonated. The imprinted particles lost only 10 % of their adsorption ability after 10 repeated uses.