Ion imprinted polymer layer modified magnetic nanocomposites for selective recycling of aqueous Ni(II)

In order to improve the capacity and selectivity of the adsorbent, ion imprinting technology was introduced to the preparation of magnetic nanomaterials, Bentonite/CoFe2O4/SiO2 @ Polyvinyl alcohol, (abbr. IICBSPVAs). Polyvinyl alcohol (PVA) layer was synthesized by polymerization on the surface of magnetic bentonite for an ideal specific surface area of IICBSPVAs. Citric acid (CA) was selected as the cross-linking reagent to keep the network more stable and to form Ni (II) active sites. The effect of pH, adsorption kinetics and adsorption isotherm were studied. The selectivity coefficients α were 2.149 (Ni(II)/Cd(II)), 2.507 (Ni(II)/Zn(II)) and 3.768 (Ni(II)/Cu(II)), respectively, which indicated that IICBSPVAs had good adsorption selectivity of Ni(II). The specific surface area (SSA) and pore volume of IICBSPVAs were 73.62 m2/g and 0.20 cm3/g, which were obviously improved compared with the previous reported work (30.56 m2/g and 0.053 cm3/g). The pseudo-second-order kinetic (R2 = 0.998) and Langmuir models (R2 = 0.973) fitted the data well. According to the XPS results, Ni (II) complexed with hydroxyl (-OH) on the ion imprinted layer and led to IICBSPVAs’ excellent selectivity.