Preconcentration of copper on ion-selective imprinted polymer microbeads

Molecular recognition-based separation techniques have received much attention in various fields because of their high selectivity for target molecules. Molecular imprinting has been recognized as a promising technique for the preparation of such systems. In this study, we have prepared a novel molecular imprinted adsorbent to remove heavy metal ions with high selectivity. The Cu(II)-imprinted poly(ethylene glycol dimethacrylate–methacryloylamidohistidine/Cu(II)) (poly(EGDMA–MAH/Cu(II))) microbeads with an average size of 150–200 μm were prepared by dispersion polymerization. These Cu(II) imprinted microbeads were used in the adsorption–desorption of copper(II) ions from metal solutions. Adsorption equilibria was achieved in about 1 h. The maximum adsorption of Cu(II) ions onto imprinted microbeads was about 48 mg/g. The pH significantly affected the adsorption capacity of imprinted microbeads. The observed adsorption order under competitive conditions was Cu(II) > Zn(II) > Ni(II) > Co(II) in mass basis. The imprinted microbeads can be easily regenerated by 0.1 M EDTA solution with higher effectiveness. The imprinted microbeads showed excellent selectivity for the target molecule (i.e. Cu(II) ions due to molecular geometry). These features make imprinted microbeads very good candidate for selective removal of Cu(II) ions at high adsorption capacity. Detection limit was increased at least 1000-folds with the preconcentration approach using the imprinted microbeads. The method was also applied to certified reference and seawater samples.