Synthesis of a novel nanostructured ion-imprinted polymer for very fast and highly selective recognition of copper(II) ions in aqueous media

This work reports the preparation of a new Cu2+-imprinted polymeric (IIP) nanoparticles, using 1,4-dihydroxy-9,10-anthraquinone (quinizarin; QZ) as a ligand. The Cu2+ ion found to form a stable 1:1 complex with QZ in dimethylsulfoxide solution. The resulting Cu2+-QZ complex was polymerized with ethyleneglycol dimethacrylate, as a cross-linking monomer, via precipitation polymerization method. The imprint copper ion was removed from the polymeric matrix using 0.1 M HNO3. The Cu2+-imprinted polymeric nanoparticles were characterized by IR spectroscopy, scanning electron microscopy (SEM), N2 adsorption-desorption isotherms and elemental analysis. The SEM micrographs showed colloidal nanoparticles of 60-110 nm in diameter and slightly irregular in shape. Optimum pH for maximum sorption was 7.0. Sorption and desorption of Cu2+ ion on the IIP nanoparticles were quite fast and achieved completely over entire investigated time periods of 2-30 min. Maximum sorbent capacity and enrichment factor for Cu2+ were 346.3 μmol g−1 and 18.4, respectively. The relative standard deviation and detection limit (3σ) of the method were evaluated as 0.97% and 0.3 ng mL−1, respectively. It was found that imprinting results in increased affinity of the material toward Cu2+ ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIP was repeatedly used and regenerated for 12 times without a significant decrease in polymer binding affinity.