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

Abstract

This work reports the preparation of a new Cu 2+-imprinted polymeric (IIP) nanoparticles, using 1,4-dihydroxy-9,10-anthraquinone (quinizarin; QZ) as a ligand. The Cu 2+ ion found to form a stable 1:1 complex with QZ in dimethylsulfoxide solution. The resulting Cu 2+–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 HNO 3. The Cu 2+-imprinted polymeric nanoparticles were characterized by IR spectroscopy, scanning electron microscopy (SEM), N 2 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 Cu 2+ 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 Cu 2+ were 346.3 μmol g −1 and 18.4, respectively. The relative standard deviation and detection limit (3 σ) 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 Cu 2+ 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.