Preconcentration of Nickel from Aqueous Environment Using Microspheric Nickel(II) Ion Imprinted Polymer

Solid-phase extraction based on molecularly imprinted polymer is developed for rapid, simple and selective preconcentration/determination of Ni(II) from aqueous solutions. Ni(II) dimethylglyoxime (DMG/Ni(II)) complex was synthesized and polymerized with cross-linker (divinyl benzene) to obtain ion imprinted polymer [poly(DVB-DMG/Ni(II))] of Ni(II). Ni(II)IIP was prepared by precipitation polymerization using dimethylglyoxime as ligand, Ni(II) as a metal ion, methacrylic acid as a functional monomer, divinyl benzene as a crosslinking agent and 2,2'-azobisisobutyronitrile as an initiator. The mixture was polymerized thermally, after polymerization, the metal was leached with a washing solvent. Blank polymer was synthesized under the same condition but in the absence of ligand and metal ion. Optimization of crosslinker, monomer and amount of Ni(DMG) was done and it was found that the optimized value for crosslinker is 0.30 mmol, monomer 3 mmol and Ni(DMG) is 8 mL. The polymer exhibited 99.98% adsorption in the presence of Zn(II), 72.50% in the presence of Mg(II), Ca(II) and Cu(II) and 73.48% in the presence of Co(II), and less than 70% adsorption was observed in the presence of Fe(II) and Cd(II). The maximum binding of Ni(II) was obtained with [poly(DVB-DMG/Ni(II))] after optimizing the amount of crosslinker, monomer and Ni(II) DMG complex for its synthesis, and the experimental parameters like effect of pH, polymer quantity, temperature and contact time during adsorption experiments. Poly(DVB-DMG/Ni(II)) microbeads were used three times without significant loss in adsorption capacity. Determination of Ni(II) in real water samples showed that the interfering matrix had been removed during preconcentration of Ni(II) from real samples on poly(DVB-DMG/Ni(II)).