Removal of Ni(II) ions from aqueous solutions using ion imprinted polymer prepared from dual vinyl monomers

Abstract

Objective: The aim of the study was to selectively remove and pre-concentrate nickel(II) ions from aqueous solutions using ion imprinted polymers. Methodology: Ion imprinted polymers (IIPs) were prepared by forming a ternary complex of nickel(II) ion with acrylamide and 1-vinylimidazole as co-monomers in porogenic methanol. Polymerization was then effected by addition of ethylene glycol dimethacrylate as a cross-linker and 1,1-azobis(cyclohexanecarbonitrile) as initiator. About 5 M HCl solution was used as a leachant for the removal of the nickel(II) ion template from the IIP particles. Similarly, control polymer (CP) material was prepared but the template inclusion was omitted. The synthesized polymer particles were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and Brunauer Emmett Teller (BET) analysis. Results: The optimum pH for quantitative removal was 4, mass of the IIP sorbent was 40 mg, contact time was 10 min and the optimum concentration was 20 mg L-1. The pseudo-second-order rate modelled the kinetic data better implying a chemisorption type of interaction between the imprinted polymer and Ni(II) ion. Based on the correlation of determination (R2 > 0.9), the Langmuir isotherm model, which implies monolayer mechanism was the best. Conclusion: The prepared IIP demonstrated superior potential on removal of Ni(II) ions from aqueous solutions compared to its corresponding CP.