Preparation and adsorption characteristics of an ion-imprinted polymer for fast removal of Ni(II) ions from aqueous solution

A novel Ni(II) ion-imprinted polymer (IIP) was synthesized by bulk polymerization for fast removal of Ni(II) ions from aqueous solution. Effects of preparation conditions on adsorption performance were investigated. Diphenylcarbazide (DPC) and N,N-azobisisobutyronitrile (AIBN) were used as ligand and initiator, respectively. Various monomers, solvents, cross-linking agents and molar ratios of template, monomer and cross-linking agent for polymerization were studied to obtain the largest adsorption capacity. The prepared Ni(II)-IIPs were characterized using Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA). The elution process has no influence on the three-dimension network structure observed on the surfaces of Ni(II)-IIPs. Ni(II) ions could be eluted from IIPs successfully with HCl solution. Effects of operating time, pH and initial concentration of Ni(II) in aqueous solution on adsorption performance were investigated too. The adsorption equilibrium was reached within 30 min. The maximum adsorption capacity of Ni(II)-IIPs was 86.3 mg g−1 at pH 7.0 with initial Ni(II) concentration of 500 mg L−1. The adsorption by Ni(II)-IIPs followed a pseudo-second-order kinetic and Freundlich isotherm models. The selectivity coefficients for all Ni(II)/interfering ions are larger than one because of the imprinting effect. The Ni(II)-IIPs also showed high reusability and stability.