The surface of polyacrylonitrile nanofibers (PAN) was chemically modified with 2-(2'-pyridyl)imidazole ligand (pim) to generate PAN-pim nanofibers. The reaction proceeds via nucleophilic attack of the pim anion on the nitrile groups of the PAN nanofibers. A 36% conversion of the acrylonitrile repeating units to AN-pim groups was obtained after 60 min at 70 degrees C using 1.0 mol/L pim ligand. The product was characterized by Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) and morphological analyses. The adsorption equilibrium and rate of nickel were studied in batch experiments and the data were correlated using the Non-ideal Competitive Adsorption (NICA) isotherm and a pseudo-homogeneous kinetic model. Equilibrium uptake of nickel at pH 3 and pH 5 was 0.3 and 0.7 mol/kg respectively, at a nickel concentration of 0.0025 mol/L. Nickel was shown to be bound predominantly as a 1:1 complex on PAN-pim. The adsorption rate was very high and equilibrium was attained in I min. The uptake rate was only slightly lower than the nickel-pim complex formation rate measured in aqueous solution. 0.1 M EDTA solution was shown to be suitable for desorption of nickel from the loaded PAN-pim even after three adsorption/desorption cycles. Nickel was successfully separated from cobalt using gradient elution with EDTA in a column system. (C) 2015 Elsevier B.V. All rights reserved.