Abstract: The current work includes the fabrication and evaluation of an ion-imprinted azo-functionalized phenolic resin for selective extraction of Ni2+ ions from aqueous media. The azo containing ligand was first synthesized by coupling of the p-aminophenol diazonium salt with resorcinol. The ligand was coordinated with Ni2+ ions template before condensation polymerization with formaldehyde and resorcinol had performed. The Ni2+ ions were extracted from the cross-linked resin matrix to finally obtain the Ni2+ ion-imprinted Ni-PARF adsorbent. The synthetic steps were extensively investigated by elemental analysis, FTIR NMR and EDX spectra. Also, the surface morphologies along with the surface areas of the adsorbent resins were evaluated using SEM and BET techniques, respectively. Batch experiments indicated that pseudo-second-order kinetic equation displayed the best fit with the experimentally obtained kinetic data and equilibrium was reached after 40 min. The isotherm studies were also in a good fit with Langmuir model and the maximum adsorption capacities of Ni2+ ions with respect to both Ni-PARF and controlled non-imprinted C-PARF adsorbents were around 260 and 100 mg/g, respectively. In presence of Co2+, Cu2+, Zn2+, and Pb2+ as competitive co-existing ions, the relative selectivity coefficients of Ni-PARF for Ni2+ were respectively 84.91, 44.97, 30.41 and 32.20. Regeneration experiments indicated that after eight adsorption/desorption cycles, Ni-PARF adsorbent still maintains around 97% of its initial efficiency.
Author keywords: Resorcinol, Azo-dye complex, Nickel(II) ions, Ion-imprinting