Polyethyleneimine‐condensed polystyrene resin: A specific adsorbent for Cu2+ over Ni2+

Abstract A polyethyleneimine grafted polystyrene adsorption resin (PSFPA) was prepared by condensation reaction of formylated polystyrene resin (PSF) with polyethyleneimine (PEI). The material has been characterized by IR spectroscopy, CHN elemental, specific surface area and pore size and thermal gravimetric analyses. It showed a superb equilibrium adsorptive capacity of 2.92 mmol/g for Cu 2+ at 318 K and no uptake of Ni 2+ at all in neither single metal nor binary systems with Ni:Cu ratio high up to 100, suggesting a potential applicability of PSFPA in refining Ni electrolyte. The Cu adsorption/desorption behaviors were further detailedly studied in static and dynamic modes by investigating pH, temperature, and initial concentration effects. Kinetic studies indicated that the adsorption of Cu 2+ by PSFPA conformed to pseudo‐second‐order kinetics, and the adsorption rate was controlled by intraparticle diffusion. The adsorption followed Langmuir isotherms and was identified as a spontaneous endothermic process.