Selective adsorption of Cu(ii) from an aqueous solution by ion imprinted magnetic chitosan microspheres prepared from steel pickling waste liquor

Abstract

To reduce costs and improve practicability, an ion imprinted magnetic chitosan (IMCS) was synthesized through co-precipitation using steel pickling waste liquor and chitosan and Cu(II) as template ions, which was then characterized by TEM, SEM, EDX, FTIR, XRD and VSM. The batch experiments were carried out for its potential application and high selectivity of Cu(II) removal, which were observed due to the paramagnetic properties and coordination reactions in the imprinted cavities. Kinetic studies revealed that the adsorption process followed a pseudo second-order model and the equilibrium data fit perfectly with the Langmuir isotherm model. The maximum adsorption capacity was 109.89 mg g⁻¹. Negative values for ΔH⁰ and ΔG⁰ indicated an exothermic and spontaneous adsorption process. The adsorption process was found to be a chemical reaction and coordination complexes were formed between the metal ions and the groups of chitosan binding mainly in the “bridge model”. Moreover, 0.2 mol L⁻¹ HCl solution was considered as the most appropriate eluent for regeneration. It showed a great performance in the experiments for practical copper wastewater and the process was considerably cost-effective.