Synthesis and characterization of a novel magnetic cation exchange resin and its application for efficient removal of Cu2+ and Ni2+ from aqueous solutions

Abstract

In this study, a novel magnetic cation exchange resin (MCER) was developed for highly efficient removal of heavy metal ions (HMIs). The MCER was systematically characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Batch experiments were conducted for investigating the HMIs (Cu2+ and Ni2+) removal performance by MCER under different conditions. The HMIs removal and potential ecological risk of real electroplating wastewater were also evaluated. As revealed, the self-prepared MCER was about 80–150 μm in size with uniform grain diameter. The superior magnetic characteristics of MCER made it easily agglomerated with others and sunk quickly in aqueous solution. For both Cu2+ and Ni2+ adsorption, the adsorption processes were equilibrated within 30 min and well described by pseudo-second order kinetic model and intra-particle diffusion kinetic model. Furthermore, the equilibrium adsorption data fitted the Langmuir isotherm model better than Freundlich model. Compared with MCER-1, the twice polymerized MCER-2 possessed obviously enhanced acid resistance in acidic conditions. The removal efficiencies of Cu2+ and Ni2+ onto MCER-2 increased gradually with the pH increasing from 2.0 to 4.0, and reached a plateau at pH 4.0–6.0. The MCER-2 could be efficiently regenerated by diluted HCl solution without noticeable loss of adsorption capacity after continuous adsorption/desorption cycles. For real electroplating wastewater treatment by MCER-2, the concentrations of target pollutants (Ni2+ and Cu2+) were decreased sharply and satisfied the requirements of emission standard of pollutants for electroplating, while the final wastewater was non-toxic (TUa <0.3). All these results indicated that the MCER-2 had great potential for the removal of HMIs from wastewater.