Preparation and high reusability of a novel acid-resistant magnetic weak acid resin for Ni2+ removal

A novel magnetic weak acid resin (MWA06) was successfully synthesized and characterized. To enhance the acid resistance and lipophilicity of the γ-Fe2O3 particles, a titanate coupling agent (TCA) was employed to modify the particle surface. Afterward, the resultant resin was obtained through copolymerization and hydrolysis reactions, with a specific saturation magnetization of 10.9 emu/g and weak acid cation exchange capacity of 8.44 mmol/g. Leaching tests in acid showed that the magnetic resin was stable at pH 2. The presence of Ca2+ in the solution had an obviously negative impact on the adsorption of Ni2+, whereas Na+ did not influence the adsorption process. The adsorption of Ni2+ was pH-dependent as the uptake capacity increased from 0.06 to 2.81 mmol/g with the pH rising from 2 to 6. The desorption efficiency was nearly 100% by using 0.01 M HCl solution as desorption agent. Moreover, MWA06 could maintain high adsorption capacities for at least 10 regeneration cycles, indicative of a good reusability.