Deep removal of copper from cobalt sulfate electrolyte by ion-exchange

SP-C was applied for the removal of Cu²⁺ from simulated cobalt sulfate electrolyte containing Co²⁺ 50 g/L and Cu²⁺ 0.5–2.0 g/L. Experimental conditions included pH of 2–4, temperature of 20–60 °C and contact time of 10–40 min. The investigation demonstrated that SP-C had recommendable efficiency in adsorbing Cu²⁺ from the electrolyte with 25- to 100-fold of Co²⁺. The optimal adsorption conditions of SP-C were pH of 4, contact time of 30 min and ambient temperature. The study also showed that the loaded resin could be effectively eluted with 2.0 mol/L H₂SO₄ solution at a contact time of 40 min; the peak concentration of Cu²⁺ in the eluate was about 35 g/L. The sorption characteristics of Cu²⁺ by SP-C could be described by Langmuir isotherm and the pseudo second-order kinetic equation. Infrared spectra showed that nitrogen atoms in the functional group coordinated with Cu²⁺ to form coordination bands.