Synthesis Of A Novel Chelating Resin And Its Properties For Copper Removal From Cobalt Electrolyte

A novel silica-supported2-aminomethyl pyridine(AMP) adsorbent was synthesized as a new adsorbent for copper removal from sulfuric cobalt electrolyte. The chelating adsorbent was synthesized through two different routs. By adopting post-grafting method, meglumine and a mixture of hydrochloric acid and ethanol were utilized in silanization as gentle but effective catalyst, and the synergy between amine and acid promotes the organic functional groups loading obviously. The synthesized silica-supported2-aminomethyl pyridine adsorbent under both amine and acid catalyzed conditions was abbreviated as Si-AMP-M-H. The characterization of Si-AMP-M-H was performed by FT-IR, XPS, SEM, elemental analysis, TG-DTG and BET. The results indicate that the modification of the silica surface was successfully performed, the AMP contents of Si-AMP-M-H was2.48mmol/g and Si-AMP-M-H was thermally stable below210℃. Modification of the silica surface by AMP implies a decrease of surface area, porous volume and pore diameter.The adsorption properties of Si-AMP-M-H for Cu2+, Ni2+and Co2+were studied by batch method. The effects of media pH, adsorption dynamics, adsorption isotherms and adsorption thermodynamics had been investigated. Adsorption capacities increased as the increase of pH value because the active adsorption sites mainly turned into dissociated forms at higher pH. The adsorption equilibriums of Cu2+, Ni2+and Co2+onto Si-AMP-M-H were attained within20～40min, the adsorption process followed a second-order type reaction kinetics. The characteristics of the adsorption process could be described by the Langmuir adsorption isotherm model and adsorption capacities were found to be0.78mmol/g,0.35mmol/g and0.25mmol/g for Cu2+, Ni2+and Co2+, respectively. Adsorption capacities of Si-AMP-M-H for metal ions is comparable to commercial silica-supported AMP adsorbent. Negative ΔG°values of Si-AMP-M-H for metal ions indicate that adsorption process is spontaneous. ΔH°values of Si-AMP-M-H for Cu2+and Ni2+were found to be exothermic, indicating that the adsorption capacities of Si-AMP-M-H for Cu2+and Ni2+could be reduced at higher tempretures. The loading test for copper separation from cobalt electrolyte containing nickel was performed with a simulated sulfuric cobalt electrolyte and Cu2+could be separated thoroughly from Ni2+and Co2+before breakthrough point, indicating that Si-AMP-M-H has a favorable selectivity for Cu2+Adsorbed Si-AMP-M-H can be readily regenerated by acid-ammonia treatment without serious performance decline. The results suggest that Si-AMP-M-H prepared here could be promising for cobalt hydrometallurgical purification process.