The synthesis and use of new amic acid extractants for the selective extraction of Cu(II),Ni(II) and Co(II) from other base metal ions in acidic medium

Abstract

ABSTRACT We investigate the separation of Co2+ and Ni2+ from base metal ions Co2+, Ni2+, Mn2+, and Li+ ions using solvent extraction in chloroform medium. We also looked at the extraction within a larger pool of metal ions, Mn2+, Ni2+, Co2+, Cu2+, Zn2+, Cd2+, and Li+. Four new ligands were synthesized via a two-step bimolecular nucleophilic substitution and were characterized by conventional means. The ligands were subjected to solvent extraction of Co2+, competitive extraction using metal ions Co2+, Mn2+, Ni2+, and Li+, selectivity tests, loading tests, pH-extraction isotherms, time-dependence, and back extraction. Ligand L4 was the best compared to the other ligands in single and competitive extraction. When considering the pool of metal ions, the percentage extraction of Cu2+ increased as the concentration of ligand L4 was increased. Furthermore, the extraction of Ni2+ and Cu2+ increases with increase of pH as expected. The selectivity changed toward Ni2+ in most of the ligands when the concentration of Cu2+ ion was reduced. Cu2+ metal ions could be 80% back-extracted using 1 mol dm−3 nitric acid during a single stripping. The new extractants extracted Ni2+ preferentially with a high selectivity over Mn2+ and Co2+ in the presence of these three metal ions. The synthesized ligands could perhaps be used in the future for the separation of Ni2+ from a solution containing Mn2+ and Co2+.