ABSTRACT 3,5-Bis[(2-hydroxy-benzylidene)-amino]-benzoic acid (H2B) and its cobalt(II) and nickel(II) complexes were synthesized and characterized via: electronic, IR, 1 H NMR and 13C NMR. Job’s continuous variation method was used to determine the mole ratio for both metal complexes. Solvent extraction studies were carried out on H2B in 5% DMF with its cobalt(II) and nickel(II) complexes using CHCl3 as organic solvent; with variable condition effects of equilibrium time, buffer pH, mineral acids, salting-out agents and complexing agents. IR spectral study indicates coordination through (N2O2) azomethine and protonated hydroxyl groups. Job’s continuous variation method showed a metal to ligand ratio, 1:1, for both metal complexes of H2B. Cobalt(II) complex of H2B showed quantitative extraction in pH range 5 – 7, while nickel(II) complex of H2B showed quantitative extraction in pH range 6 – 8. Nickel was successfully separated from cobalt by four-cycle extraction at 10-3 M HNO3 aqueous mixture of Ni(II) and Co(II) {10 µgcm-1 each} in 5% H2B/DMF using 0.05 M cyanide as masking agent and CHCl3 as organic solvent.
