Abstract
Liquid-liquid extraction of Ni(II) ion by Kelex 100 and 8-sulfonamidoquinolines in chlorobenzene was studied at 25°C. The extraction equilibrium was established only slowly, requiring generally 24h mechanical shaking. The extractants (HL) behaved as bidentate monoanionic chelating ligands, forming 1:2 (Ni2+:L-) complexes on metal extraction. The overall extraction constants (log Kex; Kex=[NiL2]org[H+]2aq/[Ni2+]aq[HL]2org were in the order of -6 for Kelex 100 and in the range of -8--10 for 8-sulfonamidoquinolines depending on the nature of organic sulfonyl groups. A small synergistic effect by trioctylphosphine oxide, 4-benzylpyridine and 6-nitroquinoline as well as by Kelex 100 itself was observed in the extraction by Kelex 100.
