SYNERGISTIC EXTRACTION OF COPPER(II) AND OTHER DIVALENT METALS WITH 3-PHENYL-4-ACYLISOXAZOL-5-ONES AND 1-PHENYL-3-METHL-4-ACYLPYRAZOL-5-ONES IN THE PRESENCE OF TRI-N-OCTYLPHOSPHINE OXIDE IN TOLUENE

The synergistic extraction of copper(II) from 1M NaNO3 aqueous solutio ns with acidic chelating extractants HL = 3-phenyl-4-acylisoxazol-5-on es (acyl = benzoyl, ''HPBI'', and p-tert-butylbenzoyl, ''HPtbBI'') and 1-phenyl-3-methyl-4-acylpyrazol-5-ones (acyl = benzoyl, ''HPMBP'', p- tert-butylbenzoyl, ''HPMtbBP'' and stearoyl, ''HPMSP''), in the absenc e and presence of tri-n-octylphosphine oxide (TOPO) in toluene at 25 d egrees C, has been studied. The TOPO-HL interaction, which is one orde r of magnitude stronger with 4-acylisoxazol-5-ones than with 4-acylpyr azol-5-ones, strongly influences the synergistic extraction efficiency . The extracted species are CuL(2) and CuL(2)(TOPO). Because of their higher acidity, the extractions performed with 4-acylisoxazol-5-ones o ccur at a lower pH range than with 4-acylpyrazol-5-ones.