Abstract
As a part of a systematic study of the synergic extractions of metals with mixtures of acidic chelating extractants and lipophilic anion-exchangers (B, X with X −6 inorganic anion), the extractions of M Cd and Zn from perchlorate, nitrate and sulphate media with 1-phenyl-3-methyl-4-benzoyl-pyrazol-5- one (HL) and tri- n-octylammonium salts (TOAH.X) or aliquat 336 (TOMA.X) in toluene have been investigated. Three key equilibria describe the extractions: (a) M 2++2 HL ⇌ ML 2 +2H +. (b) B.X + HL ⇌ B.L +H ++X − with B efficiency TOMA < TOAH and X efficiency ClO 4 < NO 3 < SO 4. (c) ML 2 + B.L ⇌ B.ML 3 with B efficiency toma > TOAH and Ni ∼ Co > Cd > ZN. As a consequence of the conflicting orders of efficiencies of TOMA and TOAH in equilibria b and c, TOAH.X is a better synergic extractant from perchlorate medium than TOMA.X whereas the inverse is observed from nitrate and sulphate media. Equilibrium c is independent of the inorganic anions. Constants of equilibria a, b and c are given. B.ML 3 species are not extracted in 1-octanol.
Published Version
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