EXTRACTION OF ZINC(II) WITH DI(2-ETHYLHEXYL) PHOSPHORIC ACID FROM PERCHLORATE AND SULFATE MEDIA

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Abstract
The distribution of Zn(II) between solutions of di(2-ethylhexyl) phosphoric acid (HDEHP) in nonpolar diluents and aqueous sulfate and perchlorate solutions was studied. The type, composition and stability of complexes formed in the system were sought in a mathematical treatment of the distribution data. At initially ˜ 10−6 M in the aqueous phase, Zn(II) is extracted as the complex ZnA2.2HA. A monosulfate. disulfate and trisulfate complexes of Zn(II) are formed in the aqueous phase in the presence of ≤0.25 M sulfate. The distribution of Zn(II) is little influenced by variations of the ionic strength and temperature, and by the substitution of dodecane diluent by heptane or decalin diluents. Macro amounts of Zn(II), up to initially 0.058 M in the aqueous phase are extracted in the form of polynuclear HDEHP complexes. Also mixed poly-nuclear zinc/sodium complexes of HDEHP are probably formed in the organic phase. There is a strong indication of the complexation of Zn(II) by HDEHP also in the aqueous phase. Cationic, mono and polynuclear complexes are formed there.