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  • 1 CSIR Regional Research Laboratory 695 019 Trivandrum India
  • 2 Sri Venkateswara University Department of Chemistry 517 502 Tirupati India
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This paper describes a theoretical method for analyzing the behaviour of65Zn during solvent extraction from ammonium thiocyanate solutions with dialkyl sulphoxides. The mechanism of extraction of Zn/II/ from thiocyanate medium by sulphoxides may be represented by the following general equation:

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$xM_{aq}^{m + } + ySCN_{aq}^ - + zS_{org} \rightleftharpoons [M_x /SCN/_y ]^{mx - y} .zS_{org}$$ \end{document}
where Mm+ is the metal ion and S is the extractant. Expressions for the distribution coefficients were derived taking into account complexation of the metal in the aqueous phase by inorganic ligands and also the dissociation of the extracted ion-pairs in the organic phase. Using these expressions, the values of the extraction constants were determined by a least-squares fit with the experimental extraction data. From these extraction constants, the various species extracted into the organic phase were resolved. The influence of the metal concentration, temperature and the diluent on the extraction of Zn/II/ has been investigated.