DILUENT EFFECT ON EXTRACTION OF TELLURIUM(IV) AND SELENIUM(IV) BY TRI-N BUTYL-PHOSPHATE

The influence of diluent on extraction of TeCl4 and SeOCl2 from 4.5 M aqueous hydrochloric acid solution by using 5 vol% and 30 vol% tri-n b utylphosphate (TBP) was studied at 1 O/A volume ratio and 303 K. For n on-polar diluents, regular solution theory of Hildebrand was applied a nd the ratio of the activity coefficient of TBP to that of metal compl ex in the organic phase (gamma(TBP)/gamma(($) over bar m)) was related to the solubility parameter (delta). It was observed that the distrib ution coefficient of both metals decreased with the increase in the so lubility parameter of the non-polar diluents. For polar diluents, effe cts of dielectric constant (epsilon) and polarity parameter (E(T)) on the extraction efficiency of the metals were studied and it was found that the distribution coefficient decreased as the polarity of solvent s increased. Finally, a comparative study between kerosene and hexane as the diluent for this system was made.