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 butylphosphate (TBP) was studied at 1 O/A volume ratio and 303 K. For non-polar diluents, regular solution theory of Hildebrand was applied and the ratio of the activity coefficient of TBP to that of metal complex in the organic phase (gamma(TBP)/gamma(($) over bar m)) was related to the solubility parameter (delta). It was observed that the distribution coefficient of both metals decreased with the increase in the solubility parameter of the non-polar diluents. For polar diluents, effects 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 solvents increased. Finally, a comparative study between kerosene and hexane as the diluent for this system was made.