FORMATION OF A 3RD PHASE IN THE EXTRACTION OF URANIUM(VI) AND PLUTONIUM(IV) NITRATES INTO VARIOUS DILUENTS BY BIS(2-ETHYLHEXYL)SULFOXIDE

The formation of a third phase in the extraction of large amounts of u ranium(VI) and plutonium(IV) by bis(2-ethylhexyl)sulfoxide (BESO) into various hydrocarbon diluents was investigated over a wide range of ex perimental conditions. Solubility of both the extracted solvates UO2(N O3)2 . 2BESO and Pu(NO3)4 . 2BESO was maximum in polarizable benzene a nd the tendency to form third phase increased in the order: benzene < n-hexane < SST < dodecane. Usefulness of some commonly employed polar modifiers like tributylphosphate (TBP), 2-ethylhexanol and isodecanol on improving the metal solvate solubility was also assessed.