Synergistic extraction of uranyl thenoyltrifluoroacetonate with trioctyl phosphine oxide

The paper is concerned with the synergistic effect of uranyl-TTA complexes with a powerful additive, trioctyl phosphine oxide (TOPO). Extraction equilibrium including the formation of adduct complexes was studied by the use of a 237U tracer. The equilibrium constants were determined in different solvents, and regularities in them were examined. The chemical form of the species extracted was found to be the 1:1 adduct, UO2A2.S (S:TOPO), and no evidence was found concerning other mixed complexes. Adduct formation constants determined in twelve inert solvent vary from lg Ksub(s)=6.79 in chloroform to 9.58 in n-hexane, while their increasing order is almost the same as that for the adducts with other phosphine oxides and TBP. The regularities in the adduct formation established are practicably useful for the selection of a suitable solvent and/or a neutral donor. (T=a (T.G.)