SOLVENT-EXTRACTION OF EUROPIUM(III) WITH BENZOYLACETONE AND BENZOYLTRIFLUOROACETONE INTO CARBON-TETRACHLORIDE IN THE ABSENCE AND PRESENCE OF TETRABUTYLAMMONIUM IONS

The solvent extraction of europium(III) in 0.1 mol dm-3 sodium nitrate solutions with benzoylacetone (Hbza) or benzoyltrifluoroacetone (Hbfa) in carbon tetrachloride was measured in the absence and presence of tetra-butylammonium ions (tba+). Although extraction with Hbfa occurred at lower pH than with Hbza, the extraction measured as a function of the beta-diketonate ion concentration in the aqueous phase was rather similar. It was also found that extraction with Hbfa was greatly enhanced by the addition of tba+, the effect, however, was negligible with Hbza. The data were analyzed from the stand point that the neutral metal chelate, Eu(bfa)3, was extacted into the organic phase and associated with ion-pairs of the reagents, bfa-tba+, in this phase. It was also found that though extraction of ion-pairs of bfa- tba+ occurred, that of bza-tba+ was negligible. Thus, the reason for the negligible extraction of the ternary complex, Eu (bza)4- tba+, was explained in terms of the negligible extraction of the bza- tba+, which might associate with Eu(bza)3 in the organic phase.