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Solvent Extraction of Europium(III) Anionic Complexes with Several β -Diketones as Ion-Pairs with Tetrabutylammonium into Chloroform

1993; Oxford University Press; Volume: 66; Issue: 6 Linguagem: Inglês

10.1246/bcsj.66.1647

1348-0634

Junji Noro, Tatsuya Sekine,

Analytical chemistry methods development

Abstract The solvent extractions of europium(III) in 0.1 mol dm−3 sodium nitrate solutions with acetylacetone (Hacac), benzoylacetone (Hbza), benzoyltrifluoroacetone (Hbfa), trifluoroacetylacetone (Htfa), and hexafluoroacetylacetone (Hhfa) into chloroform were measured in both the absence and presence of tetrabutylammonium (tba+). From the results and those with 2-thenoyltrifluoroacetone (Htta) in a previous study it was concluded that extractions with the CF3– containing β-diketones, Hbfa, Htfa, Hhfa, and Htta are greatly enhanced by the addition of tba+. This could be explained in terms of the extraction of a ternary complex, EuA4− tba+ (A− is a β-diketonate ion). However, extractions with Hacac and Hbza were nearly the same when tba+ was added. The enhancement of extraction was statistically treated by assuming an association of EuA3 and A−tba+ in the organic phase. The equilibrium constants for an association with different β-diketones were compared, and the reasons for the difference in the association equilibrium as well as the enhancement of extraction are described.