Periodic variations of lanthanides synergic extraction by thenoyltrifluoroacetone and triphenylphosphine oxide mixture

The synergic extraction of the different lanthanides, except Pm and Lu, by thenoyltrifluoroacetone (HTTA) and triphenylphosphine oxide (TPPO) mixture in benzene from an aqueous perchlorate medium of constant ionic strength of 0.2, was investigated. Analysis of results showed that the main adduct extracted contains the lanthanide chelates together with two TPPO molecules. The different extraction and formation constants for the lanthanides investigated have been determined. The variations of the logarithmic values of the chelate extraction constant and the adduct formation constant with the different lanthanides was discussed in the light of the tetrad and the inclined-W effects. The experimental results showed that the nature of coordination by adduct formation for the Yb-Sm group is different than that of the Pr-La group. 11 references, 6 figures, 1 table