摘要

Solvent extraction of the trivalent lanthanoids (except Pm) with mixtures of a chelating extractant, either 1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedione (thenoyltrifluoro-acetone, HTTA) or 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) and diphenylsulphoxide (S), from chloride solutions has been studied in C(6)H(6). It was found that, in the presence of a diphenylsulfoxide, the lanthanoids were extracted as Ln(TTA)(3)a <...S and LnP(3)a <...S. The extraction data have been analyzed by a graphical method taking into account aqueous phase speciation and the plausible complex extracted into the organic phase. On the basis of the experimental data, values of the equilibrium constants have been calculated. Positive values of the synergistic coefficients show that all lanthanoids are extracted synergistically upon the addition of compound S to the chelating extractant. The separation of the lanthanoids with synergistic mixtures was, in most cases, a little higher than those obtained using HTTA or HP alone.