Influence of aggregation on the extraction of trivalent lanthanide and actinide cations by purified Cyanex 272, Cyanex 301, and Cyanex 302

Abstract

SummaryThe extraction of trivalent lanthanide (Sm3+, Eu3+) and actinide (Am3+, Cm3+) cations from 1.0 M NaNO3inton-dodecane solutions of bis(2,4,4-trimethylpentyl)phosphinic acid (HC272), bis(2,4,4-trimethylpentyl)monothiophosphinic acid (HC302), and bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HC301) is reported. In each case, the dependence of the distribution ratios on the total extractant concentration is approximately second power. Using NMR, the dimerization constant of HC301 is determined to be 0.67 ± 0.06 at 25.0 °C in deuteratedn-heptane, implying that the average aggregation of the extractant changes greatly across the extractant concentration range studied. When the effect of aggregation is considered for each of the extractants, the stoichiometries of the extracted complexes are found to be M(H(C272)2)3, M(C302)3, and M(C301)3.