SYNERGISTIC EXTRACTION OF EUROPIUM AND THULIUM BY MIXTURES OF HIGH-MOLECULAR-WEIGHT BETA-DIKETONES AND NEUTRAL ORGANOPHOSPHORUS ESTERS

Solvent extraction of europium(III) and thulium(III) has been investigated by high molecular weight β-diketone derivatives, such as dodecylbenzoyltrifluoroacetone (LIX 51), benzoylisooctanoylmethane (LIX 54) and dibenzoyl-methane (DBM), in the presence of neutral donors, such as tributyl phosphate (TBP) and trioctylphosphine oxide (TOPO). The distribution ratio was largely enhanced by a synergistic effect. Tris-β-diketonates forms mono- and di-adducts with TBP and TOPO depending on the kind of β-diketones and central metals. The extraction constants with β-diketones alone were of the order LIX 51>>LIX 54>DBM, whereas the adduct formation constants followed the order LIX 51>DBM>LIX 54. The separation factor between thulium and europium decreased in the presence of neutral ligands. © 1990, The Japan Society for Analytical Chemistry. All rights reserved.