ENHANCED EXTRACTION AND SEPARATION OF TRIVALENT LANTHANOIDS WITH 4,4,4-TRIFLUORO-1-PHENYL-1,3-BUTANEDIONE AND CROWN-ETHER

Synergistic extraction of the trivalent lanthanoids Nd, Eu and Tm with mixtures of 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) and 18-c rown-6, dicyclohexano-18-crown-6 or dibenzo-18-crown-6 (CE) in 1,2-dic hloroethane from perchlorate solutions was investigated. Characteristi c ion-pair extraction of the Nd(III) or Eu(III) was observed with 1,2- dichloroethane containing Hbtfa and crown ether, in which the cationic complex, Ln(btfa)(2).CE+, was formed and extracted. On the other hand , the heavier lanthanoid, Tm(III), was extracted as Tm(btfa)(3).CE. Th e addition of a crown ether to the metal chelate system not only enhan ces the extraction efficiency of these trivalent metal ions but also i mproves the selectivities significantly among the lighter and middle l anthanoids. Hence, such a system would be of practical value in the mu tual or group separation of trivalent lanthanoids.