SYNERGIC EXTRACTION OF TRIVALENT GADOLINIUM, EUROPIUM AND AMERICIUM RADIONUCLIDES BY 15-CROWN-5 OR 18-CROWN-6 MIXED WITH THENOYLTRIFLUOROACETONE FROM PERCHLORATE MEDIUM

Synergic extraction of trivalent Eu, Gd and Am from aqueous perchlorate medium has been studied using mixtures of thenoyltrifluoroacetone (HTTA) and 15-crown-5 or 18-crown-6 (CE) in chloroform at (25 +/- 1)-degrees-C. Slope analysis of the extraction results indicated a general formula of M(TTA)3.(CE)2 for the extracted species. The stability order took the sequence Eu(TTA)3.(CE)2 > Am(TTA)3.(CE)2> > Gd(TTA)3.(CE)2 with 15C5 and Am(TTA)3.(CE)2 > Eu(TTA)3.(CE)2 > Gd(TTA)3.(CE)2 with 18C6. The synergic factors, extraction constants and formation constants of the extracted species were determined and discussed in terms of the correspondence between cavity size of the crown ethers and ionic crystal radii.