Extraction Separation of Am(III) and Eu(III) with TPEN Isomers and Decanoic Acid

Abstract

TPEN isomers with different positions of nitrogen donors in pyridyl groups, t2pen, t3pen and t4pen, were synthesized and the extraction separation of Am(III) and Eu(III) with these ligands and a fatty acid, decanoic acid, was investigated. All isomers were similar in the complexation in the aqueous phase, such as the protonation and the complex formation of Eu, however, the extraction behavior of Am and Eu was quite different. The synergistic extraction effect for Am was observed for t2pen and the high separation factor of about 100 was measured under the condition that the initial molar ratio of t2pen to decanoic acid in the organic phase is kept at 1:2. The value is comparable to that for the extraction system with BTP. On the other hand, the extractability of other isomers, t3pen and t4pen, was very low and no separation of Am and Eu was observed. Only t2pen, in which nitrogen donors in four pyridyl groups are positioned in the vicinity of the skeletal structure (N-C-C-N structure), is available for the extraction separation of Am.