Am/Eu separation with a new ligand, N,N,N',N'-tetrakis((4-butoxypyridin-2-yl)methyl)ethylenediamine (TBPEN), a hydrophobic derivative of TPEN

Matsumura, Tatsuro  ; Inaba, Yusuke*; Mori, Atsunori*; Takeshita, Kenji*

We are developing a new MA/Ln separation process with TPEN and its derivatives for P&T technology. TPEN is a hexadentate soft-donor ligand that has six soft-donor sites as a kind of podand type molecule and can encapsulate a metal ion. TPEN has good selectivity of Am(III) from Ln(III) and has potential to establish partitioning of MA. From the viewpoint of practical application, the hydrophobicity of TPEN must be improved. Because the dissolution of a slight amount of TPEN (about 10 mol/l) to water will restrict decontamination of Ln in extraction process. In this study, the hydrophobicity of TPEN was improved by introducing alkyl groups and the effect of the introduction of alkyl groups on the separation of Am(III) and Eu(III) was examined. One of them, N,N,N',N'-tetrakis((5-butoxypyridin-2-yl)-methyl)ethylenediamine, TBPEN, showed good selectivity and the maximum separation factor, SF, was 91 at pH 3.02. The hydrophobicity of TBPEN is checked by the distribution data between water and chloroform, and improved successfully. The approach for development of hydrophobic derivatives of TPEN was effective.