MA/Ln separation with new ligand, hydrophobic derivatives of TPEN

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

We are developing a new MA/Ln separation process with derivatives of TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine) for P&T technology. TPEN is a hexadentate ligand, which has good selectivity of Am(III) from Ln(III). However, there is a serious problem for the practical application. This is to the dissolution of a slight amount of TPEN (about 10 mol/l) to water. High enrichment of Am(III) will be restricted by the dissolution of TPEN to water. In this study, the hydrophobicity of TPEN is improved by introducing alkyl groups and the selectivity of Am(III) and Eu(III) is examined. We succeeded to synthesize a new hydrophobic derivative of TPEN, TBPEN (N,N,N',N'-tetrakis((5-butoxypyridin-2-yl)-methyl)ethylenediamine. It showed good selectivity and the maximum separation factor, SF, was 91 at pH 3.0. A hydrophobic derivative of TPEN that has potential of application to the MA/Ln separation process was synthesized successfully.