Extraction and separation of Am(III) and Sr(II) by N,N,N',N'-tetraoctyl-3-oxapentanediamide (TODGA)

Suzuki, Hideya*; Sasaki, Yuji  ; Sugo, Yumi; Apichaibukol, A.; Kimura, Takaumi 

The promising extractant for the partitioning of HLLW, TODGA, was used and investigated for the extraction of Sr(II) and separation from Am(III). Both metal ions can be extracted by TODGA based on the extraction reaction accompanying the neutral HNO as well as the counter anion, NO. The mixture of TODGA and monoamide can reduce the distribution ratio of Sr(II), compared to the D(Sr) without monoamide, this solvent may extract only Am(III) with holding Sr(II) in the aqueous phase. After extraction of An by TODGA and monoamide, Sr(II) remaining in HLLW can be extracted by using enough high concentration of TODGA at the next step. Because of its high D value, Sr(II) can be coextracted with An by TODGA. It was observed that D(Sr) decrease with an increase of HNO from 3M to 6M HNO at the same TODGA concentration, while Am(III) has still high D values at least until 6M HNO. By using 6M HNO of aqueous phase, An and Sr(II) can be separated after coextraction.