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

By using an extractant, N,N,N',N'-tetraoctyl-3oxapentanediamide (TODGA), extraction and separation of Sr(II) from Am(III) were investigated for the partitioning of high level liquid waste (HLLW). Both metal ions, accompanied with the counter anion, NO3-, and HNO3 without dissociation, were extracted by TODGA. We used two distinct methods for the separation of Am(III) and Sr(II). A mixture of TODGA and monoamide reduced the distribution ratio D of Sr(II) compared to that without monoamide, whereas D(Am) was still high value under the identical condition. After extraction of Am(III) by TODGA and monoamide, Sr(II) remaining in HLLW can be extracted by using enough concentration of TODGA at the next step. In the other method, Sr(II) was coextracted with Am(III) by TODGA. It was observed that D(Sr) decreased with an increase of HNO3 from 3 M to 6 NI HNO3 at the same TODGA concentration, while D(Am) increased until 6 M HNO3. By using 6 M HNO3, Am(III) and Sr(II) were separated after coextraction.