Separation of Am from lanthanides and Cm using the ADAAM(EH)-DTBA extraction system and elucidation of its complexation with DTBA through DFT calculations

ADAAM-DTBA抽出系におけるAmのCmとLnの相互分離とDFT計算によるDTBAとの錯形成の解明

佐々木 祐二  ; 金子 政志   ; 熊谷 友多   ; 伴 康俊  

Sasaki, Yuji; Kaneko, Masashi; Kumagai, Yuta; Ban, Yasutoshi

ADAAM(EH)-DTBA抽出系を使って高レベル廃液からAnとLnの相互分離法を開発した。ADAAM(EH)はCmと中希土からAmの分離が可能である。また、pH:2以下の条件でDTBAを用いるとAmと軽希土の分離が可能となり、Nd/Am分離比は10を超える。したがって、この抽出系はCmとLnの混合相からAmの単離を可能とする。DFT計算により、金属-DTBAの錯形成の特徴が明らかになり、NdよりAmとDTBAの結合が高いことを示唆した。

We developed a method called the alkyl-diamide amine (ADAAM(EH))-diethylenetriamine-triacetic acid-bis(diethylacetamide) (DTBA) technique for separating actinide (An) and lanthanide (Ln) elements from high-level liquid waste. ADAAM(EH) exhibits a high separation factor (SF) not only for Am/Cm but also for light/heavy Ln under acidic conditions (1.5 M HNO). Consequently, Am can be separated from Cm as well as from middle Ln (Sm, Eu, and Gd) using ADAAM(EH) as an extractant. DTBA enables the stripping of Am and potentially separates it from Ln in the organic phase at low pH ( 2). The lowest SF among the light Ln, observed for Nd/Am, exceeded 10, indicating that Am can be separated from light Ln by stripping using DTBA from the ADAAM(EH) extraction solvent. The density functional theory calculations for understanding the coordination bond properties of metal-DTBA complexes are performed, which supported higher affinity of DTBA toward Am than Nd.