Recent investigations have used a 2-ethylhexyl diamide amine (ADAAM-EH) for Am/Cm separations in combination with N,N,N′,N′-tetraethyldiglycolamide as an aqueous complexant to achieve an unprecedented separation factor of 41. The aim of this research effort is to understand the speciation of trivalent lanthanide (Ln) and actinide (An) ions in the organic phase of an ADAAM-EH extraction system, both with and without phase modifiers (PM) (1-octanol and tri-n-butyl phosphate (TBP)). Leveraging spectroscopic techniques in combination with distribution ratio measurements provides an understanding of organic phase f-element ligand complexation. In the absence of PM, Ln is extracted in a stoichiometric 1:1 [M(ADAAM-EH)₁(NO₃)_x(H₂O)₁](NO₃)_3–x complex. The addition of 1-octanol at 20 vol % results in multiple species present. One of the species is the same as the no PM case, and the other species results in an increased −OH coordination to the inner sphere, potentially displacing some NO₃. In the case of TBP, increasing concentration results in additional red-shifted bands in the UV–visible spectra, suggesting the complexation of additional ligands of either ADAAM-EH or TBP. The new system knowledge obtained by and spectroscopic experiments will provide benchmarking information for computational studies of the inner- and outer-sphere coordination environments of f-element cations and insights into ADAAM-EH adduct formation with PM, like 1-octanol and TBP.

中文翻译：

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使用 ADAAM-EH 增强 f 元素分离：调相剂和 DGA 水性络合剂的影响


最近的研究使用 2-乙基己基二酰胺胺 (ADAAM-EH) 进行 Am/Cm 分离，并结合 N,N,N',N'-四乙基二甘醇酰胺作为水性络合剂，实现前所未有的 41 分离因子。这项研究工作是为了了解 ADAAM-EH 萃取系统有机相中三价镧系元素 (Ln) 和锕系元素 (An) 离子的形态，无论是否使用相改性剂 (PM)（1-辛醇和三正-磷酸丁酯（TBP））。利用光谱技术与分配比测量相结合，可以了解有机相 f 元素配体络合。在不存在 PM 的情况下，以化学计量比 1:1 [M(ADAAM-EH) ₁ (NO ₃ ) _x (H ₂ O) ₁ ](NO ₃ ) _3–x 复杂。添加 20 vol% 的 1-辛醇会导致多种物质的存在。其中一种物质与无 PM 情况相同，另一种物质导致与内球的 -OH 配位增加，可能取代一些 NO ₃ 。对于 TBP，增加浓度会导致紫外可见光谱中出现额外的红移带，表明 ADAAM-EH 或 TBP 的额外配体发生络合。通过光谱实验获得的新系统知识将为 f 元素阳离子内外球配位环境的计算研究提供基准信息，并深入了解 ADAAM-EH 与 PM（如 1-辛醇和 TBP）形成加合物。