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Extraction of Actinides Including Neptunyl (V) by Asymmetrical N,N'-Dimethyl-N,N'-Dioctyl-Diglycolamide in Comparison with Symmetrical N,N,N',N'-Tetraoctyl-Diglycolamide-Sterically Structural Insight into Actinide Separations
Ist Teil von
Solvent extraction and ion exchange, 2020-07, Vol.38 (5), p.485-495
Ort / Verlag
Taylor & Francis
Erscheinungsjahr
2020
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
The extraction of NpO
2
+
along with UO
2
2+
, Am
3+
, and Pu
4+
from HNO
3
solutions is achieved by using an asymmetrical N,N′-dimethyl-N,N′-dioctyl-diglycolamide (DMDODGA, L) as extractant. In contrast to symmetric tetraalkyl-diglycolamide ligands, such as the well-studied N,N,N′,N′-tetraoctyl-diglycolamide (TODGA, L′) which fails to catch NpO
2
+
, DMDODGA exhibits considerably good ability to extract neptunyl (V) as well as actinide ions of other oxidation states from HNO
3
solutions. The extracted complex of NpO
2
+
with DMDODGA formed during the extraction in the organic phase mainly is the 1:2 complex, [NpO
2
L
2
]
+
, which is confirmed by the absorption spectrum of the complex in the UV-Vis-NIR region. The stoichiometries of the extracted complexes of Pu
4+
with TODGA and DMDODGA deduced from slope-analysis method show seemingly to be different from each other and to be out of the expectation. However, by comparing the absorption spectra of the extracted complex species of Pu
4+
with DMDODGA and TODGA with the reflectance spectrum of PuL′′
3
∙4(NO
3
)∙EtOH, a solid compound of Pu
4+
with N,N,N′,N′-tetramethyl-diglycolamide (TMDGA, L′′), it is clearly found that the two extracted complex species and the solid complex share similar coordination geometry of Pu
4+
surrounded by three tridentate DGA ligands.