Solvent Extraction of Various Metals Including Actinides by Bidentate and Tridentate Diamides

Abstract

Many diamide-type extractants were synthesized and tested for the extraction of actinides (III), (IV), (V) and (VI). The diglycolamides (DGA) with two amidic oxygen and one ether oxygen, which show the tridentate feature, have the high extractability of actinides (An). In order to increase the lipophilic property, the diglycolamides with the different functional groups attached to N atoms were synthesized and examined for their extractability.It was found that N, N, N', N'-tetraoctyl-diglycolamide (TODGA) and N, N, N', N'-tetradecyldiglycolamide (TDDGA) exhibit the satisfactory dissolution into n-dodecane with less solubility in H2O. The results of various metal extractions using TODGA revealed that the divalent, trivalent and tetravalent metals with ionic radius of 90-120 pm gave notably high D values. After elucidation of the effect on substitution of the functional group, the chemical form of DGA to have high performance on An extraction was proposed.

A multi-faceted approach to probe organic phase composition in TODGA systems with 1-alcohol phase modifiers

“…7,8 In the literature, the combination of solvent extraction, extended X-ray absorption ne structure (EXAFS), UV-vis, and FT-IR spectroscopy has led to an understanding of the Ln-TODGA structure in the organic phase. [10][11][12][13][14] TODGA coordinates to Lns in a trischelate complex, [Ln(TODGA) 3 ] 3+ , with outer-sphere nitrate anions (NO 3 − ) positioned in the cles of the octyl arms. 13,15,16 These nitrates interact with co-extracted H 2 O molecules forming an extended hydrogen bonding network.…”

“…13,15,16 These nitrates interact with co-extracted H 2 O molecules forming an extended hydrogen bonding network. 10,11 Once this network extends beyond the cles, NO 3 − and H 2 O molecules interact with (TODGA)$(HNO 3 ) 1-2 adductsincreasing the number of molecules associated with each Ln or aggregate. The size of these aggregates rapidly increases with higher HNO 3 and Ln concentrations.…”

“…The size of these aggregates rapidly increases with higher HNO 3 and Ln concentrations. 10 In various solvent extraction systems, a threshold commonly referred to as the limiting organic concentration (LOC) describes the highest concentration of either Ln or HNO 3 in the organic phase before the organic phase splits forming a third phase. 17 Third phase formation (TPF) involves splitting the organic phase into light (diluent rich) and heavy (extractant rich) phases.…”

Separation of Am(III), Cm(III), and Cf(III) using capillary electrophoresis

“…Separation of trivalent actinides and lanthanides is one of the most difficult, because their physical and chemical properties are so similar [1,2]. The separation of trivalent actinides and lanthanides is of current interest in the field of the reprocessing of spent nuclear fuel [3][4][5][6][7][8][9][10][11][12][13]. In solution chemistry, ion exchange chromatography and solvent extraction have been well studied for the separation of lanthanides and actinides [3][4][5][6][7][8][9][10][11][12][13].…”

“…The separation of trivalent actinides and lanthanides is of current interest in the field of the reprocessing of spent nuclear fuel [3][4][5][6][7][8][9][10][11][12][13]. In solution chemistry, ion exchange chromatography and solvent extraction have been well studied for the separation of lanthanides and actinides [3][4][5][6][7][8][9][10][11][12][13]. Capillary electrophoresis (CE) also shows promise for the separation of trivalent actinides because the separation behavior of lanthanides using complex-forming agents is well established for CE [14][15][16][17], and the separation of all lanthanides has been accomplished within several minutes [14,15].…”