Solvent extraction of An(III) and Ln(III) using TODGA in aromatic diluents to suppress third phase formation

Abstract

The extraction of nitric acid, trivalent actinides and lanthanides with N,N,N ,N -tetra-n-octyl-3-oxapentanediamide (TODGA) dissolved in the aromatic diluents 1,4-diisopropylbenezene and tert-butylbenzene was studied. Nitric acid extraction proceeds along the formation of 1:1 and 2:1 HNO3-TODGA adducts. An(III) and Ln(III) distribution ratios were determined as a function of nitric acid, TODGA and Ln(III) concentrations. Distribution ratios are approximately an order of ag i de lower in aromatic diluents compared to aliphatic diluents.No third phase formation was observed when contacting the solvent with an aqueous phase containing 1.5 mol/L Er(NO3)3 in 2 4.3 mol/L HNO3. Slope analysis indicates the formation of 1:3 and 1:4 M(III):TODGA complexes. Using TRLFS, the formation of a previously unknown 1:2 complex in organic phases loaded with Ln(III) was observed for the first time.

Effect of diluent on the extraction of europium(iii) and americium(iii) with N,N,N′,N′-tetraoctyl diglycolamide (TODGA)

“…In general, the observed values are consistent with the previously reported stoichiometries of extracted complexes of An 3+ and Ln 3+ with diglycolamides. 38,45,75–78 Its noteworthy that 1 : 4 coordination, although observed also in other works 30,38,79 is not possible within the first solvation shell of Eu 3+ and Am 3+ due to geometrical hindering. 80 As spectroscopic methods i.e.…”

“…It is well known that extraction of HNO 3 via some organic phases containing TODGA occurs. 33,[38][39][40][41]49,52 Therefore, two sets of experiments were performedwith the organic phase presaturated with 4 M HNO 3 as well as with a nonpreconditioned set of diluents. Saturation of the organic solvent (diluent and TODGA) was performed by contacting the solvent with the same volume of 4 M HNO 3 by shaking machine for 60 minutes and then the phases were let to separate by gravity for 120 minutes.…”

“…The family of diglycolamides are known extracting agents for trivalent lanthanides and actinides in solvent extraction, with expected application in partitioning and transmutation of a nuclear fuel [22][23][24][25] and in radiopharmaceutical industry for 225 Ac production. [26][27][28][29] While the behavior of diglycolamides with respect to equilibrium distribution ratios, acid extraction and kinetics was extensively evaluated, [30][31][32][33][34][35][36][37][38][39][40][41][42] the effect of the diluent on the extraction was evaluated only in a few studies. [42][43][44][45][46][47] From the available data, correlations of diluent properties against the distribution ratios seems rather difficult.…”

“…43,44 At the same time it was shown that the nature of the diluent does not affect the results of time resolved laser uorescence measurements luminescence spectra of Eu 3+ . 38,45 In order to bring deeper insight into diluent effects, we performed a systematic study of the molecular diluent inuence on solvent extraction of americium and europium by N,N,N 0 ,N 0 -tetraoctyl diglycolamide (TODGA) from nitric acid media. Three different groups of diluents consisting of alkanes, long chained alcohols and ketones were studied.…”

“… 43,44 At the same time it was shown that the nature of the diluent does not affect the results of time resolved laser fluorescence measurements luminescence spectra of Eu 3+ . 38,45 …”