Extraction of Nitric Acid, Americium(III), Curium(III), and Lanthanides(III) into DMDOHEMA Dissolved in Kerosene

Geist, Andreas; Berthon, Laurence; Charbonnel, Marie-Christine; Müllich, Udo

doi:10.1080/07366299.2020.1794523

Cited by 11 publications

(12 citation statements)

References 60 publications

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“…In fact, their affinity for a given An(III) is similar to that of Ln(III) with a similar ionic radius. 11,12 This is also the case for diglycolamides; [13][14][15][16][17] the Am(III) and Cm(III) distribution ratios obtained by solvent extraction experiments fall within those of light Ln(III). For example, TODGA (N,N,N,N-tetraoctyl diglycolamide) extracts Am(III) and Cm(III) slightly less well than Eu(III), SF Eu/Am ≈ 8 and SF Eu/Cm ≈ 5.…”

Section: Introductionmentioning

confidence: 67%

Spectroscopic investigation of the covalence of An(iii) complexes with tetraethylcarboxamidopyridine

et al. 2022

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Section: Introductionmentioning

confidence: 67%

Spectroscopic investigation of the covalence of An(iii) complexes with tetraethylcarboxamidopyridine

et al. 2022

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“…The metal complexes are in the polar region, while unbound amphiphilic ligands are largely at the interface. This is the so-called third phase, which, while very interesting, is highly undesirable in any extraction process, not least because high concentrations of uranium and plutonium may risk nuclear criticality. ,,,,− …”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study of the Aggregation Behavior of N,N,N′,N′-Tetraoctyl Diglycolamide

et al. 2022

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Liquid–liquid extraction is a commonly used technique to separate metals and is a process that has particular relevance to the nuclear industry. There has been a drive to use environmentally friendly ligands composed only of carbon, hydrogen, nitrogen, and oxygen. One example is the i-SANEX process that has been developed to separate minor actinides from spent nuclear fuel. The underlying science of such processes, is, however, both complex and intriguing. Recent research indicates that the liquid phases involved are frequently structured fluids with a hierarchical organization of aggregates. Effective flow-sheet modeling of such processes is likely to benefit from the knowledge of the fundamental properties of these phases. As a stepping stone toward this, we have performed molecular dynamics simulations on a metal free i-SANEX system composed of the ligand N , N , N ′, N ′-tetraoctyl diglycolamide (TODGA), diluent hydrogenated tetrapropylene (TPH), and polar species water and nitric acid. We have also studied the effects of adding n -octanol and swapping TPH for n -dodecane. It would seem sensible to understand this simpler system before introducing metal complexes. Such an understanding would ideally arise from studying the system’s properties over a wide range of compositions. The large number of components, however, precludes a comprehensive scan of compositions, so we have chosen to study a fixed concentration of TODGA while varying the concentrations of water and nitric acid over a substantial range. Reverse aggregates are observed, with polar species in the interior in contact with the polar portions of the TODGA molecules and the organic diluent on the exterior in contact with the TODGA alkyl chains. These aggregates are irregular in shape and grow in size as the amount of water and nitric acid increases. At a sufficiently high polar content, a single extended cluster forms corresponding to the third phase formation. No well-defined bonding motifs were observed between the polar species and TODGA. The cluster size distribution fits an isodesmic model, where the Gibbs energy change of adding a TODGA molecule to a cluster ranges between 4.5 and 7.0 kJ mol –1 , depending on the system composition. The addition of n -octanol was found to reduce the degree of aggregation, with n -octanol acting as a co-surfactant. Exchanging the diluent TPH for n -dodecane also decreased the aggregation. We present evidence that this is due to the greater penetration of n -dodecane into the reverse aggregates. It is known, however, that the propensity for the third phase formation is greater with n -dodecane as the diluent than is the case with TPH, but we argue that these two results are not contradictory. This research casts light on the drivin...

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“…The simulation protocols as well as force field parameters for the malonamides and n -dodecane are given in the Supporting Information. Simulation compositions and corresponding concentrations represent typical LLE conditions − and are given in Table . Graph theoretic analysis is performed on the simulation trajectories for two types of graphs: one representing the malonamide self-association network and the other representing the hydrogen bonding network.…”

Section: Methodsmentioning

confidence: 99%

Impact of Water Extraction on Malonamide Aggregation: A Molecular Dynamics and Graph Theoretic Approach

2021

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Solution structure in liquid−liquid extraction affects the efficacy of separation; however, even for simplified organic phases, structural characterization and attribution of aggregation to intermolecular interactions are fundamental challenges. We investigate water uptake into organic phases for two malonamides commonly applied to actinide and lanthanide separations. Extracted water induces reorganization of the amphiphilic extractant molecules, although we find this rearrangement is not strongly manifested in small-angle X-ray scattering making it challenging to probe without methods such as atomistic simulation. Using a graph theoretic approach to define hydrogen bonded water/malonamide aggregates from molecular dynamics simulations, we find evidence of a characteristic aggregate size by water number that results from geometric accommodation of the surrounding malonamide molecules. This implies a degree of size selectivity inherent to these water-in-oil aggregates. Conversely, we find no evidence of a characteristic size of the aggregates with respect to their malonamide number. By defining a separate graphical representation of self-association of the amphiphilic malonamides, we quantify how water affects the local and nonlocal topology of the malonamide network, providing a basis for characterization of the structure and impact of polar solutes in increasingly complex organic phases.

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Extraction of Nitric Acid, Americium(III), Curium(III), and Lanthanides(III) into DMDOHEMA Dissolved in Kerosene

Cited by 11 publications

References 60 publications

Spectroscopic investigation of the covalence of An(iii) complexes with tetraethylcarboxamidopyridine

Spectroscopic investigation of the covalence of An(iii) complexes with tetraethylcarboxamidopyridine

Molecular Dynamics Study of the Aggregation Behavior of N,N,N′,N′-Tetraoctyl Diglycolamide

Impact of Water Extraction on Malonamide Aggregation: A Molecular Dynamics and Graph Theoretic Approach

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