Theoretical Exploration of the Synergistic Effect of Phosphate and Amidoxime for Uranium Recovery from Seawater.

Highly selective extraction of uranium from seawater is currently extremely challenging. Although the amidoxime group (HAO) is the commonly used ligand in seawater uranium extraction, it also has strong binding capacity for vanadium ion. It has been shown that the introduction of phosphate groups into amidoxime-based adsorbents can improve the adsorption performance of materials through a synergistic effect between functional groups.

Development of Neural Network Potentials for Studying Chemical Behaviors of La/Nd Ions in Molten LiCl-KCl-CsCl in Combination with Raman Spectroscopy.

The chemistry of molten salts has attracted great research interest owing to their wide applications in diverse fields. In the pyrochemical reprocessing of spent nuclear fuel or molten salt nuclear reactors, lanthanide elements as the principal fission products bring about changes in the composition and properties of molten salts. Herein, we report a comprehensive study on the coordination chemistry of the representative trivalent lanthanide ions (La/Nd) in LiCl-KCl-CsCl using a multiscale strategy combining Raman spectroscopy, deep learning, and large-scale molecular dynamics (MD) simulations.

Actinide endohedral inter-metalloid clusters of the group 15 elements.

Inter-metalloid clusters in Zintl chemistry have been extensively studied due to their unique electronic structures and potential applications. In this work, we explored a series of actinide endohedral inter-metalloid clusters of the group 15 elements [An@Bi] (An = Th-U) and [An@Sb] using density functional theory (DFT). [Th@Bi] and [U@Bi] exhibit symmetry, while [Pa@Bi] and [An@Sb] (An = Th-U) have structures.

Theoretical insights into selective extraction of Am(III) from Cm(III) and Eu(III) with asymmetric N-heterocyclic ligands.

Separation of lanthanide (Ln) and minor actinide (MA) elements and mutual separation between minor actinide elements ( Am(III) and Cm(III)) represent a crucial undertaking. However, separating these elements poses a significant challenge owing to their highly similar physicochemical properties. Asymmetric N-heterocyclic ligands such as -ethyl-6-(1-pyrazol-3-yl)--(-tolyl)picolinamide (Et--Tol-A-PzPy) and -ethyl--(-tolyl)-1,10-phenanthroline-2-carboxamide (ETPhenAm) have recently received considerable attention in the separation of MAs over Ln from acid solutions.

Heterocyclic Ligands with Different N/O Donor Modes for Am(III)/Eu(III) Separation: A Theoretical Perspective.

Excellent "CHON" compatible ligands based on a heterocyclic skeleton for the separation of trivalent actinides [An(III)] from lanthanides [Ln(III)] have been widely explored, the aim being spent nuclear fuel reprocessing. The combination mode of a soft/hard (N/O) donor upon the coordination chemistry of An(III) and Ln(III) should play a vital role with respect to the performance of ligands. As such, in this work, two typical experimentally available phenanthroline-derived tetradentate ligands, CyMe-BTPhen () and Et-Tol-DAPhen (), and two theoretically designed asymmetric tetradentate heterocyclic ligands, and , with various N/O donors were investigated using scalar relativistic density functional theory.

Theoretical Insights on the Complexation of Americium(III) and Europium(III) with Diglycolamide- and Dimethylacetamide-Functionalized Calix[4]arenes.

Separation of minor actinides from lanthanides is one of the biggest challenges in spent fuel reprocessing due to the similar physicochemical properties of trivalent lanthanides (Ln(III)) and actinides (An(III)). Therefore, developing ligands with excellent extraction and separation performance is essential at present. As an excellent pre-organization platform, calixarene has received more attention on Ln(III)/An(III) separation.

Insights into the Reduction Mechanisms of Np(VI) to Np(V) by Carbohydrazide.

An efficient approach to Np separation in the Plutonium Uranium Reduction EXtraction (PUREX) process is to adjust Np(VI) to Np(V) by free-salt reductants, such as hydrazine and its derivatives. Recently, carbohydrazide (CO(NH)), a derivative of hydrazine and urea, has received much attention, which can reduce Np(VI) to Np(V) in the extraction reprocessing of spent nuclear fuel. Herein, according to the experimental observations, we examine the reduction mechanism of four Np(VI) by one carbohydrazide molecule using multiple theoretical calculations.

Theoretical Insights into the Selectivity of Hydrophilic Sulfonated and Phosphorylated Ligands to Am(III) and Eu(III) Ions.

The separation of lanthanides and actinides has attracted great attention in spent nuclear fuel reprocessing up to date. In addition, liquid-liquid extraction is a feasible and useful way to separate An(III) from Ln(III) based on their relative solubilities in two different immiscible liquids. The hydrophilic bipyridine- and phenanthroline-based nitrogen-chelating ligands show excellent performance in separation of Am(III) and Eu(III) as reported previously.

Experimental and theoretical studies on the extraction behavior of Cf(iii) by NTAamide(C8) ligand and the separation of Cf(iii)/Cm(iii).

In this work we studied the extraction behaviors of Cf(iii) by NTAamide (,,',','',''-hexaocactyl-nitrilotriacetamide, C8) in nitric acid medium. Influencing factors such as contact time, concentration of NTAamide(C8), HNO and NO as well as temperature were considered. The slope analysis showed that Cf(iii) should be coordinated in the form of neutral molecules, and the extraction complex should be Cf(NO)·2L (L = NTAamide(C8)), which can achieve better extraction effect under the low acidity condition.

Theoretical Insights into the Substitution Effect of Phenanthroline Derivatives on Am(III)/Eu(III) Separation.

Separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) poses a huge challenge in the reprocessing of spent nuclear fuel due to their similar chemical properties. ,'-Diethyl-,'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) is a potential ligand for the extraction of An(III) from Ln(III), while there are still few reports on the effect of its substituent including electron-withdrawing and electron-donating groups on An(III)/Ln(III) separation. Herein, the interaction of Et-Tol-DAPhen ligands modified by the electron-withdrawing groups (CF, Br) and electron-donating groups (OH) with Am(III)/Eu(III) ions was investigated using scalar relativistic density functional theory (DFT).

Actinide-doped boron clusters: from borophenes to borospherenes.

Similar to graphene and fullerene, metal-doping has been considered to be an effective approach to the construction of highly stable boron clusters. In this work, a series of actinide metal-doped boron clusters AnB (An = Pa, Np, Pu, Am, Cm, Bk, and Cf) have been explored using extensive first-principles calculations. We found that the quasi-planar structure of B transforms to an endohedral borospherene An@B after actinide metal doping.

Theoretical insights into the separation of Am(III)/Eu(III): designing ligands based on a preorganization strategy.

Separation of trivalent actinide (An(III)) and lanthanide (Ln(III)) is a worldwide challenge of nuclear waste treatment. Designing ligands with efficient An(III)/Ln(III) separation performance is still one of the key issues for the disposal of accumulated radioactive waste and the recovery of minor actinides. Recently, N-heterocyclic ligands modified with amide groups have shown excellent An(III)/Ln(III) separation performance.

Theoretical Insights into Phenanthroline-Based Ligands toward the Separation of Am(III)/Eu(III).

The bistriazinyl-phenanthroline representative ligand, BTPhen, shows excellent extraction and separation ability for trivalent actinides and lanthanides. Herein, we first designed three phenanthroline-based nitrogen-donor ligands (L, L, and L), and then studied the structural and bonding properties as well as thermodynamic properties of the probable complexes, ML(NO) (M = Am or Eu and L = L, L, or L), using scalar relativistic density functional theory. Our charge decomposition analysis revealed an obviously higher charge transfer from the ligand to Am(III) compared with the Eu(III) case for the studied complexes.

Reduction of Np(VI) with hydrazinopropionitrile water-mediated proton transfer.

Effectively adjusting and controlling the valence state of neptunium (Np) is essential in its separation during spent fuel reprocessing. Hydrazine and its derivatives as free-salts can selectively reduce Np(VI) to Np(V). Reduction mechanisms of Np(VI) with hydrazine and four derivatives have been explored using multiple theoretical methods in our previous works.

Theoretical insights into selective extraction of uranium from seawater with tetradentate N,O-mixed donor ligands.

The competition of uranium and vanadium ions is a major challenge in extracting uranium from seawater. In-depth exploration of the complexation of uranium and vanadium ions with promising ligands is essential to design highly efficient ligands for selective recovery of uranium. In this work, we systematically explored the uranyl and vanadium extraction complexes with three tetradentate N,O-mixed donor analogues including the rigid backbone ligands 1,10-phenanthroline-2,9-dicarboxylic acid (PDA, L) and 5-cyclopenta[2,1-:3,4-']dipyridine-2,8-dicarboxylate acid (L), as well as the flexible ligand [2,2'-bipyridine]-6,6'-dicarboxylate acid (L) using density functional theory (DFT).

Construction of the Largest Metal-Centered Double-Ring Tubular Boron Clusters Based on Actinide Metal Doping.

Metal doping has been considered to be an effective approach to stabilize various boron clusters. In this work, we constructed a series of largest metal-centered double-ring tubular boron clusters An@B (An = Th, Pa, Pu, and Am). Extensive global minimum structural searches combined with density functional theory predicted that the global minima of An@B (An = Th, Pu, and Am) are double-ring tubular structures.

Theoretical Insights into the Selective Separation of Am(III)/Eu(III) Using Hydrophilic Triazolyl-Based Ligands.

Designing ligands with efficient actinide (An(III))/lanthanide (Ln(III)) separation performance is still one of the key issues for the disposal of accumulated radioactive waste and the recovery of minor actinides. Recently, the hydrophilic ligands as promising extractants in the innovative Selective ActiNide Extraction (i-SANEX) process show excellent selectivity for Am(III) over Eu(III), such as hydroxylated-based ligands. In this work, we investigated the selective back-extraction toward Am(III) over Eu(III) with three hydrophilic hydroxylated triazolyl-based ligands (the skeleton of pyridine , bipyridine , and phenanthroline ) using scalar-relativistic density functional theory.

Theoretical Probing of Size-Selective Crown Ether Macrocycle Ligands for Transplutonium Element Separation.

Effective separation and recovery of chemically similar transplutonium elements from adjacent actinides is extremely challenging in spent fuel reprocessing. Deep comprehension of the complexation of transplutonium elements and ligands is significant for the design and development of ligands for the in-group separation of transplutonium elements. Because of experimental difficulties of transplutonium elements, theoretical calculation has become an effective means of exploring transplutonium complexes.

Theoretical Insights on Improving Amidoxime Selectivity for Potential Uranium Extraction from Seawater.

Extraction of uranium from seawater is one of the important ways to solve the shortage of terrestrial uranium resources. Thereinto, the competition between uranyl and vanadium cations is a significant challenge in the commonly used amidoxime-based adsorbents for extracting uranium from seawater. An in-depth understanding of the extraction behaviors of modified amidoxime groups with uranyl and vanadium ions is one of the effective means to design and develop efficient adsorbents for selective uranium sequestration.

Theoretical probing of twenty-coordinate actinide-centered boron molecular drums.

The exploration of metal-doped boron clusters has a great significance in the design of high coordination number (CN) compounds. Actinide-doped boron clusters are probable candidates for achieving high CNs. In this work, we systematically explored a series of actinide metal atom (U, Np, and Pu) doped B boron clusters An@B (An = U, Np, and Pu) by global minimum structural searches and density functional theory (DFT).

Theoretical insights into the possible applications of amidoxime-based adsorbents in neptunium and plutonium separation.

Efficient separation of neptunium and plutonium from spent nuclear fuel is essential for advanced nuclear fuel cycles. At present, the development of effective actinide separation ligands has become a top priority. As common adsorbents for extracting uranium from seawater, amidoxime-based adsorbents may also be able to separate actinides from high-level liquid waste (HLLW).

Theoretical Insights into the Separation of Am(III)/Eu(III) by Hydrophilic Sulfonated Ligands.

In this work, we focused on the separation of Am(III)/Eu(III) with four hydrophilic sulfonated ligands () based on the framework of phenanthroline and bipyridine through scalar relativistic density functional theory. We studied the electronic structures of [M(NO)] (M = Am, Eu) complexes and the bonding nature between metal and ligands as well as evaluated the separation selectivity of Am(III)/Eu(III). The tetrasulfonated ligand with a bipyridine framework has the strongest complexing ability for metal ions probably because of the better solubility and flexible skeleton.

Theoretical Insights into the Reduction Mechanism of Np(VI) with Phenylhydrazine.

Effectively adjusting and controlling the valence state of neptunium from the spent fuel reprocessing process is essential to separating neptunium. Hydrazine and its derivatives as free-salt reductants have been experimentally demonstrated to effectively reduce Np(VI) to Np(V). We have theoretically investigated the reduction mechanisms of Np(VI) with hydrazine and three derivatives (HOCHNH, CHNH, and CHONH) in previous works.