Selective Extraction Of Uranium Research Articles

In Situ Synthesis of Uranyl‐Imprinted Nanocage for Selective Uranium Recovery from Seawater

AbstractAn adaptive coordination structure is vital for selective uranium extraction from seawater. By strategy of molecular imprinting, uranyl is introduced into a multivariate metal–organic framework (MOF) during the synthesis process to guide the in situ construction of proper nanocage structure for targeting uranyl binding. Except for the coordination between uranium with four oxygen from the materials, the axial oxygen of uranyl also forms hydrogen bonds with hydrogen from the phenolic hydroxyl group, which enhances the binding affinity of the material to uranyl. Attributing to the high binding affinity, the adsorbent shows high uranium binding selectivity to uranyl against not only the interfering metal ions, but also the carbonate group that coordinates with uranyl to form [UO2(CO)3]4− in seawater. In natural seawater, the adsorbent realizes a high uranium adsorption capacity of 7.35 mg g−1, together with an 18.38 times higher selectivity to vanadium.

In Situ Synthesis of Uranyl‐Imprinted Nanocage for Selective Uranium Recovery from Seawater

Adaptive coordination structure is vital for selective uranium extraction from seawater. By strategy of molecular imprinting, uranyl is introduced into the m ultivariate metal-organic framework (MOF) during the synthesis process to guide the in-situ construction of proper nanocage structure for targeting uranyl binding. Except for the coordination between uranium with four oxygen from the materials, the axial oxygen of uranyl also forms hydrogen bonds with hydrogen from the phenolic hydroxyl group, which enhances the binding affinity of the material to uranyl. Attributing to the high binding affinity, the adsorbent shows high uranium binding selectivity to uranyl against not only the interfering metal ions, but also the carbonate group that coordinates with uranyl to form [UO 2 (CO) 3 ] 4 - in seawater. In natural seawater, the adsorbent realizes a high uranium adsorption capacity of 7.35 mg g -1 ,t ogether with an 18.38 times higher selectivity to vanadium. Integrated into account the high reusability, this adsorbent is a promising alternative for uranium recovery from seawater.

Mussel-inspired dual-crosslinked polyamidoxime photothermal hydrogel with enhanced mechanical strength for highly efficient and selective uranium extraction from seawater

• Mussel-inspired photothermal PAO hydrogel adsorbents were successfully fabricated. • PDA contributes to excellent hydrophilicity and photothermal conversion capacity. • Light irradiation yields the high uranium sorption capacity of 12.67 mg-U/g-Ads. • Excellent adsorption selectivity towards U(VI) over V(V) can be obtained. • Fe 3+ coordination endows with excellent tensile strength and self-recovery ability. The efficient development of selective adsorbents for uranium extraction from seawater is necessary for their potential application in nuclear power generation. The amidoxime-based adsorbents have been recognized as the potential candidates, whereas they still suffer from a much higher affinity towards V(V) present in the seawater over U(VI), leading to the extremely limited commercial use. In this work, we develop a novel mussel-inspired photothermal polyamidoxime (PAO) hydrogel adsorbent, in which polydopamine (PDA) chains are linked to PAO (PDA-PAO) via Michael addition. Dual-crosslinked Fe@PDA-PAO hydrogel structure is constructed by noncovalent bonds between the catechol of PDA chains (e.g. π-π stacking and hydrogen bonds) as well as ionic coordination of Fe 3+ . PDA contributes to the improved hydrophilicity and high photothermal conversion efficiency. As a result, after immersing in real seawater for 6 weeks, light-irradiated Fe@PDA-PAO hydrogel delivers high uranium sorption capacity (12.67 mg-U/g-Ads) together with high U/V mass ratios (1.17), which are superior to currently available hydrogel adsorbents. Meanwhile, Fe 3+ coordination endows Fe@PDA-PAO hydrogel with excellent tensile strength and self-recovery ability, which are of great significance to withstand the harsh conditions of ocean environment for practical applications. The results presented here reveal that Fe@PDA-PAO hydrogel holds tremendous potential for practical applications in the uranium-selective extraction from seawater.

Functionalized polyarylether-based COFs for rapid and selective extraction of uranium from aqueous solution

Selective uranium extraction from aqueous solution is critical for both radioactive contamination remediation and uranium recovery from seawater. Herein, amidoxime (−AO) and carboxyl (–COOH) groups are equipped on a polyarylether-based covalent organic framework (COF) for fabrication of post-modified adsorbents, JUC-505-AO and JUC-505-COOH. The maximum adsorption capacities (Qm) of JUC-505-AO and JUC-505-COOH are 395 mg⋅g−1 and 464 mg⋅g−1, respectively. JUC-505-COOH shows preponderant uranium extraction efficiencies of 36–95% at low pH 2–4, and its removal performances are almost unaffected at high temperature ranging from 25 to 80 °C. Whereas, JUC-505-AO exhibits an impressive adsorption kinetics with the adsorption process equilibrates within 20 min (C0 = 20 mg⋅L-1), and marked sorption selectivity toward uranium against coexisting metal ions. JUC-505-AO also capable of extracting uranium with fast kinetics and capacity (Qm = 4604 μg⋅g−1) from real seawater. U L3 edge X-ray absorption spectra analysis reveals that uranyl ions in JUC-505-AO are anchored by coordinating with O and N from the oxime groups by η2 mode with the coordination numbers of 5 or 6. Meanwhile, HOH⋅⋅⋅O hydrogen bonds between the coordinated water of the hydrated uranyl ions and the oxygen atoms on the skeleton of JUC-505-AO were observed by density functional theory simulations.

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, L1) and 5H-cyclopenta[2,1-b:3,4-b']dipyridine-2,8-dicarboxylate acid (L3), as well as the flexible ligand [2,2'-bipyridine]-6,6'-dicarboxylate acid (L2) using density functional theory (DFT). These ligands coordinate to the uranyl cation in a tetradentate fashion, while L1 and L3 act as tridentate ligands toward VO2+ due to the smaller ionic radius of VO2+ and larger cleft sizes of L1 and L3. Bonding analyses show that the metal-ligand bonding orbitals of the uranyl complexes [UO2L(CO3)]2-, [UO2L(OH)]-, and [UO2L(H2O)] mainly arise from the interactions of the U 5f, 6d orbitals and N, O 2p orbitals. Because of the rigid structure and more suitable chelate ring size, the L1 ligand possesses a stronger complexing ability for uranyl ions than other ligands, while the L3 ligand has weaker binding affinity than L1 and L2. All these ligands prefer to coordinate with the uranyl cation rather than vanadium ion, indicating the selectivity of these ligands to [UO2(CO3)3]4- over H2VO4- and HVO42- in seawater. This is mainly attributed to the metal ion size-based selectivity and structural preorganization of the ligands. These results demonstrate that the backbone of these ligands affect their extraction behaviors. It is expected that this work might prove useful in designing efficient ligands for uranium extraction from seawater.

A Novel Hierarchical Three-Dimensional Ultramicroscopic Porous Bio-Adsorbent for Robust and Selective Uranium Extraction from Natural Seawater

A Novel Hierarchical Three-Dimensional Ultramicroscopic Porous Bio-Adsorbent for Robust and Selective Uranium Extraction from Natural Seawater

Self-Emulsifying Air-in-Water Hipes-Templated Construction of Amidoxime Functionalized and Chain Entanglement Enhanced Macroporous Hydrogel for Fast and Selective Uranium Extraction

Self-Emulsifying Air-in-Water Hipes-Templated Construction of Amidoxime Functionalized and Chain Entanglement Enhanced Macroporous Hydrogel for Fast and Selective Uranium Extraction

Ultrafast and Highly Selective Extraction of Uranium from Seawater by Salicylaldoxime Intercalated Layered Double Hydroxide

Ultrafast and Highly Selective Extraction of Uranium from Seawater by Salicylaldoxime Intercalated Layered Double Hydroxide

The confinement effect of layered double hydroxides on intercalated pyromellitic acidic anions and highly selective uranium extraction from simulated seawater.

Oxygen-rich pyromellitic acidic anions (PMA4-) have been intercalated into MgAl-layered double hydroxides to fabricate the MgAl-PMA-LDH (abbr. PMA-LDH) composite exhibiting excellent adsorption performance toward uranium (U(VI)). Benefiting from the large number of functional groups of -COO-, the PMA-LDH displays an extremely large maximum U adsorption capacity (qUm) of 352 mg g-1 and an ultra-fast sorption rate, reaching uptakes of ∼97% within 30 min and >99% in 1 h at the initial U concentration (CU0) of 113 ppm. Over a very wide pH range of 5-11, high U removals (>93%) are achieved at CU0 = 105 ppm. Moreover, in the presence of highly concentrated competitive ions, ultra-high selectivity of UO22+ is observed, giving a very large distribution coefficient (Kd) of ∼106 mL g-1. Moreover, the PMA-LDH exhibits effective capture of UO22+ in contaminated simulated seawater, showing high uptakes of >93% at CU0 ∼ 10 ppm and >98% at CU0 ∼ 100 ppm. The dispersion effect of LDH layers may contribute to the increase of U adsorption capacity, and the confinement effect of LDH is conducive to the improvement of sorption selectivity toward U. The exploration of the interaction mechanism of UO22+ with PMA4- confined within the LDH gallery offers an important basis for the fabrication of new kinds of organic/inorganic hybrid materials. The PMA-LDH is a highly effective adsorbent which can be applied to uranium extraction from seawater and uranium disposal in nuclear wastewater.

Effect of alkyl chain configuration of tertiary amines on uranium extraction and phase stability – Part I: Evaluation of phase stability, extraction, and aggregation properties

Amine-based extraction processes are broadly exploited for the selective extraction of uranium from sulfuric leaching liquors. The molecular forces (that is, the enthalpy associated with the multi-scale structuration of tertiary amines) are balanced by entropic effects that have not yet been identified. This first part in a series of reports describes the effects of the alkyl chain configuration on the phase stability and aggregation properties of tertiary amines. It is demonstrated that tertiary amines with longer or slightly branched alkyl chains provide better phase stability and enable constant extraction of uranium. In comparison, more branching of the alkyl chains hinders the formation of a highly curved interfacial layer, thus preventing efficient extraction. Combined small-angle scattering determination of the nanostructures in the organic phase and oil–water surface tension measurements revealed that the alkyl chains effects on the efficiency of the extraction process and phase stability are associated with reverse aggregates with smaller polar core volumes and less co-extracted water, suggesting that packing of the alkyl chains has a direct impact on the extraction efficiency of the solvent extraction system.

In-situ grown bilayer MOF from robust wood aerogel with aligned microchannel arrays toward selective extraction of uranium from seawater

Metal-organic frameworks (MOFs) have been widely applied in the recovery of specific guest molecules due to their excellent properties including high porosities, adjustable pore size and abundant chelating functions. However, the granular MOF crystals bring a great challenge to the recycling and reusing from aqueous media, and thus seriously limit their practical application. In this work, MOF bonded wood aerogel prepared by means of in-situ growth strategy was developed for uranium extraction from natural seawater. Eco-friendly and biocompatible wood aerogel possesses run-through microchannel arrays enclosed by aligned cellulose nanofibers (CNFs), contributing to the free and fast diffusion of uranyl ions (UO22+), and thus result in the sufficient coordination with active chelation sites of MOF crystals. To increase the loading content of MOF, bilayer MOF architecture (CMPM) was prepared by using hydroxyl functional groups in CNFs and polydopamine (PDA) coating as nucleation centers of MOF, respectively. The resultant CMPM adsorbents exhibited good reversible compressibility and fragility resistance, which were critical to extend its service life. Moreover, the excellent photothermal conversion capability of PDA enabled CMPM to acquire high temperature under simulated sunlight irradiation. Owing to the apparently endothermic behavior of UO22+, light-irradiated CMPM achieved high adsorption capacity (5.81 mg-U/g-Ads) together with excellent UO22+ selectivity in natural seawater after 30 days. Therefore, this work provides a feasible solution in promoting the practical application of MOF adsorbents.

Vertically Aligned Polyamidoxime/Graphene Oxide Hybrid Sheets’ Membrane for Ultrafast and Selective Extraction of Uranium from Seawater

AbstractWith the continuous research and development of amidoxime (AO)‐based adsorbents, industrialization production of uranium from seawater gradually becomes a reality. However, the currently available AO‐based adsorbents still suffer from low adsorption rate and poor selectivity. Herein, vertically aligned polyamioxime–graphene oxide (VA‐PG) sheet membrane is fabricated by directional freeze casting. The run‐through microchannels contribute to the free diffusion of uranyl ions (UO22+), leading to the fast adsorption kinetics. Furthermore, partially reduced graphene oxide allows high photothermal conversion efficiency and rapid in‐plane heat transfer, resulting in the fast temperature rise under simulated sunlight irradiation. Because of the endothermic behavior of UO22+, light‐irradiated VA‐PG can simultaneously satisfy the requirements of high adsorption capacity (13.63 mg‐U g‐Ads−1), high adsorption rate (0.43 mg g−1 day−1), and excellent selectivity toward U(VI) over V(V) (U/V = 1.24) in natural seawater, indicating the right direction for a breakthrough in the field of uranium extraction from seawater.

Core-shell nanoparticles bearing Schiff base ligand for the selective extraction of uranium from REE leach liquors

The synthesis of core-shell (Fe3O4@SiO2) magnetic nanoparticles (MNP) functionalized using a Schiff base ligand (bis(3-methoxysalicylaldehyde)-o-phenylenediimine; MeOSalophen) for uranium extraction is reported. Extractive performances with respect to pH, adsorption kinetics, chemical nature of the equilibration phase, and elemental selectivity were evaluated and a maximal adsorption capacity of 92 mg g−1 at pH 6 in presence of sulfate ions for an equilibration time of 4 h was determined. The functionalized MNP offer very high affinity for uranyl ion (Kd > 11,000 mL g−1) as well as a high degree of selectivity for this element over several metal ions present in leach liquors containing rare earth elements. While Th was also extracted with the functionalized MNP, equivalent extractive performances were achieved with the non-functionalized counterpart, suggesting that this element is most likely adsorbed on the surface of the silica coating layer. The Schiff base-functionalized core-shell nanoparticles also exhibited a high degree of reusability in the conditions tested.

Nanospace Decoration with Uranyl-Specific "Hooks" for Selective Uranium Extraction from Seawater with Ultrahigh Enrichment Index.

Mining uranium from seawater is highly desirable for sustaining the increasing demand for nuclear fuel; however, access to this unparalleled reserve has been limited by competitive adsorption of a wide variety of concentrated competitors, especially vanadium. Herein, we report the creation of a series of uranyl-specific “hooks” and the decoration of them into the nanospace of porous organic polymers to afford uranium nanotraps for seawater uranium extraction. Manipulating the relative distances and angles of amidoxime moieties in the ligands enabled the creation of uranyl-specific “hooks” that feature ultrahigh affinity and selective sequestration of uranium with a distribution coefficient threefold higher compared to that of vanadium, overcoming the long-term challenge of the competing adsorption of vanadium for uranium extraction from seawater. The optimized uranium nanotrap (2.5 mg) can extract more than one-third of the uranium in seawater (5 gallons), affording an enrichment index of 3836 and thus presenting a new benchmark for uranium adsorbent. Moreover, with improved selectivity, the uranium nanotraps could be regenerated using a mild base treatment. The synergistic combination of experimental and theoretical analyses in this study provides a mechanistic approach for optimizing the selectivity of chelators toward analytes of interest.

Sequential separation and selective extraction of uranium and thorium from monazite sulfate leach liquor using dipropylamine extractant

Monazite mineral is the main source of uranium and thorium, which are mainly associated with rare earth elements (REEs). So, their separation is the crucial task to satisfy their application for nuclear fuel. Dipropylamine was used for the first time in the selective extraction and separation of uranium and thorium from Monazite sulfate leach liquor. The extraction of thorium (98%) was achieved using dipropylamine in kerosene at pH 1; it was followed by selective extraction of uranium (97%) by Dipropylamine at pH 3. The thermodynamic analysis demonstrated that uranium (VI) and thorium (IV) extraction by dipropylamine is an exothermic process. From the stripped liquor (1 M H2SO4), Th and U were precipitated as oxalate and peroxide, respectively, for technological application. Thus, marketable pure thorium and uranium products were prepared in addition to rare earth concentrate.

Rapid and selective uranium extraction from aqueous solution under visible light in the absence of solid photocatalyst

Rapid and selective uranium extraction from aqueous solution under visible light in the absence of solid photocatalyst

Two-Dimensional Ion-Imprinted Silica for Selective Uranium Extraction from Low-Level Radioactive Effluents

Two-Dimensional Ion-Imprinted Silica for Selective Uranium Extraction from Low-Level Radioactive Effluents

High-Capacity Amidoxime-Functionalized β-Cyclodextrin/Graphene Aerogel for Selective Uranium Capture.

Uranium extraction from seawater is a grand challenge of mounting severity as the energy demand increases with a growing global population. An amidoxime-functionalized carboxymethyl β-cyclodextrin/graphene aerogel (GDC) is developed for highly efficient and selective uranium extraction via a facile one-pot hydrothermal process. GDC reaches equilibrium in 1 h, and the maximum adsorption capacity calculated from Langmuir model is 654.2 mg/g. Benefiting from the chelation and complexation reaction, the obtained GDC has an excellent selectivity even when the competitive cations, anions, and oil pollutants exist. In addition, the aerogel possesses great mechanical integrity and remains intact after 10 compression cycles. Meanwhile, the GDC can be easily regenerated and maintains a high reusability of 87.3% after 10 adsorption-desorption cycles. It is worthwhile to mention that GDC exhibits an excellent extraction capacity of 19.7 mg/g within 21 days in natural seawater, which is greatly desired in uranium extraction from seawater.

A self-assembled supramolecular organic material for selective extraction of uranium from aqueous solution

A self-assembled supramolecular organic material for selective extraction of uranium from aqueous solution

Selective extraction of uranium from seawater with biofouling-resistant polymeric peptide

Selective extraction of uranium from seawater with biofouling-resistant polymeric peptide