Uranium Adsorption Research Articles

Promising porous materials for uranium extraction from seawater

Uranium extraction from seawater is a promising approach for ensuring continued uranium fuel supply to the nuclear power industry. However, extracting uranium by this route is challenging due to the low concentration of uranium, high ionic strength, and marine micro-organisms in seawater. Recently, a range of novel porous adsorbent materials have been developed for uranium extraction from ocean water. These adsorbents rely on specific pore characteristics and functional groups (hydroxyl, carboxyl, amidoxime, phosphate, etc.) to achieve a high affinity and selectivity for uranyl ions (UO22+) relative to other ions. Relying strongly on coordination principles, specific binding sites for uranium are assembled in these porous materials, with cooperative actions of several functional groups often used to achieve strong uranium capture and adsorption selectivity. In addition to traditional adsorbents, adsorption-photocatalytic and adsorption-electrocatalytic materials are also being pursued, which include both specific adsorption sites and photocatalytic or electrocatalytic moieties in their frameworks. These innovative strategies allow the conversion of uranyl ions into harvestable solid products (such as UO2 or Na2O(UO3·H2O)x) and result in high extraction efficiencies together with good biofouling resistance. This perspective aims to capture some of the recent breakthroughs in the design of porous materials for selective uranium extraction from seawater.

High-adsorption-capacity and recyclable double-network hydrogel nanofibers for dynamic uranium sorption

Extracting uranium (U) from seawater is an important future energy development direction. Due to the shortcomings of traditional uranium adsorption systems, double-network hydrogel nanofibers were fabricated via electrospinning and steam crosslinking. These hydrogel nanofibers combined the unique beaded network structure of electrospun nanofibers and the flexibility of a double-network hydrogel. The stretched PAO molecular chains in the hydrogel nanofibers provided a larger specific surface area and more binding sites that could combine with U. According to the results, the hydrogel nanofibers exhibited high water permeability, high hydrophilicity, high adsorption efficiency, rapid filtration, and a high recycling rate during uranium extraction. Moreover, an average adsorption capacity of 134 mg-U/g was obtained after 30 h of immersion in dilute U-containing seawater via a flow-through column system. These new hydrogel nanofibers show great potential as a next-generation adsorbent for uranium extraction from seawater.

Anodic Electrodepositing Bioinspired Cu-BDC-NH2@Graphene Oxide Membrane for Efficient Uranium Extraction.

The challenge of removing trace levels of heavy metal ions, particularly uranium, from wastewater is a critical concern in environmental management. Uranium, a key element in long-term nuclear power generation, often poses significant extraction difficulties in wastewater due to its low concentration, interference from other ions, and the complexity of aquatic ecosystems. This study introduces an anodic electrodeposited hierarchical porous 2D metal-organic framework (MOF) Cu-BDC-NH2@graphene oxide (GO) membrane for effective uranium extraction by mimicking the function of the superb-uranyl-binding protein. This membrane is characterized by its hierarchical pillared-layer structures resulting from the controlled orientation of Cu-BDC-NH2 MOFs within the laminated GO layers during the electrodeposition process. The integration of amino groups from 2D Cu-BDC-NH2 and carboxylate groups from GO enables a high affinity to uranyl ions, achieving an unprecedented uranium adsorption capacity of 1078.4 mg/g and outstanding selectivity. Our findings not only demonstrate a breakthrough in uranium extraction technology but also pave the way for advancements in water purification and sustainable energy development, proposing a practical and efficient strategy for creating orientation-tunable 2D MOFs@GO membranes tailored for high-efficiency uranium extraction.

Highly efficient and selective capture of uranium from groundwater by using an ultrathin 2D MOF nanosheet with pocket-like cavities

Highly efficient and selective removal of uranium from aqueous media is crucial for the sustained development of nuclear energy. Herein, we utilized the intrinsic advantages of two-dimensional (2D) metal–organic frameworks (MOFs) and developed an ultrathin 2D MOF nanosheet with cavity structure. The preconcentration of the pocket-like cavities on the MOF nanosheet and sufficient interactions with the adsorption sites in the cavity structure realized highly efficient removal of uranium from water. Even in the low concentration range of 0.05–1 ppm, relatively high removal ratios and fast adsorption kinetics still can be achieved. Additionally, the MOF nanosheet exhibited extremely high anti-interference capability, which can efficiently reduce uranium pollution (0.05–1 ppm) in acid groundwater to the safe level (≤30 ppb) recommended by World Health Organization, and the removal performance was comparable to that in deionized water. The adsorption mechanism was thoroughly studied by Fourier transform infrared analysis, X-ray photoelectron spectroscopy, and density functional theory calculations, which revealed that the interactions between uranyl ions and the carboxylate groups dominated uranium adsorption, and the H-bonding interactions in the pocket-like cavities played an important role in uranium extraction.

3D/2D MnO/MXene heterostructure with high efficiency for adsorbing uranium

An innovative MnO/Ti3C2 MXene heterostructure, consisting of three-dimensional (3D) MnO nanosheet array directly assembled on two-dimensional (2D) Ti3C2 MXene nanosheets, was synthesized via a simple hydrothermal-annealing strategy for uranium elimination. This unique 3D/2D heterostructure derived substantially high specific surface area (311.9 m2/g) and exposed considerable amount of surface oxygen groups, including surface lattice M–O and adsorbed –OH. Through a comprehensive exploration encompassing adsorbent dosage, pH, ionic strength, initial U(VI) concentration, and environmental conditions, the MnO/Ti3C2 MXene heterostructure demonstrated an extraordinary proficiency and specificity in the removal of U(VI). This composite exhibited an outstanding adsorption capacity of 862.1 mg/g, with a removal efficiency of 99.7 % and rapid kinetics (above 90 % within 20 s). The kinetic study indicated the adsorption process followed chemisorption dynamics and single-layer adsorption behavior. Comprehensive analyses validated the structural integrity and confirmed the successful uranium adsorption via strong interaction between UO22+ and surface unsaturated oxygen groups. Notably, the MnO/Ti3C2 MXene maintained excellent recyclability, highlighting its potential for large-scale applications. It emerges as a promising candidate for uranium removal, offering insights for optimizing composite materials in diverse environmental conditions and fostering advancements in water purification technologies.

Kinetics and thermodynamics of uranium(VI) and thorium(IV) ions adsorption from aqueous solutions onto nanokaolinite

Kinetics and thermodynamics of uranium(VI) and thorium(IV) ions adsorption from aqueous solutions onto nanokaolinite

Rapid capture of uranium over acid-tolerant hybrid nanofibrous membrane

Efficient capture uranium from seawater/wastewater is important to not only supply raw material for nuclear energy but also avert the environmental threat from uranium-containing solutions. It is of great significance to design highly efficient adsorbents with stability and recyclability. Herein, the acid-tolerant nanofibrous adsorbent was synthesized by a combination of chitosan (CS) and polyvinyl alcohol (PVA) co-electrospinning, crosslink treatment, acrylonitrile grafting and amidoximation. The resultant CS/PVA-AO nanofibers exhibited the maximum uranium adsorption capacity of 714 mg g−1, larger than that of CS based sorbents. The CS/PVA-AO nanofibers demonstrated reliable stability in acid conditions as well as in adsorption–desorption cycling. The model fitting investigation showed that the uranium adsorbed on CS/PVA-AO nanofibers by the Langmuir adsorption model with the pseudo-second-order adsorption kinetics. This research provides a more efficient and convenient option for uranium recovery from seawater/wastewater.

Incorporation of phytic acid into reed straw-derived hydrochar for highly efficient and selective adsorption of uranium(VI)

Abstract An innovative phytic acid modified reed straw-derived hydrochar composite (PA-C-RBC) was prepared by using inexpensive reed straw and non-toxic phytic acid for the removal of uranium(VI) from aqueous environment. Several characterization results showed that PA-C-RBC was rough and porous with a large number of hydroxyl, carboxyl, and phosphate groups. The uranium(VI) adsorption process by PA-C-RBC conformed to pseudo-second-order kinetic and Langmuir models, and the theoretical maximal adsorption capacity could attain 418.78 mg/g at pH 5.0. PA-C-RBC had 72.66 % of selectivity and 6772.99 mL/g of distribution coefficient for U(VI). Due to the strong chelating between the hydroxyl and phosphate groups on PA-C-RBC and U(VI), PA-C-RBC had excellent adsorption selectivity. These finding highlighted a high potential for removing U(VI) from aqueous solutions.

High efficiency adsorption of uranium by magnesia-silica-fluoride co-doped hydroxyapatite

Hydroxyapatite has a high affinity to uranium, and element doping can effectively improve its adsorption performance. In this study, magnesia-silica-fluoride co-doped hydroxyapatite composite was prepared by hydrothermal method, and the effect of single-phase and multiphase doping on the structure and properties of the composites was investigated. The results showed that the specific surface area of Mg–Si–F-nHA composites increased by 63.01% after doping. Comparing with nHA, U(VI) adsorption capacity of Si-nHA, Mg–Si-nHA and Mg–Si–F-nHA composites increased by 13.01%, 17.39% and 22.03%, respectively. The adsorption capacity of Mg–Si–F-nHA composite reached 1286.76 mg/g. Adsorbent dosage and pH obviously affected U(VI) adsorption, and the experimental data can be fitted well by PSO and Sips models. The physicochemical characterization before and after adsorption suggested that complexation, ion exchange and precipitation participated in uranium adsorption. In conclusion, different elements doping can effectively improve the uranium adsorption properties of hydroxyapatite composites.

Rational Synthesis of Functionalized Covalent Organic Frameworks via Four-Component Reaction.

The construction of function-oriented covalent organic frameworks (COFs) remains a challenge as it requires simultaneous consideration of diversified structures, robust linkage, and tailorable functionalities. Herein, we report the rational synthesis of functionalized COFs via a four-component reaction strategy. Through the four-component Debus-Radziszewski reaction, 11 N-substituted imidazole-based COFs with diversified structures were facilely constructed from readily available building blocks. By forming the N-substituted imidazole linkage, these synthesized COFs displayed ultrastability toward strong acids and base. Moreover, the four components reaction allows the rational synthesis of COFs with tailorable functionalities. As an example, the phosphonate-functionalized COF (LZU-530) was rationally constructed for the efficient adsorption of uranium(VI). The uranium(VI) uptake of LZU-530 reaches up to 95 mg·g-1 in 2 M HNO3, which is the highest uptake of the existing organic porous materials under such harsh conditions. Our results highlight the use of multicomponent reaction for the rational synthesis of robust and functionalized COFs toward targeted applications.

How to Rapidly Evaluate Uranium Adsorption Capacity Using Only a Portable Geiger Counter?

AbstractThe development of the nuclear industry has stimulated research in uranium extraction from seawater (UES) by adsorption. However, in practical applications, it's hard to equip various ion concentration measurement instruments for real‐time characterizing uranium adsorption capacity. Given the radioactive property of uranium, if only a Geiger counter is possessed, how it can be utilized to rapidly evaluate uranium adsorption in the adsorbent? This study proposes the Geiger‐Uranium‐Distance model, which establishes correlations among Geiger counter readings, uranium adsorption capacity, and distance, thereby offering a viable approach. While maintaining a constant radius for the adsorbent stack point, during the laboratory phase, the average molecular mass (MA) and the kGg(z) values of the original adsorbent are determined. In practical applications, the surrounding radiation background GE (µSv h−1) is detected. Subsequently, the Geiger counter is vertically positioned above the stacked point of adsorbent after uranium adsorption. Utilizing the measured radiation intensity value G (µSv h−1), and employing the equation , the uranium adsorption capacity Qe can be obtained.

Clay minerals/sodium alginate/polyethylene hydrogel adsorbents control the selective adsorption and reduction of uranium: Experimental optimization and Monte Carlo simulation study

Clay minerals formations are potential geological barrier (host rocks) for the long-rerm storage of uranium tailing in deep geological repositories. However, there are still obstacles to the efficient retardation of uranium because of the competition between negatively charged regions at the clay minerals end face, surface and between layers, as well as low mineralization capacity. Herein, employing a simple method, we used sodium alginate (SA), an inexpensive natural polymer material, polyethylene (PE), and the natural clay minerals montmorillonite (Mt), nontronite (Nt), and beidellite (Bd) to prepare three hydrogel adsorbents, (denoted as Mt/PE-@SA, Nt/PE-@SA, and Bd/PE-@SA), respectively. The application of obtained hydrogel adsorbents further extends to uranium(VI) removal from aqueous. Due to the synergistic action of SA group and PE group, hydrogel adsorbents showed select adsorption and mineralization effect on uranium(VI), among which the maximum uranium(VI) adsorption capacity of Nt/PE-@SA was 133.3 mg·g-1 and Mt/PE-@SA exhibited strong selectivity for uranium(VI) in the presence of coexisting metal ions. Cyclic voltammetry studies indicated the mitigation and immobilization of uranium species onto adsorbents by both reduction and mineralization. Besides, the synergistic adsorption of SA and PE on clay minerals was hypothesized, and the idea was supported by structure optimizations results from Monte Carlo dynamics simulation (MCD). Three obtained hydrogel adsorbents structural model was constructed based on its physicochemical characterization, the low energy adsorption sites and adsorption energies are investigated using MCD simulation. The simulation results show that obtained hydrogel adsorbents have a strong interaction with uranium(VI), which ensures the high adsorption capacity of those materials. Most importantly, this work demonstrates a new strategy for preparing mineral-based hydrogel adsorbents with enough stability and provides a new perspective for uranium(VI) removal in complex environment.

K doped defective g-C3N4 decorated with cyano group for boosting visible-light driven photocatalytic removal of uranium

Utilizing elemental doping and defect engineering are effective means to enhance the efficiency of g-C3N4 materials for photocatalytic removal of uranium. In this investigation, we synthesized a defective g-C3N4 photocatalyst co-decorated with K+ doping and cyano groups (KHCN) through a straightforward one-step alkali etching process. The alkali etching not only enhances the specific surface area to improve the adsorption of uranium by KHCN but also significantly accelerates the photocatalytic removal of uranium through the introduction of K+ and cyano groups. The KHCN can almost completely remove 40 mg/L of U(VI) under air and visible LED light irradiation (pH 5.0, 298.15 K). Notably, the photocatalytic removal of U(VI) by KHCN demonstrated excellent selectivity and reusability. The mechanism studies reveal that alkali etching-induced introduction of K+ ions and cyano groups enhances visible light absorption, strengthens the efficiency of photogenerated carrier separation, and reduces the band gap. The activation of U(VI) in solution primarily occurs through photogenerated e- and O2–, subsequently immobilizing as metastudtite ((UO2)O2·2H2O). This study provides a viable approach for synthesizing highly efficient photocatalytic materials for uranium removal, leveraging synergistic doping and defect engineering.

Prediction of Uranium Adsorption Capacity in Radioactive Wastewater Treatment with Biochar.

Recently, Japan's discharge of wastewater from the Fukushima nuclear disaster into the ocean has attracted widespread attention. To effectively address the challenge of separating uranium, the focus is on finding a healthy and environmentally friendly way to adsorb uranium using biochar. In this paper, a BP neural network is combined with each of the four meta-heuristic algorithms, namely Particle Swarm Optimization (PSO), Differential Evolution (DE), Cheetah Optimization (CO) and Fick's Law Algorithm (FLA), to construct four prediction models for the uranium adsorption capacity in the treatment of radioactive wastewater with biochar: PSO-BP, DE-BP, CO-BP, FLA-BP. The coefficient of certainty (R2), error rate and CEC test set are used to judge the accuracy of the model based on the BP neural network. The results show that the Fick's Law Algorithm (FLA) has a better search ability and convergence speed than the other algorithms. The importance of the input parameters is quantitatively assessed and ranked using XGBoost in order to analyze which parameters have a greater impact on the predictions of the model, which indicates that the parameters with the greatest impact are the initial concentration of uranium (C0, mg/L) and the mass percentage of total carbon (C, %). To sum up, four prediction models can be applied to study the adsorption of uranium by biochar materials during actual experiments, and the advantage of Fick's Law Algorithm (FLA) is more obvious. The method of model prediction can significantly reduce the radiation risk caused by uranium to human health during the actual experiment and provide some reference for the efficient treatment of uranium wastewater by biochar.

Dual-functional metal-organic frameworks-based hydrogel micromotor for uranium detection and removal

Self-propelled micro/nanomotors have attracted great attention for environmental remediation, however, their use for radioactive waste detection and removal has not been addressed. Engineered micromotors that are able to combine fast detection and highly adsorptive capability are promising tools for radioactive waste management but remain challenging. Herein, we design self-propelled micromotors based on zeolite imidazolate framework (ZIF-8)-hydrogel composites via inverse emulsion polymerization and show their potential for efficient uranium detection and removal. The incorporation of magnetic ferroferric oxide nanoparticles enables the magnetic recycling and actuation of the single micromotors as well as formation of swarms of worm-like or tank-treading structure. Benefited from the enhanced motion, the micromotors show fast and high-capacity uranium adsorption (747.3 mg g−1), as well as fast uranium detection based on fluorescence quenching. DFT calculation confirms the strong binding between carboxyl groups and uranyl ions. The combination of poly(acrylic acid-co-acrylamide) with ZIF-8 greatly enhances the fluorescence of the micromotor, facilitating the high-resolution fluorescence detection. A low detection limit of 250 ppb is reached by the micromotors. Such self-propelled micromotors provide a new strategy for the design of smart materials in remediation of radioactive wastewater.

RIGP-Induced Surface Modification of Cellulose for the Preparation of Amidoxime-Modified Cellulose/Graphite Oxide Composites with Enhanced Uranium Adsorption

RIGP-Induced Surface Modification of Cellulose for the Preparation of Amidoxime-Modified Cellulose/Graphite Oxide Composites with Enhanced Uranium Adsorption

Preparation of Ag-Loaded Amidoxime-Functionalized Wool Fibers via Thiol-ene Click Reaction for Uranium(VI) Adsorption with Good Antibiofouling Properties

Preparation of Ag-Loaded Amidoxime-Functionalized Wool Fibers via Thiol-ene Click Reaction for Uranium(VI) Adsorption with Good Antibiofouling Properties

Selective adsorption of U(VI) in multi-carbonate solutions by g-C3N4/ZrO2-loaded amidoxime polyacrylonitrile

Uranium extraction from seawater is essential for the sustainable development of nuclear energy. Nevertheless, the complex coexistence of ions in seawater can significantly impact the practical uranium species distribution and uranium adsorption process. In this paper, a novel g-C3N4/ZrO2-loaded amidoxime polyacrylonitrile (g-C3N4/ZrO2-AO) was synthesized and investigated as an adsorbent for uranium in U(VI)–CO3, Ca/Mg–U(VI)–CO3, U(VI)–P–CO3 and U(VI)–X–CO3 (X = F, Cl, Br, I) solutions. The uranium adsorption capacity (qe) of g-C3N4/ZrO2-A reached ∼104.5 + 1.5 mg·g1 in U(VI)–CO3 solution, which correlated with a monolayer chemisorption process. High pH and [NaHCO3] decreased qe values because of the electrostatic repulsion and occupation of adsorption sites by excess CO32-. Adsorption of uranium by g-C3N4/ZrO2-AO was impeded in the Ca/Mg–U(VI)–CO3, U(VI)–P–CO3 and U(VI)–X–CO3 (X = F, Cl, Br, I) solutions, possibly due to the formation of various U(VI) complexes. The amidoxime groups inside the g-C3N4/ZrO2-AO have been proved with good uranium selectivity. FTIR and XPS verified the NH2-CN-OH and Zr-OH acted as the primary U(Ⅵ) adsorption sites. This paper opens up opportunities for practical applications of amidoxime polyacrylonitrile-based composites towards the uranium recovery from seawater.

Selective capture of uranium by p-block bismuth-based metal–organic framework

Energy shortage severely impedes the advancement of human society and economy. The vigorous development of nuclear energy is a viable solution to address this issue. The escalating depletion of uranium resources necessitates prioritizing the selective extraction of uranyl from seawater and wastewater to ensure the prosperity of nuclear power. A bismuth-based MOF, CAU-17, was synthesized by the one-step solvothermal method for targeted selection of uranyl in the first time. The uranium adsorption tests demonstrated that CAU-17 exhibited a high adsorption capacity of 421.9 mg g−1 (T = 25 °C, pH = 7), exceptional selectivity, outstanding salt tolerance, and favorable stability with 83.6 % of the initial capacity retained after 5 cycles. Through the utilization of XPS and theoretical calculations, it was elucidated that the carboxyl oxygen that connects the Bi played a pivotal role in the binding process between CAU-17 and uranium ions, with bismuth acting as an electron regulator through its bridging effect with carboxyl oxygen. This work not only presents an exceptional uranium adsorption material but also elucidates the role of core metal atoms in MOFs during the binding to uranium process, thereby offering a novel perspective for future advancements in MOFs-based adsorbents.

Hierarchical porous cellulose monolith prepared by thermally induced phase separation for high-efficiency uranium adsorption

The development and application of new and efficient adsorption materials are key issues in the treatment of nuclear wastewater. This paper introduces a novel hierarchical porous amidoxime cellulose monolith synthesized through thermally induced phase separation (TIPS). The inherent hydrophilicity of cellulose, combined with the graded porous structure achieved through TIPS (with a specific surface area of 10.36 m2/g), endows the material with strong mass transfer ability. The adsorption properties of this amidoxime cellulose monolith for uranyl ions were evaluated in both batch and flow-through column adsorption scenarios. Remarkably, the adsorption saturation was achieved within a concise period of 13 h in batch adsorption. The hierarchical porous structure of the amidoxime cellulose monolith exhibited exceptional adsorption performance for uranyl ion, achieving a removal rate of 99.99 %. Moreover, this removal rate was sustained for 200 min, and the monolith proved recyclable for at least 5 cycles in flow-through column adsorption tests involving nuclear wastewater. When used for adsorption in real wastewater environments, the material achieved the removal of over 99.96 % of total α and β radioactivity. These findings underscore the high efficiency of the newly developed hierarchical porous amidoxime cellulose monolith in uranyl ion adsorption. They emphasize its substantial potential for the efficient adsorption and removal of uranyl ion from nuclear wastewater.