Removal Of Uranium Research Articles

CdS@NiCr-LDH Z-scheme heterojunction with high adsorption–photocatalysis for uranium(VI) removal without any sacrificial agent

The use of photocatalysis for the removal of U(VI) has the advantages of being green, eco-friendly and sustainable. It is common practice to enhance the photocatalytic activity of photocatalysts by adding sacrificial agents, however, this is uneconomical and contrary to the vision of carbon neutrality and carbon peak in the world. Herein, we fabricate a Z-scheme heterojunction for the photocatalytic removal of uranium (VI) based on CdS nanorods@NiCr layered double hydroxide (CdS@NiCr-LDH). Excellent photocatalytic efficiencies and removals were achieved under visible light irradiation without any sacrificial agent. The optimum uranium(VI) removal rate of CdS@NiCr-LDH was 0.057 min‐1, which was 6.3 and 5.0 times higher than that of CdS and NiCr-LDH, respectively. In particular, the U(VI) removal amount over CdS@NiCr-LDH reached 2246.14 mg g−1. The CdS@NiCr-LDH heterojunction creates a narrower energy band gap (Eg = 2.06 eV), which is more favorable for visible light absorption, according to UV–vis DRS results. According to ESR and DFT calculations, possesses an intrinsic electric field between NiCr-LDH and CdS composite that efficiently prevents electron-hole complexation, resulting in highly efficient removal of U(VI) under visible light irradiation without the need of sacrificial agents. This work lays the foundation for research on photocatalytic U(VI) treatment by CdS@NiCr-LDH in wastewater.

A Phosphorylated Dendrimer-Supported Biomass-Derived Magnetic Nanoparticle Adsorbent for Efficient Uranium Removal.

A novel biomass-based magnetic nanoparticle (Fe3O4-P-CMC/PAMAM) was synthesized by crosslinking carboxymethyl chitosan (CMC) and poly(amidoamine) (PAMAM), followed by phosphorylation with the incorporation of magnetic ferric oxide nanoparticles. The characterization results verified the successful functionalization and structural integrity of the adsorbents with a surface area of ca. 43 m2/g. Batch adsorption experiments revealed that the adsorbent exhibited a maximum adsorption capacity of 1513.47 mg·g-1 for U(VI) at pH 5.5 and 298.15 K, with Fe3O4-P-CMC/G1.5-2 showing the highest affinity among the series. The adsorption kinetics adhered to a pseudo-second-order model (R2 = 0.99, qe,exp = 463.81 mg·g-1, k2 = 2.15×10-2 g·mg-1·min-1), indicating a chemically driven process. Thermodynamic analysis suggested that the adsorption was endothermic and spontaneous (ΔH° = 14.71 kJ·mol-1, ΔG° = -50.63 kJ·mol-1, 298. 15 K), with increasing adsorption capacity at higher temperatures. The adsorbent demonstrated significant selectivity for U(VI) in the presence of competing cations, with Fe3O4-P-CMC/G1.5-2 showing a high selectivity coefficient. The performed desorption and reusability tests indicated that the adsorbent could be effectively regenerated using 1M HCl, maintaining its adsorption capacity after five cycles. XPS analysis highlighted the role of phosphonate and amino groups in the complexation with uranyl ions, and validated the existence of bimodal U4f peaks at 380.1 eV and 390.1 eV belonging to U 4f7/2 and U 4f5/2. The results of this study underscore the promise of the developed adsorbent as an effective and selective material for the treatment of uranium-contaminated wastewater.

Effects and mechanism of uranium(VI) removal by wood biochar loaded with MnFe2O4

BackgroundUranium (U) seriously threatens environmental health due to its chemical and radioactivity toxicity unless it is immobilized by adsorption materials. MethodsHere, MnFe2O4 was used to modify biochar derived from apple tree branches to obtain MnFe2O4-biochar (MFBC), which was used for U(VI) removal. The mechanisms were explored by advanced analytical techniques, including scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS), Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Significant findingsThe MFBC displayed a considerable adsorption rate of U(VI), with a maximum adsorption capacity of 83.00 mg/g at pH 6.0 and 313 K. The removal behavior was well described by the Freundlich and pseudo-second-order kinetic models. The dominant removal mechanism was complexation between the negatively charged O-containing groups on the MFBC and the positively charged U(VI). This work demonstrates the potential of MFBC to remediate U(VI)-contaminated wastewater.

Ultrafast Removal of Thorium and Uranium from Radioactive Waste and Groundwater Using Highly Efficient and Radiation-Resistant Functionalized Triptycene-Based Porous Organic Polymers.

Thorium (Th) and uranium (U) are important strategic resources in nuclear energy-based heavy industries such as energy and defense sectors that also generate significant radioactive waste in the process. The management of nuclear waste is therefore of paramount importance. Contamination of groundwater/surface water by Th/U is increasing at an alarming rate in certain geographical locations. This necessitates the development of strategic adsorbent materials with improved performance for capturing Th/U species from radioactive waste and groundwater. This report describes the design of a unique, robust, and radiation-resistant porous organic polymer (POP: TP-POP-SO3NH4), which demonstrates ultrafast removal of Th(IV) (<30 s)/U(VI) (<60 s) species present in simulated radioactive wastewater/groundwater samples. Thermal, chemical, and radiation stabilities of these POPs were studied in detail. The synthesized ammoniated POP revealed exceptional capture efficiency for trace-level Th (<4 ppb) and U (<3 ppb) metal ions through the cation-exchange mechanism. TP-POP-SO3NH4 shows a significant sorption capacity [Th (787 mg/g) and U (854 mg/g)] with an exceptionally high distribution coefficient (Kd) of 107 mL/g for Th. This work also demonstrates a facile protocol to convert a nonperforming POP, by simple chemical modifications, into a superfast adsorbent for efficient uptake/removal of U/Th.

Advanced Uranium Removal with Pure, Nonfluorinated Ionic Liquids: Fine-Tuning Hydrophilic and Hydrophobic Properties for Enhanced Selectivity.

Ionic liquids (ILs) have significant potential for eco-friendly extraction of uranium from aqueous solutions, which is critical for nuclear technology, fuel cycle management, and environmental protection. This study examines the impact of the adjustable hydrophobic/hydrophilic properties of ILs on the removal of uranium(VI) (UO22+) from aqueous solutions utilizing both a novel hydrophilic IL (1-butoxyethyl-1-methylmorpholinium butoxyethylphosphite - Mor1-2O4-BOEP) and 1-heptyl-1-methylmorpholinium heptylphosphite (Mor1-7-HP) as an example of a hydrophobic IL with a similar structure. The transfer mechanism of uranyl ions from water to organic or solid phases closely depends on the physicochemical properties of ILs, especially their hydrophobicity. The hydrophobic Mor1-7-HP extracts uranyl via neutral complex formation as UO2(NO3)2-(Mor1-7-HP)2. Conversely, hydrophilic Mor1-2O4-BOEP induced selective precipitation as UO2(NO3)-(BOEP), transferring uranyl to the solid phase. Optimization of the working parameters, in terms of acidity of the aqueous solution and amount of ILs used, allowed the extraction of over 98% of U(VI). The stoichiometry of the organic complex and the precipitate was determined using physicochemical techniques. These tunable H-phosphonate-based ILs have advantages over traditional solvent extraction and conventional ILs, allowing easier handling, improved selectivity, and lower environmental impact. This work advances uranium separation techniques with applications in hydrometallurgy, particularly in the treatment of wastewater and radioactive waste for sustainable uranium recovery.

Effective uranium extraction from seawater through immobilization of conjugated microporous polymers on collagen fiber membrane

Extracting uranium from seawater has become an important method to supplement the nuclear industry. Herein, we introduce a simple route to load conjugated microporous polymers onto collagen fiber membranes, resulting in a novel membrane adsorbent material (CMPA-F/CFM) for uranium capture. Its Langmuir adsorption capacity reaches 304.9 mg·g−1 (at 318 K), with fast adsorption kinetic of 60 min, and excellent adsorption selectivity with Kd = 4.69 × 104 mL·g−1 under the temperature of 298 K, initial concentration of 50 mg·L-1, and pH = 7, thus allowing a satisfactory adsorption performance in a 7-day real ocean experiment with a uranium adsorption capacity of 1.25 mg·g−1. Furthermore, in continuous dynamic adsorption experiments, CMPA-F/CFM could treat up to 19.0 L·g−1 of low-enriched uranium (LEU) solution (1 mg·L-1), with a uranium removal rate of up to 87.5 % (10 L of seawater). This study demonstrates broad potential application of membrane adsorption in extraction of low-enriched uranium.

Preparation of amine or carboxyl groups modified cellulose beads for removal of uranium (VI) ions from aqueous solutions

In the present study, cellulose beads were prepared using the phase inversion method and then activated with epichlorohydrin. The epoxy groups of the activated beads were modified with Nα,Nα-bis(carboxymethyl)-L-lysine hydrate (CML), and tetraethylenepentamine (TEPA) ligands. These modified beads, coded as cellulose-COOH and cellulose-NH2, respectively, were used to remove of uranium (VI) ions from aqueous medium. The prepared adsorbents were characterized using FTIR, SEM, zeta-potential, and analytical methods; the performance of both the modified beads for the removal of uranium (VI) ions was optimized using different operational parameters in a batch system. The amount of adsorbed uranium ions on cellulose-COOH and cellulose-NH2 beads was 462.9 ± 13.7 and 127.4 ± 5.1 mg/g, respectively. The results are acceptable regarding the equilibrium kinetics for the adsorption of uranium (VI) ions, which followed the second-order kinetic model. The prepared activated cellulose beads could be utilized in many technological applications by making appropriate modifications in the reactive epoxy groups of cellulose.

A novel bidentate diamide ligand DODQ for the separation of uranium and rare earth ions in nitric acid medium

High efficiency extractants play a necessary role in the selective removal of uranium from rare earth minerals. In this paper, a novel cyclic bidentate diamine extractant, 1, 4-dioctyl-1, 4-dihydroquinoxaline-2, 3-dione (DODQ), was synthesized, and the complexation and extraction of UO22+ in nitric acid medium were systematically studied. The results indicate that DODQ exhibits a unique combination of properties in removing UO22+, with an extraction capacity 132 times higher than that of DODPhOA (acyclic structure). Extraction isotherm experiments and slope analyses illustrate the formation of a 1:1 DODQ/UO22+ regime during the extraction process. Electrospray mass spectrometry, fluorescence spectroscopy, and X-ray crystal diffraction analyses further corroborated its stoichiometric properties. In addition, DODQ can remove UO22+ from rare earth solutions containing UO22+ with high selectivity. This study provides an alternative method to separate uranium from the leaching solution of rare earth ore and has a new understanding of the coordination and complexing behavior of UO22+ with bidentate oxygen-containing ligands.

Facile fabrication of new bioadsorbents from Moringa oleifera and alginate for efficient removal of uranium(VI)

Facile fabrication of new bioadsorbents from Moringa oleifera and alginate for efficient removal of uranium(VI)

Constructing amidoxime adsorption sites on the core-shell structured natural silk protein for uranium capture

Amidoxime-based fiber adsorbents hold significant promise for uranium extraction. However, a notable issue is that these adsorbents primarily originate from synthetic polymer materials, which, aside from providing good mechanical support, have no other functions. In recent study, we shifted our focus to silk fiber (SF), a natural protein fiber known for its unique core-shell structure and rich amino acids. The shell layer, due to its abundant functional groups, makes it easily modifiable, while the core layer provides excellent mechanical strength. Leveraging these inherent properties, an amidoxime-based fiber adsorbent was developed. This adsorbent utilizes amino and carboxyl groups for enhanced performance synergistically. This method involves establishing uranium affinity sites on the outer sericin layer of SF via chemical initiation of graft polymerization (CIGP) and amidoximation (SF-g-PAO). The water absorption ratio of SF-g-PAO is as high as 601.16 % (DG = 97.17 %). Besides, SF-g-PAO demonstrates an exceptional adsorption capacity of 15.69 mg/g in simulated seawater, achieving a remarkable removal rate of uranyl ions at 95.06 %. It can withstand a minimum of five adsorption-elution cycles. Over a 4-week period in natural seawater, SF-g-PAO displayed an adsorption capacity of 4.95 mg/g. Furthermore, SF-g-PAO also exhibits impressive uranium removal efficiency in real nuclear wastewater, with a removal rate of 63 % in just 15 min and a final removal rate of 90 %. It is hoped that this SF-g-PAO, prepared through this straightforward method and characterized by the synergistic action of amino and carboxyl groups, can offer innovative insights into the development of uranium extraction adsorbents.

Decoration of phosphoric acid groups onto Ti3C2Tx MXene for enhanced uranium removal

The construction of novel MXene-based composites with superb abilities through functionalization is an effective strategy to enhance the potential of this emerging inorganic lamellar material for environmental adsorption applications. The present work systematically investigated the adsorption performance of Ti3C2Tx MXene modified with phosphate functional groups that facilitate the capture of uranyl ions. After introducing phosphate groups via a two-step modification of 3-aminopropyltriethoxysilane (APTES) and phytic acid (PA), the synthesized Ti3C2-APTES-PA is significantly superior to pristine Ti3C2Tx nanosheets in terms of adsorption capacity, adsorption selectivity and reusability for uranium. The maximum uptake capacity of Ti3C2-APTES-PA at pH = 5 reaches 323 mg/g, which is 2.5 times higher than that of unmodified MXene. Furthermore, the large selectivity coefficient (SU/M > 16.2) declares that Ti3C2-APTES-PA preferentially adsorbs uranium among substantial competing ions. Ti3C2-APTES-PA also shows good cycling performance that its adsorption capacity remained 92.3 % after 6 cycles. When it comes to treating simulated uranium tailings pond leachate and radioactive wastewater from mines, high U(VI) removal rates of 88.9 % and 96.8 % can be achieved by our ternary composite at a dosage of 0.05 g/L. The underlying adsorption mechanism was unraveled by spectroscopic analysis to be the formation of coordination complexes of uranyl ions with phosphate groups on PA and hydroxyl groups on Ti3C2Tx substrate, as well as the reduction of a small amount of adsorbed U(VI) to U(IV) by MXene. The overall results imply that Ti3C2-APTES-PA is an effective uranium chelating scavenger for the treatment of environmental radioactive wastewater.

Cinnamic Acid: A Low-Toxicity Natural Bidentate Ligand for Uranium Decorporation.

Uranium accumulation in the kidneys and bones following internal contamination results in severe damage, emphasizing the pressing need for the discovery of actinide decorporation agents with efficient removal of uranium and low toxicity. In this work, cinnamic acid (3-phenyl-2-propenoic acid, CD), a natural aromatic carboxylic acid, is investigated as a potential uranium decorporation ligand. CD demonstrates markedly lower cytotoxicity than that of diethylenetriaminepentaacetic acid (DTPA), an actinide decorporation agent approved by the FDA, and effectively removes approximately 44.5% of uranyl from NRK-52E cells. More importantly, the results of the prompt administration of the CD solution remove 48.2 and 27.3% of uranyl from the kidneys and femurs of mice, respectively. Assessments of serum renal function reveal the potential of CD to ameliorate uranyl-induced renal injury. Furthermore, the single crystal of CD and uranyl compound (C9H7O2)2·UO2 (denoted as UO2-CD) reveals the formation of uranyl dimers as secondary building units. Thermodynamic analysis of the solution shows that CD coordinates with uranyl to form a 2:1 molar ratio complex at a physiological pH of 7.4. Density functional theory (DFT) calculations further show that CD exhibits a significant 7-fold heightened affinity for uranyl binding in comparison to DTPA.

Artemisinin gum reinforced porous amidoxime aerogel with high efficiency adsorption for uranium extraction from seawater

The extraction of uranium resources from the ocean is of great importance in energy exploration. This work reported a polysaccharide composite aerogel to adsorb uranium from the ocean, a facile freeze-drying strategy was explored to create a physically crosslinked artemisia sphaerocephala krasch gum (ASKG)-poly(amidoxime) (PAO) aerogel (ASKG@PAO). Due to the excellent hydrophilicity and swelling properties of artemisia spherecephala krasch gum, the ASKG@PAO can quickly and stably adsorb uranyl ions in the ocean. The batch adsorption test results show ASKG@PAO (mASKG: mPAO = 1:1) has an excellent uranium removal rate (93.92 %) and a high uranium adsorption capacity (341.11 mg/g). Desorption kinetic experiments show that the ASKG@PAO can desorb 90 % of the uranyl ions within 10 min and retain a removal rate of 87.3 % after five adsorption–desorption cycles. In addition, ASKG@PAO has excellent selectivity for uranyl ions. Consequently, ASKG@PAO aerogel has significant potential for extracting marine uranium resources.

Fabrication of cellulose-collagen based biosorbent as eco-friendly scavengers for uranyl ions

The aim of the present research is to fabricate a biosorbent using agricultural waste for removal of uranium from contaminated water i.e. “waste to wealth” approach. Cellulose extracted from wheat straw was mercerized and a novel semi-interpenetrating polymer network (semi-IPN) was fabricated through graft copolymerization of polyvinyl alcohol onto hybrid mercerized cellulose + collagen backbone. Response surface methodology was used for optimization of different reaction parameters as a function of % grafting (195.1 %) was carried out. Semi-IPN was found to possess higher thermal stability. Adsorption results revealed that the optimum parameters for the elimination of uranium using semi-IPN were: adsorbent dose = 0.15 g, pH = 6.0, contact time = 120 min and initial U (VI) concentration = 100 μg/L. The pseudo-second-order kinetic model gave the best description of the adsorption equilibrium data as the calculated qe value is nearest to the experimental qe for the different initial U(VI) concentrations. Adsorption experiments followed Langmuir isotherm with R2 = 0.999. Furthermore, recyclability and reusability studies showed that the adsorption efficiency of semi-IPN was 82 % after 5 cycles indicating the superior recycling execution of fabricated biosorbent. Thus, the fabricated ecofriendly device can be used effectively for the removal of uranium from contaminated wastewater sources.

The adsorption properties of the corm tunic structure of Crocus (Iridaceae) and its use as a biomarker for the environmental concentration of uranium

AbstractIn this study, we investigated whether the corm tunic structure, which is the underground part of the Crocus (Iridaceae) plant, can be used for adsorption and recovery/removal of uranium from an aqueous solution. The characterization of this structure, which has not been studied for its interaction with metals before, has been elucidated by point zero charge (PZC), FTIR, and SEM analyses. Extensive investigations were conducted on the adsorption properties of the biomass used and the pH, temperature, time, adsorbent dosage, and uranyl ion concentration variables were optimized. The experimental data were interpreted using theoretical adsorption models. The Langmuir model revealed a maximum adsorption capacity of the material to be 0.286 mol kg−1. Adsorption kinetics were also described using pseudo-first order, pseudo-second order, Elovich, and intra-particular diffusion models. It is shown that the adsorption pH reaches the highest adsorption at the natural pH of the uranium solution. Experimental studies showed that the adsorption was endothermic and spontaneous. It has been shown that this biomaterial can be used as an adsorbent for the removal of uranium as well as a biomarker for determining the environmental uranium concentration.

Insights on the Mechanism of Uranium Removal via Nanofiltration in Alkalinity and Salinity Dominated Groundwater Systems

Insights on the Mechanism of Uranium Removal via Nanofiltration in Alkalinity and Salinity Dominated Groundwater Systems

Photo‐enhanced uranium recovery from spent fuel reprocessing wastewater via S‐scheme 2D/0D C3N5/Fe2O3 heterojunctions

AbstractRe‐extracting environmentally transportable hexavalent uranium from wastewater produced by spent fuel reprocessing using the photocatalytic technology is a crucial strategy to avoid uranium pollution and recover nuclear fuel strategic resources. Here, we have designed S‐scheme 2D/0D C3N5/Fe2O3 heterojunction photocatalysts based on the built‐in electric field and the energy band bending theory, and have further revealed the immobilization process of hexavalent uranium conversion into relatively insoluble tetravalent uranium in terms of thermodynamics and kinetics. According to the results, the hexavalent uranium removal and recovery ratios in wastewater are as high as 93.38% and 83.58%, respectively. Besides, C3N5/Fe2O3 heterojunctions also exhibit satisfactory catalytic activity and selectivity even in the presence of excessive impurity cations (including Na+, K+, Ca2+, Mg2+, Sr2+, and Eu3+) or various organics (such as xylene, tributylphosphate, pyridine, tannic acid, citric acid, and oxalic acid). It is believed that this work can provide a potential opportunity for S‐scheme heterojunction photocatalysts to re‐enrich uranium from spent fuel wastewater.

Spatially confined coordination platform in covalent organic framework for selective uranium adsorption from aqueous solutions

The use of covalent organic frameworks (COFs) to remove uranium from nuclear wastewater, especially capture uranium by well-defined nanopores and customizable groups, is highly desired. The development of an ideal binding site with optimal balance between adsorption capacity and selectivity has remained an attractive challenge. Herein, a staggered stacking self-assembly approach was adapted to control the pore size and confine space of dioxin-linked COF-316 with modified functional groups to achieve higher capture efficiency. EXAFS analysis suggested that COF-316-COOH and COF-316-AO both have high affinities toward U(VI) owing to inner-sphere surface complexation by two or three atoms, DFT calculations further revealed that the uranyl cation was coordinated by = NOH or –COOH groups from two adjacent COF layers. The synergistic coordination in multi-confined interlaminar position provides an ideal spatial coordination platform for uranium, and the merits of capacity, selectivity and stability underscore the potential application of COF-316-AO for efficient uranium removal.

A sodium alginate gel bead adsorbent doping with amidoxime-modified hydroxyapatite for the efficient adsorption of uranium

In this work, the modified‑sodium alginate gel beads were prepared by sol-gel method. Due to the presence of water channels in the sodium alginate gel bead, amidoxime groups and PO43− were exposed to the surface of the adsorbent to the maximum extent, resulting in the excellent adsorption capacity of modified‑sodium alginate gel beads. The introduction of amidoxime-modified hydroxyapatite significantly improved the adsorption capacity and the adsorption rate of the gel beads. The adsorption capacity increased from 308.7 to 466.0 mg/g and the adsorption equilibrium time was shortened from 300 min to 120 min. The modified‑sodium alginate gel bead possessed the advantages of short adsorption time, high adsorption efficiency and large adsorption capacity, which could be regarded as a potential adsorbent for uranium. Moreover, the uranium removal ability on the modified gel beads was mainly attributed to the Coulomb force between PO43− and uranium and the complexation between uranium and amidoxime groups. In summary, this work would provide a new idea for the modification and application of sodium alginate-based materials.

Study on the remediation of uranium-contaminated soils by compound leaching: Screening of leaching agents and a pilot-scale application

To solve the problem of soil environmental pollution resulting from uranium mine development and production, a soil slurry reactor was used to evaluate the use of chemical leaching to remediate uranium-contaminated soils and to analyze possible uranium removal mechanisms through laboratory-scale trials and pilot-scale trials. A laboratory-scale trial comparing different reagents and operating methods revealed that the removal of total uranium from contaminated soil could reach 91.18% under optimal conditions when FeCl3, OA, NaClO2, and HEDP were used as eluents.Based on the optimal ratio and operating conditions determined from laboratory-scale trials, a pilot-scale trial was conducted around a uranium mining area: soil leaching remediation was conducted in two 3 m3 soil-slurry reactors to verify the practicality of the leaching technology and examine the functionality of the remediated soil. The experimental results showed that the rate of uranium removal from contaminated soil by the chemical leaching method was greater than 80%. FTIR, XRF and enzyme activity analysis proved that remediation restored the original soil function and reduced the ecological risk, indicating that the chemical leaching technology was environmentally friendly and economical. These findings provide insight to guide the future assessment and remediation practices of uranium-contaminated sites.