Efficient Uranium Adsorption Research Articles

Synergistic modulation of interfacial and coordination microenvironment for highly efficient uranium extraction

Extracting uranium from wastewater is highly essential for addressing environmental pollution and sustainable development of nuclear power. However, the design and synthesis of functional adsorbents for selective and rapid uranium adsorption remains extremely challenging. Herein, we report the synthesis of a functionalized hyper-cross-linked polymers (PHCP-Q) via an interfacial and coordination microenvironment synergistic modulation strategy for efficient uranium adsorption. The generated interfacial hydrophilic microenvironment allows the rapid migration of uranyl from the solution to the adsorbent and thus enables fast adsorption kinetics. Meanwhile, the fine-tuned coordination microenvironment within pore space creates the hexa-coordinated nano-pocket structure and thereby enhances the selective recognition of uranyl. Remarkably, PHCP-Q achieves adsorption equilibrium within simply 60 min and shows high saturation U(VI) adsorption uptake of 608.95 mg/g. More importantly, PHCP-Q with the cooperation of binding sites exhibits the highest distribution coefficient by an order of magnitude compared with that of other PHCPs. Besides, PHCP-Q possesses good physicochemical stability and recyclability. This study provides a new insight into the future design of highly effective uranium adsorbents by synergistically modulating interfacial and coordination microenvironment, which can be extended to the extraction of other target ions.

Synthesis, characterization, and kinetic approach of a polyvinyl chloride embedded-thiosemicarbazide sequestering agent for efficient uranium adsorption from aqueous solution

A new promising polyvinyl chloride embedded-thiosemicarbazide sequestering agent (PVC-TSC), was exploited to separate U(VI) from its water solution. Specifications for PVC-TSC were carried out efficaciously using respective performances such as BET, TGA, 1H NMR, SEM-EDX, 13C NMR, FT-IR, XPS, and GC–MS analyses, which assure a satisfactory synthesis. Variables like initial pH, agitation duration, temperature, starting U(VI) concentration, PVC-TSC dosage, co-existing ions, and eluting agents have all been fine-tuned by experimental optimization. In conditions of 298 K, pH 4.5, 30 min of agitation, and 0.63 × 10−3 mol/L uranium ions, the maximal sorption competence of PVC-TSC is 30 mg/g. Based on the adsorption-distribution isotherm estimation, the experimental value of 30.12 mg/g is similar to the theoretical value that Freundlich came up with. However, Langmuir's value is higher and more in line with the practical data. Modeling of the U(VI) kinetics adsorption by PVC-TSC yielded a theoretical retaining capacity of 29.66 mg/g for first-order (PFO) modeling and 32.051 mg/g for second-order (PSO) modeling, as suggested by a hybrid PFO and PSO kinetic model. By taking into account the thermodynamical factors ΔS° (−0.063 kJ/mol.K), ΔH° (−16.2 kJ/mol), and ΔG°, the adsorption evolution was anticipated to be exothermic, spontaneous, and best performed at down temperatures. From a cost perspective, eluting the loaded PVC-TSC composite with 0.5 M H2SO4 yields a 90 % efficiency rate for U(VI) ions.

In-situ preparation of HPO42− intercalated NiFe layered double hydroxides for efficient U(VI) removal

The development of high-efficiency adsorption materials for efficient removal of U(VI) from nuclear wastewater has become a concern of environmental protection. LDHs, as adsorbent materials, lack functional groups, resulting in low adsorption performance. Herein, a novel and excellent radiation stable HPO42−-intercalated NiFe-LDH material (NiFe-LDH-P(x)) is synthesized by in-situ co-precipitation method. The effect of HPO42− content on the U(VI) performance of NiFe-LDH-P(x) is studied in detail. The results reveal that intercalation of HPO42− increases the interlayer spacing and specific surface area of NiFe-LDH, as well as the active sites between the interlayers. Therefore, NiFe-LDH-P(x) with moderate HPO42− content (10 %) can reach highest U(VI) adsorption capacity (350.88 mg·g−1). FTIR, SEM and XPS analyses educe that the efficient adsorption of uranium on NiFe-LDH-P(10 %) is mainly attributed to complexation, electrostatic attraction and ion exchange. In summary, NiFe-LDH-P(10 %) has great potential in removing uranium from wastewater, which provides a new idea for the synthesis of efficient adsorbents.

Efficient uranium adsorption of low-cost and eco-friendly MQ2-collagen fibers (M = Mo, W; Q = S, Se) composite materials prepared by co-ball milling

Efficient uranium adsorption of low-cost and eco-friendly MQ2-collagen fibers (M = Mo, W; Q = S, Se) composite materials prepared by co-ball milling

Efficient uranium sequestration ability and mechanism of live and inactivated strain of Streptomyces sp. HX-1 isolated from uranium wastewater

Prokaryotes are effective biosorbents for the recovery of uranium and other heavy metals. However, the potential mechanism of uranium bioaccumulation by filamentous strain (actinobacteria) remains unclear. This study demonstrates the potential for and mechanism of uranium bioaccumulation by living (L-SS) and inactivated (I-SS) Streptomyces sp. HX-1 isolated from uranium mine waste streams. Uranium accumulation experiments showed that L-SS and I-SS had efficient uranium adsorption potentials, with removal rates of 92.93 and 97.42%, respectively. Kinetic and equilibrium data indicated that the bioaccumulation process was consistent with the pseudo-second-order kinetic, Langmuir, and Sips isotherm models. FTIR indicated that the main functional groups of L-SS and I-SS binding uranium were uranyl, carboxyl, and phosphate groups. Moreover, the results of XRD, XPS, SEM-EDS, and TEM-EDS analyses revealed for the first time that L-SS has biomineralization and bioreduction capacity against uranium. L-SS mineralize U(VI) into NH4UO2PO4 and CaU(PO4)2∙1.5H2O through the metabolic activity of biological enzymes (phosphatases). In summary, Streptomyces sp. HX-1 is a novel and efficient uranium-fixing biosorbent for the treatment of uranium-contaminated wastewater.

Uranium adsorption efficiency of diglycolamic acid functionalized graphitic carbon nitride adsorbent: Kinetic, isotherm, and thermodynamic studies

This study proposes the use of diglycolamic acid-functionalized graphitic carbon nitride (HDGA-gCN) as an adsorbent for uranium removal. Our experiments showed that at pH 6.0, HDGA-gCN had a high adsorption capacity of 263.2 mg g−1 and achieved equilibrium in 30 min. The adsorption isotherm was well-fitted by the Langmuir model, and the adsorption kinetics followed a pseudo-second-order equation. U(VI) adsorption on HDGA-gCN is due to electrostatic interactions between the amine, diglycolamic acid, and uranium species. The thermodynamic parameters indicate that adsorption is spontaneous and exothermic. The loaded U(VI) can be desorbed using 0.1 M Na2CO3, and HDGA-gCN exhibited an exceptional adsorption percentage for U(VI) compared to other coexisting ions. HDGA-gCN had faster kinetics, adsorption capacity, and reusability, making it suitable for U(VI) remediation.

Facile and scalable synthesis of functionalized hierarchical porous polymers for efficient uranium adsorption

Efficient uranium capture from wastewater holds great importance for the environmental remediation and sustainable development of nuclear energy, but it is a tremendous challenge. Herein, a facile and scalable approach is reported to fabricate functionalized hierarchical porous polymers (PPN-3) decorated with high density of phosphate groups for uranium adsorption. The as-constructed hierarchical porous structure could allow rapid diffusion of uranyl ions, while abundant phosphate groups that serve as adsorption sites could provide the high affinity for uranyl. Consequently, PPN-3 shows a high uranium adsorption uptake of 923.06 mg g−1 and reaches adsorption equilibrium within simply 10 min in uranium-spiked aqueous solution. Moreover, PPN-3 affords selective adsorption of uranyl over multiple metal ions and possesses a rapid and high removal rate of U(VI) in real water systems. Furthermore, this study offers direct polymerization strategy for the cost-effective fabrication of phosphate-functionalized porous organic polymers, which may provide promising application potential for uranium extraction.

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.

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.

Identification of oxygen sites in β-ketoenamine-linked covalent organic frameworks for highly efficient uranium adsorption through experimental and theoretical studies

Anthropogenic activities involving unintended uranium leakage from nuclear accidents, large-scale uranium mining, or nuclear weapon production have caused health and environmental concerns.

One-step synthesis of phospho-rich, silica-enhanced chitosan aerogel for the efficient adsorption of uranium(VI)

In this study, an amorphous silica reinforced, phosphoric-crosslinked chitosan foam (P-CTS@SixOy) was prepared. The introduction of amorphous silica not only increased the affinity of the adsorbent for uranium, but also improved the stability of the material. The number of active sites of P-CTS@SixOy was increased by the introduction of phosphate groups. The material exhibited excellent uranium adsorption performance with the removal capacity and efficiency of 850.5 mg g−1 and 98.1 %, respectively. After regenerations, the morphology of P-CTS@SixOy still maintained, and the uranium adsorption efficiency remained above 90 %, manifesting the excellent cycle performance of P-CTS@SixOy. In the dynamic adsorption experiment, P-CTS@SixOy successfully concentrated the volume of uranium-containing solution, and exhibited excellent uranium adsorption performance. The analysis of kinetics, isotherms, and thermodynamics manifested that the uranium adsorption behavior of P-CTS@SixOy was a spontaneous, endothermic, monolayer chemical adsorption process. X-ray photoelectron spectroscopy, Scanning Electron Microscope, and Fourier Transform Infrared Spectrometer were used to characterized the P-CTS@SixOy before and after adsorption, which demonstrated that the main interaction mechanism between uranium and P-CTS@SixOy was the complexation. These studies indicated the huge application prospect of P-CTS@SixOy in the treatment of large-scale uranium-containing wastewater.

Phytate-modified MOFs grown on carbon nanotubes for efficient adsorption of uranium(Ⅵ) from seawater

The selective separation of uranium through adsorption remains a formidable challenge. Therefore, a one-step hydrothermal method was initially employed to anchor the metal-organic framework onto carbon nanotube oxides (NH2-MIL-101@MWCNT, the BET surface area of 1017.63 m2·g−1). Subsequently, a surface-functionalized composite nanoparticle (named PA-MIL-101@MWCNT, the BET surface area of up to 368.14 m2·g−1) was synthesized through phosphorylation via the Mannich reaction for uranium adsorption. Batch adsorption experiments unequivocally demonstrated that the modification with phytic acid led to a significant improvement in the uranium adsorption capacity of the composite material, achieving a maximum adsorption capacity of 599.77 mg·g−1. The initial adsorption rate of PA-MIL-101@MWCNT was exceptionally rapid, achieving 73.84 % of the maximum adsorption capacity within 10 min. Adsorption kinetics and thermodynamics indicated that uranium adsorption follows a single-molecule chemisorption mechanism. PA-MIL-101@MWCNT exhibits exceptional resistance to ionic interference within natural seawater, demonstrating excellent stability and recyclability. XPS and DFT calculations strongly supported the notion that the uranium adsorption mechanism was associated with the oxygen atoms in the PO and P-O functional groups. These findings suggest that PA-MIL-101@MWCNT can be considered an excellent material for uranium extraction from seawater, which is significant to the sustainable utilization of nuclear energy materials.

Redox-active phytic acid-based self-assembled hybrid material for enhanced uranium adsorption from highly acidic solution

Achieving efficient uranium adsorption from highly acidic wastewater is still considered challenging. Here, an inorganic-organic hybridized self-assembly material (rPFE-10) with redox activity was constructed by phytic acid (PA), ethylenediamine (EDA), and Fe(II) via a facile one-pot route, and further applied for U(VI) removal. In the static adsorption experiment, rPFE-10 achieved the maximum U(VI) adsorption capacity of 717.1 mg/g at the optimal pH of 3.5. It also performed preeminently in a highly acidic condition of pH = 1.0, with the highest adsorption capacity of 551.2 mg/g and an equilibrium time of 30 min. Moreover, rPFE-10 exhibited a pH-responsive adsorption selectivity for U(VI) and An-Ln (S(U(VI)) and S(An-Ln)), which increased to 69 % and 94 % respectively as pH decreased from 3.0 to 1.0. Additionally, the spectral analysis revealed a reconstruction mechanism induced by multiple synergistic adsorption, in which U(VI) exchange with EDA+/2+ and Fe2+/3+ and earned suitable coordination geometry and ligand environment to coordinate with PA (mainly P-OH), while partial U(VI) is reduced by Fe(II) in framework. This work not only highlights the facile strategy for enhanced U(VI) retention in highly acidic solution, but expands the potential application of supramolecular self-assembly material in treatment of nuclear wastewater.

Synthesis of pH responsive malononitrile functionalized metal organic framework MIL-100(Fe) for efficient adsorption of uranium U(VI) from real-life alkaline leach liquor

The porous framework of MIL-100(Fe) was functionalized using malononitrile (MN), through an in-situ Knoevenagel condensation reaction to introduce abundant –CN groups on the surface of the developed adsorbent. The resultant MN-functionalized MIL-100(Fe) exhibited excellent Uranium (U(VI)) removal capacity (i.e., 270 mg/g) at highly alkaline pH (⁓ 10). Different coexisting cations and anions show negligible influence on the U-removal and it was 92.1–99.7 % in presence of different co-ions, with the concentration from 10 to 50 mg/L. Moreover, MIL-100(Fe)_MN showed extremely selective U removal from the actual alkaline leach liquor (⁓ 97 %), without any pH adjustment and leaching of the constituent Fe. The surface-grafted –CN groups were predominantly active towards the coordinative interactions with the U(VI) ionic moieties, as evident from the XPS and FTIR analysis. The MIL-100(Fe)_MN adsorbent was also subjected to five consecutive adsorption-desorption cycles, with >90 % U removal after 5th cycle. Moreover, the regenerated MIL-100(Fe)_MN was structurally and functionally resilient, as observed from the morphological and crystallographic analysis. A convection-pore diffusion based transport model was used to analyze the optimized mass transfer parameters. Overall, the present study highlights the simple design and development of malononitrile-functionalized MIL-100(Fe) as an efficient and selective adsorbent for U(VI) removal from U-rich alkaline leach liquor.

A novel phosphorylated hyper-crosslinked porous polymer for efficient uranium adsorption in water

As the nuclear resource industry rapidly progresses, efficient adsorbents play a vital role in separating and eliminating uranium from aqueous solutions. Herein, 9,9-dimethyl-fluorenylphosphonic acid was designed as a phosphate functional monomer and the triptycene as a rigid backbone monomer. Through the “knitting” strategy, a novel triptycene-based phosphorylated hyper-crosslinked porous polymer (TPP-DFP) was obtained by the above monomers. The resulted polymer TPP-DFP has a high BET surface area of 1397.62 m2/g with a rich porosity. The porous polymer TPP-DFP was the first time used for uranium adsorption from water and showed outstanding adsorption performance. The maximum uranium adsorption capacity of TPP-DFP was 414.26 mg/g, which was higher than that of most of other porous adsorbents. In the presence of impurity ions such as Ca2+, Mg2+, Al3+, Co2+, Ni2+, V5+, NO3−, CO32− etc., TPP-DFP exhibited high selectivity (Su up to 99%) for uranium. In addition, TPP-DFP has excellent reusability, and the removal percentage of uranium can reach more than 95% after 5 adsorption–desorption cycles. According to the XPS experiment, the mechanism of interaction between TPP-DFP and U(VI) was mainly due to the complex formed by the phosphate functional groups and U(VI). The theory DFT calculation indicated a 1:2 ratio of U(VI) and phosphate functional group on the two-distinct graft chain, which was consistent with the experimental results. Accordingly, the “knitting” polymerization technique showed potential for preparation effective adsorbents for uranium extraction from water.

In-situ constructing amidoxime groups on metal-free g-C3N4 to enhance chemisorption, light absorption, and carrier separation for efficient photo-assisted uranium(VI) extraction

The development of inexpensive and efficient semiconductor catalysts for photo-assisted uranium extraction from seawater remains a huge challenge. Herein, we have successfully synthesized amidoxime-rich g-C3N4 (AO-C3N4) by simply amidoximing a cyano-rich precursor for photo-assisted uranium extraction from seawater. The amidoxime groups not only served as the U(VI) binding sites for efficient uranium adsorption, but also significantly improved the visible light absorption capacity and carrier separation efficiency via introducing defect energy level, resulting in the excellent photocatalytic activity for AO-C3N4 towards photo-assisted uranium extraction. In the process of photo-assisted uranium extraction, U(VI) was first adsorbed by the amidoxime groups on the AO-C3N4 and then reduced to U(IV), while (UO2)O2·2H2O and (UO2)O2·4H2O were further formed by the oxidation of U(IV) by superoxide radicals (·O2-). Moreover, the generated reactive oxygen species (ROS) under light endowed AO-C3N4 with outstanding antibacterial properties, preventing the limitation of uranium extraction capacity from marine biofouling.

Rational design phosphorylation Mg-Fe layered dioxides nanosheets for efficient capture of uranium from wastewater

As the nuclear industry boomed, lots of uranium has entered the water environment and caused great damage to ecological environment. Designing and preparing efficient uranium adsorption materials is essential to solve the problem. Phosphorylated Mg-Fe layered dioxides (P-MF LDOs) nanosheets with a favorable memory effect were prepared by calcination and in-situ phosphorylation for uranium extraction from wastewater (UEW). The unique phosphating method resulted in a uniform distribution of phosphate functional groups in the surface of LDOs, which gave it great ability for capture of uranium. The adsorption capacity of P-MF LDOs was 2.31 times that of pure MF LDOs. According to the Langmuir model, the theoretical extraction capacity of P-MF LDOs was as high as 909.09 mg g−1, which was significantly higher than that of similar sorbents. Additionally, it exhibited excellent anti-interference ability. The results of the adsorption mechanism study revealed that the binding modes included surface complexation, mineralization reaction, dissolution-precipitation, and memory effect. In conclusion, P-MF LDOs represent a type of highly efficient uranium adsorbent with simple preparation and high adsorption capacity for UEW. This study provides new insights into the development of inorganic clay-based uranium adsorbents.

The preparation of amino-reinforced phosphorylated biochar for efficient uranium adsorption

The preparation of amino-reinforced phosphorylated biochar for efficient uranium adsorption

Efficient uranium adsorption and mineralization recycle by nano-MgO biochar with super-hydrophilic surface

How to treat uranium-containing wastewater effectively by adsorption and recycle waste adsorbent is an agent problem affecting the sustainable development of nuclear energy. This study successfully developed a super-hydrophilic nano-MgO biochar (MBC) for the efficient and selective separation of UO22+ and mineralization recycle of waste MBC. The optimum operating parameters, kinetics, isotherms, thermodynamics and adsorption selectivity of adsorption by MBC, were studied. The adsorption kinetics was well characterized by the Elovich model and the adsorption isotherm was well fitted by the Langmuir-Freundlich model. The adsorption process was spontaneous and endothermic. The selectivity test results showed that MBC had outstanding selectivity and efficiency for UO22+ in high concentration coexisting ion solution. The predominant adsorption mechanism of UO22+ by MBC was MgU2O7 microprecipitation mechanism, and the mineralization recycle of UO22+ is a feasible recovery method for uranium.

Synthesis of Amidoxime‐modified Hollow Organic Porous Nanospheres for Efficient Uranium Adsorption from Aqueous Solution

AbstractDespite its disadvantages, nuclear power still has some advantages over traditional fossil fuels and could have a part to play in solving the current energy crisis. Among them, nuclear waste (mainly uranium and plutonium) is the inevitable product of the extensive development and application of nuclear power, and its recovery and storage technology are on the focus of scientific research. Herein, amidoxime‐modified hollow organic porous nanospheres (HOPNs‐AO) were prepared by co‐hyper‐crosslinking from polylactide‐b‐polystyrene (PLA‐b‐PS) diblock copolymer and benzeneacetonitrile based on the Scholl coupling reaction. Owing to the specific adsorption property of amidoxime groups for uranyl ions, the obtained HOPNs‐AO exhibited excellent adsorption capacity (qmax=519.5 mg ⋅ g−1), chemical stability, and selectivity for uranyl ions in an aqueous solution. In addition, HOPNs‐AO can still maintain more than 80 % adsorption capacity in the fifth cycle. The above results indicate that the successful design of this material provides a meaningful way for the recovery of uranium ions in aqueous solution.