Synthesis and fabrication of segregative and durable MnO2@chitosan composite aerogel beads for uranium(VI) removal from wastewater

Facilitated electron-hole separation and enhanced uranium(VI) capture via La-doped WO3: Insights into oxygen vacancies and superior recyclability

WO3-based materials are theoretically promising photocatalysts for uranium(VI) removal due to their stability and narrow bandgap (∼2.8 eV), but they are limited by a lack of adsorption sites and a tendency for photogenerated electron-hole pairs to recombine. Herein, La-doped WO3 (W0.9La0.1O3-x) rich in oxygen vacancies (OVs) was prepared via a facile hydrothermal method. La doping and the introduction of OVs provided abundant active sites, optimized the band structure, increased electron density, and inhibited electron-hole pair recombination of W0.9La0.1O3-x, which resulted in a maximum U(VI) extraction capacity of up to 1199.73 mg/g through synergistic adsorption-photocatalytic reduction processes. Interestingly, W0.9La0.1O3-x demonstrated excellent stability and increased recyclability, superior to that of most reported adsorbents and photocatalysts, probably owing to the strong stability of W and La atoms as well as the additional OVs formed from self-reduction of W0.9La0.1O3-x during photocatalytic reaction process. Overall, this study expands the application of WO3-based materials for U(VI) removal from wastewater and provides valuable theoretical insights and technical guidance for addressing the challenge of balancing removal rate and stability of U(VI) extraction materials.

Calcium phytate cross-linked polysaccharide hydrogels for selective removal of U(VI) from tailings wastewater

Efficient uranium capture from rare earth tailings wastewater holds great importance for human health and sustainable development. Herein, we present a simple and eco-friendly approach to form a single network hydrogel through electrostatic interaction between chitosan and sodium alginate. Subsequently, calcium phytate is introduced as a natural crosslinking agent to generate a secondary cross-linked network, leading to a composite hydrogel (CS-SA/PCa) with a doubly enhanced network structure for efficient adsorption of uranium from wastewater. The established multistage porous structure enables the rapid diffusion of uranyl ions, and the abundant phosphate groups serving as adsorption sites can offer high affinity for U(VI). Most importantly, CS-SA/PCa is formed through physical cross-linking of sustainable biopolymers, avoiding the use of toxic chemical agents. In addition, CS-SA/PCa exhibited significantly better mechanical properties than those of single-network physical hydrogels crosslinked by electrostatic interactions, which overcame the weak mechanical properties of physical hydrogels. It provides a new method for the manufacture of environmentally friendly, low-cost and robust physical hydrogels based on natural polymers.

Hydrochar-nanocomposite membrane combined hydrothermal pretreatment for nutrient upcycling from anaerobic digestate

Efficient resource recovery is crucial for sustaining food production and alleviating stress on ecosystems. This study combines hydrothermal pretreatment with polyvinylidene fluoride (PVDF)-hydrochar nanocomposite membranes for near-complete resource recovery in kitchen waste treatment. The dual-functionalized pretreatment, which combines targeted conversion/enrichment with adsorption/filtration, effectively addresses the limitations of existing membrane separation technologies, including low nutrient recovery selectivity, low flux, and high costs. Within a wide pH range (3-11), the optimized lanthanum-doped hydrochar demonstrated over 99% phosphorus recovery, alongside exceptional nutrient recovery potential (over 289.71 mg P/g). The innovative composite membrane design successfully processed over 1,000 bed volumes of biogas slurry containing high phosphorus levels across three in-situ rejuvenation cycles, achieving nearly a 30-fold increase in membrane utilization compared to pristine PVDF membranes (36 bed volumes). The durability and fouling resistance of the composite membranes were enhanced through a synergistic mechanism that included ligand exchange and retention, as well as improved membrane surface properties. This facilitated the selective and efficient recovery of nutrients (99.33% P and 50.81% N) and enabled a profitable turnaround for anaerobic by-product upcycling ($28.51/ton). This study offers novel solutions to address the phosphorus scarcity crisis and promotes the integration of organic waste management with low carbon value addition.

Insight into sequestration and release characteristics of uranium(VI) on phlogopite in the presence of humic acid

Knowledge of the sorption speciation and surface configuration of uranium(VI) at the mineral/water interface is essential to construct reliable retention and migration models. However, the ubiquitously existing natural organic substances at U(VI)-contaminated sites readily interact with U(VI) and interfere with the environmental fate of U(VI). In this work, the adsorption behavior and mechanism of U(VI) on phlogopite in the presence of humic acid (HA) were investigated by combining batch experiments, cryogenic time-resolved laser fluorescence spectroscopy (TRLFS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. The batch sorption experiments at different HA concentrations suggested that HA had little effect at pH < 4 but suppressed U(VI) sorption on phlogopite from pH 4 to 12. Fluorescence spectral characteristics indicated the formation of multiple surfaces and aqueous U(VI)-humate species, whose abundances varied with pH. The TRLFS coupled with EXAFS spectra suggested that the HA-U(VI) hybrids preferentially bind to surface sites via U(VI) rather than HA. The humate uranium species increased uranium release and migration risk in the natural environment. These findings elucidate the species characteristics and environmental behavior of U(VI) in the presence of natural humic acid and provide guidance for remediation treatments and safety assessment of uranium-contaminated sites.

Functionalized 2D multilayered MXene for selective and continuous recovery of rare earth elements from real wastewater matrix

Rare earth elements (REEs) are the "fuel" for high-tech industry, yet their selective recovery from complex waste matrices is challenging. Herein, we designed a 2D multilayered MXene Ti3C2Tx adsorbent for selective extraction of REEs in a broad pH range. By establishing strong Lewis acid-base interactions, extraction capacities of Ti3C2Tx to Eu(III) and Ho(III) reached 892.8 and 649.2 mg/g, respectively, even at pH 2.0. Following the Valence Matching Principle, the Ti3C2Tx adsorbent also demonstrated high selectivity for recovery of various REEs from real REEs processing wastewater and actual sludge from magnet manufacturing industry. To demonstrate the practical feasibility, a layer-stacked membrane of Ti3C2Tx supported on polyethersulfone substrate was fabricated for continuous recovery of REEs and exhibited excellent removal of Eu(III) (99.1 % at pH 5.0), showcasing its potential for large-scale applications. DFT calculations and material characterization demonstrated that chemisorption between Lewis acid (REEs cations) and Lewis base (F and O) sites is the main adsorption process involved in the uptake of Eu(III) and Ho(III). Finally, both the Ti3C2Tx adsorbent and membrane were successfully regenerated and reused via simple acid wash. Overall, the results demonstrate the Ti3C2Tx-based recovery as a promising path for sustainable harvesting of REEs.

Morphology Effect of FeWO4 Boosting Efficiency of Photocatalytic Uranium Extraction under Visible Light and Mechanism Investigation

Wolframite (FeWO4) is a type of polyoxometalate known for its high chemical stability and electronic properties, which makes it an excellent photocatalyst. While FeWO4 has been widely utilized in the domain of organic catalysis, there are currently no documented reports regarding its use in the degradation of U(VI). In this study, the effect of changing the microscopic morphology of the FeWO4 catalyst to enhance its photocatalytic activity was explored. We effectively adjusted the microstructure and crystallinity of the FeWO4 catalyst by varying the hydrothermal synthesis temperature, subsequently analyzed in detail using synchrotron radiation and theoretical calculations. Additionally, the degradation rate of U(VI) in nuclear wastewater reached 98.8% using the FeWO4 catalyst samples synthesized at 200 °C, and the effect of coexisting ions on the performance of FeWO4 was studied, and the results showed that the degradation effect of certain amounts of Na+, Mg2+, K+, and Ca2+ on U(VI) was almost negligible, and it still maintained more than 90% of its initial performance after six cycles, which highlights the wide application prospects of the catalyst in the field of nuclear wastewater treatment in the future. Therefore, FeWO4 exhibits excellent photocatalytic uranium-extraction ability, anti-interference ability, stability, and a low-cost advantage. It holds great application prospects in the field of extracting radioactive uranium from nuclear wastewater.

A mechanically robust chitosan-based macroporous foam for sustainable Se(IV) elimination from wastewater

The contamination of water resources by selenium (Se), particularly in the highly toxic Se(IV) oxidation state, poses a significant environmental and public health concern due to its detrimental impacts on humans and aquatic ecosystems. In this work, we report a novel composite foam (CFC) by incorporating chitosan (CS), cellulose nanofibers (CNF) and iron oxyhydroxide (FeOOH) nanoparticles through a one-pot fabrication process. The CFC foam features a three-dimensional porous structure, conferring both exceptional mechanical strength and superior adsorption performance for Se(IV), with a maximum equilibrium adsorption capacity of 90 mg/g achieved within 3 h. It maintained stable removal efficiency across a wide pH range and demonstrated strong resistance to interference from common anions and ionic strength variations. The primary adsorption mechanism involves electrostatic interactions and complexation between Se(IV) and functional groups presented in the CFC foam. Molecular dynamics simulations further confirmed the stability and effectiveness of Se(IV) adsorption at the molecular level. Additionally, CFC foam exhibited satisfactory practical applicability and durability, maintaining high Se(IV) removal performance over sequential adsorption processes. This study highlights the potential of CFC foam as an effective and sustainable material for Se(IV) remediation in wastewater, offering a promising solution for mitigating Se pollution and improving water quality.

Superoleophobic Hierarchical Honeycomb Hydrogels for Effective Heavy Metal Removal in Crude Oil Emulsion

Here, we designed a bioinspired hydrogel surface with underwater superoleophobicity for heavy metal adsorption, effectively addressing the challenge of adsorption site clogging caused by crude oil emulsions. Mimicking the reentrant structures of lotus leaf undersides, silica dioxide (SiO2) nanoparticles were self-assembled on the hydrogel surface, forming a stable hydration layer that imparts unique superoleophobic properties in an aqueous environment. The poly(vinyl alcohol)-sodium alginate-SiO2 capsule (PSSC) exhibited a hierarchical honeycomb pore structure with a nano screen mesh, achieving excellent adsorption capacities for typical cationic heavy metals (Pb2+, Cu2+, Cd2+, and Cr3+) in both aqueous solutions and crude oil emulsions. The optimal pH for heavy metal adsorption was determined to be between 4 and 5, while increasing temperature significantly inhibited the adsorption process. Maximum adsorption capacities of Pb2+, Cd2+, Cu2+, and Cr3+ reached 291.5 mg/g, 278.7 mg/g, 259.4 mg/g, and 171.4 mg/g in crude oil emulsions. Competitive adsorption was observed in multicomponent systems, with Cr3+ being adsorbed preferentially. The adsorption mechanisms were primarily governed by chemical adsorption, physical adsorption, and electrostatic attraction, with functional groups such as -COOH and -OH on the hydrogel surface playing a key role in metal ion binding. This study demonstrates the potential of PSSC as an efficient, cost-effective adsorbent for removing heavy metals from complex matrices, such as wastewater and crude oil emulsions, and highlights its applicability in various environmental remediation scenarios.

Zeolitic imidazolate framework functionalized magnetic multiwalled carbon nanotubes as efficient adsorbents for rapid extraction of fluoroquinolones

Herein, a new, environmentally friendly, and economical magnetic solid-phase extraction method for fluoroquinolones (FQs) from milk samples was developed using novel recyclable zeolitic imidazolate framework functionalized magnetic multiwalled carbon nanotubes (Fe3O4@MWCNTs@SiO2@ZIF-8) as adsorbents. Various characterization techniques, including scanning electron microscopy, N2 adsorption-desorption analysis, and vibrating sample magnetometry, demonstrated that the adsorbent possessed a remarkable specific surface area, pore volume, and superparamagnetic properties, rendering it an excellent adsorbent. Combined with high-performance liquid chromatography, this method exhibited excellent linearity (R2 ≥ 0.9991) over the concentration range of 0.5-500 μg L-1, low limits of detection (0.10-0.34 μg kg-1), and low limits of quantification (0.30-1.00 μg kg-1). Finally, the developed method was successfully applied to analyze FQs in milk samples with recoveries ranging from 83.3% to 107.7% and relative standard deviations below 4.2%. The high efficiency and sensitivity of this method highlight the potential application of Fe3O4@MWCNTs@SiO2@ZIF-8 for analyzing FQs in complex matrices.

Magnetic coconut shell biochar/sodium alginate composite aerogel beads for efficient removal of methylene blue from wastewater: Synthesis, characterization, and mechanism

The challenges of recovering powdered biochar and its limited adsorption capacity are major obstacles to the application of agricultural waste in dye adsorption. To address these issues, this work fabricates Fe3O4-modified coconut shells biochar (mCSB)/sodium alginate (SA) aerogel beads using an in-situ crosslinking-gelation method and freeze-drying technology for methylene blue (MB) removal from wastewater. The spherical mCSB/SA aerogel beads with good magnetic properties (12.8 emu·g-1) can be easily separated from aqueous solutions, thereby completely avoiding the hazard of secondary pollution and device obstruction associated with powdered adsorbents. The absorption capability of MB by mCSB/SA aerogel beads was analyzed and optimized at different conditions. Furthermore, the maximum adsorption capacity of mCSB/SA aerogel beads is 625 mg·g-1 for MB, following the Langmuir isotherm model (R2 = 0.9997). Additionally, the adsorption process of MB on mCSB/SA aerogel beads is found to be spontaneous and endothermic, following the pseudo-second-order kinetic (R2 = 0.9991). Encouragingly, the adsorption efficiency of mCSB/SA aerogel beads remains above 95 % even after 5 times of reusability cycles, demonstrating excellent regeneration ability. This work proposes a straightforward and scalable fabrication strategy to convert agricultural waste into efficient adsorbents for wastewater treatment, adhering to the principles of sustainable development.

Collaborative disposal of beryllium-containing wastewater with modified graphite@chitosan from waste lithium-ion batteries

In order to recover and effectively remove beryllium from beryllium-containing wastewater and relieve the environmental pressure caused by waste batteries. In this study, the gel material was synthesized based on the modified graphite material separated from the waste battery, and the graphite-@chitosan composite gel (CWBG@CH) was designed and synthesized. Interestingly, CWBG@CH has a maximum fitted adsorption capacity (Qemax) of 83.54 mg/g at pH = 6 and 35 °C. The adsorption process of CWBG@CH is controlled by surface complexation and electrostatic attraction. Strong coordination and synergistic adsorption between Be and the carbonic acid/hydroxyl group and phosphoric acid/amino group on CWBG@CH enhances the adsorption capacity and selectivity of CWBG@CH for Be. At the same time, the adsorption-desorption efficiency of the CWBG@CH in 5 times is >85 %. This discovery provides a direction for the recycling of graphite materials from waste batteries and indicates the great potential of CWBG@CH to remove Be(II) from aqueous solutions.

A robust amphiphilic ionic covalent organic framework intercalated into functionalized graphene oxide hybrid membranes for ultrafast extraction uranium from wastewater

The efficient capture of uranium from wastewater is crucial for environmental remediation and the sustainable development of nuclear energy, yet it poses considerable challenges. In this study, amphiphilic ionic covalent organic framework intercalated into graphene oxide (GO) nanosheets functionalized with polyethyleneimine (PEI) were used to construct hybrid membranes with ultrafast uranium adsorption. These hybrid membranes achieved equilibrium in just 10 min and the adsorption capacity was as high as 358.8 mg g-1 at pH = 6. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses revealed that the strong interaction between sulfonic acid groups and uranyl ions was the primary reason for the high adsorption capacity and selectivity. The extended transition state and natural orbitals for chemical valence (ETS-NOCV) analysis revealed that the interaction between the 7 s and 5f orbitals of uranyl and the 2p orbitals of S and O in the sulfonate was the primary reason for the strong interaction between the sulfonate and the uranyl ion. This research presents an effective method for the rapid extraction of uranium from wastewater.

Scavenging Radionuclide by Shapeable Porous Materials

Nuclear energy is a competitive and environmentally friendly low-carbon energy source. It is seen as an important avenue for satisfying energy demands, responding to the energy crisis, and mitigating global climate change. However, much attention has been paid to achieving the effective treatment of radionuclide ions produced in nuclear waste. Initially, advanced adsorbents were mainly available in powder form, which meant that additional purification processes were usually required for separation and recovery in industrial applications. Therefore, to meet the practical requirements of industrial applications, materials need to be molded and processed into forms such as beads, membranes, gels, and resins. Here, we summarize the fabrication of porous materials used for capturing typical radionuclide ions, including UO2 2+, TcO4 -, IO3 -, SeO3 2-, and SeO4 2-.

π-electron injection activated dormant ligands in graphitic carbon nitride for efficient and stable uranium extraction

Graphitic carbon nitride (CN) as an adsorbent exhibit promising potential for the removal of uranium in water. However, the lack of active sites seriously restricts its practical application. In contrast to the traditional method of introducing new ligands, we propose a strategy to activate original ligands on CN by injecting π electrons, which can be realized by grafting 4-phenoxyphenol (PP) on CN (PCN). Compared with CN, the maximum adsorption capacity of PCN for uranium increased from 150.9 mg/g to 380.6 mg/g. Furthermore, PCN maintains good adsorption properties over a wide range of uranium concentrations (1 ∼ 60 mg/L) and pH (4 ∼ 8). After 5 consecutive cycles, PCN exhibited sustained uranium removal performance with a little of losses. The experimental and theoretical results show that the enhancement of adsorption performance is mainly due to the ligands activation of CN by delocalization of π electrons from PP. Furthermore, this activation can be enhanced by irradiation, as the CN can be photoexcited to provide additional photoelectrons for PP. As a result, dormant ligands such as N-CN, C-O-C, C-N-H and N-(C)3 can be activated to participate in coordination with uranium. This work provides theoretical guidance for the design and preparation of high efficiency uranium adsorbent.

Development of a NiFe2O4 covalent organic framework based magnetic solid-phase extraction approach for specific capture of quinolones in animal innards prior to UHPLC-Q-Orbitrap HRMS detection

This study aimed to present a selective and effective method for analyzing quinolones (QNs) in food matrix. Herein, a NiFe2O4-based magnetic sodium disulfonate covalent organic framework (NiFe2O4/COF) was prepared using a simple solvent-free grinding method, and was adopted as a selective adsorbent for magnetic solid phase extraction of QNs. Coupled with UHPLC-Q-Orbitrap HRMS, an efficient method for simultaneous detection of 18 kinds of QNs was established. The method exhibited good linearity (0.01-100 ng g-1), high sensitivity (LODs ranging from 0.0011 to 0.0652 ng g-1) and precision (RSDs below 9.5%). Successful extraction of QNs from liver and kidney samples was achieved with satisfactory recoveries ranging from 82.2% to 108.4%. The abundant sulfonate functional groups on NiFe2O4/COF facilitated strong affinity to QNs through electrostatic and hydrogen bonding interactions. The proposed method provides a new idea for the extraction of contaminants with target selectivity.

Phytic acid-functionalized polyamidoxime/alginate hydrogel for targeted uranium extraction from acidic wastewater

Efficient removal of uranium from radioactive wastewater is crucial for both environmental protection and sustainable development of nuclear energy. However, selectively extracting uranium from acidic wastewater remains a significant challenge. Here we present a phytic acid-functionalized polyamidoxime/alginate hydrogel (PAG) via a facile one-step hydrothermal reaction. The PAG, leveraging the robust binding affinity of phytic acid and the selective coordination of amidoxime for U(VI), exhibited high efficiency and selectivity in adsorbing U(VI) from acidic uranium-containing wastewater. At pH 2.50, U(VI) adsorption equilibrium was achieved within 60 min, showcasing a maximum theoretical adsorption capacity of 218.34 mg/g. Additionally, the PAG demonstrated excellent reusability, maintaining a uranium removal rate exceeding 90 % over five adsorption-desorption cycles. Remarkably, the as-synthesized PAG removed 94.1 % of U(VI) from actual acidic uranium-contaminated groundwater with excellent anti-interference performance, reducing U(VI) concentration from 272.0 μg/L to 16.1 μg/L and making it meet the WHO drinking water standards (30 μg/L). The adsorption mechanism was elucidated through XPS and DFT calculation, revealing that the uranyl ion primarily coordinated with phosphate and amidoxime groups on phytic acid and polyamidoxime, respectively. These findings underscore the promising potential of PAG hydrogel for addressing acidic uranium-containing wastewater from uranium mining and metallurgy.

Unlocking the potential of surface modification with phosphate on ball milled zero-valent iron reactivity:Implications for radioactive metal ions removal

Numerous investigations have illuminated the profound impact of phosphate on the adsorption of uranium, however, the effect of phosphate-mediated surface modification on the reactivity of zero-valent iron (ZVI) remained enigmatic. In this study, a phosphate-modified ZVI (P-ZVIbm) was prepared with a facile ball milling strategy, and compared with ZVIbm, the U(VI) removal amount (435.2 mg/g) and efficiency (3.52×10-3 g·mg-1·min-1) of P-ZVIbm were disclosed nearly 2.0 and 54 times larger than those of ZVIbm respectively. The identification of products revealed that the adsorption mechanism dominated the removal process for ZVIbm, while the reactive modified layer strengthened both the adsorption pattern and reduction performance on P-ZVIbm. DFT calculation result demonstrated that the binding configuration shifted from bidentate binuclear to multidentate configuration, further shortening the Fe-U atomic distance. More importantly, the electron transferred is more accessible through the surface phosphate layer, and selectively donated to U(VI), accounting for the elevated reduction performance of P-ZVIbm. This investigation explicitly underscores the critical role of ZVI's surface microenvironment in the domain of radioactive metal ion mitigation and introduces a novel methodology to amplify the sequestration of U(VI) from aqueous environments.

Construction of hierarchical porous and polydopamine/salicylaldoxime functionalized zeolitic imidazolate framework-8 via controlled etching for uranium adsorption

Efficient uranium extraction from seawater is critical for the development of the nuclear industry. Herein, a polydopamine/salicylaldoxime decorated hierarchical zeolitic imidazolate framework-8 (H-PDA/SA-ZIF-8) is constructed by using a controlled etching process. Benefiting from the combination of PDA/SA and the zeolitic imidazolate framework-8 (ZIF-8), as well as a controlled etching process, the H-PDA/SA-ZIF-8 possesses multiaffinity sites, excellent specific surface area (1234.92 m2 g-1), and a hierarchical pore structure. The H-PDA/SA-ZIF-8 exhibits excellent adsorption capacity (Qm = 869.6 mg g-1), selectivity, and reusability in uranium adsorption. The adsorption process of H-PDA/SA-ZIF-8 fits very well with the Langmuir isotherm model and pseudo-second-order models, and the adsorption process equilibrates within 20 min (C0 = 20 mg L-1). Furthermore, the H-PDA/SA-ZIF-8 shows remarkable antibacterial ability. Impressively, the adsorption capacity of H-PDA/SA-ZIF-8 to uranium in natural seawater reaches 6.9 mg g-1 after circulation for 15 days. Therefore, the H-PDA/SA-ZIF-8 is a promising and fascinating material for uranium extraction from natural seawater.

Synthesis and fabrication of magnetically separable phosphate-modified magnetic chitosan composites for lead(II) selective removal from wastewater

To address the urgent need for efficient removal of lead-containing wastewater and reduce the risk of toxicity associated with heavy-metal wastewater contamination, materials with high removal rates and easy separation must be developed. Herein, a novel organic-inorganic hybrid material based on phosphorylated magnetic chitosan (MSCP) was synthesized and applied for the selective removal of lead (II) from wastewater. From the characterization and the experimental results can be obtained that the magnetic saturation strength of MSCP reaches 14.65 emu/g, which can be separated quickly and regenerated readily, and maintains high adsorption performance even after 5 cycles, indicating that the adsorbent possesses good magnetic separation performance and durability. Also, MSCP showed high selective adsorption performance for lead in the multiple metal ions coexistence solutions at pH 6.0 and room temperature, with an adsorption coefficient SPb-MSCP of 78.85%, which was much higher than that of MSC (the SPb-MSC was 11.59%). Additionally, in the single lead system, the sorption characteristics of Pb(II) on MSCP and MCP had obvious pH-responsiveness, and their adsorption capacity increased with the increase of solution pH, reaching the maximal values of 80.19 and 72.68 mg/g, respectively. It is noteworthy that the acid resistance of MSCP with an inert layer coated on the core is significantly improved, with almost no iron leaching from MSCP over the entire acidity range, while MCP has 7.63 mg/g of iron leaching at pH 1.0. Significantly, MSCP exhibited a maximum adsorption capacity of 102.04 mg/g, which matches the Langmuir model at pH 6.0 and 298.15 K, and points to the pseudo-second-order kinetics of the chemisorption process of Pb(II) on MSCP. These findings highlight the great potential of MSCP for Pb(II) removal from aqueous solution, making it a promising solution for Pb(II) contamination in wastewater.

Enhanced adsorption dynamics and thermal stability of radioactive Sr(II) by lamellar Nb-doped sodium vanadosilicate via self-assembly and conditional natroxalate intercalation

To promote the environmentally friendly and sustainable development of nuclear energy, it is imperative to address the treatment of wastewater generated by the nuclear industry. This necessitates the enhancement of fission product reclamation efficiency post-treatment. This study aims to combine defect control and confined self-assembly strategies for the precise design of interlayer spacing (14.6 Å to 15.1 Å), leading to the fabrication of conditional natroxalate-functionalized vanadosilicate, and its potential application in the efficient adsorption and reclamation of 90Sr. Na0.03Natroxalate2.47Si1.44Nb0.08V1.92O5·1.2 H2O (Nb4-NxSiVO), with a layer spacing of 14.9 Å, exhibits the highest Sr(II) adsorption capacity (248.76 mg/g), enabling effective separation with Cs+. The natroxalate embedded within the confined interlayers demonstrates excellent stability, offering rapid (within 10 min) and stable adsorption sites for Sr(II). Furthermore, Nb4-NxSiVO exhibits a wide band gap and exceptional thermal stability before and after adsorption, rendering hard desorption of 90Sr. The findings highlight the potential of Nb4-NxSiVO as a promising adsorbent for rapid and selective purification of 90Sr-containing wastewater and further application in nuclear batteries.

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.