With the rapid development of the nuclear industry in recent years, thorium, as the core fuel of the fourth-generation thorium-based molten salt reactors, is prone to produce thorium-containing radioactive wastewater in the process of its development and utilization, which poses a persistent hazard to the environment. Covalent organic frameworks (COFs), especially imine COFs, have abundant adsorption sites and good structural stability, which are expected to realize efficient enrichment and recovery of Th(IV) in complex aqueous systems. The porphyrin moiety, with its unusual electronic structure and abundant coordination sites, is a potential material for metal ion adsorption. For this regard, in this study, two 3D porphyrin COFs (3D-Por-COF-A and 3D-Por-COF-B) with multiple N-sites and excellent Th(IV) adsorption properties were synthesised by incorporating porphyrins into 3D imine COF materials. At pH = 4.5, the maximum saturated adsorption capacity of 3D -Por-COF-A was able to reach 575.2 mg/g, whereas that of 3D -Por-COF-B was 407.7 mg/g, both of which conformed to the Langmuir adsorption isotherm model, and reached 90 % of the maximum adsorption capacity within 20 min. Both materials showed high selective separation ability for Th(IV), (K-d = 9.1 & times; 10(3) and 7.2 & times; 10(3) mL/g, respectively) and maintained high adsorption levels (>80 %) after five cycles. The adsorption mechanisms of the two COFs were then further analyzed with density-functional theory (DFT). This study provides a new vision for the application of porphyrin-like COFs materials for Th adsorption and provides a reference for the subsequent development of high-performance actinide adsorption materials.

Amino-hydroxyurea (HSC) has shown excellent performance and application prospects in spent fuel reprocessing. However, its residue affects the subsequent separation process. Introducing the homologous gases NO2 and O2 is an effective way to solve this problem. A macroscopic reaction kinetic model for the gas-liquid reaction was established based on the film-penetration theory. By fitting the experimental data to the model, key parameters such as the reaction rate constant k 1 and the mass transfer constant of NO2 k NO2,G were obtained. Similarly, the characteristic parameters of the gas-liquid reaction, such as the Hatta number γ, the enhancement factor E, and the penetration time θ, were analyzed to characterize the gas-liquid reaction process and the intensity of the absorption of reaction gases NO2 and O2 in the liquid phase.

Aqueous zinc-iodine (Zn-I2) batteries demonstrate promising potential for large-scale energy storage applications. However, the uncontrolled "shuttle effect" of polyiodides (I3 -, I5 -) results in capacity loss, lower Coulombic efficiency (CE), and poor cycling reversibility. Herein, we propose alkyne-rich covalent organic frameworks (COFs) as functional separator coatings to effectively suppress the "shuttle effect", establishing a protective solid electrolyte interphase (SEI) layer to stabilize the Zn metal anode. The effect of different alkyne contents in COFs on the performance of Zn-I2 batteries is investigated, and the results demonstrate that increasing alkyne content significantly improves CE, ion migration rate, and cycling stability. Remarkably, the 100% alkyne-functionalized TAPT-BPTA-COF separator exhibited excellent ion selectivity, effectively blocking the diffusion of polyiodide species, while favoring the transport of Zn2+. This selective transport ensures uniform deposition of Zn2+ on the anode during cycles, thereby reducing internal resistance and improving cycle performance. Notably, the Zn||TAPT-BPTA-COF||I2 battery delivers an initial capacity of 8.4 mAh cm-2 at 20 mA cm-2, retaining 70.1% of the initial capacity over 1200 cycles with 99% CE. Complementary spectroscopic analyses and visualization experiments further confirm that the fully alkyne-conjugated electronic structure of COFs enhances electrical conductivity. This study provides a molecular design strategy for developing high-performance, COF-based electrochemical materials for Zn-I2 battery systems.

Thorium ions, known for their elevated toxicity and radioactivity, pose substantial ecological hazards, highlighting the need for efficient technologies to selectively eliminate them from water. The solid adsorption approach has gained widespread use in removing thorium ions because of its notable effectiveness, convenience, and straightforward operation. The key to this method's success is the solid-phase adsorbent, underscoring the pressing need to develop exceptionally efficient adsorbents for thorium ion removal. Here, we present a novel in situ synthesis approach for enhancing an aluminum-based Metal-Organic Framework (Al-MOF) through the incorporation of iron oxide (Fe3O4). The resulting Fe3O4/Al-MOF composite adsorbent demonstrates exceptional performance: (a) unparalleled adsorption capacity, achieving a remarkable Th(IV) uptake of 3058.0 mg g(-1), significantly outperforming the unmodified Al-MOF (1324.6 mg g(-1)); (b) outstanding selectivity, exhibiting high specificity for Th(IV) adsorption (SFTh/metals > 1000); (c) superb reusability, with excellent regeneration capabilities (85 % retention after 6 cycles). Through combined FT-IR and XPS analyses, we confirm that carboxylate oxygen atoms and Fe-O adsorption sites are key contributors to the Th(IV) adsorption mechanism. This work advances the design of efficient MOF-based composite adsorbents through valuable insights.

To address the critical challenge of improving the performance and stability of metal-organic frameworks (MOFs) for nuclear wastewater treatment, we present an innovative strategy-a progressive proportional loading approach for incorporating graphene oxide (GO) and silica (SiO2) into the SU-102(Zr) MOF matrix. Although oxide/MOF composites have been extensively investigated, the crucial influence of oxide loading ratios-a fundamental design parameter-has been systematically neglected. Our findings indicate a nonlinear relationship between GO/SiO2 content and the structural stability and adsorption efficiency of the composite, consistent with the 'optimality principle' in interfacial engineering. By synthesizing a series of x SiO2/GO@SU-102(Zr) composites (x = 3.125, 6.25, and 12.5 wt%), we demonstrate that the 6.25 wt% loading ratio achieves unprecedented performance in highly acidic conditions (0.3 M HNO3). This optimized composite exhibits record-breaking thorium adsorption (76.28 mg g-1 (initial uptake) and 59.63 mg g-1), surpassing all reported MOF-based adsorbents in such harsh environments, and exceptional stability (superior thermal and acid resistance compared to its counterparts). Density functional theory calculations elucidate the synergistic adsorption mechanisms, emphasizing the enhanced interfacial interactions between Th(IV) ions and the composite components. This study establishes a generalized design framework for oxide/MOF composites and opens new avenues for applications in nuclear waste remediation, heavy metal recovery, and advanced separation technologies. Our findings highlight the transformative potential of precision loading strategies in realizing the full capabilities of MOFs for addressing real-world environmental challenges.

Since the continuous development of nuclear energy, substantial amounts of radioactive thorium wastewater are inevitably produced. The discharge of radioactive thorium wastewater not only pollutes the natural environment but also endangers human health. Due to its affordability, simplicity, and high effectiveness, the adsorption method has emerged as the most often used method for treatment. Covalent organic framework (COF) materials are excellent adsorbents with various characteristics, including superior chemical stability, design flexibility, and various architectures, and thus are widely used in separating radioactive nuclides. Herein, we synthesized two structurally similar COFs that vary in their pore dimensions and the connectivity of their modules. After incorporating hydroxyl groups into the structure of Tb-TMT formed by benzene-1,3,5-tricarbaldehyde (Tb) and 2,4,6-trimethyl-1,3,5-triazine (TMT), the uptake capacity of thorium ions is significantly enhanced. The differences in solution pH, contact time, initial concentration, and competitive ion experiments between the materials before and after hydroxyl functionalization were studied. Additionally, the research assessed their reuse capabilities. In this research, the Hb-TMT exhibits an outstanding adsorption capacity for Th(IV) ions, with a remarkable adsorptive capacity reaching 543.5 mg g(-1), and it showes good uptake efficiency within 5 min with excellent selectivity (K-d = 1.2 x 10(4)). After three cycles of regeneration, Hb-TMT still maintains a high level of adsorption capacity for Th(IV) (> 80%) and has good reusability. Furthermore, the role of nitrogen-oxygen synergistic effect on hydroxyl-functionalized COF is highlighted by density functional theory (DFT) calculations. This study provides fresh insights for choosing functional groups in functionalized COFs, specifically for radionuclide adsorption.

The rise of nuclear energy has created an urgent need to treat wastewater containing thorium. Among various methods, the adsorption method stands out for its simplicity and cost-effectiveness. Covalent organic framework materials (COFs) possess unique structures and properties, making them promising candidates for this purpose. The adsorption performance of three imine-COFs (COF-OH1, COF-OH2, COF-OH3) towards Th(IV) was investigated. The results showed that the three COFs had ordered structures and good stability, while their physicochemical properties (e.g., surface area and pore size) varied systematically with increasing hydroxyl group content. Adsorption experiments indicated that within the pH range of 3-5, the adsorption capacity of COFs for Th(IV) increased with the rise of pH. The three COFs exhibited rapid adsorption kinetics, reaching equilibrium within 45 minutes, consistent with the pseudo-second-order kinetic model. Isotherm studies showed that it fitted the Langmuir model better, indicating a preference for monolayer adsorption. Under multi-component adsorption conditions, COF-OH1 had better selectivity for Th(IV) than the other two COFs. Density functional theory (DFT) calculations revealed the coordination interaction and electron transfer between Th(IV) and COFs. The results suggested that an increase in hydroxyl groups might promote tautomerism and hinder adsorption in specific cases due to steric hindrance and shielding effects. This study emphasizes the potential of structural design and group modification in imine-COFs to achieve efficient and selective adsorption of Th(IV). This research provides a theoretical foundation and new insights for the development of innovative adsorbents in this field.

The removal of thorium from contaminated water sources is crucial for environmental protection and nuclear waste management. Herein, we present a dual-strategy design of a thiophene-integrated porphyrin covalent organic framework (TAPP-BTD-COF) that combines rigid macrocyclic scaffolds with flexible thiophene linkages, incorporating complementary N and S donor sites. This tailored COF achieves efficient and selective capture of Th(IV) from acidic aqueous solutions. By leveraging the topological arrangement of the porphyrin core to modulate the conformation of thiophene-based connectors, a coordination environment with N–S synergistic sites is created, which significantly enhances Th(IV) selectivity over competing ions. At pH 4.5, the synthesized TAPP-BTD-COF exhibits a high adsorption capacity of 437.18 mg g-1 and reaches equilibrium within 20 minutes. It demonstrates exceptional selectivity for Th(IV), with a separation factor exceeding 2.6×10³ relative to common interfering ions, and retains over 90% adsorption capacity after three consecutive cycles. Mechanistic studies confirm that the high performance originates from N–Th / S–Th dual-dentate coordination. This work provides a strategic design of functional COFs for thorium recovery and represents a highly efficient adsorbent system for Th(IV) removal from aqueous streams.

Aqueous zinc-iodine (Zn─I2) batteries are promising candidates for large-scale energy storage owing to their inherent safety, low cost, and high theoretical capacity. However, their practical application is hindered by the polyiodide shuttle effect, sluggish iodine redox kinetics, and uncontrolled zinc dendrite growth. Herein, we design a functional separator modified with metallophthalocyanine-based covalent organic frameworks (MPc-COFs, M═Co, Ni, Cu) to simultaneously regulate iodine electrochemistry and zinc deposition behavior. The optimized Gr@CoPc-COF@GF separator leverages a synergistic mechanism: atomically dispersed Co active sites strongly adsorb polyiodides to suppress shuttling while accelerating iodine redox kinetics, and the well-ordered CoPc-COF nanochannels facilitate uniform Zn2+ flux. As a result, the corresponding Zn─I2 battery delivers a high specific capacity of 208.6 mAh g-1 at 571 mA g-1 and achieves excellent capacity retention with 96.97% Coulombic efficiency after 48 h of open-circuit rest. This work presents a rational separator design strategy for high-performance Zn─I2 batteries, highlighting the importance of molecular-level engineering in advanced energy storage systems.

The capture and separation of uranium and thorium from acidic nuclear waste streams are imperative for safeguarding the environment and human well-being. Metal-organic frameworks (MOFs), an emerging class of porous materials, offer considerable potential for U(VI)/Th(IV) adsorption owing to their customizable pore size and processability. Nonetheless, the development of MOFs with robust adsorption capabilities for U(VI)/Th(IV) in acidic conditions poses a significant challenge. In this study, we introduce a feasible MOF design approach: the integration of high-valent metal centers with oxygen-rich organic ligands. Employing this strategy, we have successfully engineered a novel MOF adsorbent, SU-102(Hf), comprising hafnium-based metal clusters and ellagic acid as the organic linker. In a 0.3 M nitric acid environment, SU-102(Hf) demonstrates outstanding chemical stability and exhibits a high adsorption capacity for both uranium (27.38 mg g- 1) and thorium ions (32.03 mg g- 1), which represent a record of simultaneous adsorption capacity of uranium and thorium binary components by MOFs in a highly acidic environment (0.3 M HNO3). Simultaneously, SU-102(Hf) also displays rapid adsorption kinetics, excellent selectivity, and recyclability for U(VI)/Th(IV) separation at pH = 3. Experimental investigations and theoretical calculations further unravel the adsorption mechanisms and key differences for Th(IV) and U(VI) ions.

Developing high-efficiency adsorbents for the selective capture of thorium from uranium and rare earth elements necessitates integrating multiple critical functions, including strong adsorption ability, exceptional selectivity, and acid-resistance performance, posing a technically challenging task. Herein, guided by the hard-soft acid-base (HSAB) principle, a series of imine-linked covalent organic frameworks (COFs) functionalized by oxygen-rich groups is designed and synthesized. The abundance of high-affinity dual-active N and O sites on the COF skeleton enables rapid adsorption kinetics and superior Th(IV) uptake. Particularly, TPT-PA-COOH and TPT-PA-SO3H exhibit record-breaking saturated adsorption capacity and Th/U separation selectivity, making them the most efficient Th(IV) adsorbent reported to date. Especially, the introduction of -COOH or -SO3H groups renders the 2D COFs highly acid-resistant, while keeping good Th(IV) adsorption capacity and selectivity even under harsh acidic conditions. These findings provide insight into the coordination mechanism between thorium and functional binding sites, thus advancing applications of COFs in the separation of thorium from radioactive wastewater.

Thorium (Th) separation from acidic solutions is crucial for both resource recovery and environmental protection, while most materials suffer from limitations such as poor selectivity, slow kinetics, and insufficient acid and radiation tolerance. In this work, a pyrazine ethylamide-functionalized pillar[5]arene (P[5]A-PEA) was designed and employed as a highly preorganized N, O-hybrid ligand for selective Th(IV) coordination and separation. The complexation behaviors between P[5]A-PEA and Th(IV) were systematically investigated by virtue of multiple techniques including UV-vis titration, Job plot analysis, FT-IR spectroscopy, ESI-MS, EXAFS, and DFT calculations. The findings reveal that each P[5]A-PEA molecule binds to a Th(IV) ion with four functional chains through amide oxygen and pyrazine nitrogen atoms, forming a stable macrocyclic chelating complex. By impregnating P[5]A-PEA into a porous resin, the composite material achieves effective Th(IV) adsorption from acidic solution with efficiencies twice higher than those of the counterpart containing small molecules PA-PEA without P[5]A platform. The results highlight the significant role of pillar[5]arene skeleton in improving Th(IV) separation efficiency. In addition, the P[5]A-PEA-based material exhibits merits such as fast adsorption kinetics, high selectivity, excellent reusability, effective dynamic Th(IV) separation, and outstanding γ-irradiation resistance even at a dose of 1000 kGy. This work demonstrates a feasible approach to efficient Th(IV) separation from complicated water environments.

Nuclear structure and properties are mainly studied by utilizing large-scale equipment such as colliders, while the chemical behavior of isotopes and their isotopologues emerges as a critical approach to investigating nuclei. Studies of isotope effects (IEs) primarily focus on the isotope separation or kinetic isotope effects of light isotopes such as H/D/T caused by mass-dependent IEs. However, barely any study has investigated whether the neutral neutron could remarkably influence medium-heavy isotopes as catalysts, since they are usually regarded as chemically similar, exhibiting inapparent mass differences. Herein, we revealed a remarkable IE of 107Ag and 109Ag with the photogenerated ability of their Ag2O isotopologues, 107Ag2O and 109Ag2O, exceeding 19.9%, despite a mass difference of less than 2%. Based on this IE in photochemistry, we processed methyl orange degradation as the model reaction and obtained an unprecedented IE k107/k109 = 1.1 with 107Ag2O and 109Ag2O serving as photocatalysts, respectively. The correlation of extranuclear electrons and the nucleus has been quantified for the first time by both theoretical calculations and experimental results, which is proportional to the Ag isotopes' nuclear charge density. This work extends our fundamental understanding of how the "humble" neutron affects extranuclear electrons during the photochemical process.

The separation of lithium isotopes is crucial for the advancement of nuclear energy technology. Electrochemical pumping through two-dimensional membranes with a quantum sieving effect offers significant advantages over conventional methods such as chemical exchange and solvent extraction for separating lithium isotope ions. This study employs molecular dynamics simulations to investigate the permeation mechanism of lithium isotope ions through oriented defective graphene under an electric field and to determine the kinetic isotope effect (KIE). Simulation results reveal that, under an applied electric field, lithium ions gain sufficient kinetic energy to penetrate through electron cloud cavities formed by carbon rings with single or double vacancy defects, whereas pristine graphene effectively blocks their permeation. Further analyses of electron cloud density, transition state search, and energy barrier calculations confirm that lithium isotope ions can traverse the membrane at specific charge densities. The calculated single-stage separation factor for lithium isotopes using single-vacancy defective graphene reaches up to 1.22, which is significantly higher than that achieved by traditional separation methods. Moreover, the separation factor is demonstrated to be directly correlated with the electron cloud density of the carbon rings constituting the defect sites in graphene.

Highly efficient capture and separation of thorium in the post-processing of the thorium‑uranium fuel cycle or from thorium-containing wastewater is crucial, but still remains a great challenge. Solid-state adsorption has been recognized as one of the most promising techniques due to its simple operation, low maintenance costs and high efficiency. In this work, two imine-linked three-dimensional (3D) covalent organic frameworks (COFs), i.e., TAPA-TFPPY COF and TAPA-TTF COF, are synthesized for selective adsorption and separation of thorium from the thorium-containing wastewater. Both 3D COFs exhibit two-fold interpenetrated pts structure with high specific surface area and uniform pore size. With such special pts topology, the interconnected channels enable the full exposure of adsorption binding sites for Th (IV) and accelerated diffusion of substrates, leading to rapid adsorption rate and high Th (IV) adsorption capability, being as high as 540.5 mg g−1 for TAPA-TFPPY COF and 1428.9 mg g−1 for TAPA-TTF COF. Competition adsorption experiments show that both 3D COFs exhibit excellent adsorption selectivity with ultrahigh partition coefficients (Kd), i.e., STh/Cs, STh/Pr, and STh/U greater than 200 for TAPA-TFPPY COF, and STh/U greater than 200, STh/Pr and STh/Nd greater than 150, and in particular, no Cs+ was detected when TAPA-TTF COF was used. The adsorption mechanism has been investigated by spectral characterization and theoretical calculations. It is revealed that Th(IV) bonds chemically to the imine nitrogen and sulfur atoms, both of which possess greater affinity towards Th(IV) than other potentially competitive metal ions, giving rise to the excellent adsorption selectivity. These 3D COFs are expected to be applied to thorium-containing wastewater to efficiently separate thorium so as to reduce the harm to the environment and humans.

Efficient separation and recovery of thorium(iv) are essential for a sustainable nuclear fuel cycle and environmental protection. Imine-based covalent organic frameworks (COFs) often face challenges due to mismatches between pore structures and mass-transfer processes during adsorption. To tackle this issue, we used 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) as a building block, incorporating large PyTTA and small BDA as linkers. We synthesized two COFs with varying pore sizes, COF-1 and COF-2, using a solvothermal method to create distinct pore environments. We systematically examined their impact on Th(iv) adsorption behavior. COF-1, with its dense skeleton and maximized active-site density, achieved excellent pore-size matching, resulting in high selectivity and a saturated adsorption capacity of approximately 200 mg g-1 at pH 4.5 and 298 K. In contrast, COF-2 formed an open framework with larger pores, enhancing mass transfer and providing faster adsorption kinetics. These findings highlight the distinct influence of pore-size engineering on adsorption capacity and kinetics, demonstrating a differentiation strategy.

Iodine is one of the key elements that must be removed from the off-gas systems of nuclear fuel reprocessing. This study systematically investigates the iodine vapor adsorption performance of the metal–organic framework (MOF) material HKUST-1(1-(2-methyl-4-(2-oxopyrrolidin-1-yl)phenyl)-3-morpholino-5,6-dihydropyridin-2(1H)-one), with particle sizes of 100 nm and 20 μm. HKUST-1 samples with varying particle sizes were synthesized via a hydrothermal method. The experimental results show that the 20 μm HKUST-1 exhibits superior crystallinity, a more intact pore structure, and a higher iodine adsorption capacity, reaching 700 mg/g, which is significantly greater than the 300 mg/g capacity of the 100 nm HKUST-1. Kinetic analysis reveals that the adsorption process follows the pseudo-second-order model, with physical adsorption as the predominant mechanism, where iodine molecules are accommodated within the pores. FTIR and XRD further confirm the structural stability of the HKUST-1 framework after iodine adsorption. However, desorption experiments show that iodine molecules are easily volatilized into the air, with a 20% weight loss observed within 10 h and a color change from black to green. The results provide experimental evidence for optimizing the application of HKUST-1 materials in iodine capture and suggest that material modification could enhance the long-term stability of iodine fixation.

Density functional theory with dispersion correction (DFT-D3) is used to investigate the adsorption and decomposition of hydrazine (N2H4) on Pt(111) surface, and the effect of water on decomposition process is considered. The stable adsorption configurations and adsorption energies are obtained for hydrazine, water and intermediate species. The hydrazine decomposition is investigated in three kinds of pathways including intramolecular dehydrogenation and intermolecular dehydrogenation via H atom or OH group assistance. It is shown that the adsorption of water in partially dissociative conformation (H and OH radicals) is the most stable on Pt (111) surface for its largest adsorption energy. The OH group can greatly promote the decomposition of hydrazine by drastically decreasing the energy barriers of dehydrogenation reactions, which are closely related to the overall PDOS distribution shifts of their transition states. From thermodynamics and kinetics points of view, the favorable decomposition pathway of hydrazine may be N2H4+OH -> N2H3+OH -> NHNH+OH -> NNH+OH -> N2.

The persistence in the environment and radiotoxicity of aqueous Th(IV) ions necessitate prompt remediation strategies. Here, we introduce a novel SiO2@Al-MOF nanocomposite synthesized in-situ, showcasing remarkable efficacy in Th(IV) removal. The strategic incorporation of silica offers dual advantages: (1) enhanced framework crystallinity as confirmed by PXRD analysis, and (2) superior thermal stability surpassing conventional Al-MOF materials. With an optimized Th(IV) adsorption capacity of 1707.0 mg g(-1) - exceeding pristine Al-MOF by 129.0 % and outperforming standard adsorbents - the composite exhibits two key strengths: (i) exceptional ion selectivity (SFTh/metals > 4 x 10(3) in multicomponent systems), and (ii) consistent regeneration capability (85 % retention after 3 cycles). These combined benefits position SiO2@Al-MOF as a promising candidate for practical thorium decontamination applications.

The rational disposal of radioactive iodine (referring to 129I and 131I) generated by nuclear reactions has become increasingly pressing due to their high chemical toxicity, fast mobility and long half-life. Herein, two threedimensional covalent organic frameworks (3D COFs), TAPA-TTF COF and TAPA-TBAP COF, have been designed and synthesized for iodine capture. The combination of tetrahedral (Td) knot with four-connected building units produces 3D COFs with two-fold interpenetrated pts topological structure, high crystallinity and large surface area. The unique pts topology allows for full exposure of functional adsorption sites to the channels, which is favorable for the adsorption of iodine. As expected, TAPA-TTF COF and TAPA-TBAP COF showed high iodine adsorption capability as high as 6.72 and 5.78 g g-1, respectively, at 75 degrees C under atmospheric pressure. Additionally, both 3D COFs also exhibited good retention capacity and reusability. The adsorption mechanism revealed that iodine molecules may readily form the electron transfer (CT) complexes with the imine groups, fully exposed it-conjugated aromatic ring and heteroatoms (S and N) of the skeleton. The strong CT interactions contribute to the extremely high iodine adsorption capability of TAPA-TTF COF and TAPA-TBAP COF. This study may provide a guidance for the design and synthesis of COFs as promising adsorbents for highly effective iodine uptake in nuclear energy field.