UiO-66-NH-(AO) MOFs with a New Ligand BDC-NH-(CN) for Efficient Extraction of Uranium from Seawater

Decorating Cage-Shaped Cavities with Carboxyl Groups on Two-Dimensional MOF Nanosheet for Trace Uranium(VI) Trapping

The efficient and complete extraction of uranium from aqueous solutions is crucial for safeguarding human health from potential radiotoxicity and chemotoxicity. Herein, an ultrathin 2D metal-organic framework (MOF) nanosheet with cavity structures was elaborately constructed, based on a calix[4]arene ligand. The large molecular skeleton and cup-shaped feature of the calix[4]arene enabled the as-prepared MOFs with large layer separations, which can be readily delaminated into ultrathin single-layer (∼1.25 nm) nanosheets. The incorporation of permanent cavity structures to the MOF nanosheets can fully utilize their structural features of readily accessible adsorption groups and exposed surface area in uranium removal, reaching ultrafast adsorption kinetics; the functionalized cavity structure endowed MOF nanosheets with the ability to preconcentrate and extract uranium from aqueous solutions with ultrahigh efficiencies, even at extremely low concentrations. As a result, relatively high removal ratios (>95%) can be achieved for uranium within 5 min, even in the ultralow concentration range of 75-250 ppb, and the residual uranium was reduced to below 4.9 ppb. The MOF nanosheets also exhibited extremely high anti-interference ability, which could efficiently remove the low-level uranium (∼150 ppb) from various real samples. The characterizations and density functional theory calculations demonstrated that the synergistic effects of multiple interactions between the carboxylate groups and cage-like cavities with uranyl ions can be responsible for the efficient and selective uranium extraction.

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.

Emerging anticancer potential and mechanisms of snake venom toxins: A review

Animal-derived venom, like snake venom, has been proven to be valuable natural resources for the drug development. Previously, snake venom was mainly investigated in its pharmacological activities in regulating coagulation, vasodilation, and cardiovascular function, and several marketed cardiovascular drugs were successfully developed from snake venom. In recent years, snake venom fractions have been demonstrated with anticancer properties of inducing apoptotic and autophagic cell death, restraining proliferation, suppressing angiogenesis, inhibiting cell adhesion and migration, improving immunity, and so on. A number of active anticancer enzymes and peptides have been identified from snake venom toxins, such as L-amino acid oxidases (LAAOs), phospholipase A2 (PLA2), metalloproteinases (MPs), three-finger toxins (3FTxs), serine proteinases (SPs), disintegrins, C-type lectin-like proteins (CTLPs), cell-penetrating peptides, cysteine-rich secretory proteins (CRISPs). In this review, we focus on summarizing these snake venom-derived anticancer components on their anticancer activities and underlying mechanisms. We will also discuss their potential to be developed as anticancer drugs in the future.

Study on uranium ion adsorption property of porous glass modified with amidoxime group

In this paper, we prepared three types of porous glasses (PGs) with specific surface areas of 311.60 m2/g, 277.60 m2/g, and 231.38 m2/g, respectively, via borosilicate glass phase separation. These glasses were further modified with amidoxime groups (AO) using the hydroxylamine method, yielding adsorbents named 1.5-PG-AO, 2-PG-AO, and 3-PG-AO. The adsorption performance of these adsorbents under various conditions was investigated, including sorption kinetics and adsorption mechanisms. The results reveal that the number of micropores and specific surface area of PG are significantly reduced after AO modification. All three adsorbents exhibit similar adsorption capabilities. Particularly, pH has a pronounced effect on U (VI) adsorption of PG-AO, with a maximum value at pH = 4.5. Equilibrium adsorption is achieved within 2 h, with a maximum adsorption capacity of 129 mg/g. Notably, a uranium removal rate of 99.94% is attained. Furthermore, the adsorbents show high selectivity in uranium solutions containing Na+ or K+. Moreover, the adsorbents demonstrate exceptional regeneration ability, with the removal rate remaining above 80% even after undergoing five adsorption-desorption cycles. The adsorption reaction of uranium on PG-AO involves a combination of multiple processes, with monolayer chemisorption being the dominant mechanism. Both the complex adsorption of AO and the ion exchange and physical adsorption of PG contribute to the adsorption of uranyl ions on the PG-AO adsorbents.

Highly Selective Extraction of U(VI) from Solutions by Metal Organic Framework-Based Nanomaterials through Sorption, Photochemistry, and Electrochemistry Strategies

With the rapid development of nuclear technology and peaceful utilization of nuclear energy, plentiful U(VI) not only is required to be extracted from solutions for a sustainable nuclear fuel supply but also is inevitably released into the surrounding environment to result in pollution and threaten human health. Thereby, realizing selective extraction of U(VI) from aqueous solutions is crucial for U(VI) pollution control and a sustainable nuclear industry. Metal organic frameworks (MOFs) have gained multidisciplinary attention due to their excellent properties including large specific surface areas, tunable pore structures, easy functionalization, etc. This Review comprehensively summarizes the research progress of MOFs and MOF-based materials on U(VI) removal from aqueous solutions by sorption, photocatalysis, electrocatalysis, membrane separation, etc. The efficient high extraction ability is dependent on the intrinsic properties of MOFs and the techniques used. The removal properties of MOF-based materials as adsorbents, photocatalysts, and electrocatalysts for U(VI) are discussed. Information about the interaction mechanisms between U(VI) and MOF-based materials are analyzed in-depth, including experiments, theoretical calculations, and advanced spectroscopy analysis. The removal properties for U(VI) of various MOF-based materials are assessed through different techniques. Finally, a summary and perspective on the direction and challenges of MOF-based materials and various pollutant removal technologies are proposed to provide some significant information on designing and fabricating MOF-based materials for environmental pollution management.

Statistically and visually analyzing the latest advancements and future trends of uranium removal

Uranium contamination and remediation is a very important environmental research area. Removing radioactive and toxic uranium from contaminated media requires fundamental knowledge of targets and materials. To explore the-State-of-the-Art in uranium contamination control, we employed a statistical tool called CiteSpace to visualize and statistically analyze 4203 peer-reviewed papers on uranium treatment published between 2008 and 2022. The primary content presentations of visual analysis were co-authorships, co-citations, keyword co-occurrence analysis with cluster analysis, which could offer purposeful information of research hots and trends in the field of uranium removal. The statistical analysis results indicated that studies on uranium removal have focused on adsorption of uranium from aqueous solution. From 2008 to 2022, biochar and biological treatment were firstly used to sequester uranium, then adsorption for uranium removal dominates with adsorbents of graphene oxide, primary nanofiber magnetic polymers and metal-organic frameworks (MOFs). In recent years, photocatalysts and metal-organic frameworks are expected to be two of the most popular research topics. In addition, we further highlighted the characteristics and applications of MOFs and GOs in uranium removal. Overall, a statistical review was proposed to visualize and summarize the knowledge and research trends regarding uranium treatment.

Hierarchical Porous Amidoximated Metal-Organic Framework for Highly Efficient Uranium Extraction

With the rapid development of industry and technology, high-efficiency extraction of uranium from seawater is a research hotspot from the aspect of nuclear energy development. Herein, a new amidoximated metal-organic framework (UiO-66-DAMN-AO) constructed through a novel organic ligand of 2-diaminomaleonitrile-terephthalic acid (BDC-DAMN) is designed via one-step post-synthetic methods (PSM), which possess the merit of abundant multiaffinity sites, large specific surface area, and unique porous structure for efficient uranium extraction. Adopting one-step PSM can alleviate the destruction of structural stability and the reduction of the conversion rate of amidoxime groups. Meanwhile, introducing the BDC-DAMN ligand with abundant multiaffinity sites endow UiO-66-DAMN-AO with excellent adsorption ability (Qm  = 426.3 mg g-1 ) and selectivity. Interestingly, the UiO-66-DAMN-AO has both micropores and mesopores, which may be attributed to the partial etching of UiO-66-DAMN-AO during the amidoximation. The presence of mesopores improves the mass transfer rate of UiO-66-DAMN-AO and provides more exposed active sites, favoring the adsorption of uranium on UiO-66-DAMN-AO. Thus, this study provides a feasible strategy for modifying metal-organic framework (MOFs) with plentiful amidoxime groups and the promising prospect for MOF-based materials to adsorb uranium from ocean.

Ultra-fast uranium capture via the synergistic interaction of the intrinsic sulfur atoms and the phosphoric acid groups adhered to edge sulfur of MoS2

In order to deal with the sudden nuclear leakage event to suppress the spread of radioactive contaminants in a short period of time, it is extremely urgent needed to explore an adsorbent that could be capable of in-situ remedial actions to rapidly capture the leaked radionuclides in split second. An adsorbent was developed that MoS₂ via ultrasonic to expose more surface defects afterwards functionalized by phosphoric acid resulting in more active sites being endowed on the edge S atoms of Mo-vacancy defects, while simultaneously increased the hydrophilicity and interlayer spacing. Hence, an overwhelming fast adsorption rates (adsorption equilibrium within 30 s) are presented and place the MoS₂-PO₄ at the top of performing sorbent materials. Moreover, the maximum capacity calculated from Langmuir model is as high as 354.61 mg·g^-1, the selective adsorption capacity (S_U) achieving 71.2% in the multi-ion system and with more than 91% capacity retention after 5 cycles of recycling. Finally, XPS and DFT insight into the adsorption mechanism, which can be explained as interaction of UO₂²⁺ on the surface of MoS₂-PO₄ by forming U-O and U-S bonds. The successful fabrication of such a material may provide a promising solution for emergency treatment of radioactive wastewater during nuclear leakage events.

Modeling and spectroscopic investigation of U(VI) removal on porous amidoxime-functionalized metal organic framework derived from macromolecular carbohydrate

The investigation of interaction mechanism of U(VI) selective removal on amidoxime-functionalized metal organic framework (i.e., UiO-66(Zr)-AO) derived from macromolecular carbohydrate is conducive to apply metal organic frameworks in actual environmental remediation. The batch experiments showed that UiO-66(Zr)-AO displayed the fast removal rate (equilibrium time of 0.5 h), high adsorption capacity (384.6 mg/g), excellent regeneration performance (<10 % decrease after three cycles) towards U(VI) removal due to the unprecedented chemical stability, large surface area and simple fabrication. U(VI) removal at different pH can be satisfactorily fitted by diffuse layer modeling with cation exchange at low pH and an inner-sphere surface complexation at high pH. The inner-sphere surface complexation was further demonstrated by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analysis. These findings revealed that UiO-66(Zr)-AO can be an effective adsorbent to remove the radionuclides from aqueous solution, which is crucial for recycling of uranium resource and decreasing the uranium harm to the environment.

Uranium extraction from seawater: material design, emerging technologies and marine engineering

Uranium extraction from seawater (UES), a potential approach to securing the long-term uranium supply and sustainability of nuclear energy, has experienced significant progress in the past decade. Promising adsorbents with record-high capacities have been developed by diverse innovative synthetic strategies, and scale-up marine field tests have been put forward by several countries. However, significant challenges remain in terms of the adsorbents' properties in complex marine environments, deployment methods, and the economic viability of current UES systems. This review presents an up-to-date overview of the latest advancements in the UES field, highlighting new insights into the mechanistic basis of UES and the methodologies towards the function-oriented development of uranium adsorbents with high adsorption capacity, selectivity, biofouling resistance, and durability. A distinctive emphasis is placed on emerging electrochemical and photochemical strategies that have been employed to develop efficient UES systems. The most recent achievements in marine tests by the major countries are summarized. Challenges and perspectives related to the fundamental, technical, and engineering aspects of UES are discussed. This review is envisaged to inspire innovative ideas and bring technical solutions towards the development of technically and economically viable UES systems.

Obtaining Water from Air Using Porous Metal-Organic Frameworks (MOFs)

Water collection from moisture in air, i.e., atmospheric water harvesting, is an urgent future need for society. It can be used for water production everywhere and anytime as an alternative water source in remote areas. However, water harvesting and collection usually relies on desalination, fog, and dewing harvesting, which are energy intensive. In this respect, metal-organic frameworks (MOFs) have broad applicability for water harvesting in water-scarce areas; therefore, the current discussion focuses on this approach. Furthermore, recent progress on MOFs for moisture harvesters is critically discussed. In addition, the design, operation, and water harvesting mechanisms of MOFs are studied. Finally, we discuss critical points for future research for the design of new MOFs as moisture harvesters for use in practical applications. MOF adsorbents offer excellent operating capacity in various temperature and pressure ranges. Rational water harvesters can thus be developed by adjusting structural properties such as the porosity, functionalities, and metal centers, thereby enabling new devices to produce water even in remote areas.

Nanoemulsion assembly toward vaterite mesoporous CaCO3 for high-efficient uranium extraction from seawater

Uranium extraction from seawater is particularly significant and regarded as an indispensable strategy for satisfying the increasing demand for nuclear fuel owing to the high uranium reserves (about 4.5 billion tons) in seawater, while remains great challenges due to the low concentration, the interference of various cations and the complexity of the marine environment. Thus, developing a highly efficient adsorbent with high adsorption capacity, excellent selectivity, low cost, and facile synthesis method is significant and urgently required. Inorganic materials show many advantages in adsorption such as low cost, fast response, high stability, etc, while conventionally, have poor capacity and selectivity especially in real seawater. Herein, mesoporous CaCO₃ (mCaCO₃) with vaterite phase is synthesized by a facile nanoemulsion strategy and "ready-to-use" for uranium adsorption without functionalization and post treatment. Surfactant Pluronic F127 not only assembles into reverse micelles to form mesopores, but also stabilizes the active vaterite phase. The obtained mCaCO₃ with high surface area (48.2 m²/g), interconnected mesopores (11 nm), and unique vaterite phase achieves highly efficient uranium adsorption with a maximum adsorption capacity of 850 ± 20 mg-U/g in uranium-spiked seawater and 6.5 ± 0.5 mg-U/g in 700 L of natural seawater for one week, as well as excellent selectivity, matching the state-of-the-art U adsorbents. After adsorption, mCaCO₃-U is dissolved with a simple acid elution to obtain concentrated uranyl solution for purification, avoiding the disposal of adsorbents. To the best of our knowledge, this is the first case to report mesoporous CaCO₃ for uranium adsorption from seawater with such a good performance. The facile synthesis, abundant raw materials and eco-friendly adsorption-desorption processes endow the mCaCO₃ as a promising candidate for large-scale uranium extraction from seawater.