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Marine biofouling is one of the most significant challenges hindering practical uranium extraction from seawater. Single atoms have been widely used in catalytic applications because of their remarkable redox property, implying that the single atom is highly capable of catalyzing the generation of reactive oxygen species (ROS) and acts as an anti‐biofouling substance for controlling biofouling. In this study, the Co single atom loaded polyacrylamidoxime (PAO) material, PAO‐Co, is fabricated based on the binding ability of the amidoxime group to uranyl and cobalt ions. Nitrogen and oxygen atoms from the amidoxime group stabilize the Co single atom. The fabricated PAO‐Co exhibits a broad range of antimicrobial activity against diverse marine microorganisms by producing ROS, with an inhibition rate up to 93.4%. The present study is the first to apply the single atom for controlling biofouling. The adsorbent achieves an ultrahigh uranium adsorption capacity of 9.7 mg g−1 in biofouling‐containing natural seawater, which decreased only by 11% compared with that in biofouling‐removed natural seawater. These findings indicate that applying single atoms would be a promising strategy for designing biofouling‐resistant adsorbents for uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

An adaptive coordination structure is vital for selective uranium extraction from seawater. By strategy of molecular imprinting, uranyl is introduced into a multivariate metal–organic framework (MOF) during the synthesis process to guide the in situ construction of proper nanocage structure for targeting uranyl binding. Except for the coordination between uranium with four oxygen from the materials, the axial oxygen of uranyl also forms hydrogen bonds with hydrogen from the phenolic hydroxyl group, which enhances the binding affinity of the material to uranyl. Attributing to the high binding affinity, the adsorbent shows high uranium binding selectivity to uranyl against not only the interfering metal ions, but also the carbonate group that coordinates with uranyl to form [UO2(CO)3]4− in seawater. In natural seawater, the adsorbent realizes a high uranium adsorption capacity of 7.35 mg g−1, together with an 18.38 times higher selectivity to vanadium. [ABSTRACT FROM AUTHOR]

An adaptive coordination structure is vital for selective uranium extraction from seawater. By strategy of molecular imprinting, uranyl is introduced into a multivariate metal–organic framework (MOF) during the synthesis process to guide the in situ construction of proper nanocage structure for targeting uranyl binding. Except for the coordination between uranium with four oxygen from the materials, the axial oxygen of uranyl also forms hydrogen bonds with hydrogen from the phenolic hydroxyl group, which enhances the binding affinity of the material to uranyl. Attributing to the high binding affinity, the adsorbent shows high uranium binding selectivity to uranyl against not only the interfering metal ions, but also the carbonate group that coordinates with uranyl to form [UO2(CO)3]4− in seawater. In natural seawater, the adsorbent realizes a high uranium adsorption capacity of 7.35 mg g−1, together with an 18.38 times higher selectivity to vanadium. [ABSTRACT FROM AUTHOR]

The extraction of uranium from seawater, which is an abundant resource, has attracted considerable attention as a viable form of energy‐resource acquisition. The two critical factors for boosting the chemical thermodynamics of uranium extraction from seawater are the availability of sufficient amounts of uranyl ions for supply to adsorbents and increased interaction temperatures. However, current approaches only rely on the free diffusion of uranyl ions from seawater to the functional groups within adsorbents, which largely limits the uranium extraction capacity. Herein, inspired by the mechanism of plant transpiration, a plant‐mimetic directional‐channel poly(amidoxime) (DC‐PAO) hydrogel is designed to enhance the uranium extraction efficiency via the active pumping of uranyl ions into the adsorbent. Compared with the original PAO hydrogel without plant‐mimetic transpiration, the uranium extraction capacity of the DC‐PAO hydrogel increases by 79.33% in natural seawater and affords the fastest reported uranium extraction average rate of 0.917 mg g−1 d−1 among the most state‐of‐the‐art amidoxime group‐based adsorbents, along with a high adsorption capacity of 6.42 mg g−1 within 7 d. The results indicate that the proposed method can enhance the efficiency of solar‐transpiration‐based uranium extraction from seawater, particularly in terms of reducing costs and saving processing time. [ABSTRACT FROM AUTHOR]

A bio-inspired cellulose paper–poly(amidoxime) composite hydrogel is explored via UV-polymerization. This hydrogel has a highly efficient uranium capture capacity of up to 6.21 mg g−1 for WU/Wdry gel and 12.9 mg g−1 for WU/Wpoly(amidoxime) in seawater for 6 weeks, due to its enhanced hydrophilicity, good hydraulic/ionic conductivity and broad-spectrum antibacterial performance. [ABSTRACT FROM AUTHOR]

• A new double-network hydrogel is explored for uranium recovery from seawater. • U-adsorption capacity of the hydrogel is greatly enhanced by added nanoclay. • Mechanical property of the hydrogel is largely improved by th double-network. • Used materials are lowcost and the hydrogel owns good U-adsorption reusability. Massive uranium recovery from seawater is a key project to provide the long-time consumption of global nuclear power, while it is still greatly difficult to achieve high-efficient adsorbents with high mechanical property. In this work, a new nanoclay-poly(amidoxime) (NC-PAO) high-strength double-network (DN) composite hydrogel adsorbent with high-efficient and fast uranium extraction capacity has been explored. The uranium adsorbing performance can be significantly enhanced by the small content of added super-hydrophilic NC (Laponite RDS sheets), because of the largely improved hydrophilicity of the hydrogel. Compared with the blank PAO DN hydrogel without nanoclay, the uranium adsorbing capacity of this NC-PAO DN hydrogel can largely increase 73.4% from 4.97 mg/g to 8.62 mg/g, after in seawater only 25 days. The uranium adsorption rate of this hydrogel from natural seawater, can reached 0.345 mg/(g∙day), which is excellent among existing uranium adsorbents. Furthermore, this hydrogel has high mechanical performance with 2.42 MPa of tensile strength and 16.13 MPa of compressive strength, which can be used in seawater for relatively longer time than traditional low-strength single-network hydrogel, owing to its double network (DN) structure (the weakly crosslinked gelatin soft network and the strongly crosslinked cellulose nanofiber (CNF) hard network). This NC-PAO DN hydrogel adsorbent will be an excellent candidate for fast uranium recovery from seawater in largescale. Most importantly, this work will inspire the development of new hydrogel-based adsorbents and even other type of adsorbents for high-efficient uranium extraction, through compositing various low-cost and super-hydrophilic nanomaterials to significantly improve the hydrophilicity of the adsorbent and designing double-network structure to largely enhance the mechanical property. [ABSTRACT FROM AUTHOR]

[Display omitted] • A charge balanced adsorbent is fabricated for uranium extraction from seawater. • The adsorbent can resistant both biofouling and abiotic fouling. • The uranium extraction capacity is highly enhanced. • The uranium adsorption ability and anti-adhesive ability are highly reusable. The extraction of uranium from seawater is vital to meet the increase demands of uranium resource for the nuclear energy industry, while it is severe hazarded by the marine fouling, including both the biofouling and abiotic fouling. Previous reports only focused on the control of biofouling and rare attention is paid to the abiotic fouling. However, the abiotic fouling is the fundamental of the biofouling. Herein, a charged balanced hydrogel adsorbent is fabricated by introducing the charge-positive tetraethylenepentamine (TEPA) into the charge-negative polyacrylamidoxime (PAO). The fabricated PAO-CB hydrogel membrane shows high anti-adhesive ability to the marine fouling, including both the biofouling and abiotic fouling, which is due to the decrease of the charge attraction between the adsorbent and the charged contaminants. Benefitting from the reduce of marine fouling, the PAO-CB hydrogel membrane shows a high uranium extraction capacity of 8.59 mg g−1, which is higher than that of PAO hydrogel membrane by 44.59%. The finding of this study indicates that the construction of charge balanced adsorbent would be an effective strategy to control the complicated marine fouling during uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A charge balanced adsorbent is fabricated for uranium extraction from seawater. • The adsorbent can resistant both biofouling and abiotic fouling. • The uranium extraction capacity is highly enhanced. • The uranium adsorption ability and anti-adhesive ability are highly reusable. The extraction of uranium from seawater is vital to meet the increase demands of uranium resource for the nuclear energy industry, while it is severe hazarded by the marine fouling, including both the biofouling and abiotic fouling. Previous reports only focused on the control of biofouling and rare attention is paid to the abiotic fouling. However, the abiotic fouling is the fundamental of the biofouling. Herein, a charged balanced hydrogel adsorbent is fabricated by introducing the charge-positive tetraethylenepentamine (TEPA) into the charge-negative polyacrylamidoxime (PAO). The fabricated PAO-CB hydrogel membrane shows high anti-adhesive ability to the marine fouling, including both the biofouling and abiotic fouling, which is due to the decrease of the charge attraction between the adsorbent and the charged contaminants. Benefitting from the reduce of marine fouling, the PAO-CB hydrogel membrane shows a high uranium extraction capacity of 8.59 mg g−1, which is higher than that of PAO hydrogel membrane by 44.59%. The finding of this study indicates that the construction of charge balanced adsorbent would be an effective strategy to control the complicated marine fouling during uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

The uranium level in seawater is ≈1000 times as high as terrestrial ores and can provide potential near‐infinite fuel for the nuclear energy industry. However, it is still a significant challenge to develop high‐efficiency and low‐cost adsorbents for massively extracting uranium from seawater. Herein, a simple and fast method through low‐energy consumption sunlight polymerization to direct fabrication of a poly(amidoxime) (PAO) hydrogel membrane, which exhibits high uranium adsorption capacity, is reported. This PAO hydrogel owns semi‐interpenetrating structure and a hydrophilic poly(acrylamide) 3D network of hydrogel which can disperse and fix PAOs well. As a result, the amidoxime groups of PAOs exhibit an outstanding uranium adsorption efficiency (718 ± 16.6 and 1279 ± 14.5 mg g−1 of muranium/mPAO in 8 and 32 ppm uranium‐spiked seawater, respectively) among reported hydrogel‐based adsorbents. Most importantly, U‐uptake capacity of this hydrogel can achieve 4.87 ± 0.38 mg g−1 of muranium/mdry gel just after four weeks within natural seawater. Furthermore, this hydrogel can be massively produced through low‐energy consumption and environmentally‐friendly sunlight polymerization. This work will provide a high‐efficiency and low‐cost adsorbent for massive uranium extraction from seawater. [ABSTRACT FROM AUTHOR]