High-efficiency uranium extraction from seawater by low-cost natural protein hydrogel.

Utilization of uranium resource in seawater are highly possible to meet the growth demands for the sustainable development of nuclear energy industry. Bio-adsorbents exhibit high performance in terms of adsorption selectivity, equilibrium speed, and environmental friendliness, while the high fabrication cost hinders their practical application. In this study, a low-cost soy protein isolate (SPI) is used to fabricate adsorbent named SPI hydrogel for uranium extraction. This is the first report on applying bio-adsorbents derived from low-cost natural proteins for uranium extraction. The SPI hydrogel showed high uranium adsorption capacity of 53.94 mg g-1 in simulated nuclear wastewater and 5.29 mg g-1 is achieved in natural seawater, which is higher than all currently available adsorbents based on non-modified natural biomolecules. The amino and oxygen-containing groups are identified as the functional groups for uranyl binding by providing four oxygen and two nitrogen atoms to form equatorial coordination with uranyl, which guarantees the high binding selectivity and affinity to uranyl ions. The low cost for accessing the raw material together with the environmental friendliness, high salt tolerance, high uranium adsorption ability, and high selectivity to uranium, make SPI hydrogel a promising adsorbent for uranium extraction from seawater and nuclear wastewater.

Ultrafast extraction of uranium from seawater using photosensitized biohybrid system with bioinspired cascaded strategy.

The highly effective utilization of uranium resources in global seawater is a viable method to satisfy the rising demands for fueling nuclear energy industry. Herein, inspired by the multi-mechanisms of the marine bacteria for uranium immobilization, CdS nanoparticles are deposited on the cell of marine bacterial strain Bacillus velezensis UUS-1 to create a photosensitized biohybrid system UUS-1/CdS. This system achieves high uranium extraction efficiency using a cascaded strategy, where the bacterial cells guarantee high extraction selectivity and the photosensitive CdS nanoparticles realize cascading photoreduction of high soluble U(VI) to low soluble U(IV) to enhance extraction capacity. As one of the fastest-acting adsorbents in natural seawater, a high extraction capacity for uranium of 7.03 mg g-1 is achieved with an ultrafast extraction speed of 4.69 mg g-1 d-1. The cascaded strategy promisingly improves uranium extraction performance and pioneers a new direction for the design of adsorbents to extract uranium from seawater.

Cuttlefish ink loaded polyamidoxime adsorbent with excellent photothermal conversion and antibacterial activity for highly efficient uranium capture from natural seawater.

Owing to the abundant uranium reserves in the oceans, the collection of uranium from seawater has aroused the widespread interest. Compared to the uranium extraction from ore, uranium collection from seawater is a more environmentally friendly strategy. The amidoxime (AO) functional group has been considered as one of the most efficient chelating groups for uranium capture. In this work, by drawing upon the photothermal character and antibacterial activity of cuttlefish ink, a cuttlefish ink loaded polyamidoxime (CI-PAO) membrane adsorbent is developed. Under one-sun illumination, the CI-PAO membrane shows a high extraction capacity of 488.76 mg-U/g-Ads in 500 mL 8 ppm uranium spiked simulated seawater, which is 1.24 times higher than PAO membrane. The adsorption rate of CI-PAO membrane is increased by 32.04%. Furthermore, exhibiting roughly 75% bacteriostatic rate in composite marine bacteria, the CI-PAO shows a dramatically antibacterial activity, which effectively prevents the functional sites on the adsorbent surface from being occupied by the biofouling blocks. After immersing in natural seawater for 4 weeks, light-irradiated CI-PAO gave high uranium uptake capacity of 6.17 mg-U/g-Ads. Hence, the CI-PAO membrane adsorbent can be considered as a potential candidate for the practical application for uranium extraction from seawater.

Amidoxime Group-Anchored Single Cobalt Atoms for Anti-Biofouling during Uranium Extraction from Seawater.

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.

Ultrasensitive Detection of Aqueous Uranyl Based on Uranyl-Triggered Protein Photocleavage.

The detection of environmental uranyl is attracting increasing attention. However, the available detection strategies mainly depend on the selective recognition of uranyl, which is subject to severe interference by coexisting metal ions. Herein, based on the unique uranyl-triggered photocleavage property, the protein BSA is labelled with fluorescent molecules that exhibit an aggregation-induced emission effect for uranyl detection. Uranyl-triggered photocleavage causes the separation of the fluorescent-molecule-labelled protein fragments, leading to attenuation of the emission fluorescence, which is used as a signal for uranyl detection. This detection strategy shows high selectivity for uranyl and an ultralow detection limit of 24 pM with a broad detection range covering five orders of magnitude. The detection method also shows high reliability and stability, making it a promising technique for practical applications in diverse environments.

Highly efficient immobilization of environmental uranium contamination with Pseudomonas stutzeri by biosorption, biomineralization, and bioreduction.

Uranium is a heavy metal with both chemotoxicity and radiotoxicity. Due to the increasing consumption of uranium, the remediation of uranium contamination and recovery of uranium from non-conventional approach is highly needed. Microorganism exhibits high potential for immobilization of uranium. This study for the first time isolated a marine Pseudomonas stutzeri strain MRU-UE1 with high uranium immobilization capacity of 308.72 mg/g, which is attributed to the synergetic mechanisms of biosorption, biomineralization, and bioreduction. The uranium is found to be immobilized in forms of tetragonal chernikovite (H2(UO2)2(PO4)2·8H2O) by biomineralization and CaU(PO4)2 by bioreduction under aerobic environment, which is rarely observed and would broaden the application of this strain in aerobic condition. The protein, phosphate group, and carboxyl group are found to be essential for the biosorption of uranium. In response to the stress of uranium, the strain produces inorganic phosphate group, which transformed soluble uranyl ion to insoluble uranium-containing precipitates, and poly-ß-hydroxybutyrate (PHB), which is observed for the first time during the interaction between microorganism and uranium. In summary, P. stutzeri strain MRU-UE1 would be a promising alternative for environmental uranium contamination remediation and uranium extraction from seawater.

Antibiofouling Ultrathin Poly(amidoxime) Membrane for Enhanced U(VI) Recovery from Wastewater and Seawater.

Although eco-friendly amidoxime-based adsorbents own an excellent uranium (U)-adsorption capacity, their U-adsorption efficiency is commonly reduced and even damaged by the biological adhesion from bacteria/microorganisms in an aqueous environment. Herein, we present an antibiofouling ultrathin poly(amidoxime) membrane (AUPM) with highly enhanced U-adsorption performance, through dispersing the quaternized chitosan (Q-CS) and poly(amidoxime) in a cross-linked sulfonated cellulose nanocrystals (S-CNC) network. The cross-linked S-CNC not only can elevate the hydrophilicity to improve the U-adsorption efficiency of AUPM but also can enhance the mechanical strength to form a self-supporting ultrathin membrane (17.21 MPa, 10 µm thickness). More importantly, this AUPM owns a good antibiofouling property, owing to the broad-spectrum antibacterial quaternary ammonium groups of the Q-CS. As a result, within the 1.00 L of low-concentration (100 ppb) U-added pure water (pH ≈ 5) and seawater (pH ≈ 8) for 48 h, 30 mg of AUPM can recover 93.7% U and 91.4% U, respectively. Furthermore, compared with the U-absorption capacity of a blank membrane without the Q-CS, that of AUPM can significantly increase 37.4% reaching from 6.39 to 8.78 mg/g after being in natural seawater for only 25 d. Additionally, this AUPM can still maintain almost constant tensile strength during 10 cycles of adsorption-desorption, which indicates the relatively long-term usability of AUPM. This AUPM will be a promising candidate for highly efficient and large-scale U-recovery from both U-containing waste freshwater/seawater and natural seawater, which will be greatly helpful to deal with the U-pollution and enrich U for the consumption of nuclear power. More importantly, the work will provide a new convenient but universal strategy to fabricate new highly enhanced low-cost U-adsorbents, through the introduction of both an antibacterial property and a high mechanical performance, which will be a good reference for the design of new highly efficient U-adsorbents.

DNA nano-pocket for ultra-selective uranyl extraction from seawater.

Extraction of uranium from seawater is critical for the sustainable development of nuclear energy. However, the currently available uranium adsorbents are hampered by co-existing metal ion interference. DNAzymes exhibit high selectivity to specific metal ions, yet there is no DNA-based adsorbent for extraction of soluble minerals from seawater. Herein, the uranyl-binding DNA strand from the DNAzyme is polymerized into DNA-based uranium extraction hydrogel (DNA-UEH) that exhibits a high uranium adsorption capacity of 6.06 mg g-1 with 18.95 times high selectivity for uranium against vanadium in natural seawater. The uranium is found to be bound by oxygen atoms from the phosphate groups and the carbonyl groups, which formed the specific nano-pocket that empowers DNA-UEH with high selectivity and high binding affinity. This study both provides an adsorbent for uranium extraction from seawater and broadens the application of DNA for being used in recovery of high-value soluble minerals from seawater.

Bio-inspired antibacterial cellulose paper-poly(amidoxime) composite hydrogel for highly efficient uranium(vi) capture from seawater.

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.