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.

High-strength and anti-biofouling nanofiber membranes for enhanced uranium recovery from seawater and wastewater.

Ultrathin fibers can increase the contact area between adsorbents and seawater during the uranium extraction process; however, their construction usually aggravates the complex spinning technology and lowers their mechanical strength. Meanwhile, high strength and antifouling ability are essential for ocean adsorbents to withstand the complex natural environment and microbial systems. Herein, we design high-strength and anti-biofouling poly(amidoxime) nanofiber membranes (HA-PAO NFMs) via a supramolecular crosslinking. Bacterial cellulose supplies the NFMs with ultrathin fiber structure, and large amounts of adsorption ligands are immobilized on the framework via the crosslinking with antibacterial ions. Thus, different from other fibers, HA-PAO NFMs achieve ultrathin diameter (20-30 nm), high BET area (51 m2 g-1), and excellent mechanical strength (13.6 MPa). The uranium adsorption capacity reaches to 409 mg-U/g-Ads in the simulated seawater, 99.2% uranium can be removed from the U-contained wastewater, and the adsorption process can be observed by the naked eye due to the significant color changes. The inhibition zones indicate their excellent anti-biofouling ability, which contributes to 1.83 times more uranium extraction amount from natural seawater than the non-antifouling adsorbents. Furthermore, they display a long service life and can be large-scale prepared, and the HA-PAO NFMs have potential in the massive uranium recovery.

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.