Significantly Enhanced Uranium Extraction from Seawater with Mass Produced Fully Amidoximated Nanofiber Adsorbent

Abstract

electricity on a large scale with ultralow greenhouse gases emission. [2] Uranium is the most critical ingredient for the production of nuclear power. In order for nuclear power to be a sustainable energy generation in the future, economically viable sources of uranium beyond terrestrial ores must be developed. [3] The oceans hold ≈4.5 billion tons of uranium, [4] making them a potential huge resource to support nuclear power production for hundreds of years. [5] All that is required is the ability to capture this element from seawater in cost-and energy-efficient ways. In the last decades, researchers worldwide have tried various methods to recover uranium from seawater and aqueous solution, such as coprecipitation, [6] ion-exchange, [7] adsorption via porous organic polymers, [8,9] and organic-inorganic hybrid adsorbents. [10][11][12][13][14][15][16] Among these technologies, the adsorption approach, particularly by using fiber-based adsorbents, is recognized as the most feasible process in terms of practicality, processability, cost, and environmental concerns. [3,17] In the 1990s, Japan Atomic Energy Agency (JAEA) research teams had successfully captured over 1083 g of uranium directly from ocean by using nonwoven fabric adsorbent, firmly establishing the practicality of uranium recovery from the oceans in appreciable quantities. [3,18] Uranium extraction from seawater via fiber adsorption has recentlyThe oceans contain hundreds of times more uranium than terrestrial ores. Fiber-based adsorption is considered to be the most promising method to realize the industrialization of uranium extraction from seawater. In this work, a pre-amidoximation with a blow spinning strategy is developed for mass production of poly(imide dioxime) nanofiber (PIDO NF) adsorbents with many chelating sites, excellent hydrophilicity, 3D porous architecture, and good mechanical properties. The structural evidences from 13 C NMR spectra confirm that the main functional group responsible for the uranyl binding is not "amidoxime" but cyclic "imidedioxime." The uranium adsorption capacity of the PIDO NF adsorbent reaches 951 mg-U per g-Ads in uranium (8 ppm) spiked natural seawater. An average adsorption capacity of 8.7 mg-U per g-Ads is obtained after 56 d of exposure in natural seawater via a flowthrough column system. Moreover, up to 98.5% of the adsorbed uranium can be rapidly eluted out and the adsorbent can be regenerated and reused for over eight cycles of adsorption-desorption. This new blow spun PIDO nanofabric shows great potential as a new generation adsorbent for uranium extraction from seawater.

A Marine‐Inspired Hybrid Sponge for Highly Efficient Uranium Extraction from Seawater

“…Compared with the survey spectrum of MS@PIDO/Alg, new strong U 4f double peaks clearly appear in the spectrum of MS@PIDO/Alg‐uranyl. As shown in the corresponding high‐resolution spectrum (Figure c), the U 4f 5/2 and U 4f 7/2 peaks shift from 391.15 and 380.30 eV (in uranyl nitrate, the raw reagent of uranium source) to 392.40 and 381.90 eV (in MS@PIDO/Alg‐uranyl), respectively, revealing the strong interaction of uranyl with adsorbent (amidoxime/imide dioxime groups) in the adsorption process . The O 1s spectrum of MS@PIDO/Alg (Figure d) can be fitted to three peaks, centered at binding energies of 530.90, 531.65, and 532.60 eV, which are attributed to COO − and COC groups from alginate, as well as CNOH groups from PIDO, respectively.…”

“…However, it is obvious that the formation of a porous structure will inevitably decrease the mechanical strength of the fibers. Moreover, after essential post‐amidoximation and subsequent alkaline treatment, the mechanical strength of these fibers is severely decreased further, making them hardly meet the requirement for real applications . Thus, to develop a new strategy for the mass production of a new adsorbent (or novel structure) that combines an excellent adsorption capability with enough mechanical strength is of great significance for industrial‐scale uranium extraction from seawater.…”

An Ion‐Crosslinked Supramolecular Hydrogel for Ultrahigh and Fast Uranium Recovery from Seawater

“…Consequently, only the superficial amidoxime groups can attain high uranium adsorption efficiency . To improve the overall uranium adsorption capacity of the amidoxime groups, one effective strategy is to dramatically increase the specific surface area of these adsorbents (for instance, by designing microporous structures or ultrathin nanofibers). However, such methods typically require specific expensive equipments and often make the adsorbents more difficult to cost‐effectively fabricate at large scales.…”

“…As shown in Figure a, after being immersed in 8, 16, and 32 ppm U‐spiked water for 96 h, the saturated uranium adsorption capacity ( Q U ) of the Zn 2+ –PAO hydrogel membrane ( m Zn 2+ : m PAO = 4:100) reached 664 ± 19.2, 868 ± 17.8, and 1188 ± 18.9 mg g −1 of M U / M dry gel , respectively. The pseudo‐second‐order kinetics described by Equation were used to research the U‐adsorption performance of this hydrogel membrane where t , k 2 , q t , and q e are the time (min), adsorption rate constant (g mg −1 min −1 ), uranium adsorption capacity (mg g −1 ) at a specific time, and uranium adsorption capacity (mg g −1 ) at equilibrium, respectively. The k 2 and q e values can be calculated from the uranium‐uptake of the samples (Figure a) based on the reported literature .…”

Functionalization and Fabrication of Soluble Polymers of Intrinsic Microporosity for CO2 Transformation and Uranium Extraction

“…The uranium content of seawater is about 99 % (approximate 40 million tons) of the total, but at the extremely low concentration (about 3.3 ppb), which leads to considerable works for [42][43][44] uranium extraction in the seawater. Moreover, real seawater, unlike simulated seawater or pure water, has more complex components, like 41,45 many trace elements not just uranium, microorganisms, and plants.…”