Preparation and modification of forcespun polypropylene nanofibers for adsorption of uranium (VI) from simulated seawater

Phytic acid-functionalized polyamidoxime/alginate hydrogel for targeted uranium extraction from acidic wastewater

Efficient removal of uranium from radioactive wastewater is crucial for both environmental protection and sustainable development of nuclear energy. However, selectively extracting uranium from acidic wastewater remains a significant challenge. Here we present a phytic acid-functionalized polyamidoxime/alginate hydrogel (PAG) via a facile one-step hydrothermal reaction. The PAG, leveraging the robust binding affinity of phytic acid and the selective coordination of amidoxime for U(VI), exhibited high efficiency and selectivity in adsorbing U(VI) from acidic uranium-containing wastewater. At pH 2.50, U(VI) adsorption equilibrium was achieved within 60 min, showcasing a maximum theoretical adsorption capacity of 218.34 mg/g. Additionally, the PAG demonstrated excellent reusability, maintaining a uranium removal rate exceeding 90 % over five adsorption-desorption cycles. Remarkably, the as-synthesized PAG removed 94.1 % of U(VI) from actual acidic uranium-contaminated groundwater with excellent anti-interference performance, reducing U(VI) concentration from 272.0 μg/L to 16.1 μg/L and making it meet the WHO drinking water standards (30 μg/L). The adsorption mechanism was elucidated through XPS and DFT calculation, revealing that the uranyl ion primarily coordinated with phosphate and amidoxime groups on phytic acid and polyamidoxime, respectively. These findings underscore the promising potential of PAG hydrogel for addressing acidic uranium-containing wastewater from uranium mining and metallurgy.

Understanding competitive Cu2+ and Zn2+ adsorption onto functionalized cellulose fiber via experimental and theoretical approach

Amidoxime groups were successfully introduced to develop a novel amidoxime-functionalized cellulose fiber (AO-Cell) for absorptive removal of heavy metal ions in wastewater. The chemical structure, and the competitive adsorption of Cu2+ and Zn2+ by AO-Cell were investigated by experiments study, Density functional theory (DFT) and molecular dynamic (MD) simulation. The results showed the N and O atoms in the amidoxime group can spontaneously interact with Cu2+ and Zn2+ through sharing long pair electrons to generate stable coordination structure, which was the dominant adsorption mechanism. Besides, the enlarged surface area, improved hydrophilicity and dispersion offered by AO-Cell facilitate the adsorption process by increasing the accessibility of absorption sites. As results of these synergetic modification, AO-Cell can remain effective in a wide pH range (1-6) and reach adsorption equilibrium within 60 min. At optimal conditions, the achieved theoretical adsorption capacity is as high as 84.81 mg/g for Cu2+ and 61.46 mg/g for Zn2+ in the solution with multiple ions. The competition between Cu2+ and Zn2+ in occupying the absorption sites arises from the difference in the metallic ion affinity and covalent index with the adsorbent as demonstrated by the MD analysis. Importantly, AO-Cell demonstrated favorable recyclability after up to 10 adsorption-desorption cycles.

Adsorbents for the Uranium Capture from Seawater for a Clean Energy Source and Environmental Safety: A Review

On the global level, uranium is considered the main nuclear energy source, and its removal from terrestrial ores is enough to last until the end of the current century. Therefore, a major focus is attracted toward the capture of uranium from a sustainable source (seawater). Uranium recovery from seawater has been reported over the last few decades, and recently many efforts have been devoted to the preparation of such adsorbents with higher selectivity and adsorption capacity. The purpose of this review is to report the advancement in adsorbent preparation and modification of porous materials. It also discusses challenges such as adsorbent selectivity, low uranium concentration in seawater, contact time, biofouling, and the solution to the problems necessary to ensure a better adsorption performance of the adsorbent.

Advances of polyolefins from fiber to nanofiber: fabrication and recent applications

Polyolefins are a widely accepted commodity polymer made from olefinic monomer consisting of carbon and hydrogen. This thermoplastic polymeric material is formed through reactive double bonds of olefins by the addition polymerization technique and it possesses a diverse range of unique features for a large variety of applications. Among the various types, polyethylene and polypropylene are the prominent classes of polyolefins that can be crafted and manipulated into diversified products for numerous applications. Research on polyolefins has boomed tremendously in recent times owing to the abundance of raw materials, low cost, lightweight, high chemical resistance, diverse functionalities, and outstanding physical characteristics. Polyolefins have also evidenced their potentiality as a fiber in micro to nanoscale and emerged as a fascinating material for widespread high-performance use. This review aims to provide an elucidation of the breakthroughs in polyolefins, namely as fibers, filaments, and yarns, and their applications in many domains such as medicine, body armor, and load-bearing industries. Moreover, the development of electrospun polyolefin nanofibers employing cutting-edge techniques and their prospective utilization in filtration, biomedical engineering, protective textiles, and lithium-ion batteries has been illustrated meticulously. Besides, this review delineates the challenges associated with the formation of polyolefin nanofiber using different techniques and critically analyzes overcoming the difficulties in forming functional nanofibers for the innovative field of applications.

Efficient adsorption of low-concentration uranium from aqueous solutions

The development of nuclear energy has led to the depletion of uranium resources and now presents the challenge of treating radioactive wastewater. Extracting uranium from seawater and nuclear wastewater has been identified as an effective strategy for addressing these issues. However, extracting uranium from nuclear wastewater and seawater is still extremely challenging. In this study, an amidoxime-modified feather keratin aerogel (FK-AO aerogel) was prepared using feather keratin for efficient uranium adsorption. The FK-AO aerogel showed an impressive adsorption capacity of 585.88 mg·g^-1 in an 8 ppm uranium solution, with a calculated maximum adsorption capacity of 990.10 mg·g^-1. Notably, the FK-AO aerogel demonstrated excellent selectivity for U(VI) in simulated seawater that contained coexisting heavy metal ions. In a uranium solution having a salinity of 35 g·L^-1 and a concentration of 0.1-2 ppm, the FK-AO aerogel achieved a uranium removal rate of greater than 90 %, indicating its effectiveness in adsorbing uranium in environments having high salinity and low concentration. This suggests that FK-AO aerogel is an ideal adsorbent for extracting uranium from seawater and nuclear wastewater, and it is also expected that it could be used in industrial applications for extracting uranium from seawater.

Effective CO2 capture by using poly (acrylonitrile) nanofibers based on the radiation grafting procedure in fixed-bed adsorption column

In this study, a new adsorbent was investigated for CO₂ adsorption in the fixed-bed column. Poly (acrylonitrile) nanofibers were prepared by electrospinning, then grafting under gamma irradiation with glycidyl methacrylate (GMA). Then, the nanofibers were modified with ethanolamine (EA), diethylamine (DEA) and triethylamine (TEA) to adsorb carbon dioxide molecules. Dynamic adsorption experiments were performed with a mixture of CH₄, CO₂ in a constant bed column at ambient pressure and temperature and CO₂ feed concentration (5%). The maximum adsorption capacity is 2.84 mmol/g for samples with 172.26% degree of grafting (DG) in 10 kGy. Also, the degree of amination with ethanolamine was achieved equal to 170.83%. In addition, the reduction of the regeneration temperature and the stability of this adsorbent after four cycles indicated the high performance of this adsorbent for CO₂ adsorption.

Constructing an ultrastable imidazole covalent organic framework for concurrent uranium detection and recovery

Uranium is one of the most important strategic resources for the development of the nuclear industry, but its unintended release has created potential environmental and health risks. It is highly desired to explore new methods that enable concurrent uranium monitoring and recovery for environmental protection and sustainable development of the nuclear industry. Here, for the first time, an imidazole fluorescent covalent organic framework (named PyTT-Tp) with ultrastable skeleton and open nanopore channel is synthesized by condensing ammonium acetate, 1,3,5-triformylphloroglucinol and pyrene-4,5,9,10-tetrone. By precisely tailoring complexing ligands, PyTT-Tp shows an excellent uranium recovery capacity of 941.27 mg g^-1 and reached equilibrium within 60 min, which can be attributed to dense selective uranium binding sites on the highly accessible open skeleton. In addition, due to the signal amplification of the pyrene-imidazole skeleton, it has an ultra-low detection limit of 4.92 nM UO₂²⁺ and an ultra-fast response time (2 s) suitable for on-site monitoring the uranium content of the extracted water. By modulating target complexing ligands, this approach can be extended to the monitoring and recovery of other strategic nuclides.

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.

Amidoxime functionalized chitosan for uranium sequestration in vivo

Amidoxime functionalized chitosan (AC) was recommended as a chelator for uranium sequestration in vivo in this study, and the structure-activity relationship was also explored. Compared with ZnNa₃-DTPA, which was a commercial uranium mobilization drug, AC exhibited excellent biocompatibility and uranium removal efficiency, whether by injection or orally, which could reduce the amounts of uranium deposited in kidneys and femurs by up to 43.6% and 32.3%. In particular, ACs still possessed the ability to mobilize uranium in vivo even if administration was delayed for 72 h.

Carbon materials for extraction of uranium from seawater

With the rapid growth of population and industrialization, the energy crisis and environmental pollution as two main difficulties urgently need to be solved nowadays. The development and utilization of nuclear energy is of great significance for solving energy support, national security and environmental protection. As the raw material of nuclear energy, a lot of uranium in seawater provide a guarantee for the sustainable and green development of nuclear power plants. Recently, various new carbon-based materials (e.g., carbon nanofibers, multiwalled carbon nanotube, graphene) have been attracted widely intense interest in extraction of uranium from seawater due to large specific surface area, excellent acid-base resistance, high adsorption performance, environmental friendly and low cost. Thus, the systematic reviews concerning the extraction of uranium from seawater on various carbon-based materials were highly desirable. In this review, the extraction methods of uranium from seawater, including electrochemical, photocatalytic and adsorption methods are briefly introduced. Then the application and mechanism of four generation carbon-based materials on the extraction of uranium from seawater are systematically reviewed in details. Finally, the current challenges and future trends of uranium extraction from seawaters are proposed. This review provides the guideline for designing carbon-based materials with high adsorption capacity and exceptional selectivity for U(VI) extraction from seawater.

Removal of Uranyl Ion from Wastewater by Magnetic Adsorption Material of Polyaniline Combined with CuFe2O4

The magnetic adsorption material of polyaniline (PANI) with amino functional group combined with CuFe2O4 (CuFe2O4/PANI nanocomposite) has been described in this work. It has been characterized by TEM, XRD, XPS, BET, FTIR, and VSM, respectively. Significantly, it exhibits extremely high maximum adsorption capacity (322.6 mg/g) for removal of uranyl ions from wastewater at a pH of 4. The adsorption process is consistent with the quasisecond-order kinetic equation, and the isotherm and kinetic data are accurately described by the Langmuir isothermal adsorption model. Furthermore, the magnetic CuFe2O4/PANI displays stable adsorption performance for uranyl ions after five cycles of recovery in acid medium, which indicates it possesses good recovery due to its magnetism and excellent regeneration ability for reusability.