Biosorption of heavy metal elements including radionuclides by microorganisms is a promising and effective method for the remediation of the contaminated places. The responses of live Saccharomyces ...cerevisiae in the toxic uranium solutions during the biosorption process and the mechanism of uranium biomineralization by cells were investigated in the present study. A novel experimental phenomenon that uranium concentrations have negative correlation with pH values and positive correlation with phosphate concentrations in the supernatant was observed, indicating that hydrogen ions, phosphate ions and uranyl ions were involved in the chernikovite precipitation actively. During the biosorption process, live cells desorb deposited uranium within the equilibrium state of biosorption system was reached and the phosphorus concentration increased gradually in the supernatant. These metabolic detoxification behaviours could significantly alleviate uranium toxicity and protect the survival of the cells better in the environment. The results of microscopic and spectroscopic analysis demonstrated that the precipitate on the cell surface was a type of uranium-phosphate compound in the form of a scale-like substance, and S. cerevisiae could transform the uranium precipitate into crystalline state-tetragonal chernikovite H2(UO2)2(PO4)2·8H2O.
The mechanisms of uranium biosorption and biomineralization by live S. cerevisiae. Display omitted
•Hydrogen ions, phosphate and uranyl ions could form a chernikovite precipitate.•Uranium desorption and phosphorus release are cell responses in uranium solution.•Tetragonal crystals of chernikovite were formed.
We present an automated separation method to simultaneously isolate short-lived activation products .sup.242g, 240Am, .sup.237U, .sup.72Ga from fresh fission products prior to gamma spectrometric ...analysis. On the basis of multi-column chromatographic units (HDEHP resin, TBP resin, DGA resin, TEVA resin, Al.sub.2O.sub.3, activated carbon) assembly, smart media compatibility between adjacent columns, chromatographic conditions optimization and process automation design, a modularized and streamline separation procedure was developed. The established method allows better recoveries of 93%, 91% and 97% for americium, uranium and gallium separately and excellent decontamination factors of more than 10.sup.5 for fission products even for large volume of samples. Because of highly efficient removal of interferents, this method coupled with well-type high-purity germanium (HPGe) gamma spectrometers achieved highly sensitive and selective analysis of activation products in spiked complicated matrix samples.
Microorganisms play a significant role in uranium(VI) biogeochemistry and influence U(VI) transformation through biomineralization. In the present work, the process of uranium mineralization was ...investigated by
Saccharomyces cerevisiae
. The toxicity experiments showed that the viability of cell was not significantly affected by 100 mg L
−1
U(VI) under 4 days of exposure time. The batch experiments showed that the phosphate concentration and pH value increased over time during U(VI) adsorption. Meanwhile, thermodynamic calculations demonstrated that the adsorption system was supersaturated with respect to UO
2
HPO
4
. The X-ray powder diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses indicated that the U(VI) was first attached onto the cell surface and reacted with hydroxyl, carboxyl, and phosphate groups through electrostatic interactions and complexation. As the immobilization of U(VI) transformed it from the ionic to the amorphous state, lamellar uranium precipitate was formed on the cell surface. With the prolongation of time, the amorphous uranium compound disappeared, and there were some crystalline substances observed extracellularly, which were well-characterized as tetragonal-chernikovite. Furthermore, the size of chernikovite was regulated at nano-level by cells, and the perfect crystal was formed finally. These findings provided an understanding of the non-reductive transformation process of U(VI) from the amorphous to crystalline state within microbe systems, which would be beneficial for the U(VI) treatment and reuse of nuclides and heavy metals.
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)34− 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.
An adsorbent was fabricated by the in situ construction of a uranyl‐imprinted nanostructure in a MOF material. Impressively, the adsorbent shows highly selective uranium extraction ability in natural seawater, which was attributed to the fitting coordination structure for uranyl.
Uranium is the main source for nuclear energy but also one of the most toxic heavy metals. The current methods for uranium removal from water present limitations, such as narrow pH operating range, ...limited tolerance to high salt concentrations, or/and high cost. We show here that a layered sulfide ion exchanger K2MnSn2S6 (KMS-1) overcomes these limitations and is exceptionally capable in selectively and rapidly sequestering high (ppm) as well as trace (ppb) quantities of UO2 2+ under a variety of conditions, including seawater. KMS-1 can efficiently absorb the naturally occurring U traces in seawater samples. The results presented here reveal the exceptional potential of sulfide-based ion-exchangers for remediating of uranium-containing wastes and groundwater and for extracting uranium from the sea.
•Natural and anthropogenic uranium contaminations cause latent risks to public health.•We reviewed the major health risks upon natural uranium exposure.•Chemotoxicity of natural uranium is ...predominant for chronic exposure at the environmental low doses.•Recent advances in toxicological mechanisms involved in the chemotoxicity of uranium are comprehensively presented.
Uranium contamination is a global health concern. Regarding natural or anthropogenic uranium contamination, the major sources of concern are groundwater, mining, phosphate fertilizers, nuclear facilities, and military activities. Many epidemiological and laboratory studies have demonstrated that environmental and occupational uranium exposure can induce multifarious health problems. Uranium exposure may cause health risks because of its chemotoxicity and radiotoxicity in natural or anthropogenic scenarios: the former is generally thought to play a more significant role with regard to the natural uranium exposure, and the latter is more relevant to enriched uranium exposure. The understanding of the health risks and underlying toxicological mechanisms of uranium remains at a preliminary stage, and many controversial findings require further research. In order to present state-of-the-art status in this field, this review will primarily focus on the chemotoxicity of uranium, rather than its radiotoxicity, as well as the involved toxicological mechanisms. First, the natural or anthropogenic uranium contamination scenarios will be briefly summarized. Second, the health risks upon natural uranium exposure, for example, nephrotoxicity, bone toxicity, reproductive toxicity, hepatotoxicity, neurotoxicity, and pulmonary toxicity, will be discussed based on the reported epidemiological cases and laboratory studies. Third, the recent advances regarding the toxicological mechanisms of uranium-induced chemotoxicity will be highlighted, including oxidative stress, genetic damage, protein impairment, inflammation, and metabolic disorder. Finally, the gaps and challenges in the knowledge of uranium-induced chemotoxicity and underlying mechanisms will be discussed.
Electrochemical uranium extraction from nuclear wastewater represents an emerging strategy for recycling uranium resources. However, in nuclear fuel production which generates the majority of ...uranium-containing nuclear wastewater, fluoride ion (F
) co-exists with uranyl (UO
), resulting in the complex species of UO
F
and thus decreasing extraction efficiency. Herein, we construct Ti
-PO
ion pair extraction sites in Ti(OH)PO
for efficient electrochemical uranium extraction in wastewater from nuclear fuel production. These sites selectively bind with UO
F
through the combined Ti-F and multiple O-U-O bonds. In the uranium extraction, the uranium species undergo a crystalline transition from U
O
to K
UO
F
. In real nuclear wastewater, the uranium is electrochemically extracted with a high efficiency of 99.6% and finally purified as uranium oxide powder, corresponding to an extraction capacity of 6829 mg g
without saturation. This work paves an efficient way for electrochemical uranium recycling in real wastewater of nuclear production.
Searching for actinide decorporation agents with advantages of high decorporation efficiency, minimal biological toxicity, and high oral efficiency is crucial for nuclear safety and the sustainable ...development of nuclear energy. Removing actinides deposited in bones after intake is one of the most significant challenges remaining in this field because of the instantaneous formation of highly stable actinide phosphate complexes upon contact with hydroxyapatite. Here we report a hydroxypyridinone-based ligand (5LIO-1-Cm-3,2-HOPO) exhibiting stronger affinity for U(VI) compared with the reported tetradentate hydroxypyridinone ligands. This is further revealed by the first principles calculation analysis on bonding between the ligand and uranium. Both in vitro uranium removal assay and in vivo decorporation experiments with mice show that 5LIO-1-Cm-3,2-HOPO can remove uranium from kidneys and bones with high efficiencies, while the decorporation efficiency is nearly independent of the treatment time. Moreover, this ligand shows a high oral decorporation efficiency, making it attractive for practical applications.
The challenges and opportunities to alloyed and composite fuel architectures designed and intended to mitigate oxidation of the fuel during a cladding breach of a water-cooled reactor are discussed ...in this manuscript focused on the oxidation performance of uranium diboride and uranium monocarbide. Several high uranium density fuels are under consideration for deployment as accident tolerant and/or advanced technology nuclear reactor fuels, including UN, U3Si2, UB2, and UC. Presented here is the literature for UB2 and UC degradation modes, thermodynamics, and oxidation performance of the pure compounds and reported alloyed and composite architectures. Furthermore, this review covers the materials and techniques for the incorporation of additives, dopants, or composite fuel architectures to improve the oxidation behavior for high uranium density fuels for use in LWRs.
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