- Magnetically modified hydroxyapatite nanoparticles for the removal of uranium (VI): Preparation, characterization and adsorption optimization. [Journal Article]
- JHJ Hazard Mater 2019 May 30; 378:120703
- Recently, magnetically modified nanomaterials have gained a great interest in the field of wastewater remediation. In this regard, the present work introduces a facile microwave-assisted pathway for …
Recently, magnetically modified nanomaterials have gained a great interest in the field of wastewater remediation. In this regard, the present work introduces a facile microwave-assisted pathway for the preparation of magnetically modified hydroxyapatite nanoparticles (MNHA) and evaluates its adsorption capability towards the removal of uranium (VI) ions from wastewaters. The prepared magnetic nanocomposite went through a full characterization procedure using different techniques, such as transmission electron microscope (TEM), X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET) surface area measurements and magnetization curve. Involvement of the prepared MNHA in the remediation of wastewater containing U(VI) ions was investigated and the factors that influence the adsorption capacity were considered and optimized. The adsorption's optimum pH was found to be 5.0 and equilibrium was attended after 120 min. A maximum adsorption capacity of 310 mg/g was achieved after 120 min at 25 °C. The experimental data were well explained by Langmuir adsorption isotherm model. Kinetically, the adsorption process follows the pseudo-second order model. Thermodynamically, it is endothermic, irreversible and spontaneous adsorption process. Removal of U(VI) ions was found to take place via complex formation between the phosphate groups on the adsorbent and uranyl ions. The recovery of U(VI) ions from MNHA beads and the reusability of the spent beads were also explored. It was concluded that the prepared MNHA nanocomposite is simple, fast, ecofriendly adsorbent for the removal of U(VI) ions from water with excellent adsorption capacity.
- Modified Citrus Pectin / Alginate Dietary Supplement Increased Fecal Excretion of Uranium: A Family. [Journal Article]
- ATAltern Ther Health Med 2019; 25(4):20-24
- CONCLUSIONS: The supplement promoted fecal excretion of what is likely ongoing low-level exposure via ingestion. This is the first report of a supplement promoting uranium excretion suggesting it may reduce negative health effects in regions where chronic uranium exposure is known.
- Advances in age-dating of individual uranium particles by large geometry secondary ion mass spectrometry. [Journal Article]
- AAnalyst 2019 Jun 14
- We present the ability to conduct single micrometer-sized uranium particle age-dating measurements on particles that are younger, smaller, and less enriched in 235U content than previously reported. …
We present the ability to conduct single micrometer-sized uranium particle age-dating measurements on particles that are younger, smaller, and less enriched in 235U content than previously reported. Specifically, we use large geometry secondary ion mass spectrometry (LG-SIMS) to precisely measure the 230Th/234U radiochronometer, combined with a systematic treatment of relevant parameters such as particle size, enrichment, and age, to achieve this development. We describe the necessary requirements for instrument background, interference rejection, abundance sensitivity, and other instrumental conditions that allow for this advance in single-particle uranium age-dating. We introduce the use of statistics developed by Feldman and Cousins to generate 95% confidence intervals in particle age, even when 230Th daughter ions are not detected. For particles where counts are limited and are of identical isotopic signatures, we provide an option for aggregating individual measurements of single particles to reduce measurement uncertainty, as if the measurement had been performed on one larger particle. The methodology is validated on a range of certified reference materials and 'real-world' samples, ranging in age from 15 to 60 years, and on individual particles ranging in equivalent size from 0.6 to 6.8 micrometers. Additionally, we provide model age calculations for particles ranging in size from 1.0 to 3.0 micrometers across enrichments ranging from natural uranium to highly-enriched uranium and on ages ranging from 0 to 60 years. Experimental results compare well with the predicted model ages, providing realistic guidance for expectations of single micrometer-sized uranium particle age-dating measurements. The age-dating capabilities described herein are directly relevant to the International Atomic Energy Agency (IAEA) and its mission to safeguard nuclear materials and monitor member state nuclear programs.
- Fabrication of stoichiometric U3Si2 fuel pellets. [Journal Article]
- MMethodsX 2019; 6:1252-1260
- Uranium silicide, U3Si2, is an accident tolerant fuel type which is gaining momentum as a replacement fuel for uranium dioxide (UO2). Idaho National Laboratories has been fabricating phase pure U3Si2…
Uranium silicide, U3Si2, is an accident tolerant fuel type which is gaining momentum as a replacement fuel for uranium dioxide (UO2). Idaho National Laboratories has been fabricating phase pure U3Si2 fuel pellets for use in various irradiation and material characterization experiments. Stoichiometric U3Si2 fuel pellets were fabricated using a powder metallurgy and arc melting technique. The use of the stoichiometric ratio to alloy uranium and silicon, and sintering in a vacuum environment allowed for the fabrication of high density (>94% theoretical density), phase pure pellets, greater than 94% U3Si2. Silicon volatilization was not observed in the as-sintered microstructure, which has been verified through XRD and SEM, thus eliminating the need to alloy a substoichiometric U/Si ratio. •Stoichiometric ratio of U to Si used to form U3Si2 phase.•Decrease in secondary phases present confirm absence of silicon volatilization.•Analysis via XRD and SEM confirm the phase purity of the U3Si2 fuel pellets.
- Uranium uptake in Paracentrotus lividus sea urchin, accumulation and speciation. [Journal Article]
- ESEnviron Sci Technol 2019 Jun 12
- Uranium speciation and bioaccumulation were investigated in the sea urchin Paracentrotus lividus. Through accumulation experiments in a well-controlled aquarium followed by ICP-OES analysis, the quan…
Uranium speciation and bioaccumulation were investigated in the sea urchin Paracentrotus lividus. Through accumulation experiments in a well-controlled aquarium followed by ICP-OES analysis, the quantification of uranium in the different compartments of the sea urchin was performed. Uranium is mainly distributed in the test (skeletal components), as it is the major constituent of the sea urchin, but in terms of quantity of uranium per gram of compartment, the following rating: intestinal tract > gonads >> test, was obtained. Combining both extended X-ray Absorption Spectroscopy (XAS) and time resolved laser induced fluorescence (TRLFS) spectroscopic analysis, it was possible to identify two different forms of uranium in the sea urchin, one in the test, as a carbonato-calcium complex, and the second one in the gonads and intestinal tract, as a protein complex. Toposome is a major calcium-binding transferrin-like protein contained within the sea urchin. EXAFS data fitting of both contaminated organs in vivo and the uranium-toposome complex from protein purified out of the gonads revealed that it is suspected to complex uranium in gonads and intestinal tract. This hypothesis is also supported by the results from two imaging techniques i.e. Transmission Electron Microscopy (TEM) and Scanning Transmission X-ray Microscopy (STXM). This thorough investigation of uranium uptake in sea urchin is one of the few attempts to assess the speciation in a living marine organism in vivo.
- Characterization of Aspergillus niger siderophore that mediates bioleaching of rare earth elements from phosphorites. [Journal Article]
- WJWorld J Microbiol Biotechnol 2019 Jun 11; 35(6):93
- Siderophores are extra-cellular inducible compounds produced by aerobic microorganisms and plants to overcome iron insolubility via its chelation and then uptake inside the cell. This work aims to st…
Siderophores are extra-cellular inducible compounds produced by aerobic microorganisms and plants to overcome iron insolubility via its chelation and then uptake inside the cell. This work aims to study the characteristics of siderophore that is produced by a rhizosphere-inhabiting fungus. This fungus has been morphologically and molecularly identified as Aspergillus niger with the ability to produce 87% siderophore units. The obtained siderophore in PDB medium gave a positive result with tetrazolium test and a characteristic spectrum with a maximum absorbance at 450 nm in FeCl3 test that did not shift in response to different pH degrees (5-9). This indicates that the obtained siderophore is a trihydroxymate in nature. After purification, the FTIR and NMR analyses showed that the obtained siderophore is considered to be ferrichrome. The purified siderophore has been further evaluated as a tool to extract uranium, thorium and rare earth elements (REEs) from Egyptian phosphorites obtained from Abu Tartur Mine area. The inductively coupled plasma atomic emission spectroscopy analysis showed that the highest removal efficiency percentage was for uranium (69.5%), followed by samarium (66.7%), thorium (55%), lanthanum (51%), and cerium (50.1%). This result confirmed the ability of hydroxymate siderophores to chelate the aforementioned precious elements, a result that paves the way for bioleaching to replace abiotic techniques in order to save the cost of such elements in an environmentally friendly way.
- Microbial communities in a former pilot-scale uranium mine in Eastern Finland - Association with radium immobilization. [Journal Article]
- STSci Total Environ 2019 Jun 04; 686:619-640
- The bacterial, fungal and archaeal communities were characterized in 17 top soil organic and mineral layer samples and in top sediment samples of the Paukkajanvaara area, a former pilot-scale uranium…
The bacterial, fungal and archaeal communities were characterized in 17 top soil organic and mineral layer samples and in top sediment samples of the Paukkajanvaara area, a former pilot-scale uranium mine, located in Eno, Eastern Finland, using amplicon sequencing and qPCR. Soil and sediment samples were in addition analyzed for radium (226Ra), sulfate (SO42-), nitrate (NO3-) and phosphate (PO43-) concentrations. New bacterial strains, representing Pseudomonas spp., were isolated from the mine and reference area and used in laboratory experiments on uptake and leaching of radium (Ra). The effect of these strains on the sulfate leaching from the soil samples was also tested in vitro. Between 6 × 106 and 5 × 108 copies g-1 DW (dry weight) of bacterial 16S rRNA genes, 5 × 105-1 × 108 copies g-1 DW archaeal 16S rRNA genes and 1 × 105-1 × 108 copies g-1 DW fungal 5.8S rRNA genes were detected in the samples. A total of 814, 54 and 167 bacterial, archaeal and fungal genera, respectively, were identified. Proteobacteria, Euryarchaeota and Mortiriella were the dominant bacterial, archaeal and fungal phyla, respectively. All tested Pseudomonas spp. strains isolates from Paukkajanvaara removed Ra from the solution, but the amount of removed Ra depended on incubation conditions (temperature, time and nutrient broth). The highest removal of Ra (5320 L/kg DW) was observed by the Pseudomonas sp. strain T5-6-I at 37 °C. All Pseudomonas spp. strains decreased the release of Ra from soil with an average of 23% while simultaneously increasing the concentration of SO42- in the solution by 11%. As Pseudomonas spp. were frequent in both the sequence data and the cultures, these bacteria may play an important role in the immobilization of Ra in the Paukkajanvaara mine area.
- Targeted Synthesis of Uranium(IV) Thiosilicates. [Journal Article]
- ICInorg Chem 2019 Jun 10
- Two new uranium(IV) thiosilicates, Cs2Na4[U2(SiS4)2(Si2S8)] and Cs2.12Na3.88[U2(SiS4)2(Si2S7)], were obtained by flux crystal growth using SiS2 as a silicon source. The former compound contains a nov…
Two new uranium(IV) thiosilicates, Cs2Na4[U2(SiS4)2(Si2S8)] and Cs2.12Na3.88[U2(SiS4)2(Si2S7)], were obtained by flux crystal growth using SiS2 as a silicon source. The former compound contains a novel Si2S86- unit that features a terminal persulfide group. The magnetic susceptibility measurements performed on this compound revealed paramagnetic behavior with a moment of 3.49 μB per uranium atom as obtained from a Curie-Weiss law fit and showed no magnetic transition down to 2 K. The structures are based on closely related isomeric planar and 3D topologies that can be transformed into one another by a rotation of the structural units.
- Ground follow-up of the airborne gamma-ray spectrometric survey data, ramlet HOMAYYER area, east abu-zeneima, southwestern Sinai, Egypt. [Journal Article]
- ARAppl Radiat Isot 2019 Jun 01; 151:129-139
- Ramlet Homayyer area is located in the southwestern part of Sinai Peninsula, Egypt, to the east of Abu-Zeneima city, located on the eastern coast of Gulf of Suez, Red Sea. The Paleozoic succession in…
Ramlet Homayyer area is located in the southwestern part of Sinai Peninsula, Egypt, to the east of Abu-Zeneima city, located on the eastern coast of Gulf of Suez, Red Sea. The Paleozoic succession in the study area (up to 300 m thick) overlies the basement complex and is covered by basaltic sheets. The lithologic nature of the Paleozoic rocks played a very important role in the localization of various mineralizations (e.g. Mn, Fe, Cu, REEs, Th … etc.) In the present study of Ramlet Homayyer area, ground spectral gamma-ray survey was conducted along N-S profiles, equally-spaced, with lengths of about 2.5 km, and the total area equals about 10 km2. The measurements were conducted using a portable gamma-ray spectrometer, model GS-512. The examination of the total-count (T.C.) radiometric contour map shows that the radioactivity values vary widely from 3.4 Ur to 101.3 Ur. The potassium (K) content in Ramlet Homayyer area ranges from 1.2% to 16.0%. The equivalent thorium (eTh) content in the study area has a maximum value reaching about 68.9 ppm. The equivalent uranium (eU) content attains its maximum value reaching about 84.0 ppm. Factor analysis technique, which provides a way of thinking about radiospectrometric elements and ratio interrelationships alltogether was carried out. The application of factor analysis technique, helped to delineate the zones of high concentrations of eU, eTh and K separately, where the first factor (F1) can delineate high eU zones, (F2) high eTh zones and (F3) high K zones. The radiometric lithologic mapping was conducted for the whole area, by testing the homogeneity of all measurements recorded indicates that the distribution of the radioactivity all over the area is not homogeneous. This indicates that the lithological cover of the study area cannot be considered as one lithologic unit, but contains different types of rock units. Each Interpreted radiometric lithologic units (IRLU) is corresponding to one geomorphological mass or features. As a result of the ground radiometric survey of the study area, chemical analyses for some selected samples were taken and conducted from the anomalous zones at G. Homayyer, G. Ghorabi and Khameila areas. These analyses showed presence of concentrations of uranium up to 147 ppm, 58 ppm, 52 ppm in addition to trace elements with high concentrations of some elements as: Y, Cr, W, Sr and Ag, which gives 6819,768,314,561 and15 ppm respectively.
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- Optimization of database for identification need of unknown spent nuclear fuel samples. [Journal Article]
- JEJ Environ Radioact 2019 Jun 04
- Recent years, the work of nuclear forensics has been greatly promoted in many aspects, and an important work is the establishment and application of nuclear forensic database. For now, this research …
Recent years, the work of nuclear forensics has been greatly promoted in many aspects, and an important work is the establishment and application of nuclear forensic database. For now, this research is mainly based on uranium ore, because there is plenty of uranium ore information that is open and is easy to form database available for attribution. However, as the potential threat of spent nuclear fuel gets more and more attention, the number of researches on the identification of spent nuclear fuel via database is increasing. Since there is no public spent nuclear fuel database that is proper for attribution, such kind of work is mainly on methodology study. This paper focuses on the use of database for the identification of spent nuclear fuel. A database is first constructed with numerical simulation results and is used to identify samples both from simulation and experimental measurements to study the availability and applicability. Then samples from real database are used to optimize the database constructed with simulation result to better meet the need of real nuclear forensics scenarios.