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This contribution describes a rapid, fieldable alpha spectroscopy sample preparation technique that minimizes consumables and decreases the nuclear forensics timeline. Functional ultrafiltration membranes are presented that selectively concentrate uranium directly from pH 6 groundwater and serve as the alpha spectroscopy substrate. Membranes were prepared by ultraviolet grafting of uranium-selective polymer chains from the membrane surface. Membranes were characterized by Fourier-transform infrared spectroscopy before and after modification to support functionalization. Membrane performance was evaluated using uranium-233 or depleted uranium in both deionized and simulated groundwater at pH 6. Functionalized membranes achieved peak energy resolutions of 31 ± 2 keV and recoveries of 81 ± 4% when prepared directly from pH 6 simulated groundwater. For simulated groundwater spiked with depleted uranium, baseline energy resolution was achieved for both isotopes (uranium-238 and uranium-234). The porous, uranium-selective substrate designs can process liters per hour of uranium-contaminated groundwater using low-pressure (<150 kPa) filtration and a 45 mm diameter membrane filter, leading to a high-throughput, one-step concentration, purification, and sample mounting process.

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Rare-earth elements (which include all lanthanides, scandium, and yttrium) play a key role in many fields including oil refining, metallurgy, electronics manufacturing, and other high-technology applications. Although the available lanthanide resources are enough for current levels of manufacturing, increased future demand for lanthanides will require new, efficient recovery methods to provide a sustainable supply. Membrane adsorbers are promising separation materials to recover lanthanides from high volumes of wastewater due to their tailorable surface chemistry, high binding capacity and high throughput. In this work, membrane adsorbers were synthesized by first using ultraviolet-initiated free radical polymerization to graft a poly(glycidyl methacrylate) (p-GMA) layer to the surface of polyethersulfone membranes. Then, the reactive epoxy groups of the grafted p-GMA were used for the covalent attachment of lysine molecules via a zinc perchlorate-catalyzed, epoxide ring-opening reaction at 35 • C. Changes in membrane surface chemistry throughout the functionalization process were monitored with Fourier Transform Infrared Spectroscopy. The degree of grafting for the p-GMA film was quantified gravimetrically and increased with increasing polymerization time. Equilibrium adsorption experiments were performed for single specie solutions of La 3+ , Ce 3+ , Nd 3+ , Na + , Ca 2+ , and Mg 2+ at pH 5.25 ± 0.25. Lysine-modified membranes showed negligible uptake of Na + , Ca 2+ , and Mg 2+. The maximum capacities modeled by the Langmuir isotherm for La 3+ and Ce 3+ were 6.11 ± 0.58 and 6.45 ± 1.29 mg/g adsorbent, respectively. Nd 3+ adsorbed to the membrane; however, the fit of the Langmuir model was not significant and it adsorbed to a lower extent than La 3+ and Ce 3+. Lower adsorption of the higher charge density species indicates that the primary binding mode is through the amine moieties of lysine and not the carboxylic acid. Dynamic adsorption experiments were conducted with 1 ppm La 3+ feed solutions at different flow rates using either a single membrane or three membranes in series. The dynamic binding capacity at 50% breakthrough was independent of flowrate within the tested range. The low-temperature membrane functionalization methodology presented in this work can be used to immobilize biomolecules with even higher specificity, like engineered peptides or proteins, on membrane surfaces.

Nuclear power plants use energy-dense fuel and provide dependable baseload energy without generating greenhouse gas emissions. Despite these advantages, the long-term management of used nuclear fuel (UNF) remains a key challenge due to its lifetime (hundreds of thousands of years) and radiotoxicity. The components of UNF that contribute the most to this challenge are the actinide elements. A potential solution to this issue is to separate these radioisotopes from the bulk of the UNF and recycle them as fuel in advanced nuclear reactors. These separations can be achieved using electrochemical reprocessing, which employs electrochemical conversion and electrodeposition in a high-temperature molten salt electrolyte medium to separate the actinides from UNF. In this short perspective, we review the current status, fundamental challenges, and future prospects of electrochemical reprocessing as they relate to UNF recycling.

In recent years, there is a strong interest to sequester uranium from seawater as a sustainable source of nuclear fuel. In this work, ethylene glycol methacrylate phosphate-grafted membrane adsorbers were synthesized using UV-initiated free-radical polymerization. The synthesized membranes were evaluated in DI water and synthetic seawater at different pH values in both batch and continuous modes of operation. A maximum capacity of 15.3 mg of U (g of the membrane)−1 was observed in synthetic seawater at pH 4.08. The membrane capacity was dependent on pH, swelling of the polymer network, and the ionic strength of the solution. During filtration, membranes with a lower degree of grafting recovered more uranium than membranes with a higher degree of grafting for a given feed condition. This work explores design considerations associated with the use of polymer-grafted membrane adsorbers to sequester uranium from seawater.

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