Developing a Broad-Spectrum f-Block Adsorbing and Rapid Uranium Detecting Swipe

Project Overview

Uranium and uranium-containing compounds are prevalent throughout nature, occurring mainly in minerals that require processing and purification, which inevitably leads to water and surface contamination. Because uranium is both a radiological and carcinogenic element, there are many concerns over exposure to the public through airborne releases and contaminated drinking water. Uranium detection, for which the preferred and most common method of environmental sampling is swiping, is also of paramount importance to both national and global security. While current swipes have many advantages, including the ability to cover a wide area, the ease of implementation as a quality control process, and the compatibility with extremely sensitive analytical techniques for chemical quantification (e.g., inductively coupled plasma-mass spectrometry), there are equally as many drawbacks, including the lack of variety in swipe materials for specific detection applications, the inability to produce quick, in-field results for positive material detection, and the selectivity of specific materials of interest over less important materials.

This work aimed to address the lack of specificity in generic swiping materials by manufacturing electrospun nanofibers with uranium-specific adsorbents. Unlike generic swipes, which consist of woven cotton microfibers, electrospinning produces non-woven nanofibers in a variety of polymeric materials. Non-woven nanofibers have a higher surface area than woven microfibers, which theoretically allows for better adsorption of particulate matter. Additionally, the electrospinning process allows for the incorporation of many different chemical constituents, including both inorganic (e.g., polyoxometalates, metal-organic frameworks, etc.) and organic (e.g., proteins, enzymes, peptides, etc.) ligands that are capable of uranium-specific adsorption. Using a semi-automated swiping procedure, dry and wet swipe experiments were performed using a traditional cotton swipe material employed by the Department of Energy, the TexWipe® TX304, and custom electrospun nanofiber materials composited with known broad-spectrum f-block element adsorbing ligands and uranium-responsive materials. This work found that nanofiber materials, without any added adsorbents, outperformed the traditional cotton swipe material, displaying between a two and seven-fold increase in sensitivity to uranium detection and a microgram-level detection threshold for dry swiping. For wet swiping, both a lacunary phosphotungstate polyoxometalate and a terbium-based metal-organic framework adsorbent-enhanced swipes resulted in the highest swiping efficiency of 51%, which is approximately 6% and 9% more efficient than the TexWipe® TX304 and plain electrospun polyvinyl alcohol nanofiber swipes, respectively. This work also reports a preliminary display of uranium indication based on a fluorescence quenching effect visible to the unaided eye. While this technology was specifically tailored for uranium and other f-block elements, the nanofiber platform is adaptable for other analytes of interest to the global security community, including beryllium, high explosives, or other critical minerals and materials.

Mission Impact

Electrospun nanofibers have the potential to enhance analyte detection relevant to nuclear forensics, safeguarding, and environmental remediation applications. Inclusion of analyte-specific ligands will allow for the manufacturing of materials for specific sensing goals, a capability severely needed in the non-proliferation mission space. This project resulted in a new swipe testing capability at Lawrence Livermore National Laboratory (LLNL), allowing for a new direction for future research in targeted swipe materials. The developed swipe technology, while focused on uranium-containing compounds, was shown to be a more efficient dry swipe in general for powders with differing morphologies without the addition of any adsorbent ligands. These results highlight a weakness in current swiping materials, and further research is recommended to develop robust swipe materials. While preliminary, this newly developed uranium indicating swipe material will provide an additional capability for health and safety technicians and first responders in determining locations of uranium contamination in the case of an accident or radiological threat. This project has also demonstrated the use of electrospun nanofibers as a platform technology for future sensing applications (e.g., high explosives, plutonium, chemical and biological warfare agents, etc.) relevant to national security.

Publications, Presentations, and Patents

Ortega, Gabriela, Jalyn-Rose Clark, and Michael Ross, "Development of Target Specific Electrospun Nanofibers for Uranium Detection" (Poster Presentation, ES&H Summer Student Poster Symposium, 2023). LLNL-POST-852511. 

Gabriela Ortega, "ES&H, LLNL, NNSA MSIIP Poster" (Poster Presentation, Livermore, CA, 2023). LLNL-POST-853402.

Anastacia Dressel, "Rare Earth Element Capture Using Functionalized Electrospun Nanofibers" (Presentation, IgniteOff! National Competition Semifinals, 2023). LLNL-PRES-852871.

Jalyn-Rose Clark, Anastacia Dressel, Michael Ross, and Ziye Dong. "Manufacturing PVA/PEI Electrospun Nanofibers for Rare Earth Element Extraction" (Poster Presentation, ES&H Summer Student Poster Symposium, Livermore, CA, 2023). LLNL-POST-852323.

Jalyn-Rose Clark, Anastacia Dressel, and Michael Ross,"Fabrication of Biofunctionalized PVA/PEI Nanofibers for Rare Earth Element Extraction" (Poster Presentation, NIF Summer Student Poster Symposium, Livermore, CA, 2023). LLNL-POST-851551. 

Anastasia Dressel and Jalyn-Rose Clark,"Electrospun PVA/PEI Nanofibers for Rare Earth Element Extraction" (Presentation, CHRES Technical Forum at the Department of Energy National Energy Technologies Laboratory, Morgantown, WV, August 2023). LLNL-PRES-851971.