ENABLING EFFICIENT RECOVERY OF DISSOLVED URANIUM

Currently, domestic nuclear reactors consume over 21 million metric tons of uranium per year, while U.S. production of uranium concentrate is reported at about 65 tons uranium annually. To close the gap, the balance is imported. Additional resources exist in the United States, but new mining projects in the United States can be slow and met with resistance, complicating the Department of Energy’s priority to source domestic nuclear fuel sources. Harvesting dissolved uranium from currently unusable water provides a paradigm shift for uranium capture and simultaneous water purification for reuse. Across the United States, uranium contamination spoils potential drinking water sources, and simultaneously the nuclear industry needs uranium. For water treatment, reverse osmosis systems are commonly offered for uranium removal, yet these systems are costly, water- and energy-intensive, and not tunable for selective purification of uranium from the reject stream. We propose developing a hybrid purification material that enables selective separation of desirable metal ions, namely the uranyl ion, UO22+, from three likely sources: acid mine drainage, groundwater in high-uranium geologic areas, and copper extraction raffinate from mining operations in the western United States. This novel material is a hybrid organic/inorganic adsorbent consisting of a nanoscale film with uranium-selective moieties prepared by layer-by- layer assembly, in which a cationic polyelectrolyte is deposited in a monolayer on a mesoporous inorganic substrate. Additional uranium selectivity will be added to the polyelectrolyte backbone through the integration of chelating groups with an established high affinity for uranium. Uranium concentrate can be efficiently recovered from the uranium-rich spent sorbent in a regeneration step, allowing for use of existing infrastructure for further enrichment and fabrication into new fuel elements. Though promising, the technology must be significantly de-risked before it can be deployed in a remediation or commercial process. To address the risks of inserting novel materials into environmental remediation and commercial processes, the key deliverable from this Phase I project is a treatment system including a novel ion exchanger and existing materials, such as natural zeolites, which maximizes selectivity of uranium over co-existing contaminants from three candidate streams. To perform work safely and ensure compliance with all local, state, and federal regulations, this proposal includes a subaward to the Radiochemistry group at Argonne National Lab for handling and testing of uranium-containing streams and all waste streams generated. A July 2020 report from Morningstar Research estimated that the uranium market would grow to over $2.3B USD by 2025, representing 40% growth over the next 5 years for a sector that has been flat for the past ten years. Commercializing this technology will reduce barriers to economic remediation of uranium and promote easier, more sustainable flowsheets for uranium production from nontraditional sources. The use of this innovation enables the circular economy for the metal value chain. With it, we as a society can begin to address centuries of legacy waste and projected demand for critical metals that greatly exceeds projected availability using conventional processes.