“Our material is tailor-made for selecting uranium over other metals present in seawater and can easily be recycled for reuse…”
US-based scientists have demonstrated a new bio-inspired material for an eco-friendly and cost-effective approach to recovering uranium from seawater.
A research team from the US Department of Energy’s Oak Ridge and Lawrence Berkeley National Laboratories, the University of California, Berkeley, and the University of South Florida developed a material that selectively binds dissolved uranium with a low-cost polymer adsorbent. The results, published in Nature Communications, could help push past bottlenecks in the cost and efficiency of extracting uranium resources from oceans for sustainable energy production.
“Our approach is a significant leap forward,” said coauthor Ilja Popovs of ORNL’s (@ORNL) Chemical Sciences Division. “Our material is tailor-made for selecting uranium over other metals present in seawater and can easily be recycled for reuse, making it much more practical and efficient than previously developed adsorbents.”
In a statement, Oak Ridge National Laboratory said that Popovs took inspiration from the chemistry of iron-hungry microorganisms. Microbes such as bacteria and fungi secret natural compounds known as “siderophores” to siphon essential nutrients like iron from their hosts. “We essentially created an artificial siderophore to improve the way materials select and bind uranium,” he said.
The team used computational and experimental methods to develop a novel functional group known as “H2BHT”—2,6-bis[hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine—that preferentially selects uranyl ions, or water-soluble uranium, over competing metal ions from other elements in seawater, such as vanadium.
The fundamental discovery is backed by the promising performance of a proof-of-principle H2BHT polymer adsorbent. Uranyl ions are readily “adsorbed,” or bonded to the surface of the material’s fibres because of the unique chemistry of H2BHT. The prototype stands out among other synthetic materials for increasing the storage space for uranium, yielding a highly selective and recyclable material that recovers uranium more efficiently than previous methods.
With a practical recovery method, saltwater extraction offers a sustainable alternative to land-mining uranium that could sustain nuclear power production for millennia.
Uranium deposits are abundant and replenishable in seawater through the natural erosion of ore-containing rocks and soil. Despite dilute concentrations, approximately 3 milligrams of uranium per ton of seawater, the world’s oceans hold massive stores of the element totaling an estimated four billion tons—a 1000 times greater supply than all land sources combined.
The development of efficient uranium adsorbents to harness this potential resource, however, has been an elusive quest since the 1960s.