A recently published study has outlined a technology that could significantly improve the ability to extract uranium from seawater – a process that's far from commercial viability now but could provide future supplies of the reactor-powering element, should land-based resources become constrained.
As noted in a recent article in MIT Technology Review, uranyl ions exist in seawater at three parts per billion. That's an extremely dispersed resource, but one potentially 1,000 times greater than known uranium reserves on land, thanks to the ocean's size. Chemical-coated plastics currently can extract about three to four milligrams of uranium for each gram of absorbent left in the ocean for several weeks. Research led by chemists at the University of North Carolina, Chapel Hill, and published in the journal "Chemical Science" debuted a material that collected four times that amount during laboratory tests.
The presence of other, competing ions attaching to the material under real-world sea conditions would likely make a commercial application less effective. Nonetheless, the paper's authors concluded that the metal-organic framework created for the study was significantly more effective than existing polymers. The paper suggests the material could also make a promising alternative to organic polymer absorbents used to extract uranium from nuclear waste or acid mine drainage.
The paper can be found here (free subscription required). It was supported by the Department of Energy's Nuclear Energy University Program.