New material efficiently extracts uranium from seawater

Coated cloth with accumulated uranium from uranium-spiked seawater. (Image from ACS Central Science, DOI: 10.1021/acscentsci.3c01291.)

Recent research published in the journal ACS Central Science describes a new material that, through electrochemical extraction, attracts hard-to-get uranium ions from seawater more efficiently than existing methods.

According to the Nuclear Energy Agency, 4.5 billion tons of uranium are floating around the ocean as dissolved uranyl ions. This reserve is over 1,000 times more than what’s on land. Extracting these ions has proven to be challenging, though, as the materials for doing so don’t have enough surface area to trap ions effectively.

This is where the new invention comes in. Rui Zhao, Guangshan Zhu and colleagues from the Northeast Normal University, Changchun developed an electrode material with lots of microscopic nooks and crannies that could be used in the electrochemical capture of uranium ions from seawater.

To create the electrodes, the team began with flexible cloth woven from carbon fibres. They coated the cloth with two specialized monomers that were then polymerized. Next, they treated the cloth with hydroxylamine hydrochloride to add amidoxime groups to the polymers. The natural, porous structure of the cloth created many tiny pockets for the amidoxime to nestle in and easily trap the uranyl ions.

In experiments, the researchers placed the coated cloth as a cathode in either naturally sourced or uranium-spiked seawater, added a graphite anode and ran a cyclic current between the electrodes. Over time, bright yellow, uranium-based precipitates accumulated on the cathode cloth.

In the tests using seawater collected from the Bohai Sea, the electrodes extracted 12.6 milligrams of uranium per gram of coated, active material over 24 days. The coated material’s capacity was higher than most of the other uranium-extracting materials tested by the team.

Additionally, using electrochemistry to trap the ions was around three times faster than simply allowing them to naturally accumulate on the cloths.

In the researchers’s view, this work offers an effective method to capture uranium from seawater, which could open up the oceans as new suppliers of nuclear fuel.