A new way to get more uranium out of seawater

The GO-Gly membrane (a); The ion rejection and enrichment properties of Go-Gly membrane for uranium and the main coexisting ions in single ion solutions (b) and simulated seawater (c), respectively. Credit: Chu Jian

Researchers at the Chinese Academy of Sciences’ Institute of Modern Physics (IMP) have come up with a new way to enrich uranium in seawater by filtering it through a membrane.

Uranium is the most important element for making nuclear power. About 4.5 billion tonnes of uranium can be found in seawater, which is 1,000 times more than what can be found on land. But because there is so little uranium in seawater and so many other ions, especially K+, Na+, Ca2+, and Mg2+, it is very hard to get uranium out of seawater. So, it is very important to enrich uranium and lower the difference between the amount of uranium and the main ions that are also present.

In a study that was published in the Chemical Engineering Journal, researchers used the differences in the sizes of the hydrated ions between UO22+ and the main other ions to come up with a good way to enrich uranium in seawater. They made a new type of glycine cross-linked composite graphene oxide (GO-Gly) membrane that is good at separating ions and can be used to enrich uranium in seawater.

Researchers say that cross-linking GO with glycine not only fixes the problem of the GO membrane swelling in solution, but also meets the need for the channel size to separate uranium from the main ions that are also present. Also, the membrane’s shape stays the same even when it is in a water solution for a long time.

Then, the researchers looked at how uranium and the main ions that were also present in single-ion solutions and simulated seawater repelled and enriched ions. It was found that the GO-Gly membrane turned away almost all of the uranium. Also, it was clear that only uranium was enriched, while the concentrations of the main ions in the simulated seawater stayed almost the same as the membrane kept filtering it.

The results show that the GO-Gly membrane is a good choice for enriching uranium in seawater before it is used. When this new method is added to the old ones, it should make it much easier to get uranium out of seawater and make it easier to use uranium resources in real life.

Further information: Jian Chu et al, Enrichment of uranium in seawater by glycine cross-linked graphene oxide membrane, Chemical Engineering Journal (2022). DOI: 10.1016/j.cej.2022.136602

Source: Chinese Academy of Sciences