Electricity zaps uranium out of seawater in higher amounts

The race to extract uranium from the sea goes on.

A team of Chinese researchers has found a more efficient way to get uranium out of seawater.

Their method, which uses an electrode, took 24 days to extract 12.6 milligrams of a uranium-containing substance per gram of natural seawater.

The method is described in a paper in ACS Central Science.

The researchers, who are from the Northeast Normal University in China, say in the paper that uranium reserves in seawater are estimated to be 4.5 billion tonnes, nearly 1000 times larger than terrestrial uranium reserves.

Unfortunately, this uranium is present in extremely low concentrations – about 3 parts per billion. The presence of dozens of other elements, like sodium and magnesium, make it very difficult to isolate.

This has led to a lot of interest in chemical ways to extract uranium. Two months ago Australian researchers announced they’d found a substance that could react with and stick to uranium in seawater.

This latest research uses a different technique: electrochemistry.

Their electrode is a cloth made from carbon fibres. It’s been coated with a couple of specially-designed polymers, as well as a substance that contains “amidoxime” groups: sections of a molecule that can trap uranium ions.

The porous cloth has plenty of nooks and crannies for uranium to be caught in. The researchers tested it by placing the cloth in both seawater collected from the Bohai Sea, and seawater spiked with uranium, then running a current through it.

Over several days, they could see a bright yellow uranium-based substance forming on the cloth. They found that using electricity made the method 3 times faster than just letting the uranium accumulate passively.

In their paper, the researchers say their work “provide[s] an effective strategy for the uranium extraction from seawater through the electrochemical process”.