China's new material extracts uranium from seawater at over eight times US benchmark

Chinese researchers have developed a new material capable of extracting uranium from seawater at more than eight times the target rate previously set by the US department of energy, SCMP reported. This marks a potential advancement in the global effort to tap the oceans as a vast source of nuclear fuel. The team from the Chinese Academy of Sciences in Qingdao recovered up to 50.4mg of uranium per gram of the material from natural seawater samples, compared with the US benchmark of 6mg per gram. The material, known as PhosCage, is a sponge-like molecular structure containing phosphate groups that chemically bind uranium. Researchers later converted it into millimetre-sized beads that could be easier to deploy and retrieve outside laboratory settings. The beads extracted 22.55mg of uranium per gram of material and remained effective through seven cycles of reuse, according to the researchers. “This work opens up a novel approach to extracting uranium from seawater and lays the groundwork for adsorbents that can capture more uranium and eventually be used on a large scale,” the team from the CAS’ Qingdao Institute of Bioenergy and Bioprocess Technology said in a statement.

Why seawater uranium matters

The technology could have particular significance for China as its nuclear power programme expands faster than domestic uranium production. China produced about 1,600 tonnes of uranium from domestic mines in 2024, while its nuclear reactors required roughly 13,000 tonnes, according to the World Nuclear Association. The gap has left the country heavily dependent on imports. Seawater offers a potentially enormous alternative resource. The world has about 7.9 million tonnes of known uranium resources on land, while the oceans are estimated to contain around 4.5 billion tonnes. Uranium has accumulated in seawater over geological time after being washed from rocks by rain and carried into the oceans through rivers. The scale of the resource is vast, but extracting it remains extremely challenging. A tonne of seawater contains only about 3.3mg of uranium, meaning enormous quantities of water would have to be processed to recover significant amounts of the metal.

The problem with finding uranium

Uranium is also surrounded by a range of other dissolved elements in seawater, creating a major separation challenge. Vanadium is particularly problematic because it can bind to the same chemical sites used to capture uranium, making it difficult to isolate the desired element. Researchers in the US have spent years attempting to overcome these challenges. Oak Ridge National Laboratory developed specialised fibres designed to capture uranium, while Pacific Northwest National Laboratory tested the technology using naturally flowing seawater from Washington's Sequim Bay. By 2016, the best US adsorbents were recovering about 6mg of uranium per gram after prolonged exposure to seawater. However, the approach remained considerably more expensive than conventional uranium mining, and the US Department of Energy largely withdrew from the programme after it ended in 2018.

China material shows uranium preference

The Qingdao researchers say their work addresses some of the key technical hurdles involved in uranium extraction. Two studies published in the Journal of Hazardous Materials and Separation and Purification Technology found that the bead-based material displayed a strong preference for uranium when exposed to multiple metals. Importantly, it was able to preferentially capture uranium over vanadium, one of the elements that has traditionally made seawater extraction particularly difficult.However, the results remain at the laboratory stage. The researchers collected seawater from the coast of Qingdao and processed 25 litres through a laboratory flow system. The material was not tested in the open ocean, where waves, currents, marine organisms and changing environmental conditions could complicate the extraction process. Neither study established the cost of producing the recovered uranium. The researchers said further work would focus on scaling up the material and reducing the overall cost of extracting uranium from seawater. For China, success on those fronts could potentially provide another source of nuclear fuel and reduce some of its dependence on imported uranium. For the wider nuclear industry, the research represents another step in the long-running effort to turn the oceans' enormous uranium reserves into a commercially viable resource.

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