China claims to extract uranium from seawater at 8 times US target rate

A team of Chinese researchers has developed a sponge-like material that they say can recover uranium from seawater at more than eight times the extraction rate targeted by the US Department of Energy (DOE). The material, called PhosCage, uses phosphate groups as chemical traps to selectively capture uranium from seawater. The research could offer another route to accessing the enormous quantity of uranium dissolved in the world’s oceans, although substantial engineering and economic hurdles remain before the technology could become commercially viable. A tiny concentration with a huge potential resource The team from the Chinese Academy of Sciences’ Qingdao Institute of Bioenergy and Bioprocess Technology reported recovering up to 50.4 milligrams of uranium per gram of adsorbent from natural seawater samples. That compares with the 6 mg-per-gram benchmark achieved by the best US adsorbents after extended seawater exposure around 2016, making the reported laboratory result more than eight times higher. The researchers subsequently formed PhosCage into millimeter-sized beads, making the material easier to handle and potentially deploy in larger systems. These beads recovered 22.55 mg of uranium per gram and remained functional through seven reuse cycles, according to the research team. The approach addresses a particularly difficult materials problem. Seawater contains only around 3.3 mg of uranium per tonne of water, meaning enormous quantities of seawater have to be processed to recover meaningful amounts. Uranium must also be separated from a mixture containing many other dissolved elements. Vanadium, in particular, can interact with the same chemical sites used to capture uranium, making selective extraction difficult. In tests containing multiple metals, the researchers found that their bead-based material showed a preference for uranium, including over vanadium. Oceans contain billions of tonnes of uranium The attraction of seawater uranium is the sheer size of the potential resource. Known uranium resources on land are estimated at around 7.9 million tonnes, while the world’s oceans are estimated to contain approximately 4.5 billion tonnes of uranium. Much of it entered the oceans over geological timescales as uranium was weathered from rocks and carried into the sea. For countries expanding nuclear power, that could represent a potentially enormous additional source of nuclear fuel. China is particularly dependent on uranium imports. According to the World Nuclear Association figures cited by South China Morning Post (SCMP), Chinese mines produced about 1,600 tonnes of uranium in 2024, compared with roughly 13,000 tonnes required by its nuclear reactors. The US has spent decades investigating whether seawater could help close this gap. Researchers at Oak Ridge National Laboratory and Pacific Northwest National Laboratory developed and tested uranium-absorbing fibers in natural seawater, including experiments at Washington’s Sequim Bay. The US program ultimately found that the economics remained unfavorable compared with conventional land-based mining. PhosCage has so far only been demonstrated under controlled laboratory conditions. The Qingdao researchers collected seawater off the coast of Qingdao and processed 25 liters through a laboratory flow system rather than deploying the material directly in the ocean. Large-scale ocean deployment would introduce challenges involving currents, waves, fouling by marine organisms, material durability, recovery of the adsorbent, and processing costs. The researchers also did not provide a cost estimate for the uranium recovered in their experiments. They say their next steps include scaling up the material and reducing the overall cost of extracting uranium from seawater.Get the latest in engineering, tech, space & science - delivered daily to your inbox.Kaif Shaikh is a journalist and writer passionate about turning complex information into clear, impactful stories. His writing covers technology, sustainability, geopolitics, and occasionally fiction. A graduate in Journalism and Mass Communication, his work has appeared in the Times of India and beyond. After a near-fatal experience, Kaif began seeing both stories and silences differently. Outside work, he juggles far too many projects and passions, but always makes time to read, reflect, and hold onto the thread of wonder.