Uranium is abundantly found in the Earth’s crust, with oceans containing approximately 4.5 billion tons — more than a thousand times what is currently obtainable through mining. This vast supply presents a promising opportunity for extracting uranium, alongside other resources, from seawater. However, accomplishing this task necessitates innovative technology capable of efficiently filtering these highly diluted elements in a cost-effective manner. Recent developments by researchers in China indicate that they are making significant strides towards this goal.
The electrochemical technique utilized is outlined in a study by [Yanjing Wang] et al., which was published in *Nature Sustainability*. The researchers claim to have achieved nearly 100% recovery of uranium from seawater at a cost of about $83 per kilogram, a considerable reduction compared to earlier methods. This figure aligns closely with current uranium spot prices, which hover between $70 and $85.
Nonetheless, the primary obstacle remains the scale-up of this laboratory prototype to an industrial format. A distinguishing feature of this low-voltage method is its ability to concurrently convert uranium oxide ions into solid uranium oxides at both ends of the cell, setting it apart from previous electrochemical techniques. The integration of the copper anode into the process allows for the deposition of UO2 on the cathode, while U3O8 is produced on the anode.
Performance data from this prototype demonstrates its efficacy in extracting UO22+ ions from an NaCl solution at concentrations ranging from 1 to 50 ppm. At a 20 ppm concentration, paired with Cl– ions (which are abundant in seawater), the extraction rate reached nearly 100%, a significant improvement over the roughly 9.1% achieved through adsorption methods. This process functions at a low cell voltage of 0.6 V and a current of 50 mA, showcasing strong selectivity for uranium. Additionally, it effectively mitigates copper contamination in the water, since any dissolved copper from the anode was found on the cathode following testing.
Experiments conducted with actual seawater samples from the East and South China Seas reported recovery rates of 100% and 85.3%, respectively, after ten hours of operation. The authors posit that through further optimization of the electrodes, this extraction method could not only be applied to seawater but could also serve uranium mining facilities and other relevant locations.
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