Study published by the American Chemical Society, researchers have developed electrodes for electrochemical extraction of uranium from seawater with high efficiency. These electrodes are self-standing, free of binding materials and minerals, porous, and have an aromatic framework.
Currently, uranium is extracted from rocks, but estimates from the Nuclear Energy Agency indicate that 4.5 billion tons of uranium float in the oceans as dissolved uranyl ions. This reserve is a thousand times more than what is available on Earth, providing a new opportunity to supply sustainable nuclear fuel, especially as limited uranium resources represent a serious obstacle to developing a sustainable nuclear energy industry.
What is Nuclear Energy?
Nuclear energy is a clean, low-carbon, and alternative energy source to fossil fuels, providing an important guarantee for green development. Uranium is the primary fuel for nuclear power reactors.
Nuclear power reactors release naturally stored energy inside the atom and convert it into heat and electricity by splitting the atom, a process known as fission. Uranium has become the preferred element in this process as all its forms are unstable and radioactive, making fission easy.
A coated cloth effectively collects uranium on its surface from uranium-rich seawater (American Chemical Society)
Extracting Uranium from Seawater
The process of extracting uranium from the sea is difficult because seawater has high ionic strength and complex interlocking ions that hinder uranium extraction. Additionally, seawater contains abundant biological deposits of marine microorganisms and other biological organisms, limiting the practical application of uranium extractants in oceans and seas.
Moreover, the materials used for uranium extraction do not have sufficient surface area to effectively capture ions. Therefore, the electrodes developed in this study contain a lot of microscopic corners and crevices that can be used for the electrochemical capture of uranyl ions from seawater.
In creating these electrodes, the researchers used a flexible woven carbon fiber cloth and coated it with two specialized monomers which were then polymerized. The cloth was then treated with hydroxylamine hydrochloride to add amidoxime groups to the polymers. The natural porous structure of the cloth created numerous small pockets, making it easy to retain uranyl ions.
During the experiments, the researchers placed the coated cloth as a cathode in uranium-filled seawater and added a graphite anode, then operated a cyclic current between the electrodes. Over time, light yellow uranium-rich deposits accumulated on the cathode cloth.
In this study, a high uranium extraction capacity was achieved within 24 days of operation, reaching 12.6 milligrams of uranium per gram of the active coated material used for extraction. The coated material’s capacity was higher than most other tested uranium extraction materials. The designed electrodes can effectively achieve electrochemical uranium extraction through adsorption and electrochemical reduction processes.
This method showed that the electrochemical approach is three times faster than the physical and chemical adsorption method, and it also exhibited good selectivity against competing ions.
This study provided a comprehensive understanding and an effective strategy for electrochemical uranium extraction using electrochemical electrodes from seawater.
