Researchers from Pohang University of Science and Technology (POSTECH) and the Korea Atomic Energy Research Institute recently developed a graphene-based technology that can separate dangerous tritium from radioactive wastewater in a liquid state.
Tritium is a radioactive hydrogen produced in nuclear power plants and mostly exists in the form of water molecules. When it enters the human body, it can emit radiation internally, making thorough management necessary; however, until now, tritium could only be separated in a gaseous state, and the removal of liquid-phase tritium remained a significant challenge.
The research team chose to use graphene, that can be made to allow only protons to pass through while blocking other radioactive isotopes, including tritium, demonstrating a unique separation capability. In their study, the team completed the separation membrane by adding a type of plastic, polytetrafluoroethylene (PTFE), to a polymer electrolyte membrane called Nafion and transferring graphene onto it.
Results from tests on the separation membrane showed that when an electric field was applied, light hydrogen ions passed through the membrane quickly, while heavy deuterium and tritium could not pass through and were concentrated. This demonstrated that relatively heavier hydrogen isotopes experience a greater energy barrier during movement, inhibiting their passage. Diffusion experiments due to concentration differences also indicated that tritium moves 3.1 times slower than protons through the membrane.
A major advantage of this technology is its ability to separate tritium at a high level even in the liquid state at room temperature, such as in nuclear power plant wastewater. In particular, while existing commercialized technologies required high processing expenses, the developed membrane allows for the filtration of tritium in water at room temperature. Its application is expected to enable effective and safe treatment of radioactive wastewater from nuclear power plants, such as the contaminated water from Fukushima.
Professor Um Woo-yong from POSTECH noted: "This technology will greatly assist in solving the radioactive wastewater issues in the nuclear and fusion industries and in the utilization of tritium," highlighting the significance of the research.
