Researchers at Ritsumeikan University recently proposed a room-temperature defluorination method using visible light to break down PFAS and other perfluorinated polymers (PFs) into fluorine ions. Their study demonstrated 100% defluorination of perfluorooctanesulfonate (PFOS) within eight hours of light exposure.
The method involves irradiating visible LED light onto cadmium sulfide and copper-doped cadmium sulfide nanocrystals with mercaptopropionic acid surface ligands in a solution containing PFAS, FPs, and triethanolamine. This irradiation generates electrons with high reduction potential, breaking the strong carbon-fluorine bonds in PFAS molecules. The process is enhanced by triethanolamine, which captures photoexcited holes, prolonging the lifetime of reactive electrons.
Laser flash photolysis confirmed the presence of hydrated electrons generated by Auger recombination, essential for PFAS decomposition. The defluorination efficiency increased with the amount of nanocrystals, triethanolamine and light exposure duration, achieving up to 100% defluorination for PFOS and 81% for Nafion, a widely used fluoropolymer.
This method offers a sustainable way to recover fluorine from waste PFAS, according to researchers, reducing reliance on fluorine production and contributing to various industries' recycling processes.
