Perfluoroalkyl substances (PFASs), also called “forever chemicals,” are a growing environmental and health problem. Since Teflon was invented in 1938, PFASs and similar chemicals have been used because they resist water and heat. This made them useful in many things like cookware, clothing, and firefighting foam. But their stability is also a big issue. PFASs don’t break down easily, so they build up in water, soil, and human bodies, causing cancer and hormone problems. These chemicals are now found in drinking water, food, and even Antarctic soil. Although there are plans to stop making PFASs, getting rid of them is hard because they only break down at very high temperatures. Products with PFASs often end up in landfills, risking future contamination.
Researchers at Ritsumeikan University have a new method to break down PFASs at room temperature. Their study, published in the journal Angewandte Chemie International Edition on 19 June 2024, describes a way to use visible light to break down PFASs into fluorine ions. They achieved 100% breakdown of perfluorooctanesulfonate (PFOS) in just 8 hours.
“This method is promising for breaking down various PFASs under mild conditions, helping us move towards a sustainable fluorine-recycling society,” says Professor Yoichi Kobayashi, the lead author.
The method uses visible LED light on cadmium sulfide (CdS) nanocrystals and copper-doped CdS (Cu-CdS) nanocrystals with mercaptopropionic acid (MPA) in a solution with PFASs, similar chemicals, and triethanolamine (TEOA). The light creates electrons in the nanocrystals that break the strong carbon-fluorine bonds in PFAS molecules.
Fluorine is important in many industries like pharmaceuticals and clean energy. Recovering fluorine from waste PFASs can reduce the need for new fluorine and support a sustainable recycling process. “This technique will help develop recycling technologies for fluorine, which is used in many industries and supports our society,” concludes Prof. Kobayashi.
