Researchers at Ritsumeikan University in Japan have introduced an innovative approach for the swift breakdown of hazardous per- and polyfluoroalkyl substances (PFAS), commonly known as “forever chemicals.” This groundbreaking method enables the degradation of these pollutants at room temperature, achieving complete breakdown in just one night and allowing for the recovery of valuable components.
PFAS are a group of synthetic chemicals characterized by their exceptional resistance to heat, water, and degradation, due to their robust carbon-fluorine bonds. These properties have made PFAS useful in various applications, including non-stick cookware, firefighting foam, and water-repellent fabrics. However, the same stability that makes them useful also means they persist in the environment indefinitely, posing serious health risks such as diabetes, fertility issues, cancers, and immune system disorders.
The new technique developed by the Ritsumeikan team utilizes semiconductor nanocrystals of cadmium sulfide (CdS), some of which are enhanced with copper. These nanocrystals are combined with a solution containing water, triethanolamine (TEOA), and the PFAS chemicals. When exposed to LED light at a wavelength of 405 nm, the nanocrystals become excited, leading PFAS molecules to adhere to their surface. Concurrently, excited electrons in the solution break the strong carbon-fluorine bonds by removing fluorine ions from the PFAS molecules.
In laboratory tests, this method effectively decomposed 100% of perfluorooctanesulfonate, a specific PFAS compound, within eight hours. Another PFAS compound, Nafion, was broken down by 81% in 24 hours. Remarkably, this process occurred at a modest temperature of 38°C (100°F), significantly lower than the 400°C (752°F) typically required. Additionally, the fluorine ions are recovered during the process and can be repurposed for other industrial uses.
While this technique is akin to other PFAS degradation methods that use catalysts, it stands out by operating at room temperature and utilizing LED light instead of UV light, which is commonly used in other methods. Previous approaches have employed supercritical water, magnetic particles, hydrogen, or boron nitride to achieve similar results. Having multiple methods available for PFAS breakdown could offer a comprehensive solution to this persistent environmental challenge.
The research was published in the journal Angewandte Chemie International Edition.
Source: Ritsumeikan University