Scientists transform 'forever chemicals' in water into fluoride with new process

Scientists have developed a new method to break down harmful "forever chemicals" by exposing them to a sunlight-activated material.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are chemicals found in many household products, including cookware, cosmetics, dental floss and waterproof clothing. True to their nickname, the chemicals take thousands of years to break down, enabling them to accumulate in the environment and our bodies.

PFAS have been used since the 1940s. Initially, they were valued for their nonstick properties, but now they are linked to a number of health impacts, including increased risks of autoimmune disease, developmental disorders, reduced fertility and cancer in humans. This has led some PFAS to be banned. But with nearly 15,000 types having been produced, roughly 98% of the U.S. population has these chemicals in their blood.

Now, a team of researchers has found a way to break down the chemicals, reducing them to components that include fluoride, which is harmless at low doses. They published their findings July 25 in the journal Small.

"PFAS contamination continues to pose a global health risk, and this research represents a critical step toward safer communities and cleaner ecosystems," lead researcher Cameron Shearer, a materials scientist at the University of Adelaide in Australia, said in a statement.

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PFAS owe their persistence to their strong chemical bonds; they consist of a head (often charged oxygen molecules) linked to a tail of carbon and fluorine atoms. For PFAS to degrade, this bond must be broken — but this process is very difficult to achieve using traditional methods.

"Many water contaminants are degraded by adding a reactive chemical that binds to the carbon," Shearer said. "However, in PFAS molecules, the carbon atoms are protected in such a way that makes this process nearly impossible."

In recent years, researchers have been developing methods to break down PFAS using materials called photocatalysts, which absorb incident light to speed up chemical reactions. The scientists behind the new study turned to a photocatalytic material called cadmium indium sulfide, known for its ability to release reactive oxygen species — or free radicals — after being exposed to visible light.

After mixing the material with one common PFAS called perfluorooctane sulfonate (PFOS), the researchers watched as the photocatalyst absorbed light to generate free radicals that attacked the fluorine atoms in the bond.

Under optimized conditions, this led to the "complete breakdown" of around 99% of the PFOS molecules. The byproducts were components which the scientists say can be isolated and used to make toothpaste and fertilizer additives.

"The materials we have developed through our research could be used as part of PFAS-treatment chains that first capture and concentrate PFAS in water, which can then be degraded through exposure to our light-activated materials," Shearer said. "We plan to build on this study through our ongoing work improving the stability of the materials before they can be applied to large scale systems."