Scientists have developed a new method of breaking down harmful “eternal chemicals” by exposure to sunlight-activated materials.
Perfluoroalkyl and polyfluoroalkyl substances (PFAs) are chemicals found in many household products, such as cooking utensils, cosmetics, dental floss, and waterproof clothing. True to their nicknames, chemicals can take thousands of years to break down and accumulate in the environment and our bodies.
PFA has been in use since the 1940s. Initially, they were evaluated for their anti-stick properties, but are now associated with many health effects, including increased risk of autoimmune disease, developmental disorders, reduced fertility, and cancer. This has resulted in some PFAs being banned. However, with around 15,000 varieties produced, about 98% of the US population have these chemicals in their blood.
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Now, a team of researchers find ways to break down chemicals, reducing them to ingredients that contain harmless fluoride at low doses. They published their findings in the Small Journal on July 25th.
“PFAS pollution continues to pose global health risks, and this research represents a critical step towards safer communities and cleaner ecosystems,” said Cameron Shearer, materials scientist at the University of Adelaide in Australia, in a statement.
Related: Scientists find an easy way to destroy “eternal chemicals.”
PFAs owe to strong chemical bonding persistence. They are made up of heads (often charged oxygen molecules) associated with the tail of carbon and fluorine atoms. This bond must be broken for PFA to deteriorate, but this process is extremely difficult to achieve using traditional methods.
“Many water contaminants break down by adding reactive chemicals that bind to carbon,” Shearer said. “However, in PFAS molecules, carbon atoms are protected in a way that makes this process nearly impossible.”
In recent years, researchers have developed methods to decompose PFA using materials called photocatalysts, absorbing incident light to speed up chemical reactions. The scientists behind the new research have transformed into a photocatalytic material called cadmium indium sulfide, known for its ability to release reactive oxygen species or free radicals after exposure to visible light.
After mixing the material with one common PFA called Perfluorooctane sulfonate (PFOS), researchers saw the photocatalyst absorb light and produce free radicals that attack the fluorine atoms in the bond.
Under optimized conditions, this resulted in “complete failure” of approximately 99% of the PFOS molecules. Byproducts are ingredients scientists call them, they can be isolated and used to make toothpaste and fertilizer additives.
“The materials we developed through our research can be used as part of a PFAS treatment chain that first captures and concentrates PFA in water, which can be degraded by exposure to photoactivating materials,” Shearer said. “We plan to build on this research through continuous work to improve material stability before applying it to large-scale systems.”
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