This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: UC Riverside environmental engineers have identified key chemical reactions that occur when ultraviolet light is used to destroy "forever chemical" pollutants in water, providing a roadmap for developing more effective cleanup technologies. The discovery, published in the journal Nature Water, details the chemistry involved in using UV light to break down per- and polyfluoroalkyl substances, or PFAS, a large group of persistent pollutants commonly known as forever chemicals.
Importantly, the researchers identified reactions and byproducts that form as treatment breaks the exceptionally strong carbon-fluorine bonds that make PFAS so difficult to destroy, said Jinyong Liu, a UCR associate professor of chemical and environmental engineering and corresponding author of the study. "Knowing this degradation mechanism gives us a better understanding of how to optimize the conditions for PFAS destruction and achieve deeper degradation, and gives us a much better roadmap for improving the technology," Liu said. He holds the university's Won and Insook Yoo Endowed Chair in Environmental Engineering.
The findings can help researchers determine which treatment technologies, combinations of technologies and operating conditions favor more complete destruction of PFAS, he said. The study also corrects degradation mechanisms reported in earlier scientific literature that were based largely on assumptions rather than experimental evidence, Liu said. The findings also could eventually help chemists design safer fluorinated compounds that break down more readily after use.
"By knowing the degradation mechanisms, we can give solid input to the fluorocarbon industry to tell them how to design compounds that can more easily be treated to protect the environment," Liu said. PFAS came into widespread use beginning in the 1940s because of their ability to resist heat, moisture, grease and stains. They have been used in thousands of products, including nonstick cookware, grease-resistant food packaging, stain-resistant carpets, cleaning products, paints, varnishes and sealants, and fire suppressants.
Over decades, PFAS have entered groundwater and contaminated drinking water and food. Exposure to certain PFAS has been associated with increased cholesterol, weakened immune response, liver effects, pregnancy complications and increased risks of kidney and testicular cancers. Because of such health concerns, the U.S.
Environmental Protection Agency in 2024 established enforceable federal drinking-water limits for several PFAS for the first time. The agency has since reconsidered portions of those regulations while retaining the stringent 4 parts per trillion limits for two of the best-known compounds. The chemistry uncovered by Liu's team involves a complex sequence of reactions.
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