At 110 degrees Celsius, a team at the University of Utah found a way to break apart some of the tough chemical bonds that help PFAS linger in the environment. The lab method could offer a lower-temperature option for destroying these pollutants after they have been removed from water.
PFAS, short for per- and polyfluoroalkyl substances, are often called “forever chemicals” because they resist natural breakdown. Their strong carbon-fluorine bonds make them useful in many products, but also hard to destroy. Filtering PFAS out of contaminated water is only part of the job: the chemicals then collect in filters or other materials, and must be dealt with so the pollution is not simply shifted into another waste stream.
Researchers at the University of Utah’s John and Marcia Price College of Engineering used reactive chemicals called nucleophiles to sever carbon-fluorine bonds. The process, known as defluorination, released nearly all the fluorine as fluoride from several tested compounds, including PFOA and trifluoroacetic acid, or TFA. TFA is a particularly stubborn, small PFAS molecule. The team also removed fluorine efficiently from two fluorinated plastics, PVDF and PCTFE, used in batteries, industrial products and munitions.
Most of the tests took place at 110 degrees Celsius (230 degrees Fahrenheit) or below. Some materials needed temperatures as high as 150 degrees Celsius. By comparison, PFAS incineration often uses temperatures of 1,000 degrees Celsius or more. Burning PFAS can also leave some of the chemicals only partly broken down, creating smaller fluorinated byproducts. Some can travel more easily through the air than the original chemicals, raising concerns that destruction could cause new pollution.
The Utah method worked in ordinary air. It did not require several specialized conditions or energy-intensive steps used by some other approaches, such as inert gas, deep-ultraviolet light, high pressure or heavy-metal catalysts. That could make the approach worth studying as part of a cleanup process: capture PFAS from water, concentrate it into a smaller amount of waste, then destroy it.
Ling Zang, a distinguished professor in the Department of Materials Science & Engineering and associate dean for research at the college, led the study. His earlier work focused on capturing PFAS through filtration and adsorption, as well as checking how well treatment works. The new research, published in Communications Chemistry, takes the next step by exploring how to destroy chemicals after capture.
The results are still from laboratory tests, not full-scale cleanup. The team plans to test the method on real waste streams, compare treatment costs and assess the safety of what remains after the reaction. Future work will also examine other reagents and conditions to improve performance and reduce environmental impacts. Those tests will help show whether a promising way to break PFAS bonds in the lab can become a useful tool for handling contaminated waste.