Scientists Cracked a Key Mystery About Destroying “Forever Chemicals” in Water
There is a group of chemicals out there with a nickname that sounds like something from a science fiction movie: “forever chemicals.” The name is not an exaggeration. These substances, officially called PFAS (per- and polyfluoroalkyl substances), are so chemically stable that they can survive in water supplies, soil, and even inside the human body for decades without breaking down. Scientists around the world have been racing to find a real solution, and a new discovery from Aarhus University in Denmark just gave that race a serious boost.
PFAS chemicals have been manufactured and used since the 1940s. You have almost certainly encountered products that contain them: non-stick cookware, waterproof jackets, microwave popcorn bags, and the foam used to fight certain kinds of fires all commonly contain PFAS. The reason these chemicals are so useful in products is exactly the same reason they are so dangerous in the environment — they are incredibly hard to break apart. The bond between carbon atoms and fluorine atoms inside a PFAS molecule is one of the strongest chemical bonds that exists in nature, which means most natural processes simply cannot touch them.
The health concerns tied to PFAS exposure are serious and have been studied for years. Scientists have linked long-term exposure to PFAS with an increased risk of certain cancers, liver damage, and disruption of the body’s hormone system — the chemical messaging network that controls things like growth and metabolism. Because PFAS accumulate in living things rather than passing through harmlessly, even small amounts in water can build up over time. This is why researchers consider PFAS contamination one of the most pressing environmental and public health challenges today.
Here is where the new discovery comes in. Scientists already knew that intense ultraviolet, or UV, light could begin to break down PFAS molecules. UV light is the high-energy part of sunlight that also causes sunburn, and in very concentrated, powerful forms it has been used experimentally in water treatment. But researchers were not entirely sure which part of the process was actually doing the heavy lifting of destroying the chemicals. The Aarhus University team set out to answer that question, and their findings surprised even people in the field.
The key turned out to be tiny reactive particles called hydrogen radicals. When intense UV light strikes water molecules, it generates these hydrogen radicals — think of them as incredibly energetic, unstable fragments that immediately start reacting with whatever they touch. Previous studies had focused on other reactive particles as the main agents of PFAS breakdown, but the new research showed that hydrogen radicals are actually the dominant force. These particles attack the strong carbon-fluorine bonds directly, gradually stripping away fluorine atoms and breaking the PFAS molecule into smaller, less persistent pieces. The process works best under the most energetic UV wavelengths, specifically those below 300 nanometers in length.
Associate Professor Zongsu Wei, who led the study, explained why identifying this mechanism matters so much beyond just satisfying scientific curiosity. “We know that PFAS are extremely stable because of the strong carbon-fluorine bonds, and breaking those bonds is the main challenge. By identifying hydrogen radicals as a dominant driver, we now have a clearer direction for how to design more efficient and sustainable technologies to actually destroy these chemicals, rather than just removing them,” he said. That distinction — between removing and destroying — is crucial. Most water treatment systems today can filter PFAS out of drinking water, but filtering only moves the chemicals somewhere else. True destruction, where the molecules are broken down completely, is the goal that has eluded scientists for so long.
The researchers are careful to point out that this is not an immediate fix. The UV-based degradation process is currently slow, and some intermediate chemical compounds form during the breakdown before the process is complete. More work is needed to speed things up and make the technology practical at the scale needed to treat real water supplies. But knowing what actually drives the destruction of PFAS gives researchers a precise target to aim for when designing the next generation of treatment systems. As Wei put it, understanding the mechanism is essential for developing solutions that are both green and scalable — meaning they can work not just in a laboratory but in the real world, for communities everywhere.
Source: ScienceDaily