From nonstick frying pans and waterproof jackets to food packaging and cosmetics, a group of chemicals has made everyday products more durable and resistant to heat, grease and water. But the same properties that make these substances useful have also created a serious environmental problem: they can persist for decades, contaminating water, soil and food and accumulating in the human body.
Now, researchers at Arizona State University and their international collaborators have developed a technology designed to destroy these chemicals in contaminated water, rather than simply trapping them in filters or transferring them into waste that still requires disposal.
In a study published on 19 October in the Proceedings of the National Academy of Sciences (PNAS), the researchers reported that their system removed more than 90% of each of the six chemicals tested and released approximately 83% of their fluorine over 58 days of continuous operation.
The substances belong to a family known as per- and polyfluoroalkyl substances (PFAS), which includes thousands of compounds used in products ranging from paints, adhesives and furniture to electronics, waterproof fabrics and firefighting foams.
“PFAS are hard to break down, and normal processes that we use don’t work,” said Bruce Rittmann, director of the Biodesign Swette Center for Environmental Biotechnology at Arizona State University, who led the study.
Why are forever chemicals so difficult to destroy?
The problem lies in their chemical structure. PFAS contain exceptionally strong bonds between carbon and fluorine atoms, making them highly resistant to many natural and chemical processes that would normally break pollutants down.
Rittmann describes the carbon-fluorine bond as one of the strongest in organic chemistry. In many PFAS molecules, fluorine atoms also surround the carbon structure, making it difficult for conventional treatments to begin breaking the chemicals apart.
This resistance has earned them the nickname “forever chemicals”. Once released, they can remain in groundwater, rivers and soil, and move through the food chain into plants, fish, livestock and ultimately humans.
Exposure to certain PFAS has been associated with increased risks of cancer, thyroid disorders, immune-system problems, reduced fertility, pregnancy complications and elevated cholesterol. However, the health effects of many other PFAS compounds remain poorly understood.
Most existing water-treatment methods rely on activated carbon, specialised filters or other separation technologies to capture PFAS. Although these approaches can reduce contamination in treated water, they do not destroy the chemicals. Instead, PFAS remain trapped in filters or concentrated waste streams that require further treatment or disposal.
The research team therefore explored a different question: could the molecules themselves be broken apart rather than simply moved elsewhere?
How does the new technology work?
The researchers turned to hydrogen gas and palladium, a metal that can activate hydrogen and help it attack the strong chemical bonds holding PFAS molecules together.
They developed a system using tiny hollow membrane fibres coated with palladium nanoparticles, then supplied hydrogen gas through the inside of the fibres.
When hydrogen reaches the palladium surface, it splits into highly reactive hydrogen atoms. Meanwhile, PFAS molecules in the surrounding water attach to the same surface, bringing the pollutants and reactive hydrogen close enough for a chemical reaction that breaks carbon-fluorine bonds.
“The palladium attracts the PFAS molecule, and the palladium attracts the hydrogen and puts them together,” Rittmann explained.
A key feature is how hydrogen is delivered. Rather than mixing it directly into the contaminated water, the researchers feed it through the membrane from the inside, delivering it directly to the palladium layer where the reaction occurs.
The team tested the technology against six PFAS compounds of regulatory concern and found that the same breakdown mechanism worked across all six.
During 58 days of continuous operation, the system treated water containing a mixture of these chemicals. It removed more than 90% of each compound and stripped away approximately 83% of the fluorine overall, providing evidence that the pollutants were being chemically dismantled rather than merely captured.
However, the results do not mean that every PFAS molecule was completely destroyed or that the technology is ready for commercial use. Further development and testing under real-world water-treatment conditions will be necessary.
One major obstacle is cost. Palladium is an expensive metal, costing around $50,000 per kilogram, according to Rittmann. Reducing the amount required is therefore among the team’s main research priorities.
The researchers believe the technology could eventually work alongside existing water-treatment systems. Conventional filtration could first concentrate PFAS from large volumes of water into a smaller waste stream, which could then be treated using the new method to break down the contaminants.
The team is also developing hybrid systems that combine palladium nanoparticles with pollutant-degrading bacteria, allowing the two components to attack contaminants through different mechanisms.
The findings offer a promising new approach to one of the most persistent forms of water pollution, although significant engineering challenges remain before the technology can be deployed widely.
For decades, efforts to tackle forever chemicals have largely focused on removing them from contaminated water. This study suggests that a more lasting solution may eventually come from destroying the chemicals themselves, preventing them from continuing to circulate through the environment and food chain.