Researchers Identify Novel Mechanism for Destroying, Not Just Removing, PFAS in Water
A new study published in PNAS has demonstrated the potential of a hydrogen-based catalytic membrane technology to remove and destroy six important per- and polyfluoroalkyl substances (PFAS) in water: PFOA, PFOS, PFNA, PFHxS, PFBS, and GenX chemicals.
PFAS, often called "forever chemicals," are highly persistent in the environment and human body because of their strong carbon-fluorine bonds, making them resistant to degradation and leading to their bioaccumulation over time. These compounds have been used in a range of industrial and consumer product applications for decades, introducing them to the environment where they can persist in water systems and enter the food chain. PFAS have come under increasing scrutiny in recent years as evidence of their health harms continues to mount, with exposure to certain PFAS linked to higher cholesterol, increased risk of some cancers, developmental complications, liver damage, and immune system effects.
The six chemicals targeted in the present study were chosen due to their regulatory relevance. For example, in April 2024, the U.S. Environmental Protection Agency (EPA) issued the first-ever national, legally enforceable drinking water standards for the six PFAS—although the limits have since been substantially rolled back by the Trump Administration. The standards for PFOA and PFOS were upheld, while the rest were withdrawn.
In this context, the new study describes a previously unidentified mechanism for destroying PFAS in water rather than simply separating and removing the contaminant.
Specifically, researchers affiliated with Rice University, Arizona State University, and Tongji University in China utilized palladium-coated membranes to capture PFAS and break down their highly stable carbon–fluorine bonds through a process called hydrodefluorination, under ambient conditions.
During a 58-day continuous-flow experiment, the system achieved removal efficiencies ranging from 93–99 percent across the six targeted PFAS, with an overall defluorination efficiency of 83 percent. The researchers found that longer-chain PFAS were generally removed and defluorinated more readily than shorter-chain compounds, while GenX was particularly resistant to degradation due to its chemical structure. (Separate research has shown that fluorinated carbon chain length plays a significant role in how a PFAS compound responds to water treatments and remediation approaches).
The technology works by delivering hydrogen gas through hollow-fiber membranes coated with palladium, a metal that activates the hydrogen and helps capture PFAS molecules from contaminated water. The activated hydrogen then helps break the strong carbon–fluorine bonds, facilitating hydrodefluorination in which fluorine atoms are progressively removed and replaced with hydrogen to produce less-fluorinated or nonfluorinated compounds. The removed fluorine is released as fluoride ions.
Based on their findings, the researchers believe that hydrogen-based catalytic membranes could offer a promising, potentially lower-energy approach to PFAS water treatment by chemically destroying contaminants rather than simply separating them from water. However, further research is needed to establish the technology's effectiveness and scalability under real-world treatment conditions.
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