Palladium membrane destroys over 90% of forever chemicals in tests

Every chemical in the PFAS family was built to last. Per- and polyfluoroalkyl substances, known as “forever chemicals”, do not rot, rust or break down in sunlight or soil. A team led by researchers at Arizona State University has now built a membrane that tears them apart instead of holding them back: over 90 percent of each of six regulated compounds was destroyed during a continuous 58-day trial, according to the study.

The problem has been that the usual cleanup tools only move the contamination around. Activated carbon filters, ion-exchange resins and reverse osmosis pull PFAS out of drinking water, but they do not destroy it. What remains is concentrated brine and hazardous filters, which facilities bury or incinerate. The chemistry explains why. The carbon-fluorine bond is widely considered the strongest single bond in organic chemistry, and the fluorine atoms wrap the carbon backbone like interlocking armor plates. As Bruce Rittmann, director of the Biodesign Swette Center for Environmental Biotechnology, put it: “There’s really no place to get a start to break it down.”

The team’s answer is a hollow fiber membrane, a bundle of microscopic straws lined on the outside with palladium nanoparticles. Pressurized hydrogen gas flows through the centre of the straws and diffuses outward until it meets the palladium, which splits paired hydrogen molecules into highly reactive single atoms. PFAS molecules in the surrounding water attach to the same metal surface, so the reactive hydrogen and the pollutant meet there. The hydrogen strips away the fluorine armor, and the molecule breaks down into harmless components. In the trial, 83 percent of the total fluorine was removed.

For the people who drink from wells near military bases, municipal landfills, airports and wastewater plants, the arrival of a method that destroys rather than traps could change what a filter has to do. PFAS already reach crops, livestock and human tissue, and exposure has been linked to kidney cancer, thyroid disease, immune dysfunction and developmental delays. The technology is not yet ready for city water systems. The sources cite one main barrier: the palladium, which trades at roughly $50,000 per kilogram, must be used in smaller quantities to make the process affordable. The likeliest path is to pair the reactor with existing filtration, which would concentrate contaminated water first so that the catalytic system only treats the smaller, more concentrated waste stream. No deployment date has been announced.

A method that works on the whole family of compounds, not just one, is what makes this result more than a laboratory curiosity. The next step is to cut the palladium bill and show the same performance outside a single study.