Researchers have found that a common and inexpensive material—iron powder—can clean up dangerous “forever chemicals” from water even better than the material most water filters use today: activated carbon.
Even more surprising, the iron powder still works well even after it rusts.
The chemicals in question are PFOS (perfluorooctane sulfonate), part of a larger group known as PFAS (per- and polyfluoroalkyl substances).
These synthetic chemicals have been used for decades in a wide range of products, including non-stick cookware, stain-resistant carpets, food wrappers, and firefighting foam.
Unfortunately, PFOS are extremely persistent in the environment and don’t break down easily—earning them the nickname “forever chemicals.”
Over time, they have contaminated soil, crops, and even drinking water, and have been linked to serious health problems like liver damage, cancer, and developmental issues.
To find better ways of removing these toxic substances from water, Professors Xiaoguang Meng and Christos Christodoulatos from the Stevens Institute of Technology, along with Ph.D. student Meng Ji, tested whether iron powder could outperform activated carbon—a standard material in most commercial water filters.
Activated carbon works through a process called adsorption, where PFOS molecules stick to its large and porous surface.
But iron powder, known in scientific terms as microscale zero-valent iron (mZVI), is already used in wastewater treatment because it’s cheap and effective. The Stevens team wanted to see how the two materials compared.
Their results, published in the journal Environmental Science & Technology in March 2025, were striking.
Iron powder was found to be 26 times more effective than activated carbon at removing PFOS from water, based on surface area. That means even small amounts of iron powder could have a big impact on cleaning contaminated water.
Even more intriguing, the researchers found that when iron powder rusted—something expected to reduce its effectiveness—it still worked nearly as well. The rust, or iron oxide, didn’t stop the particles from removing PFOS. In fact, the rusty surface remained active, continuing to pull harmful chemicals out of the water.
These surprising results have drawn attention from other scientists, and the team is now working to understand exactly why the rusted iron remains so effective. Understanding this could help create better, large-scale water purification systems in the future.
This discovery offers hope for more affordable and efficient ways to remove toxic forever chemicals from the environment, helping protect both public health and the planet.
Source: KSR.
