If you read the labels of everyday products such as lubricants, pesticides, and non-stick cookware, you are likely to come across a common acronym: PFAS. This stands for per- and polyfluoroalkyl substances (PFAS), a group of man-made chemicals known for their ability to repel water, grease, and dirt.

There are thousands of different PFAS compounds—more than 4,000 have been identified to date. What they all share is a highly resistant chemical structure composed of carbon and fluorine atoms linked by extremely strong bonds. This exceptional stability means that these compounds do not readily break down over time. As a result, they persist in the environment and can accumulate in soil, water, and even living organisms.

Effects on Human Health

Numerous scientific studies have examined the potential impact of PFAS on the human body. Findings suggest that exposure to these compounds may lead to adverse health effects, including hepatotoxicity, immunotoxicity, increased cancer risk, reduced fertility, and thyroid disorders, among others.

The International Agency for Research on Cancer (IARC) has classified perfluorooctanoic acid (PFOA) as carcinogenic to humans and perfluorooctane sulfonate (PFOS) as possibly carcinogenic.

The primary source of human exposure to these substances is drinking water, in which some PFAS compounds can have a half-life of up to 92 years.

For these reasons, the European Union’s Drinking Water Directive has established a limit of 0.50 μg/L for the total concentration of PFAS and 0.1 μg/L for the sum of 20 specific PFAS compounds.

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In 2024, the U.S. Environmental Protection Agency (EPA) announced new drinking water regulations establishing maximum contaminant levels for five PFAS compounds. Specifically, the limits for PFOA and PFOS were set at 4 ng/L, while perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and hexafluoropropylene oxide dimer acid (GenX) were limited to 10 ng/L. Moreover, these regulations are expected to become even more stringent in the future.

Can These Substances Be Removed from Water?

Several strategies exist for removing PFAS from drinking water, including ion-exchange resins and nanofiltration. However, many of these methods are either insufficiently effective or too costly, highlighting the need for new solutions.

One promising approach involves removing PFAS through adsorption—the adhesion of molecules to the surface of porous materials. This method is particularly attractive due to its high efficiency, low cost, and scalability potential.

Activated carbons, in particular, stand out as porous materials with a high specific surface area and excellent adsorption capacity, making them strong candidates for water purification. These conventional, low-cost adsorbents have proven highly effective in removing long-chain PFAS (compounds containing more than six carbon atoms), but they are much less efficient when it comes to short-chain PFAS (fewer than six carbon atoms).

For this reason, new materials must be developed to remove these contaminants from drinking water more effectively and sustainably. Researchers at IMDEA Energy, in collaboration with Canal de Isabel II, have launched a joint project to develop a system capable of rapidly and efficiently removing PFAS from drinking water.

The system is based on advanced porous materials specifically designed to capture these contaminants and integrate easily into conventional drinking water treatment processes. The ultimate goal is to ensure that drinking water reaches PFAS concentrations that are safe for human health.

Published in The Conversation.