The contamination of groundwater, surface water, and drinking water by perfluoroalkyl and polyfluoroalkyl substances (PFAS), known as "forever chemicals," affects millions of people worldwide. PFAS molecules from industrial manufacturing, firefighting foams, and consumer products, which reach freshwater and marine environments, are generating growing concern about the health risks to people and animals.

Now, a promising new method developed by scientists at Flinders University (Australia) paves the way for removing the most difficult-to-capture variants of these persistent pollutants from water.

The research team, led by Dr. Witold Bloc, has discovered adsorbents that effectively capture PFAS, including short-chain PFAS, which are particularly difficult to remove using existing technologies.

The study, published in the prestigious journal Angewandte Chemie International Edition, demonstrates the use of a nanoscale molecular cage that acts as a highly selective “PFAS trap.”

“While some long-chain PFAS can be partially removed using existing water treatment technologies, capturing short-chain PFAS, which are more mobile in water, remains a major unsolved challenge,” says Dr. Witold Bloch, project leader, from the School of Science and Engineering at Flinders University.

“We discovered that a nanoscale cage captures short-chain PFAS by forcing them to cluster favorably within its cavity. This unusually strong binding mechanism differs from that of traditional adsorbent materials,” explains Bloch.

The team embedded these molecular cages in mesoporous silica, an adsorbent that typically does not exhibit PFAS-binding properties.

A Reusable System

First author Caroline Andersson, a PhD candidate in Chemistry at Flinders University, says the presence of the embedded nanoscale cage allows for the removal of a wide range of PFAS from water, including short-chain variants, which are very difficult to isolate.

“The most exciting aspect of this project was that we first conducted in-depth studies on how PFAS bind within the cage at a molecular level,” Andersson explains. “That allowed us to understand the precise behavior of the binding and then use that knowledge to design an effective adsorbent for PFAS removal.”

Laboratory tests showed that the adsorbent material can remove up to 98% of PFAS at environmentally relevant concentrations from model tap water.

“The adsorbent also proved reusable, remaining highly effective after at least five reuse cycles.” “These results highlight its potential for integration into water filtration systems to purify drinking water in the final stage of treatment,” Bloch adds.

“This research represents an important step toward the development of advanced materials capable of tackling one of the world’s most persistent environmental pollutants,” he concludes.