With new environmental regulations requiring the removal of industry-retired, long-chain chemicals known as perfluoroalkyl and polyfluoroalkyl substances (PFAS) from drinking water, there are concerns regarding a new breed of these "forever chemicals" called short-chain PFAS. PFAS are often called forever chemicals because they don’t break down in the environment, human bodies, and are resistant to water, grease, and heat. 

Researchers at the University of Illinois Urbana-Champaign are helping shift the focus to include mitigation of the short-chain PFAS, which the investigators say are just as persistent as their long-chain counterparts, more mobile, and harder to remove from the environment.

A study directed by chemical and biomolecular engineer Xiao Su uses electrosorption rather than filters and solvents, combing synthesis, separations testing, and computer simulations to help design an electrode that can attract and capture a range of short-chain PFAS from environmental waters.

The research was supported in part by the United States National Science Foundation (NSF) through a research grant and the National Center for Supercomputing at Illinois, one of five facilities created by NSF's Supercomputer Centers Program.

A paper published in the Journal of the American Chemical Society describes how Su and team designed and synthesized a new class of copolymers that were used to prepare electrodes to selectively extract short-chain PFAS from aqueous solutions and contaminated wastewater via electrosorption. The authors showed that the bound PFAS contaminants could be released from the electrodes by applying an electric potential to achieve "nearly 100%" regeneration, which eliminates the need for the use of chemicals to regenerate the new PFAS selective electrodes.

"One of the challenges of working with short-chain PFAS is that they are not well studied,” said Su. “We know that they contain fewer carbon and fluorine atoms, making them shorter molecules and, therefore, more mobile, or freer to interact within the natural environment. They are more hydrophilic, meaning they are more apt to bond with water molecules. These properties combined make them more difficult to separate from water than their long-chained counterparts."

The work is a critical early step in removing short-chain PFAS from the environment, which have replaced long-chain PFAS in many industries.

To learn more, visit www.new.nsf.gov.