RIP Forever Chemicals? Scientists Aim To Rid PFAS of Lifespan Label

University of Texas at Dallas scientists are working to limit the lifespan of potentially hazardous forever chemicals by developing new technologies to remove them quickly and efficiently from the environment.

Dr. Mario Wriedt, associate professor of chemistry and biochemistry, is investigating the use of metal-organic frameworks to physically bind to and remove per- and polyfluoroalkyl substances (PFAS) from contaminated sites, including water resources. His research is funded by a recent $581,000, three-year grant from the Department of Defense's Strategic Environmental Research and Development Program.

PFAS, often described as forever chemicals, are a class of some 15,000 chemicals that have been used since the 1950s in industrial processes and in a wide variety of consumer products, including nonstick cookware, food packaging, firefighting foam, water- and stain-resistant textiles, cleaning products and cosmetics. Although their properties make them useful, PFAS contain strong chemical bonds between carbon and fluorine atoms that make the materials extremely difficult to degrade naturally.

Certain human-made PFAS are prevalent in the environment and can accumulate and remain in the human body for several years. People can be exposed to the chemicals by consuming water or food containing PFAS or by using products made with them.

"The beauty of MOFs is that they are nontoxic; they are extremely stable; and they work in a matter of seconds, not days."

Dr. Mario Wriedt, associate professor of chemistry and biochemistry in the School of Natural Sciences and Mathematics

According to the Centers for Disease Control and Prevention, nearly all people in the U.S. have PFAS in their blood. Research studies suggest associations between PFAS exposure and adverse health outcomes, such as increased cholesterol, impaired immune function and cancer.

"PFAS have been dubbed forever chemicals for a reason," Wriedt said. "They don't easily break down in the environment or in the human body."

Although efforts have been made in recent years to ban or restrict the use of some PFAS in products and processes, they still can be found in drinking water, groundwater, soil and air.

"The good news is, we have identified this as a problem. There is a large research community looking into developing alternatives to PFAS, but we still have to deal with the mess that is already out there that won't go away on its own," said Wriedt, who is a Fellow, Francis S. and Maurine G. Johnson Chair in the School of Natural Sciences and Mathematics.

For decades, remediation of PFAS contaminants, especially from water sources, has relied on well-established technologies such as activated carbon and ion exchange resins. These techniques, which work by chemically sticking to, or simply adsorbing, PFAS, are relatively inexpensive, yet have their limitations; activated carbon can take significant time to complete a cycle of water treatment and only adsorbs a few kinds of PFAS.

Wriedt and his research group are taking a different approach by concentrating on metal-organic frameworks, or MOFs, which are highly porous materials whose nano-sized pockets can be specifically designed to trap a variety of materials, from water or other gaseous molecules in the air to pollutants in water.

"The beauty of MOFs is that they are nontoxic; they are extremely stable; and they work in a matter of seconds, not days. They also are tunable - that is, we can tailor-make them on the atomic scale for very specific applications," Wriedt said. "We are working to design their pore geometry so that they stick specifically to PFAS molecules and not to other co-contaminants commonly found in water."

Other materials can easily get clogged with co-contaminants that compete with PFAS for adsorption sites, Wriedt said. Further, once those materials are saturated with PFAS, they often end up in a landfill, which creates a new problem.

"Most importantly, unlike activated carbon, which has limitations to be reclaimed, we can simply wash the PFAS out and reuse our MOFs for another round of adsorption," Wriedt said.

Wriedt and his colleagues, who include collaborators at the University of Central Florida, the University of Nebraska-Lincoln and Clarkson University, are testing the effectiveness of their custom-designed materials in the lab on simulated water samples as well as on field samples, such as groundwater that has been impacted from PFAS-based firefighting foams.

Wriedt also is investigating ways to use MOFs as photocatalysts to break the chemical bonds of washed-out PFAS and transform them into nonharmful products.

"Ultimately we hope to use our fundamental understanding of the way MOFs behave to develop materials that can be scaled up and that can outcompete existing technologies in terms of cost," he said.

Media Contact:

Amanda Siegfried, UT Dallas, 972-883-4335, [email protected], or the Office of Media Relations, UT Dallas, (972) 883-2155, [email protected].