Tough stuff: Clemson University researchers take on ‘forever chemicals’

Imagine two bodybuilders locking hands as if in an arm wrestling position, their biceps and forearms straining as their palms press against each other.

For researchers such as Clemson University’s Kevin Finneran, that is a good way to think of PFAS, the abbreviation for per- and polyfluoroalkyl substances– also known as “forever chemicals.”

The strength of their chemical bonds makes them excellent at repelling water and grease and extinguishing fires but also notoriously difficult to clean up.

It is a challenge that Clemson engineers and scientists are taking on, as the discovery of PFAS in thousands of water supplies across the nation raises health concerns.

Clemson’s Department of Environmental Engineering and Earth Sciences is home to three leading PFAS experts– Tanju Karanfil, Ezra Cates and Finneran.

Each uses a different approach in the fight against PFAS, including microwaves, UV radiation and microbiology.

Finding solutions to PFAS contamination is one of our key strengths,” said Debora F. Rodrigues, the department chair. “Their work has real impact– protecting people’s health and making our water safer.”

PFAS is a family of chemicals that have been used for decades in industry and consumer products ranging from non-stick frying pans and food wrappers to stain-repellent upholstery and firefighting foams, according to the U.S. Environmental Protection Agency.

Peer-reviewed studies have shown that health hazards include increased risk of some cancers, reproductive effects such as decreased fertility and developmental effects or delays in children, according to the EPA.

PFAS chemicals are hard to clean up because the ultra-strong carbon-fluorine bonds that make them so attractive for commercial uses also make them difficult to break apart. It takes decades for PFAS chemicals to break down naturally, if at all, and conventional water treatments don’t work.

Microwaves

Karanfil, a professor in the department and Clemson’s senior vice president for research, scholarship and creative endeavors, is taking the battle against PFAS to water utilities.

Many utilities use grains of activated carbon to pull PFAS out of the water to ensure they comply with regulations.

The PFAS and other pollutants cling to the activated carbon, so it periodically needs to be treated or thrown away in landfills. Current options are expensive and come with environmental risks.

PFAS is so tough that conventional chemical treatments often fail to destroy it, raising the risk of re-contamination. Sending the activated carbon to landfills also poses potential hazards — the PFAS could leach out.

Another option is to haul the activated carbon to a facility where it is heated to about 1,000 degrees Celsius. That destroys the PFAS but is energy intensive.

The basic idea behind Karanfil’s proposed alternative can be found in many kitchens– microwaves. The difference is that these microwaves would be much more powerful than the ones on the average household countertop.

Karanfil and his team are working with water utilities and the EPA to develop the technology.

“This is about giving utilities a smarter, cleaner way forward,” Karanfil said. “Our early results show microwave regeneration could reduce energy use, cut costs, and preserve carbon better than traditional methods—all while keeping PFAS out of landfills and incinerators. That’s a win for utilities, and a win in the battle against PFAS.” (Read more here, here and here.)

Ultraviolet light

While Karanfil harnesses the power of microwaves, Cates is taking a different path—shining ultraviolet light directly into the problem.

UV radiation has been used to treat drinking water and wastewater for many years, said Cates, an associate professor in the department.

The UV lamps won’t break down PFAS, but the high-energy photons they emit can be used to excite catalysts that will, he said.

Cates and his team have suspended catalyst particles in water and exposed them to UV radiation inside a reactor. The approach has been effective for degrading some types of PFAS, but to make it worth scaling up it would need to get most of them.

So they are looking at a simpler technique called vacuum UV photolysis.

“If we go to shorter wavelengths, those photons can directly be absorbed by PFAS and cause them to break apart,” Cates said. “Really, what we want to get is conversion to inert products.”

He is working with a Rutgers University startup that has made efficient lamps that operate at a unique wavelength. They want to shift that wavelength to a slightly different one that would work better for PFAS.

“The reason I’m excited about that is because it will be just an exceedingly simple process– almost boring,” Cates said.

Microbiology and chemistry

Finneran, a professor in the department, works at the intersection of microbiology and chemistry to see if both PFAS and another common type of pollutant, chlorinated solvents, can be treated at the same time while they are still in the ground at contaminated sites.

His work is particularly helpful at sites where firefighters have used PFAS-containing foam for training, often for years, contaminating the soil. But it could also be helpful at private industrial sites with similar issues, Finneran said.

“In this case, what I’m studying is, when we adsorb PFAS compounds onto different types of activated carbons in the ground, can we still treat chlorinated solvents that are also in the ground, microbially and chemically?” he said. “Those are really well established technologies, but it does turn out that PFAS compounds and the technologies we’re using to treat them do really disrupt this.”

Finneran is now expanding his focus to track how PFAS and their precursors move through wastewater treatment systems and what can be done to make the facilities more effective at removing trace amounts of contamination.

Jesus M. de la Garza, the director of Clemson’s School of Civil and Environmental Engineering, said the push for PFAS-free water reflects the school’s broader mission to address urgent, real-world problems.

“From the beginning, our school was created to focus on things that truly matter—society’s grand challenges tied to infrastructure and the environment,” he said. “Access to PFAS-free water is one of those critical issues.”