April 22, 2020
Content source: UNC Research
By Megan May
Working across disciplines, UNC-Chapel Hill environmental engineer Orlando Coronell and chemist Frank Leibfarth have developed a filtration resin that has thus far been successful in removing most PFAS from water.
PFAS, or per-and polyfluoroalkyl substances, are a family of over 5,000 chemicals. They are byproducts in the production of everyday items like Teflon, food packaging, stain-resistant fabrics, firefighting foam, and even makeup. Over the course of decades, these chemicals have made their way into drinking water sources around the world.
Although PFAS are used in the production of thousands of goods, their effects on human health are largely unknown. But, two types in particular, PFOA and PFOS, have been associated with a host of health complications including high cholesterol, thyroid disease, weakened immune system, and kidney and testicular cancer.
The NC PFAS Testing Network, established at UNC by the NC Policy Collaboratory, was born out of this public health concern. Since 2018, scientists from UNC-Chapel Hill, five other UNC system universities, and Duke University explore topics like private well contamination, atmospheric deposition, accumulation in the environment, human and animal health effects, and PFAS removal from water.
As of now, conventional filtration systems in water treatment plants and homes only remove a portion of total PFAS. In addition, many systems that can eliminate PFAS will do so only at the beginning of their lifetime. As the the part that removes contaminated particles — called the resin — breaks down, its efficacy diminishes. The deficiency in these technologies, according to Leibfarth, is that they weren’t made specifically for PFAS.
We looked at the chemical structure of PFAS and made a resin specifically for these molecules. I think this is really key, Leibfarth says.
The resin mimics PFAS by including fluorine in its structure, as well as charged ions to capture PFAS molecules, ultimately pulling them out of water.
The fluorous component draws it into the resin, and then the ionic component does ion exchange and makes it stick there, Leibfarth explains.
The team tested 21 PFAS that are commonly found in North Carolina, specifically from the Cape Fear River basin — a drinking water source for over 1.5 million people.
Initial testing showed they removed about 85 percent of all 21 PFAS, including 100 percent of PFOA and PFOS. The resin even absorbed 70 to 80 percent of short-chain PFAS, which have been particularly hard to remove from water.
More good news: The resin can be cleaned with a simple methanol solution and reused multiple times. Additionally, the device using this technology is not very different from what is currently used, so Coronell expects the barriers to move it from the lab to implementation will not be burdensome.
This technology could be used either in municipal drinking water plants or as an under-the-sink device in homes with private wells — an important fact, Coronell notes, because about 15 percent of Americans, or up to 50 million people, depend on private wells for drinking water. The resin could also potentially be used to treat wastewater or in diagnostic testing.
With their findings published in a peer-reviewed journal, and the resin patent protected, Coronell and Leibfarth are looking ahead to next steps, like ensuring the resin works in real-world scenarios.
Can we flow water over it at a high rate? How fast can we remove that PFAS? What kind of capacity does this resin really have? At what volume of water does our resin start to not work, and how often do we have to regenerate it? Leibfarth asks.
All these things will go both into the efficacy of the material but also the economics of implementation.
If the team can secure enough funding, Leibfarth hopes this technology will be commercially implemented in the next five years. Getting it up and running as quickly and safely as possible is important, he says, because PFAS aren’t going away anytime soon.
Fluorinated compounds will continue to be made because consumers will continue to demand them, Leibfarth says.
And it’s a problem that’s a product of our modern society, but we need modern solutions, then, to that problem.
Orlando Coronell is an associate professor in the Department of Environmental Sciences and Engineering within the UNC Gillings School of Global Public Health.
Frank Leibfarth is an assistant professor in the Department of Chemistry within the UNC College of Arts and Sciences.