By Theo Schwinke
A University of Missouri researcher has discovered a new method to remove so-called "forever chemicals" from our drinking water.
Per- and polyfluoroalkyls (PFAS) are industrial chemicals used to manufacture thousands of products, including cosmetics, carpeting, non-stick cookware, stain-resistant fabrics, firefighting foams, food packaging and waterproof clothing.
They're everywhere — the environment, our food and even in our bodies. Peer-reviewed studies have shown that exposure to PFAS may lead to decreased fertility, developmental delays in children and increased risk of some cancers. And they take hundreds or even thousands of years to break down.
For roughly the past 10 years, researchers have been looking for ways to remove PFAS from the environment or at least degrade them into harmless, inorganic compounds.
Now, Feng "Frank" Xiao, an associate professor in Mizzou's College of Engineering, and team have found a simple solution using common tools and materials.
"You don't need organic solvent or really high temperatures," Xiao, an expert in degrading PFAS, said. "Just heat the PFAS with granular activated carbon, or GAC."
GAC is composed of granules of coal, wood or other carbon-rich materials that have been heated. It is already commonly used to filter a wide range of harmful chemicals from contaminated water or air. Consumers use it to clean household aquariums or filter drinking water, and it can be purchased online for just a few dollars per pound.
In a paper recently published in the journal Environmental Science and Technology , Xiao and his team describe how they heated PFAS with common GAC at 572 degrees Fahrenheit. As a result, the researchers achieved 90% mineralization of the PFAS, breaking the forever chemicals down into harmless, inorganic fluorine.
Before now, reaching this level of mineralization required temperatures in excess of 1292 degrees Fahrenheit, high pressure or solvents. Xiao's method is much more cost effective and sustainable, as GAC is inexpensive and can be reheated again and again.
Potential applications
The key to Xiao's innovation is the combination of GAC and heat.
"Once GAC is involved, the thermal degradation of PFAS occurs much faster, and the mineralization is more intense," Xiao said. "It's not an expensive process, compared to reverse osmosis, and it can be done at local scale with a regular furnace."
The discovery represents a significant breakthrough in managing PFAS-containing solid wastes, biosolids and spent adsorbent media that are major concerns to farmers and communities.
"In the Midwest, we use a lot of herbicides and give animals a lot of pharmaceuticals," Xiao said. "These substances can contain high amounts of PFAS. Through this new removal method, we can drastically reduce the compounds' presence in our lives."
Xiao chose Mizzou for the opportunities he has to collaborate with other leading researchers and for the quality of the scholarship of undergraduate and graduate students.
"I teach environmental courses, and the students really care about the environment. They care about the water quality, and they care about our ecosystem," Xiao said.
Xiao communicates to those students his passion for practical research and the opportunities they have to create a better world through engineering.
"The real-world application of this discovery is that we can effectively and efficiently remove forever chemicals and other contaminants from our water," he said. "This is the technology we need."
