New Filter Fights Forever Chemicals

Pollution comes in various forms, some obvious, others not so much. One example of the latter type is known by the ominous label of “forever chemicals,” generally defined as PFAS, or per- and polyfluoroalkyl substances. They’re synthetically produced organic compounds that are widely used in a bewildering range of products, from yoga pants to phone screens to cosmetics to Teflon frying pans to house paint, and feature exceptionally strong chemical bonds—the very quality that makes them both so useful and so persistent. 
 
But PFAS chemicals have an insidious way of sneaking their way into the human body through drinking water, food, and even the skin. All of which is a bad thing because they’ve been linked to various types of cancer, liver and thyroid disease, infertility, and a host of other health issues. Their ubiquity and persistence make removing them from where they don’t belong an especially tough problem, for which a team of chemical engineers at the University of British Columbia (UBC) has developed a simple and powerful answer.
 
“What’s really unique is that we destroy the PFAS,” explained lead researcher Johan Foster, professor of chemical and biological engineering at UBC. Although as he points out, “there’s thousands of different PFAS compounds out there,” not all of them are a problem. “The ones that are worrisome are the ones that are soluble in water, because we can drink them. They can get into our bodies and into our systems, and those are the ones that are dangerous because they cause all these health effects. Those PFAS compounds will attach to our catalyst, we’ll break them down, and you end up with some very simple nontoxic chemicals at the end.” The UBC solution is remarkably uncomplicated in principle. 
 
“In its very simplest form, it’s just activated carbon with an iron catalyst on it,” Foster said. “It’s an iron oxide, very straightforward to make, very scalable.” 
 
The system also needs ultraviolet light, which works with the patented iron oxide photocatalyst to break down PFAS substances. Recently published research described tests in which more than 85% of one common PFAS called perfluorooctanoic acid, or PFOA, was eliminated in about three hours of treatment.

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The big difference from other PFAS mitigation techniques is that UBC’s treatment isn’t just filtering out the PFAS, but actually breaking it down into harmless forms. Foster notes that granulated activated carbon systems are used in everything from the Brita pitcher in your refrigerator to large municipal water systems to remove contaminants from water. 
 
“What do you do with it afterwards? On a small scale like a Brita filter, well, you throw it in the garbage. It ends up back in the ground probably. So you’re just basically kicking the can down the road,” Foster said. “On a municipal level they can reactivate the carbon, so once it’s already inundated with chemicals, they heat it up to reactivate that system. But what you’ve done is you’ve basically evaporated all of that PFAS into the atmosphere. That’s why we’re finding PFAS in glaciers and in lakes on the top of mountains—places it has no business being, but it is because it’s put back into the atmosphere. 
 
“Our system will absorb the PFAS, but then destroy it.”
 
Other methods for vanquishing PFAS chemicals tend to be rather impractical. 
 
“If you take all the water and you heat it up to a few hundred degrees Celsius, you’ll start to degrade the PFAS,” Foster said. “Well, heating all of the drinking water for a municipality is rather tough, especially to that level. It’s a lot of energy.” 
 
For now, he added, “we’re trying to do this on kind of a single home level or single business, where we’re talking about gallons per minute.” 
 
Foster and his team have founded a startup called ReAct Materials to develop the commercial potential of the system, including possibly handling contaminants other than PFAS substances.

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“This certainly works for PFAS. We think it’ll work for other organics,” he said. For now, however, “We’re really focusing on capturing and destroying the PFAS because it’s the one that nobody else can do.” 
 
Eventually the hope is that the system could be part of a large municipal water treatment solution. “This is very scalable, and that’s one of the huge advantages,” Foster said. 
 
Fortunately, those “forever chemicals” that are so troublesome may not be so eternal after all.
 
Mark Wolverton is a technology writer in Narbeth, Pa.