Dr. Johan Foster, an associate professor in the department of chemical and biological engineering, and his team have developed a possible solution to trap and break down highly resilient ‘forever chemicals’ found in water sources.
Per- and polyfluoroalkyl substances (PFAS) or ‘forever chemicals’ are used across a range of products from basic textiles to firefighting foam due to the strength of the carbon-fluorine bond found within the molecule, making them resistant to water and heat.
While this chemical property makes PFAS useful in industry, their persistence comes at a cost with PFAS contaminating ecosystems all over the world for extended periods. PFAS also remain in body tissue and have been linked to health issues like liver disease and impaired thyroid function.
Part of the problem with detecting PFAS in water is their low concentration.
“If you take … a normal wooden toothpick, you break that in half, and you throw it into an Olympic sized swimming pool — that's two and a half million liters of water — that half a toothpick [sized amount of PFAS] will contaminate that much water to the levels that it will start to cause problems with human health,” said Foster.
But Foster’s team has developed a technique to address PFAS in water.
It uses a filter made of activated carbon and an iron catalyst, generated by burning biomass such as wood chips or agricultural waste covered in iron metal salts.
When added to water, the activated carbon works like a sponge, absorbing and trapping contaminants. The iron catalyst attaches to the hydrophilic heads of PFAS molecules, triggering a reaction to break down molecules, ultimately turning them into non-toxic byproducts like carbon dioxide and fluoride.
The filter differs from other technologies aimed at destroying PFAS which involve heating water to extremely high temperatures, requiring significant amounts of energy and making them impractical for large-scale applications.
Unlike conventional methods that filter out PFAS without destroying them or use large amounts of energy, Foster’s approach is energy-efficient and scalable.
“Our system is different because [there] is activated carbon in this catalyst. We can put energy into our system so we can expose it to light, UV light, and our system actually works better, but it also works in the dark, so a lot less energy.”
One of the team's challenges was determining the most effective metal to use as a catalyst for breaking down PFAS. While they experimented with various metals, including several that showed promise, iron proved the most effective for this application. Foster described this research as ongoing.
“We're still in the process of doing research in this area. We're trying to figure out the exact mechanism of how this actually degrades.”
Foster’s team is already in the process of commercializing their technology through their startup, ReAct Materials, to help bring clean water to communities around the world.
“Be passionate about these things, because this is a solvable problem,” said Foster.
“It's a huge problem. It's going to take a lot of work from scientists, from governments, from companies, to solve this problem, but it is a solvable problem.”
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