Two experts at the University of Alberta say a newly discovered method to dispose of toxic substances known as “forever chemicals” in the lab is a step forward in finding ways to remove the stubborn substances from the environment.
The chemicals, which belong to a group called per- and polyfluoroalkyl substances (PFAS), are used in an abundance of products because of how durable and stable they are. They can repel fats and water, they can withstand high heat without breaking down and they’re resistant to chemical degradation. But these same traits pose a challenge.
“These molecules are extremely resistant, which makes them useful — but you also can’t get rid of them,” explains Rylan Lundgren, associate professor in the Department of Chemistry.
The chemicals the researchers studied are a particular type of PFAS called perfluoroalkyl carboxylic acids. “These chemicals don’t break down in the environment. At all. They keep building up, and they’re toxic,” says Shira Joudan, who will join the U of A next January as an assistant professor.
Lundgren and Joudan are co-authors of an expert perspective in the journal Science explaining the significance of a recent study led by researchers in William Dichtel’s lab at Northwestern University outlining the new method to destroy these chemicals.
“(Lundgren) studies fundamental organic chemistry reactivity, and I study these environmental contaminants called PFAS — I look at their environmental behaviour as a chemist,” says Joudan. “And so together we have this combined expertise that could really help translate the impact of this work.”
Persistent and pervasive
There are about 5,000 different PFAS, and their stability means they can easily travel through everything from the atmosphere to bodies of water, reaching areas as far-flung as the Arctic and remote villages in the Himalayas, according to Joudan. They’re even found in our food and drinking water.
“They’re added to all sorts of things in our lives, whether it’s to help cleaning products spread better, to put out fires — there are many different applications and usages of all these chemicals,” says Joudan. “It’s to the point where anywhere you look, they’re there.”
The researchers who found the new method for disposing of the chemicals turned their attention to a different area of the molecules than most typically do, explains Lundgren. Rather than focusing on the carbon-fluorine bonds in these molecules, which are more stable and tough to break, the new method starts by dismantling another group within the molecule.
“They found that if you focus on the carboxylic acid unit, once that group is destroyed the rest of the molecule kind of unravels in a way that was very unexpected,” says Lundgren. “There’s an inroad to destroying these molecules that are otherwise extremely stable.”
New process shows promise
The process of destroying the PFCA molecules involves water at about 80 C and two chemicals that are quite common, making the new method a lot more accessible than the current standard methods of dealing with these chemicals. It requires no extreme conditions such as high temperatures or high pressure, uses less energy to fuel the process, and doesn’t need any expensive, specialized chemicals or catalysts.
Additionally, the method uses chemical degradation, meaning the molecules are broken apart and destroyed for good — an improvement over remediation methods that use physical separation, which simply rearranges the molecules and leaves byproducts that still need to be dealt with.
“This group did a bit of a deep dive into the fundamentals of how this all happens with the hope that one day this will be able to apply to remediation of really contaminated sites in the environment. Right now there’s not a lot of options, and this is a completely different option than what’s currently being investigated,” says Joudan.
While the new method is an exciting step forward, Joudan points out there’s still a tremendous amount of work that needs to be done to effectively use it in actual remediation attempts. She says the next steps may involve further refining the process and scaling it so it can tackle remediation at a larger scale than just in a container in a chemistry lab.
“Environmental remediation is going to be much harder than chemically destroying the compounds after you get them,” says Lundgren. “It’s great that we can do this, this will definitely help, but you’ve got to track down all this stuff.”
“It is information towards something, but we still need regulations to ban or highly limit usage,” adds Joudan.