Canberra: A team of international scientists has defined a pathway to safely and completely destroy materials contaminated with per- and polyfluoroalkyl substances (PFAS) by burning them in a hazardous waste incinerator.
The PFAs also known as “forever chemicals” persist and accumulate in the environment, causing significant harm to human and animal health, Xinhua news agency reported.
It is the first study to trace the entire chain of chemical reactions as PFAS break down during incineration, according to the researchers from the Commonwealth Scientific and Industrial Research Organization (CSIRO), the University of Newcastle, the Colorado State University in the US, and the National Synchrotron Radiation Laboratory (NSRL) in Hefei, China.
PFAS occurs in a range of consumer, industrial, and commercial products, such as non-stick food packaging and cookware, and legacy firefighting foams. The chemicals can leach into soils and groundwater, travel long distances, and do not fully break down naturally.
There is currently a moratorium on burning PFAS in the US, and regulatory uncertainty elsewhere, as improper incineration does not completely destroy them, and risks spreading them further through the air. It also creates harmful greenhouse gas emissions, the researchers said.
“There are over 15,000 types of PFAS, but all of them share a strong fluorocarbon chain which doesn’t break down naturally. This is what makes them so persistent in our environments,” CSIRO Environmental Chemist and study co-author Lu Wenchao said.
Some of the chemicals formed during PFAS incineration exist for just 1 millisecond: shorter than a housefly’s wing flap. But identifying these intermediary molecules is crucial to determining what harmful products are formed throughout the process, Wenchao said.
The interdisciplinary team studied a common type of PFAS called perfluorohexanoic acid.
Wenchao added that using specialised equipment at the NSRL, the team detected the short-lived molecules, created as the PFAS burned.
“By taking ‘snapshots’ of the chemical reactions as they occur, we can see what intermediaries or harmful free radicals form inside the incinerator,” he said, adding these chemicals had been hypothesised, but never actually detected.
Eric Kennedy, co-author from the University of Newcastle, said their results shed light on how PFAS can be safely destroyed at high temperatures, with intermediary molecules identified to ensure no harmful byproducts are formed.
The ultimate goal of incinerating PFAS is a process called “mineralisation,” which converts the strong fluorocarbon chains into inorganic compounds like calcium fluoride, carbon dioxide, carbon monoxide, and water, said the researchers.
They added that these byproducts can, in turn, be captured at the source and transformed into reusable materials such as industrial chemicals, concrete, fertilisers, and fuels.
