An international research team say that they are closer to establishing a route by which per- and polyfluoroalkyl substances (PFAS) can be safely destroyed via incineration.
Concern around PFAS contamination is on the rise with the so called “forever chemicals" being found to persist and accumulate in the environment, leading to negative impact on human and animal health. PFAS has been found in consumer, industrial, and commercial products from non-stick food packaging to legacy firefighting foams.
There is currently a moratorium on burning PFAS in the US, and during 2023 the European Chemicals Agency (ECHA) published a ‘universal restriction proposal’ covering at least 10,000 per- and polyfluoroalkyl substances (PFAS). The proposal is aimed at reducing PFAS emissions into the environment and making products and processes safer.
Researchers from Australia’s national science agency, CSIRO alongside scientists from Australia’s University of Newcastle, Colorado State University, US, and the National Synchrotron Radiation Laboratory in Hefei, China, have defined a pathway for PFAS to be destroyed safely and completely, inside a hazardous waste incinerator. They focused their study on a common type of PFAS called perfluorohexanoic acid.
“There are over 15,000 types of PFAS, but all of them share a strong fluorocarbon chain which doesn’t break down naturally,” said CSIRO environmental chemist and study co-author, Dr Wenchao Lu. Publishing their work in Science Advances the team said this is the first study to trace the entire chain of chemical reactions of PFAS breakdown during incineration.
Improper incineration does not destroy PFAS, and risks spreading particles further through the air.
Using specialised equipment at the National Synchrotron Radiation Laboratory, the researchers were able to ionise and then detect the short-lived molecules created as the PFAS is burned. This information, the researchers say, sheds light on how PFAS can be safely destroyed at high temperatures. “This study has identified intermediary molecules that are critical for us to ensure the PFAS molecule is completely destroyed, and to ensure no harmful byproducts are formed,” said Newcastle University’s Professor Eric Kennedy co-author of the study.
The researchers say that the goal of incinerating PFAS is ‘mineralisation’. This breaks the strong fluorocarbon chains into inorganic compounds like calcium fluoride, carbon dioxide, carbon monoxide, and water. These byproducts can be captured at the source and transformed into reusable materials such as industrial chemicals, concrete, fertilisers and fuels. While further research is needed, these insights offer a promising option for destroying PFAS safely, and for good, the researchers said.
In recent years research into PFAS removal has led to several interesting development including the development of 3D printed ceramic lattices, or ‘monoliths’, which have proven successful in removing 75% of perfluorooctanoic acid (PFOA), one of the most common forever chemicals, from water.
Further reading
• US takes decisive steps to tackle PFAS in the environment
• US EPA seeks solutions for bio-persistent chemicals
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