Ellen Phiddian
Cosmos science journalist
They’re called “forever chemicals” for a reason: PFAS are diabolically difficult to break down.
But 2 different teams of chemists have found new ways to break them up – with light.
Both studies have just been published in Nature.
The stability of PFAS, or per- and polyfluoroalkyl substances, comes from fluorine atoms bonded to carbon atoms.
This bond is very strong, and highly unusual in nature, making it very difficult to break down and virtually impossible to decompose.
Each of the new studies has found a catalyst which uses light energy (a photocatalyst) to break this carbon-fluorine bond.
“Our approach is a fundamental advancement in organic synthesis that achieves activation of these challenging carbon-fluorine bonds across a variety of situations,” says co-author on one paper, Professor Garret Miyake, a chemist at Colorado State University, USA.
“Our method is more sustainable and efficient and can be used to address stubborn compounds in plastics, for example, in addition to the obvious uses around PFAS.”
Miyake and colleagues’ catalyst is a combination of organic (carbon-containing) molecules. They break PFAS down in the presence of blue LED light.
The other study, led by Professor Yan-Biao Kang from the University of Science and Technology of China, uses a different organic molecule, called KQGZ, to attack the carbon-fluorine bond.
This catalyst, when heated with PFAS to 40°-60°C, could use light to break the substances down into pure carbon and fluoride salts.
These substances could then be recycled into more PFAS, or used in other materials.
The researchers analysed a range of different catalysts, and while KQGZ worked best, they suspect there may be even more effective agents out there.
Meanwhile, Miyake’s colleagues say that their research could also be adapted to breaking down other hard-to-recycle materials, like plastics – and making them into more useful materials.
But they are next looking at the viability of testing their compound out of the lab and in the environment.
“We need to make this technology more practical so it can be used in water or soil – places where PFAS are found,” says study co-author Dr Mihai Popescu.
“We need the chemistry we are showcasing here to be useful in those conditions and that is where a lot of work remains.”
