UNSW scientists fighting PFAS

A team of scientists at the University of New South Wales (UNSW) Sydney have developed a catalyst system that can break down the PFAS chemicals that contaminate water.

Per-and poly-fluoroalkyl substances (PFAS) are known as “forever chemicals” because they are resistant to degradation. They can take over 1,000 years to break down and are generally resistant to heat, stains, grease and water. As such, they’re found in a multitude of products including carpet, makeup, non-stick cookware, oil- and grease-resistant food packaging, and fire-fighting foams.

PFAS chemicals have been continuously making their way into water systems since they became mass produced in the 1940s. They also contaminate the air we breathe.

Concerns have been growing globally about the potential health impacts of PFAS. The World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) reclassified perfluorooctanoic acid (PFOA) – part of the lab-grown chemicals that make up PFAS – from a possible human carcinogen to a Group 1 carcinogen in 2023.

Much-needed progress

Scientists have been searching for an eco-friendly process to degrade PFAS, and the new catalyst system could play a key role in helping break down common types of branched PFAS. The method was developed by Dr Jun Sun and Professor Naresh Kumar from UNSW’s School of Chemistry, who worked alongside Professor Denis O’Carroll, Professor Michael Manefield and Dr Matthew Lee from the UNSW School of Civil and Environmental Engineering.

Kumar says that when PFAS was first being produced globally, nobody realised that the chemical is essentially indestructible.

“PFAS is such a robust chemical that it cannot be degraded within the human body,” he says.

Dr Sun says there is an ongoing need to come up with an energy-efficient and environmentally friendly way to remove PFAS from water.

Since PFAS doesn’t break down, even if it was removed from water sources, there would still be a question about how to dispose of it.

“You could bury it in the ground, but it’ll still end up in your groundwater supply which is where the problem started in the first place,” says UNSW water expert Professor Stuart Khan.

Degrading, in a good way

Previous research has shown nano zero-valent metals (nZVMs) and vitamin B12 can be used to degrade PFAS. Kumar and Sun tested their method by mixing the PFAS chemicals with nZVMs and the porphyrin ring in a buffer solution and measured the breakdown of the PFAS.

“We did this by following how much fluoride is released as those strong carbon-fluoride bonds are broken down,” says Sun. “So, by simply measuring the amount of fluoride ion that is produced by the reaction, we can tell how much of the PFAS have been degraded.”

“We also compared these results to the existing B12 catalysts and found that the cobalt porphyrin ring we have used was more efficient and faster at degrading branched PFAS,” says Dr Sun.

The results revealed that approximately 75 per cent of the fluoride had been released from branched PFOS and PFOA within five hours. The B12 based catalyst system only showed less than 8 per cent defluorination within five hours.

Future steps

Kumar says the next step is to try the research on a pilot scale to see if it can be done out of the laboratory on a real sample, then try it in a real water purification system or sites which are contaminated with PFAS.

In a world where PFAS has even been discovered in remote locations such as Antartica, the only other options are to reduce the use of the chemicals or find a safe alternative.

“As modern consumers, if we really want to limit our use of PFAS, we need to do our research and look into what products are made from – because there is PFAS in a lot of things that you wouldn’t even consider,” says O’Carroll.

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