Harmful ‘forever chemicals’ could be destroyed in simple way, study finds

19 Aug 2022

Image: © Farknot Architect/Stock.adobe.com

These human-made ‘forever chemicals’ can last for thousands of years, impacting soil and making water unsafe to drink.

Scientists claim to have found a way to break down some harmful ‘forever chemicals’, which could reduce environmental contamination.

PFAS, or per and polyfluoroalkyl substances, are human-made compounds that are known as forever chemicals as they can last for thousands of years, impacting soil and making water unsafe to drink.

Researchers at the University of Stockholm warned this week that rainwater almost everywhere on Earth has unsafe levels of these chemicals.

Existing methods to deal with PFAS are expensive and ineffective, as the substances are extremely difficult to break down.

But in a new study published in the journal Science, US chemists say they have found a simple way to break down almost a dozen types of these chemicals using inexpensive solvents, reagents and heated water.

“Even just a tiny, tiny amount of PFAS causes negative health effects, and it does not break down,” said study lead Prof William Dichtel. “We can’t just wait out this problem.”

The researchers from UCLA and Northwestern University said that their method severed some of the strongest known molecular bonds in PFAS. This initiated a chemical reaction that “gradually nibbled away at the molecule” until it was gone, according to UCLA’s Prof Kendall Houk.

Houk said that due to the lack of harmful byproducts, the technology could eventually make it easier for water treatment plants to remove PFAS from drinking water.

The Achilles’ heel

When studying the compounds, the researchers said they found a weakness in the unyielding carbon-flourine bonds of PFAS.

At one end of the molecule, there is a group that often contains charged oxygen atoms. The research team targeted this head group by heating the PFAS in dimethyl sulfoxide with sodium hydroxide, a common reagent. The process decapitated the head group, leaving behind a reactive tail.

“That triggered all these reactions, and it started spitting out fluorine atoms from these compounds to form fluoride, which is the safest form of fluorine,” Dichtel said. “Although carbon-fluorine bonds are super strong, that charged head group is the Achilles’ heel.”

The researchers said they successfully degraded 10 of these forever chemicals, but they still have a long way to go.

The US Environmental Protection Agency has identified more than 12,000 PFAS compounds. These are found in products from non-stick cookwear and waterproof make-up to electronics and food packaging.

Despite the long journey ahead, Dichtel remains optimistic about breaking down these forever chemicals.

“Our work addressed one of the largest classes of PFAS, including many we are most concerned about,” Dichtel said.

“There are other classes that don’t have the same Achilles’ heel, but each one will have its own weakness. If we can identify it, then we know how to activate it to destroy it.”

10 things you need to know direct to your inbox every weekday. Sign up for the Daily Brief, Silicon Republic’s digest of essential sci-tech news.

Leigh Mc Gowran is a journalist with Silicon Republic