UW spearheads research to eliminate hazardous ‘forever chemicals’

A team of researchers at the University of Washington (UW) has developed a new way to destroy “hazardous” forever chemicals using “supercritical water,” which is formed through high temperature and pressure in a reactor.

Forever chemicals, known scientifically as per- and polyfluoroalkyl substances (PFAS), are thousands of artificial substances found in everyday objects. Recent national investigations are discovering these chemicals are harmful to the health of humans and animals as peer-reviewed studies have linked them to some cancers, decreased fertility, thyroid disease, and developmental delays.

It was recently discovered that PFAS exist in aqueous film-forming foam (AFFF), one of the most effective foams to fight and extinguish fires. When AFFF is used to suppress a fire, the PFAS within the foam seeps into the ground and the water supply, contaminating the entire area and making it nearly impossible to remove. The Department of Defense created a mandate that military organizations must phase out firefighting foams containing PFAS by 2024, while many states are considering restricting or banning AFFF altogether.

PFAS are synthetic and do not appear naturally in the environment.

EPA to designate ‘forever chemicals’ as hazardous substances

“Those chemicals are very persistent, they are long chain hydrofluorocarbons,” lead author and mechanical engineering associate professor Dr. Igor Novosselov said. “So that means they have several Cs strung together, Cs being carbon and then fluorine molecules attach to the carbon. It makes this a very stable structure. And if you just heat the water, nothing happens to Teflon, right? Teflon can withstand heat and nothing happens, so you have to be very aggressive about breaking them apart.”

The molecular bond in PFAS is what makes them harmful, according to studies, as the chemicals are virtually indestructible and do not fully degrade in the environment or within living tissue.

Today nearly all Americans, including newborn babies, have PFAS in their blood, and more than 200 million people may be drinking PFAS-tainted water, according to the Environmental Working Group.

“Chemicals that survive forever in normal water, such as PFOS and PFOA, can be broken down in supercritical water at a very high rate,” Novosselov said in a UW-sponsored Q+A. “If we get the conditions right, these recalcitrant molecules can be completely destroyed, leaving no intermediate products and yielding only harmless substances, such as carbon dioxide, water, and fluoride salts, which are often added to municipal water and toothpaste.”

Supercritical water has been achieved at 220 atmospheres and 374 degrees Celsius, according to Novosselov.

The genesis of this project came from originally designing the reactor to break down chemical warfare agents, taking the university five years to make. The pressure inside the reactor is 200 times higher than at sea level.

“You probably cannot treat the whole ocean like this, for example. But we could possibly use this to treat existing problems, such as forever chemical waste at manufacturing sites,” Novosselov said.

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