The undoing of toxic “forever chemicals” may be found in products in your pantry.

Perfluoroalkyl and polyfluoroalkyl substances, also known as PFAS, can persist in the environment for centuries. While the health impacts of only a fraction of the thousands of different types of PFAS have been studied, research has linked exposure to high levels of some of these widespread, humanmade chemicals to health issues such as cancer and reproductive problems.

Now, a study shows that the combination of ultraviolet light and a couple of common chemicals can break down nearly all the PFAS in a concentrated solution in just hours. The process involves blasting UV radiation at a solution containing PFAS and iodide, which is often added to table salt, and sulfite, a common food preservative, researchers report in the March 15 Environmental Science & Technology.
“They show that when [iodide and sulfite] are combined, the system becomes a lot more efficient,” says Garrett McKay, an environmental chemist at Texas A&M University in College Station who was not involved in the study. “It’s a big step forward.”

A PFAS molecule contains a chain of carbon atoms that are bonded to fluorine atoms. The carbon-fluorine bond is one the strongest known chemical bonds. This sticky bond makes PFAS useful for many applications, such as water- and oil-repellant coatings, firefighting foams and cosmetics (SN: 6/4/19; SN: 6/15/21). Owing to their widespread use and longevity, PFAS have been detected in soils, food and even drinking water. The U.S. Environmental Protection Agency sets healthy advisory levels for PFOA and PFOS — two common types of PFAS — at 70 parts per trillion.

Treatment facilities can filter PFAS out of water using technologies such as activated carbon filters or ion exchange resins. But these removal processes concentrate PFAS into a waste that requires a lot of energy and resources to destroy, says study coauthor Jinyong Liu, an environmental chemist at the University of California, Riverside. “If we don’t [destroy this waste], there will be secondary contamination concerns.”

One of the most well-studied ways to degrade PFAS involves mixing them into a solution with sulfite and then blasting the mixture with UV rays. The radiation rips electrons from the sulfite, which then move around, snipping the stubborn carbon-fluorine bonds and thereby breaking down the molecules.

But some PFAS, such as a type known as PFBS, have proven difficult to degrade this way. Liu and his colleagues irradiated a solution containing PFBS and sulfite for an entire day, only to find that less than half of the pollutant in the solution had broken down. Achieving higher levels of degradation required more time and additional sulfite to be poured in at spaced intervals.

The researchers knew that iodide exposed to UV radiation produces more bond-cutting electrons than sulfite. And previous research has demonstrated that UV irradiation paired with iodide alone could be used to degrade PFAS chemicals.

So Liu and his colleagues blasted UV rays at a solution containing PFBS, iodide and sulfite. To the researchers’ surprise, after 24 hours of irradiation, less than 1 percent of the stubborn PFBS remained.

What’s more, the researchers showed that the process destroyed other types of PFAS with similar efficiency and was also effective when PFAS concentrations were 10 times that which UV light and sulfite alone could degrade. And by adding iodide the researchers found that they could speed up the reaction, Liu says, making the process that much more energy efficient.

In the solution, iodide and sulfite worked together to sustain the destruction of PFAS molecules, Liu explains. When UV rays release an electron from iodide, that iodide is converted into a reactive molecule which may then recapture freed electrons. But here sulfite can step in and bond with these reactive molecules and with electron-scavenging oxygen in the solution. This sulfite “trap” helps keep the released electrons free to cut apart PFAS molecules for eight times longer than if sulfite wasn’t there, the researchers report.

It’s surprising that no one had demonstrated the effectiveness of using sulfite with iodide to degrade PFAS before, McKay says.

Liu and his colleagues are now collaborating with an engineering company, using their new process to treat PFAS in a concentrated waste stream. The pilot test will conclude in about two years.

U.S. and Soviet leaders … signed agreements on space, science and technology, health and the environment…. The space agreement … outlines plans for cooperation in fields such as meteorology, study of the natural environment, planetary exploration and space biology.

Update
The 1972 space agreement led to the first inter­national human spaceflight, the Apollo-Soyuz mission, during which Soviet and U.S. crews socialized in space (SN: 7/26/75, p. 52). Apollo-Soyuz encouraged decades of collaboration that continues today on the International Space Station. Now, Russia’s war in Ukraine has prompted many countries to pull back on scientific endeavors with Russia, in space and on Earth (SN: 3/26/22, p. 6). While NASA remains committed to the space station, the head of Russia’s space agency has threatened to end the cooperation in retaliation for sanctions imposed in response to the war. Russia has yet to make moves to abandon the station, though the country has ceased supplying rocket engines to the United States.