‘Forever chemicals’ that contaminate drinking water eliminated with new process
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Researchers have developed a way to break down ‘forever chemicals’ which can persist in natural environments for thousands of years making even rainwater unsafe to drink.
Known as PFAS (per- and polyfluoroalkyl substances), the group of around 12,000 different chemicals are commonly found in non-stick cookware, waterproof cosmetics, firefighting foams and products that resist grease and oil.
But despite their utility, they have been associated with dangerous health effects in humans, livestock and the environment.
Scientists have been experimenting with many remediation technologies, but most of them require extremely high temperatures, special chemicals or ultraviolet light and sometimes produce by-products that are also harmful and require additional steps to remove.
Chemists at UCLA and Northwestern University in the United States have developed a simple way to break down almost a dozen types of these nearly indestructible 'forever chemicals' at relatively low temperatures with no harmful by-products.
The researchers show that in water heated between 80°C to 120°C, common, inexpensive solvents and reagents severed molecular bonds in PFAS that are among the strongest known and initiated a chemical reaction that “gradually nibbled away at the molecule” until it was gone.
The simple technology, the comparatively low temperatures and the lack of harmful by-products mean there is no limit to how much water can be processed at once, Houk added. The technology could eventually make it easier for water treatment plants to remove PFAS from drinking water.
Simulations of the new process suggest that the only by-products of the process should be fluoride – often added to drinking water to prevent tooth decay – carbon dioxide and formic acid, which is not harmful.
The current work degraded 10 types of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl ether carboxylic acids (PFECAs), including perfluorooctanoic acid (PFOA). The researchers believe their method will work for most PFAS that contain carboxylic acids and hope it will help identify weak spots in other classes of PFAS. They hope these encouraging results will lead to further research that tests methods for eradicating the thousands of other types of PFAS.
Over the past 70 years, PFAS have contaminated virtually every drop of water on the planet, and their strong carbon-fluorine bond allows them to pass through most water treatment systems completely unharmed.
They can accumulate in the tissues of people and animals over time and cause harm in ways that scientists are just beginning to understand. Certain cancers and thyroid diseases, for example, are associated with PFAS.
For these reasons, finding ways to remove PFAS from water has become particularly urgent.
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