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These chemicals are also known as PFAS, which is short for poly and perfluoroalkylated substances. They have been produced in large quantities for more than 70 years and are found in a range of products, including textiles, food packaging, non-stick cookware, and medical devices. Their strong carbon-fluorine bonds make them resistant to degradation, earning them the nickname 'forever chemicals'.
This resistance has led to widespread contamination around the world, with traces of PFAS found in drinking water and livestock. Chronic exposure to PFAS has been associated with negative human health effects. However, researchers from Oxford and Colorado State University have now shown it is possible to destroy a wide range of these fluorine-containing PFAS chemicals while also recovering their fluorine content for reuse in industrial processes.
Professor Véronique Gouverneur, from the University of Oxford's Department of Chemistry, said: "Fluoride recovery is important because our reserves of fluorspar, essential for the manufacturing of life-saving medicines, are rapidly depleting due to extensive mining. "Our method not only eliminates waste from PFAS chemicals but also contributes to a circular fluorine chemistry by transforming persistent pollutants into valuable fluorochemicals." The method works by reacting PFAS samples with potassium phosphate salts in the solid state.
The reactants are ground together with ball bearings, breaking down the long-lasting PFAS chemicals and allowing the researchers to extract the fluorine content from the resulting product. In the study, the recovered fluoride was then used to generate common fluorinating reagents, which worked effectively in industrial reactions. The recovery of fluoride for re-entry into the fluorochemical industry contributes towards enabling a circular fluorine economy.
This is particularly important given fluorspar is categorised as critical for many industrial processes by nations around the world. The team's method enables the mechanical destruction of all PFAS classes, including those commonly found in products such as non-stick coatings, electrical insulation, and industrial tubing. This means the fluorine content from everyday waste such as Teflon tape could be recovered and used to generate important fluorine-containing chemicals, including precursors to pharmaceutical and agrochemicals such as cholesterol-lowering statin medications, anti-seizure agents, and herbicides.
Dr Long Yang, also from the University of Oxford's Department of Chemistry, and one of the lead authors of the study, added: "The mechanochemical destruction of PFAS with phosphate salts is an exciting innovation, offering a simple yet powerful solution to a long-standing environmental challenge. "With this effective PFAS destruction method, we hope to shift away from the notion of PFAS as 'forever chemicals'.".
