PFAS, known as "forever chemicals," have been in the news since the extent of contamination was revealed in February 2023 by a Le Monde investigation. These "miracle molecules," widely used after the Second World War, can be found in food packaging, cosmetics, fire-fighting foam and certain medical devices. In addition to their proven toxicity – they interfere with the endocrine and immune systems, and some are already classified as carcinogens by the International Agency for Research on Cancer (IARC) – these synthetic compounds have in common that they are persistent in the environment.

And with good reason: They're mainly made up of carbon and fluorine atoms, whose chemical bond is virtually indestructible. As Marie-Pierre Krafft, a physical chemist and French National Center for Scientific Research (CNRS) research director at the Institut Charles-Sadron at the University of Strasbourg, explained: "The carbon-fluorine bond is the most stable single bond in organic chemistry. This is due to the unique electronic properties of fluorine, which is the most electronegative element."

In just a few years, cleaning contaminated land, water and industrial waste of these PFAS (per- and polyfluoroalkyl substances) has become a major challenge for researchers from a wide range of scientific disciplines. Before even asking the question of how to fund the clean-up, the challenge is to find a way, or rather ways, to solve this chemical puzzle. To break this bond, "we have to resort to much more intensive techniques than for other pollutants, under much more extreme conditions – at very high temperatures or with high concentrations of additives – and carry out successive cycles," said Stéfan Colombano, a research engineer at the Bureau of Geological and Mining Research (BRGM).

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