Perfluorinated and polyfluorinated alkyl compounds (PFAS) are considered to be “indestructible” chemicals. They are practically not broken down and accumulate in people and the environment. The suspected health consequences include asthma, cancer and changes in the reproductive organs – and how to get rid of PFAS has been completely unclear. Now there are first attempts to destroy the resistant molecules.
The most important ingredient in breaking the carbon-fluorine bonds characteristic of this class of substances is heat. In a study published in the Journal of Environmental Engineering, the US Environmental Protection Agency found that a technique known as “supercritical water oxidation” destroyed 99 percent of the PFAS contained in a water sample.
PFAS have a combination of properties that make them unique and suitable for many technical applications. They are both oil and water repellent and resistant to high temperatures and chemicals. They therefore appear in many consumer goods as well as in applications such as extinguishing foam for fire fighting. That’s why you can find them almost everywhere now. In Germany, too, the soil and groundwater are polluted in several districts; in 2019, PFAS made drinking water unusable in Rastatt. Studies show measurable levels in blood and breast milk in the entire European population.
The first attempts with new methods to destroy the “indestructible” materials give rise to hope. In the recently published study by the US Environmental Protection Agency (EPA), the experts mixed water contaminated with PFAS with oxidizing substances and heated it to a pressure of more than 220 bar above its critical temperature of 374 degrees Celsius. The water becomes supercritical, it is neither gas nor liquid. In this state, even water-repellent substances such as PFAS dissolve much better, and at the same time the state accelerates chemical reactions.