New method to get rid of the threat of perfluorocarboxylic acids

Often referred to as permanent chemicals due to their chemical stability and pervasiveness in the environment, PFAS (perfluoroalkyl and polyfluorinated substances) are a class of thousands of chemicals widely used in a variety of consumer, commercial, and industrial products.

A growing number of recent studies have highlighted their widespread and persistent presence in the environment, where they readily contaminate drinking water, livestock, and agricultural products. This is worrying because chronic exposure to these pollutants, even at low levels, is associated with a number of adverse health effects, including thyroid disease, liver damage, and various types of cancer.

However, the carbon-fluorine bonds that make up these molecules are remarkably strong, making PFAS degradation challenging.

Current methods require aggressive, energy-intensive and expensive treatments, such as incineration at excessively high temperatures.

Brittany Trang’s team at Northwestern University in Evanston presents a novel, low-energy approach to breaking down PFAS containing perfluorocarboxylic acids (PFCAs) using a sodium hydroxide-mediated defluorination pathway.

PFAS can easily contaminate agricultural products, among other things. In the image, an agricultural field. (Photo: Amazings/NCYT)

Trang and colleagues found that decarboxylation of the compound’s acid group in mixtures of water and the dipolar aprotic solvent dimethyl sulfoxide (DMSO) decomposes carboxylic acids into carbon dioxide and intermediate reactive perfluoroalkyl ions that can rapidly degrade into benign non-organic fluoride ions.

According to the results, under these conditions, perfluorooctanoic acid (PFOA) degrades completely with more than 90% defluorination and minimal formation of fluorocarbon by-products at relatively mild temperatures.

The study authors also used computational analyzes and experiments to evaluate the process and better understand the mechanisms underlying carboxylic acid mineralization.

The study is titled “Low-temperature mineralization of perfluorocarboxylic acids.” And it has been published in the academic journal Science. (Source: AAAS)