Media release

From: AAAS

New, low-temperature approach to degrading perfluorocarboxylic acid “forever chemicals”

A new approach to mineralizing perfluorocarboxylic acids – one of the largest groups of per- and polyfluoroalkyl substances (PFAS) – shows great promise in the effort to degrade these harmful and environmentally ubiquitous pollutants under relatively mild conditions, according to a new study. The fundamental knowledge gained could be applied to addressing other intractable PFAS classes in the future. Often called “forever chemicals” due to their chemical stability and omnipresence in the environment, PFAS are a class of thousands of chemicals widely used in various consumer, commercial, and industrial products. A growing number of recent studies have underscored their pervasive and persistent environmental presence, where they easily contaminate drinking water, livestock, and agricultural products. This is concerning because chronic exposure to these pollutants – even at low levels – is associated with a host of adverse health effects, including thyroid disease, liver damage, and several cancers. However, the carbon-fluorine bonds that make up these molecules are remarkably strong, making PFAS degradation a significant challenge. Current methods require harsh, energy-intensive, and expensive treatments, such as incineration at exceedingly high temperatures. Brittany Trang and colleagues present a novel, low-energy approach to decomposing carboxylic acid-containing PFAS (PFCAs) using a sodium hydroxide-mediated defluorination pathway. Trang et al. discovered that decarboxylation of the compound’s acid group in mixtures of water and the dipolar aprotic solvent dimethyl sulfoxide (DMSO) breaks PFCAs into carbon dioxide and reactive perfluoroalkyl ion intermediates that can further degrade rapidly into benign nonorganic fluoride ions. According to the findings, under these conditions, perfluorooctanoic acid (PFOA) is completely degraded with more than 90% defluorination and minimal formation of fluorocarbon byproducts at relatively mild temperatures. The authors also used computational analyses and experiments to evaluate the process and better understand the mechanisms underlying PFCA mineralization. “Trang et al. provide insight into how these seemingly robust compounds can undergo nearly complete decomposition under unexpectedly mild conditions,” write Shira Joudan and Rylan Lundgren in a related Perspective. “Hopefully, the fundamental findings of Trang et al. can be coupled with efficient capture of PFAS from contaminated environmental sites to provide a possible solution to the forever chemical problem.”