A Detailed Chemical Kinetic Model for the Destruction of Per- and Polyfluoroalkyl Substances (PFAS): Pyrolysis and Incineration of Short-Chain Perfluorinated Carboxylic and Sulfonic Acids

Chemical processes to destroy per- and polyfluoroalkyl substances (PFAS) are being actively developed to deal with contaminated soil and water, legacy waste streams, and unwanted stockpiles of these hazardous compounds. Common to these processes are complex networks of chemical reactions, including thermal decomposition, oxidation and/or hydrolysis steps, and the development and optimization of destruction technology requires predictive chemical kinetic modelling tools. Here we report the first detailed chemical kinetic model targeted at PFAS destruction, capable of describing the pyrolysis and incineration of perfluorinated carboxylic acids up to C3 and perfluorinated sulfonic acids up to C2. Simulations of the pyrolysis and incineration of these PFAS indicate that reaction is initiated via degradation of the acid headgroup, followed by chain-shortening via carbonyl (acyl fluoride) intermediates. Although applied to gas-phase degradation of short-chain perfluorinated acids, the model provided here should prove useful as a basis for modelling the destruction of a diverse range of PFAS both in condensed and supercritical phases.