Poly- and perfluorinated alkyl substances (PFAS) possess distinct physicochemical properties that make these chemicals extremely desirable for a wide use of applications. Despite their valuable functionality, the high persistence of these chemicals and their direct degradation products pose both environmental and public health concerns. Although incineration remains the most common PFAS remediation method, the complete combustion and pyrolysis mechanism of PFAS is unknown. Reaction Mechanism Generator (RMG), a software tool that automates the generation of detailed kinetic reaction mechanisms, has often been used for predictive kinetic modeling of gas-phase hydrocarbon combustion. The recent addition of extensive halocarbon thermochemistry, kinetics, and transport to RMG database has enabled RMG to model the halogen (fluorine, chlorine, and bromine) chemistry involved in halocarbon combustion, however, even with this database extension, RMG fails to automatically construct accurate mechanisms relating to PFAS thermal degradation. In this work, we present the addition of new CH2F2 and perfluorocarboxylic acid-specific degradation chemistry to RMG to improve its ability to construct accurate halocarbon combustion and PFAS degradation mechanisms. Several of RMG's pre-existing reaction families are updated to include perfluorocarboxylic acid degradation reactions, and 6 new families are created specifically for perfluorocarboxylic acid chemistry. The training data of RMG-database is updated with nearly 200 newly calculated reaction rates for reactions involved in CH2F2 degradation, 206 high-pressure limit reaction rate coefficients for PFAS chemistry calculated using RRKM/ME theory, and new thermochemical parameters for C1-C8 perfluorinated carboxylic acids, C4-C6 perfluoroalkyl ether carboxylic acids and relevant species. With these database additions now publicly available on the main distribution of the most recent RMG version, RMG can automatically construct extensive PFAS-related mechanisms that include more accurate chemistry than before.
