Computational Study of the Gas-Phase Thermal Degradation and the Reaction Rate Coefficients of Perfluoroalkyl Ether Carboxylic Acids

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 7, 2025

Perfluoroalkyl ether carboxylic acids (PFECA), which are replacements for legacy per- and polyfluorinated alkyl substances (PFAS), exhibit undesirable properties often require thermal remediation. Detailed kinetic evaluation of the pyrolysis PFECA was achieved computationally using density functional ωB97xD/6-311+G (d,p) to establish homolytic bond dissociation energies acid carboxylate forms ∼90-100 kcal/mol as low 65 ± 3 kcal/mol, respectively. The negatively charged oxygenated radical products collapse with activation (Ea) Ea(β-scission) ∼ 12-42 Ea(1,2-F-shift) 24-47 Ea(oxygen atom-shift) 33-35 enthalpies (ΔH) ΔH(F-loss) 56-71 kcal/mol. perfluoroalkoxyl intermediates transform via Ea(β scission) 2-9 Ea(F-loss) 25-43 have lifetimes in microsecond-to-nanosecond range at 1000 K 1 atm, some radicals stable hours or even days respect unimolecular processes. results provide new fundamental thermodynamic parameters partitioning degradation pathways specific structure-activity relationships intermediates, leading final products. These critical modeling treatment related PFAS.

Language: Английский

The influence of functional groups on the pyrolysis of per- and polyfluoroalkyl substances

Journal of Analytical and Applied Pyrolysis, Journal Year: 2024, Volume and Issue: unknown, P. 106820 - 106820

Published: Oct. 1, 2024

Language: Английский