Degradation of Perfluorooctanoic Acid (PFOA) on Aluminum Oxide Surfaces: New Mechanisms from Ab Initio Molecular Dynamics Simulations

27 March 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Perfluorooctanoic acid (PFOA) is a part of a large group of anthropogenic, persistent, and bio-accumulative contaminants known as per- and polyfluoroalkyl substances (PFAS) that can be harmful to human health. In this work, we present the first ab initio molecular dynamics (AIMD) study for systematically investigating a wide range of temperature-dependent degradation dynamics of PFOA on (100) and (110) surfaces of gamma-Al2O3. Our results show that PFOA degradation does not occur on the pristine (100) surface, even when carried out at high temperatures. However, introducing an oxygen vacancy on the (100) surface facilitates an ultra-fast (< 100 fs) defluorination of C-F bonds in PFOA. We also examined degradation dynamics on the (110) surface and found that PFOA interacts strongly with Al(III) centers on the surface of gamma-Al2O3, resulting in a stepwise breaking of C-F, C-C, and C-COO bonds. Most importantly, at the end of the degradation process, strong Al-F bonds are formed on the mineralized gamma-Al2O3 surface, which prevents further dissociation of fluorine into the surrounding environment. Taken together, our AIMD simulations provide critical reaction mechanisms at a quantum level of detail and highlight the importance of temperature effects, defects, and surface facets for PFOA degradation on reactive surfaces, which have not been systematically explored or analyzed.


per- and polyfluoroalkyl substances
ab initio molecular dynamics
computational chemistry
quantum mechanics calculations
ab initio calculations
PFAS removal technologies
water treatment
environmental chemistry
density functional theory

Supplementary materials

Supporting Information
Additional details on the adsorption of PFOA on a pristine gamma-Al2O3 (100) surface, adsorption and degradation mechanisms on a gamma-Al2O3 (100) surface with an oxygen-vacancy defect at 700 and 1200 C, degradation mechanisms of PFOA on a gamma-Al2O3 (110) surface at 1200 C, and adsorption of PFOA on the gamma-Al2O3 (100) and (110) surfaces at 25 C.


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