The unseen threat of perfluoroalkyl substances (PFAS) as pollutants is developing into a significant global challenge. Much research is ongoing to define the true risk of PFAS to human health, develop industrial alternatives to PFAS, improve their detection and develop effective strategies to degrade them. Governments across the globe are lowering exposure levels considered safe to human health and the environment (NHRMC, 2025), which is calling for portable and sensitive PFAS detectors to be developed. Electrochemical methods, which can claim low cost, portability and sensitivity advantages over, for example, gas chromatography, are one of the PFAS sensing technologies being developed. There is an ongoing debate, which is relevant to both PFAS detection and degradation, regarding the scope of reactive oxygen species, and especially superoxide towards the degradation of perfluorinated pollutants.
In this study, we seek to resolve this debate by investigating the fate of electrochemically-generated superoxide species in the presence and absence of PFAS. We have produced experimental voltammograms on glassy carbon electrodes for the generation of superoxide by the reduction of oxygen within an aprotic solvent, acetonitrile, along with oxygen/superoxide voltammetry in the addition of 1H,1H,2H,2H-Perfluoro-1-octanol and undecafluorohexanoic acid. With the assistance of surface tension experiments and digital simulations of voltammograms, we elucidate the change in shape of the voltammograms when PFAS is added to the oxygen/superoxide system. We explore the hypothesises of the adsorption of dissolved oxygen on the electrode with PFAS acting as a surfactant, and the electrochemical-chemical (EC) reaction involving the formation of hydrogen peroxide from electrochemically generated superoxide and the acidic proton from the PFAS. In this way, we demonstrate that superoxide molecules generated electrochemically in aprotic solvents can react with PFAS that possess an exchangeable proton, but ultimately are unlikely to attack, hence effectively degrade, the fluorinated portion of the molecule.
National Health and Medical Research Council. (2025). Australian Drinking Water Guidelines: Part 5: Factsheets: Per- and poly-fluoroalkyl substances (PFAS). Commonwealth of Australia. https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/physical-chemical-characteristics/cas-numbers-1763-23-1-pfos-335-67-1-pfoa-355-46-4-pfhxs