Perfluorooctanoic acid (PFOA, C7F15COOH) is a synthetic carboxylic acid that has been extensively used in the manufacture of a wide range of consumer goods for over half a century. PFOA persists indefinitely in the environment, and epidemiology studies have shown that there is a significant link to PFOA exposure and human kidney/testicular cancer, thyroid disease, high cholesterol and pregnancy-induced hypertension. For wastewaters being considered for reuse, the removal or complete degradation of PFOA or its sulfonated analogue PFOS (perfluorooctanesulfonic acid, C8F17SO3H) is necessary. Direct potable reuse of wastewaters relies upon additional filtration (microfiltration and reverse-osmosis) after secondary treatment, plus the inclusion of an Advanced Oxidation Process (AOPs) as the final polishing step. Unfortunately, AOPs are oxidizing systems, creating highly energetic species such as the hydroxyl radical (OH) or sulfate radicals (SO4-), but PFO(X) (X = A,S) is not readily oxidized. An alternative approach would be to use reducing radicals, such as the hydrated electron (eaq-) or formate radical (CO2-). These species are expected to react with PFO(X) to produce a fluoride ion, and a carbon-centered radical which can then add dissolved oxygen to form a peroxyl radical. While this a promising approach, these reactions would have to occur competitively against the reactions of these two radicals with dissolved oxygen. To establish the feasibility of this approach kinetics for these two radicals with PFOA and PFOS need to be quantitatively established. In this project we have determined these absolute rate constants utilizing the electron pulse radiolysis and transient absorption measurements using facilities at the Radiation Research Laboratory, University of Notre Dame. Temperature-dependent measurements were also performed to elucidate the corresponding Arrhenius parameters for these reactions.

Removing PFOA and PFOS from water by reductive processes

2019 Fall National Meeting

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