Wastewater remediation and recycling using Advanced Oxidation Processes (AOPs) is dependent upon the oxidative degradation of recalcitrant, potentially harmful chemical contaminants of emerging concern. However, for perfluorinated compounds (PFCs), which persist in the environment due to their widespread commercial use, the highly oxidized backbones of these molecules make their destruction by AOPs difficult. As these compounds are linked to negative health outcomes like carcinogenesis and thyroid disease, other quantitative removal approaches are required. One possible methodology is the use of Advanced Reduction Processes (ARPs) utilizing the hydrated electron (e-aq), which has previously been shown to degrade perfluoralkyl substances in water. Despite this radical’s efficacy, the kinetics for the reactions of e-aq with common PFCs are not well-studied and reported rate constants vary by many orders of magnitude. In this work, electron pulse-radiolysis measurements for the reduction of aqueous solutions of two common PFCs, PFOA and PFOS, were performed. The reaction of e-aq with each PFC was directly monitored using the transient absorption of this radical. Second-order rate constants for the reactions at room temperature are determined; for PFOA k = (2.07 ± 0.09) x 1010 M-1 s-1, and for PFOS k = (3.48 ± 0.17) x 109 M-1 s-1. The temperature-dependence of e-aq reduction kinetics for PFOA were measured over the range 5oC – 75 oC, giving an Arrhenius activation energy of 9.3 ± 1.1 kJ mol-1.

Absolute rate constant measurements for hydrated electron reductive destruction of aqueous perfluoroalkyl species in water

2019 Spring National Meeting

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