Download or read book Oxidative Transformation of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) written by Eniola Oye-Bamgbose and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Perfluoroalkyl and Polyfluoroalkyl substances (PFAS) are anthropogenic chemicals with unique properties and wide applications in industrial and consumer products. However, studies have shown that the once highly valued PFAS are persistent pollutants, ubiquitous in the environment, and are developmental and reproductive toxins. To meet the stringent drinking water guidelines for PFAS, technologies that can destroy PFAS are urgently sought for. As multiple carbon-fluorine bonds render many conventional destruction processes ineffective, advanced oxidation-based treatment methods are some of the very promising methods for the destruction of PFAS in contaminated environmental matrices. Nevertheless, if effective oxidation-based treatment methods are to be developed, it is essential to know all the transformations PFAS can undergo during oxidation. This thesis focused on PFAS oxidation with and without the addition of external oxidants divided into two studies. The first study focused on the non-additive oxidation and degradation of perfluorooctanoic acid (PFOA) using nonthermal plasma, and the second on the additive oxidation of unknown PFAS using persulfate-based total oxidizable precursor assay.The first study was centered on plasma-based water treatment of perfluorooctanoic acid, which relies on only an electrical discharge to convert water and gas molecules to a mixture of highly reactive oxidative species. The objective was to achieve a complete mass balance of PFOA after treatment by performing a total fluorine mass balance analysis. A 16 [mu]M PFOA solution was treated with a nonthermal plasma generated in nanosecond long pulses. After 30 min of treatment, a 42% reduction in PFOA concentration was achieved. The degradation of PFOA also led to the generation of shorter chain perfluorocarboxylic acids. Specifically, 0.08 [mu]M of perfluorobutanoic acid, 0.2 [mu]M of perfluoropentanoic acid, 0.5 [mu]M of perfluorohexanoic acid, 1.5 [mu]M of perfluoroheptanoic acid and 9.1 [mu]M of free fluoride ions were produced. Total fluorine mass balance analysis using combustion ion chromatography suggested that in addition to the measured degradation products, other unmeasured compounds possibly such as gaseous fluorinated products, trifluoroacetic acid, and perfluoropropionic acid were also produced. In the second study, conventional uses of persulfate oxidation process, which degrades selected PFAS under very restrictive conditions, was repurposed for the measurement of many unidentifiable PFAS, through the total oxidizable precursor assay. The study was aimed at investigating how the presence of co-contaminants affects PFAA precursor oxidation and finding solutions to improve precursor oxidation during the assay. Seventy aqueous film-forming foam impacted groundwater samples received from Environment and Climate Change Canada were subjected to the assay. Initial analysis of the groundwater samples showed a diverse range of PFAS levels with the maximum sum of concentrations measured to be 2.33 mg/L, and several PFAA precursors were detected. The results after oxidation showed a direct correlation between matrix complexities (i.e. the presence of co-contaminants) and the extent of PFAA precursor oxidation. There was incomplete oxidation of PFAA precursors in samples with a high concentration of co-contaminants. The implementation of a previously developed clean-up procedure improved precursor oxidation during TOP assay by an average of +52%.To further investigate how the presence of co-contaminants affect PFAA precursor oxidation during the TOP assay, mixtures of 6:2 FTSA or 6:2 FTAB and natural organic matter were prepared respectively. Only at low and intermediate COD levels of no more than 230 mgO2/L, 100% loss of the precursors can be largely accounted for by the generation of C3-C7 PFCAs. The results showed that the presence of co-contaminants in TOP assay not only affects the oxidation loss of precursors but also the type of products generated"--