Surface fluorination on TiO2 catalyst induced by photodegradation of perfluorooctanoic acid
•Photoabatement of PFOA solutions with TiO2 slurry.•HPLC–MS analysis to determine the intermediates of PFOA degradation.•XPS analyses of TiO2 to monitor surface variations induced by fluoride ions.
The photoabatement of perfluorooctanoic acid in aqueous solution has been performed with a commercial nano-sized TiO2-based photocatalyst content of 0.66 g/L under an UV irradiation of 95 W/m2. PFOA degradation intermediates were investigated by HPLC–MS and 19F-NMR analysis. Evidences of a degradation mechanism based on two competitive pathways are discussed: photo-redox and β-scission pathways. Shorter perfluorinated carboxylic acids, CnF2n+1COOH (n = 1–6), as expected degradation intermediates, were identified and their concentration trends over time were determined. The apparent pseudo-first order kinetic constant expressed as rate of PFOA disappearance was also measured: kapp 0.1296 h−1. The influence of fluoride ions on TiO2 surface was analyzed by XPS technique, revealing a surface modification that affects the performances of the catalyst.
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Journal: Catalysis Today - Volume 241, Part A, 1 March 2015, Pages 8–14