View article

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, C_nF_2n+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: k_app 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.