Decomposition of perfluorooctanoic acid photocatalyzed by titaniumdioxide : Chemical modification of the catalyst surface induced byfluoride ions

The degradation of perfluorooctanoic acid (PFOA) in water was investigated both as photolysis andphotocatalysis by slurry titanium dioxide. Different surfactant concentrations, the catalyst nature andconcentration as well as the irradiation power of the UV lamp were evaluated. The reactions were con-ducted using merely the natural dissolved oxygen (DO), in order to simulate conditions of non-enrichedwater, as industrially feasible. The photomineralization of PFOA was monitored by total organic car-bon (TOC) analysis and ionic chromatography (IC). Finally, the photocatalytic powder was analyzed atdifferent reaction times by X-ray photoelectron spectroscopy (XPS) and by X-ray powder diffraction(XRD) technique in order to study and interpret the catalyst deactivation phenomena occurred duringthe treatment.