Photocatalytic decomposition of perfluorooctanoic acid by iron and niobium co-doped titanium dioxide

The photocatalytic decomposition of perfluorooctanoic acid (PFOA) in aqueous solution using Fe and Nb co-doped TiO2 (Fe:Nb-TiO2) prepared by sol-gel method was investigated. The photocatalytic activity of Fe:Nb-TiO2 towards PFOA degradation was compared to that of pure TiO2 synthesized using the same method, and that of the commercially available TiO2 photocatalyst, Aeroxide TiO2 P25 (AO-TiO2 P25). The photocatalysts were characterized by XRD, DRS, BET-N2 adsorption isotherm, and SEM-EDX techniques and the data were correlated to the photocatalytic activity. Fe:Nb-TiO2 showed the highest activity compared to the undoped TiO2 and the commercially available TiO2. Such activity was attributable to the effects of co-doping both on the physico-chemical properties and surface interfacial charge transfer mechanisms. Perfluorocarboxylic acids (PFCAs) with shorter carbon chain length and fluoride ions were identified as photocatalytic reaction intermediates and products.