Fe-modified TiO2 photocatalysts for the oxidative degradation of recalcitrant water contaminants

Fe–TiO2 with enhanced photocatalytic oxidation activity was synthesized by hydrolysis of titanium butoxide. Sol–gel process leads to less active Fe–TiO2 particles than bare TiO2; meanwhile, the hydrothermal synthesis of Fe–TiO2 seems to promote the stabilization of Fe3+ in the TiO2 structure promoting the photo-oxidation activity of TiO2 towards the degradation of azo-dyes and the inactivation of Escherichia coli (E. coli) in water. Photocatalysts were characterized by X-ray diffraction (XRD), diffusive reflectance spectrophotometry (DRS), and N2 adsorption–desorption. The TiO2 synthesized by the hydrothermal synthesis reaches the TiO2 Degussa P-25 photo-oxidation activity towards the degradation of orange II. Furthermore, Fe loading of TiO2 in hydrothermal synthesis improves remarkably the photoactivity of HT. The comparative performance of the photocatalysts towards the direct photo-oxidation of iodide, the photocatalytic degradation of orange II and the photocatalytic disinfection of water infected with E. coli suggested different mechanisms of oxidation: a surface-hole-oxidation mode for hydrothermally synthesized TiO2 particles and a homogeneous phase oxidation mode promoted by radical dotOH radicals produced in the TiO2 P25 surface.