Characterization of Fe/Ti/Si complex particles prepared by the sol-gel method and their photocatalytic reactivity for liquid-phase oxidation of tetracycline

Ti/Si, Fe/Ti, Fe/Ti/Si complex particles of different Ti and Fe contents we re prepared by the sol - gel method and used as photocatalysts. The photoca talytic reactivity of these catalysts were investigated as a function of th e Ti and Fe contents during the liquid - phase oxidation of tetracycline, w hich shaved a dramatic enhancement at low Fe content. The UV - vis, FT - IR , XRD, XPS and Raman spectra investigation indicated that the titanium oxid e particles anchored onto Si-O-Si tetrahedral network were highly dispersed with the size being about 10nm to 12nm in the Ti/Si, Fe/Ti/Si complex part icles. The Fe/Ti/Si complex particles were proved to be the optimum photoca talysts in the present reaction. The promoting effects were attributed to t he cooperation function of the multi - components, the generation of active . OH radicals and the intermediate midgap in the titanium oxide semiconduc tor caused by Fe3+. The Tig particles existed in the low crystalline anatas e phase and formed Si-O-Ti, Ti-O-Fe tetrahedral coordination network due to the inclusion of Ti4+ and Fe3+ ions into the SiO2 matrix. These catalysts had significant surface defects, large specific surface area and high photo catalytic reactivity related to fast electron and hole separation. It was f ound that titanium oxide semiconductor particles of low crystalline anatase - rutile mixed phases of about 16nm in size and existed in the Ti-O-Fe tet rahedral coordination network due to the inclusion of Fe3+ ions into the Ti g matrix in the Fe/Ti complex particles. The titanium oxide semiconductor d oped with Fe3+ enhanced UV light absorption and activity in the degradation of organic pollutants due to the highly surface defects and the formation of intermediate gap state. But, these particle size increased and stabiliza tion was lower as compared to Ti/Si complex particles. The highly dispersed and highly stable Fe/Ti/Si complex particles existed in the Fe2O3, Fe3O4, FeO species and Si-O-Si, Ti-O-Ti, Si-O-Ti, Ti-O-Fe tetrahedral coordination networks due to the inclusion of Ti4+ and Fe3+ ions into the SiO2, TiO2 ma trix.