Preparation And Phtocatalytic Activities Of Modified Titanium Dioxide Nanoparticals

With the accelerated development of global industrialization, energy demand and environmental protection meet a serious challenge. Nano-TiO₂ has received considerable attention for its wide rang applications in the utilization of solar energy and environment protection. The present study aims to prepare modified titanium dioxide nanoparticals and to enhance the photocatalytic efficiency. Here are the results:Sectionâ… TiO₂, TiO_2-xN_x and various concentations of Fe³⁺ doped TiO_2-xN_x composite films were prepared by sol-gel method. The crystal structure, the element composition and valance state, the absorption properties for UV-visible light of the prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), ultraviolet-visible diffuse reflection (UV-Vis-DRs), and their photocatalytic properties were studied by the degradation of sudanâ… . Results indicated that some oxygen atoms in the lattice of anatase TiO₂ were substituted by nitrogen atoms. With the atomic ratio of Fe³⁺/Ti⁴⁺ increasing, the absorption borders of Fe³⁺ doped TiO_2-xN_x films shifted gradually to visible region until 740nm. The film with Fe³⁺/Ti⁴⁺ of 0.4% showed the highest catalytic performance according to the results of photocatalytic degradation of sudanâ… which was decomposed up to 97% after 4.5 hours. The photocatalytic activities of the composite films were greatly influenced by the atomic ratio of Fe³⁺/Ti⁴⁺ and decreased when the doping proportion of Fe³⁺/Ti⁴⁺ reached to 0.6% because Fe³⁺ had formed crystal of ferric oxide on the surface of TiO_2-xN_x film and covered the active catalytic center. Appropriate doping ratio can reduce the possibility of electron-hole combination and then improved efficiency of the nano-catalyzer.Sectionâ…¡The wet gel particles of Nano-TiO₂ prepared by sol-gel method were dried by infrared drying (IFD) and supercritical fluid drying (SCFD) technology respectively. The properties of the prepared samples were characterized by XRD, SEM and BET. The photocatalytic degradation activities to Sudanâ… were also studied. The results showed that the morphology, particle size and surface area of the two kinds of samples were of the same nature, the samples prepared by IFD were mixed phases of anatase and rutile with diameter range of 10nm-30nm. Compared with SCFD, the photocatalytic degradation activity of IFD sample was superior to that of SCFD sample. The IFD method has many advantages such as shorter drying time, simpler preparation steps, no special equipments needed, and higher photocatalytic activity.Sectionâ…¢Phototocatalytic system of methyl orange decomposition by Fe³⁺ doped TiO_2-xN_x nanoparticals with 0.4% atomic ratio of Fe³⁺/Ti⁴⁺ were explored in detail. The photocatalysis reactor was designed and the influences of various factors were investigated respectively. Except for temperature, all of other investigated factors including the pH, the original concentration of methyl orange, the oxygen content, and the coexistent ions in the system had influences on the phtocatalytic efficiency. The optimizing conditions for photocatalytic degradation of methyl orange were established. This result can also be taken as a guide for choosing photocatalytic conditions of degradating other organic pollutants by TiO₂.