Papers by Keyword: Photo Catalytic

Abstract: Different morphologies of molybdenum trioxide have been synthesized via low-temperature liquid phase method, hydrothermal synthesis and the direct decomposition method. Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize the as-synthesized products and the photo catalytic degradation properties were studied for different nitrogen of dyes. The results indicate that the discoloration rate of methylene red was the best and it could be more than 90 percent in the same conditions. Therefore, the synthesized MoO3 powder is a kind of photocatalayst with excellent performance.

Abstract: Titanium dioxide is a cheap, chemically stable and non-toxic material. However its photocatalytic properties are unstable and it is a modest semiconductor and a mediocre insulator. For several applications it would be interesting to make it either more insulating or more conducting. The goal of this work was to modify the photocatalytic properties of nano-crystalline TiO2 powders by wet chemical routes and hydrothermal methods to understand the mechanism leading to these modifications The principal factors that influence the photocatalytic properties are on the one hand the concentration and nature of the chemical and physical conditions in TiO2, and on the other hand the morphology of the powders. The study was split into two parts. The fist part describes the modifications of the material obtained by chemical preparation's parameters. Like: preparation method, pH., additives, surfactants, and temperature. The second part describes the modifications obtained by modifying the photo catalysis reactors. Several analysis techniques have been used to characterize the TiO2 samples. They are essentially divided in four categories. The chemical analyses included electron probe microanalyses. The structure and morphology analyses of powders were carried out with x-ray diffraction. The photo catalytically properties in batch or CRS mode were measured in room temperature. Finally optical transmission provided information on the electronic states and morphology of the samples. The results imply that powders with anatase 40% and rutile 60 % with 15nm crystallite size have the optimum properties.

Abstract: The photo-catalytic efficiency and durability of nano-TiO2 photo-catalytic cementitious materials for oxidizing nitrogen dioxide were investigated under simulated sunlight irradiation. The experimental results showed that the photo-catalytic efficiency increased with increase of the content of nano-TiO2. When 15wt% nano-TiO2 was added, the photo-catalytic efficiency was equal to 223% of that of standard cement. When activated carbon was used as the carrier of nano-TiO2, the photo-catalytic efficiency of cementitious nano-TiO2 could be enhanced markedly. For example, the photo-catalytic efficiency could reach to 85.7%, which was as much as 359% of that of standard cement when the contents of activated carbon and nano-TiO2 were both 10wt%. Compared with nano-TiO2 powder, the photo-catalysis durability of cementitious nano-TiO2 supported by activated carbon could be improved clearly for that activated carbon could absorb nitrogen dioxide effectively, which was favored to the photo-oxidation of nano-TiO2 on nitrogen dioxide.

Abstract: The photocatalytic Ag and Ni doped TiO2 films were prepared by sol-gel method and coated on glass fiber roving. The films were calcined at 500 °C for 1 hour with a heating rate of 10°C/min. The surface morphology and properties of synthesized TiO2 films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and UV-vis diffuse reflectance spectroscopy (DRS). The results show that TiO2-1Ag and TiO2-1Ag-1Ni films give rapidly kill P.aeruginosa bacteria under UV irradiation and TiO2-1Ni films give well kill P.aeruginosa bacteria under visible light.

Abstract: Ag nano-particles were deposited on the surface of TiO2 self-assembled films by photo-reduction of Ag+ solution. SPM, XPS and UV-Vis spectrophotometer were employed to characterize the microstructure and photo-catalytic performance of the films. An obvious enhancement of photo-catalytic activity had been observed. Since rutile had a lower optical band gap than anatase, a higher photo-catalytic efficiency improvement of rutile than that of anatase was obtained under the help of Ag nano-particles, which acted as electron acceptors.