Materials Science Forum Vols. 809-810

Abstract: The small-stones-like BaSb₂O₆ had been successfully prepared through two-step reaction by using inexpensive Sb₂O₃ reactant. The effects of reaction conditions (temperature, time) on photocatalytic efficiency were researched. The photocatalytic activity of BaSb₂O₆ was evaluated by photodegradation of methylene blue (MB). The results showed that the decolorization rate of methylene blue was over 90% under ultraviolet lamp (500 W) beam for 40min. Its structures and morphologies had been investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM). The results showed that XRD pattern of BaSb₂O₆ was consistent with standard card and morphology of BaSb₂O₆ was smooth close-packed state "small stones", fine particles & no agglomeration.

Abstract: Zinc borate (4ZnO·B₂O₃·H₂O) crystallites at diverse pH values were prepared by a hydrothermal method. The phase composition, morphologies and photocatalytic properties of the samples were characterized by XRD, SEM, UV–vis spectro-scopy and UV–vis diffuse reflectance spectro-scopy. Results show that the 4ZnO·B₂O₃·H₂O microcrystalline obtained at pH=9 shows a new clintheriforms morphologies assembled by nanowiskers. Superior UV-light photocatalytic activity of the samples for MB, RhB and MO is observed especially higher than that of P25 for MB. These samples exhibit morphology-related ultraviolet absorbing ability with different optical band gaps from 4.01 eV to 4.22 eV. Band gaps are responsible for the highly UV-light photocatalytic activity.

Abstract: Using butyl titanate as titanium source, lanthanum nitrate as a source of lanthanum, iron nitrate as an iron source, the titanium dioxide powder of lanthanum/iron single-doped and co-doped were synthesized by the sol-gel combustion method. The doped TiO₂ powders were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (IR), and the photocatalytic activity was studied with methyl blue, methylene chloride and formaldehyde as the source of pollution. The results show that we obtain TiO₂ anatase when the heat treatment temperature was 450 °C. When the amount of doped Lanthanum and iron were 0.5%, the grain size of the powder was significantly reduced and the degradation efficiency for organic pollutions was highly improved compared with pure TiO₂.

Abstract: Hydrogen zeolite was modified with CeO₂ by impregnation - filtration - heat treatment. Hydrogen-zeolite samples before and after modification were characterized by XRD and SEM. The catalytic efficiency of modified hydrogen-zeolite was investigated. Such modification conditions were explored: as the CeO₂ percentage, calcination temperature, calcination time, impregnation temperature. The results show that the optimal CeO₂ percentage is 0.5%, calcination temperature is 600°C, calcination time is 2h, impregnation temperature is 75°C. The aspirin yield reaches 78.3% under the optimal conditions, compared with that (64.8%) catalyzed by sulfuric acid and that (70.4%) catalyzed by unmodified zeolite. XRD, SEM characterizations show that Ce ions can be doped into the zeolite framework. And the modification makes the zeolite particle size become smaller, which is reduced to 50.5nm from 56.76nm. A high efficient and eco-enviromently catalyst was got by modification.

Abstract: Boron-BiVO₄ samples were synthesized by sol-gel method. They were characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction. Photocatalytic activity of the obtained BiVO₄ samples was investigated through degrading methylene blue (MB). The results reveal that boron-BiVO₄ catalysts have monoclinic scheelite structure. The BiVO₄ and Co-BiVO₄ photocatalysts were responsive to visible light. Co-BiVO₄ photocatalyst showed higher photocatalytic activity than pure BiVO₄, resulting in the significantly improved efficiency of degradation of MB.

Abstract: With sodium carbonate and calcium oxide as sintering additives, through the thermodynamic analysis and sintering experiment, study the thermodynamic behavior of fly ash with both in the sintering process; the sintering products were analyzed by XRD. The research results show that sodium carbonate as sintering additive fly ash thermal decomposition of the main phase of nepheline (NaAlSiO₄), calcium oxide as sintering additives, and fly ash sintered products mainly 12CaO·7Al₂O₃、2CaO·Al₂O₃·SiO₂ and 2CaO·SiO₂ etc., And the temperature of the above substances generated is very favorable, fly ash and calcium oxide sintered at high temperature. Through sintering can effectively decompose the fly ash of quartz and mullite, soluble in acid or alkali salts, lay the foundation for the extraction of aluminum and silicon material from fly ash.

Abstract: Citric acid modification of activated carbon to examine citric acid concentration, temperature and time modified adsorption properties of activated carbon. The results demonstrate that with the extension of temperature and treatment time, the adsorption properties of modified activated carbon were then decreased overall trend. Better process for citric acid modified activated carbon: citric acid concentration of 50%, modified temperature is 30°C, modified time is 5h. Lagergren adsorption rate equation with primary and secondary adsorption rate equation and the average absolute deviation from the rate on the adsorption properties of these factors affects the processing; secondary adsorption kinetics model was found to better describe the various factors affecting the adsorption process under conditions.

Abstract: Dry waters with an average diameter of 82 μm were prepared by a high speed mixed route. The formaldehyde absorption kinetics of dry waters was investigated by simulating indoor formaldehyde pollution in glass chamber. The results showed that pseudo-second order model could be used to simulate the adsorption process; the adsorption rate was highest in the initial 60 minutes; when the adsorption lasted for 180 minutes, the adsorption reached equilibrium.

Abstract: RGO/BiVO₄ powders were prepared by a hydrothermal method. The crystal structure of RGO/BiVO₄ was investigated by X-ray diffraction (XRD). Scanning electron microscope (SEM) was used to characterize the micro-morphology of RGO/BiVO₄. The recombination rate of photogenerated electron-hole pairs were investigated by fluorescence spectrophotometer. Photocatalytic properties of the prepared samples were examined by studying the degradation of model dyes magenta.

Abstract: In the present study, catalyst of SO₄^2-/ZrO₂-TiO₂-SiO₂-Al₂O₃ has been prepared by sol-gel method and doped by Y, La and Chitosan, respectively. The catalytic ability of modified catalysts for the synthesis of hexyl butyrate has been tested. It has been shown that the catalytic ability has been improved obviously after modification. Under the best experimental conditions, with Y doping 1%, La doped 1.5% and Chitosan doped 4%, the catalytic ability has been improved from 76.7% to 90.7%, 92.1% and 93.9%. Characterized by XRD, SEM and IR, it has been found that the grain sizes of catalysts are smaller which due to higher specific surface andimprove the catalytic ability. With abundant amino groups at the surface, the Chitosan doping improves the capacity of SO₄^2- for catalysts.