| Printing and dyeing wastewater from textile industry contains a large number of refractory organic pollutants, Titanium dioxide (TiO2) photocatalysis technology has been widely used in textile wastewater treatment fields because of its super oxidizing abilities.HoweverOthere are several obvious problems in the application of TiO2 powders: separation of photocatalyst from the reaction media and catalytic efficiency decline and loss in continuous processing. In this research, it is found that the immobilization of TiO2 catalyst on lime glass plates support could solve the problem concerned with separation, the loss of catalyst in the process of recycling as well as the effect of particles blocking the light irradiation depth.Under different conditions, immobilized TiO2 photocatalysts is prepared by sol gol dip-coating method, in which lime glass plates act as substrates in the current study. The optimal condition of preparation, the surface microscopic characteristics, the decoloration efficiency of methylene blue (MB) solution, deactivation and regeneration of immobilized TiO2 photocatalysts are investigated. The main study contents are summarized as follows:1. Immobilized TiO2 photocatalysts are prepared in different conditions, including speed of withdrawal from the coating solution, number of coating, calcination temperature and calcination time. Based on a second-order polynomial model, response surface equation of the immobilized TiO2 photocatalysts degrading MB solution is estimated by using the ultraviolet degradation efficiency of MB solution as the dependent variable, and using the speed of withdrawal from the coating solution, number of coating, calcination temperature,calcination time and photocatalytic time as independent variables. The degradation efficiency of MB solution under ultraviolet light were 79.80%?99.32% under the different photocatalytic time, and the optimal condition of preparation immobilized TiO2 photocatalysts is obtained.2. The immobilized TiO2 photocatalysts are analyzed using characterization methods including the thermogravimetric-differential scanning calorimetry, scanning electron microscope, X-ray diffraction, Energy-dispersive X-ray spectroscopy. With the increasment of calcination temperature, the quality and structure of the thin film would change gradually.The thin film will be full of anatase TiO2 and crystallite dimension is 10?20 nm when the calcination temperature is 500 ?. The uniform surface, little agglomeration phenomenon of TiO2 thin film is obtained under low speed of withdrawal from the coating solution and multiple number of coating, O and Ti content in the film accounts for over 70% of the total element content. surface morphology and anatase TiO2 content of TiO2 thinˇfilm determine degradation efficiency of immobilized TiO2 photocatalysts to MB solution.3. Through the experiment of immobilized TiO2 photocatalysts degradation to MB solution, it is found that the degradation rate to MB solution is much higher in low concentrations, strong acidic or alkaline MB solution. The higher intensity of uv irradiation is, the faster the degradation rate of MB solution will be. The adsorption and photocatalytic performance of immobilized TiO2 photocatalysts are effected adversely with Fe2+?Cu2+?Cl-?SO42-?HCO3-?H2PO4- in the MB solution. The immobilized TiO2 photocatalysts degradation rate to malachite green and methyl orange solution is 93.51% and 87.62% respectively.4. In the cycling experiment of immobilized TiO2 photocatalysts degradating MB solution, MB solution of high concentration or uv light irradiation for a short period of time will gradually deactivted the photocatalytic performance of immobilized TiO2 photocatalysts until the completely inactivation. After uv light irradiation to the deactivated catalyst in water or calcination in high temperature, the high performance of immobilized TiO2 photocatalysts will be regenerated. |
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