Study On The Photocatalytic Degradation Of Btxs In Water By Poly-silicon/tio₂/uv System

Since 1976, the photocatalytic technology of water treatment based on the semiconductor (such as TiO₂) has attracted more attention. The support of catalyst plays a key role to improve the photocatalytic performance of catalyst. Poly-Si has been taken for a good support for TiO₂, due to its wide light adsorption and strong photoelectric effect, also comes from the coupling between TiO₂ and poly-Si. However, there is no report deal with this. In this work, the Poly-Si/TiO₂ photocatalytic catalyst has been prepared for the first time. The effect of crystal style and composite of Poly-Si/TiO₂, the pH, reaction time and the BTXs concentration on the removal rate of BTXs have been studied. Furthermore, the machenism of photocatalytic oxidation of BTXs also has been discussed.Firstly, the TiO₂/Poly-Si photocatalysts have been prepared by sol-gel method and characterized by the X-ray diffraction (XRD), scanning electron micrographs (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Results show that, the photocatalyst with 2 times of TiO₂ coating prepared at 550℃for 2 hours having excellent performance of degradation of BTXs.Secondly, as the main chemicals on the behalf of organic pullution in water, the degration rates of BTXs in the fully-mixed reactor and 3-phase fluidized bed have been investigated to discuss the effect of pH, content and other factors on the photocatalytic oxidation of BTXs. Results show that, (1)In the fully-mixed reactor, the best conditions are that: reaction time is 120min, pH=5.8, and the photocatalyst usage is 1.0g/L;(2) In the 3-phase Fluidized Bed, the best condition are that: the gas-flow rate is 5.0 L/min. The degradation rate of BTXs can reachs 92%.Finally, the effects of the initial concentration of BTXs on the BTXs degradation in water have been investigated. By the first rate of kinetics theory, the best initial concentration is 10.0mg/L.In conclusion, the photocatalyst shows a potential application in the fields of wastewater treatment.