居室空气污染的吸附光催化净化机理研究

In recent years, how to control indoor volatile organic compounds (VOCs) has become an important topic. Many researchers are devoted to develop effective and feasible technologies for VOCs purification. Photocatalytic oxidation (PCO) technology is one of the most prospectful technology for indoor air purification efficiently removing and destroying low-level VOCs, killing bacteria and deodorizing under room temperature. However low activity and deactivation of photocatalyst hinder its real applications. Through this project, titanium dioxide film with good adsorbability prepared by the new method significantly increases the photocatalysis performance in degrading VOCs. Moreover, the new process named ozone/photocatalysis which combined ozone and photocatalysis not only greatly increases the capability of photocatalysis in degrading VOCs, but also avoids the deactivation of the photocatalyst, which means the photocatalysis is much more feasible and effective for indoor air purification..To make up the poor mass transfer of film photocatalyst which limits photocatalytic reaction rate, four kinds of the modified TiO2 thin film photocatalysts were prepared by doping carbon black or SiO2 powder and compounding SiO2 to improve their adsorbabilities. The photocatalytic activity of the carbon doped titanium dioxide was more than two times of that of the original TiO2, and even higher than that of the same kind of TiO2 film photocatalysts reported in literature. The specific surface area and adorbability of the photocatalyst increased due to the pore formed when the doped carbon black was oxidized and removed by baking. Carbon black doped titanium dioxide film was very stable. In the degradation of reactive brilliant red X-3B, its activity remained stable during 4 months experiment and was not influenced by SO42－、NO3－ and ions resulting in alkalinity and hardness in water.The degradation of volatile organice compounds were conducted under three different experimental systems. In a reactor with volume of 0.76L, photocatalytic degradation of toluene, benzene and chloroform was investigated in dry condition. It was showed that, at low inlet concentration and flow rate smaller than 0.2L/min (i.e. retention time larger than 3.825min), the photocatalytic removal rate of toluene, benzene and chloroform was higher than 90%, following first order reaction. The corresponding half-life time of toluene and benzene is about 1.0-1.34min and 0.65-1.1min respectively. When load was larger than 1.0mg/h, the amount of removed toluene and benzene did not increase with load; however the amount of removed chlorform increased all along in the range of 0-6.2mg/h. The activity of carbon black doped photocatalyst was much higher than that of P25 titanium dioxide. And germicidal lamp was better than black light lamp with same power In a reactor with volume of 1.44L, the influence of inlet concentration, flow rate, humidity, photocatalyst and UV light source on the degradation of toluene by O3/UV, TiO2/UV and O3/TiO2/UV were investigated, and the performances of these three technologies were compared. The removal rate of toluene decreased with the increase of inlet concentration or flow rate. At relatively large flow rate, the removal rate dropped sharply. The photocatalytic degradation of toluene followed the first-order kinetics at low inlet concentration and small flow rate, while it deviated at high inlet concentration or large flow rate. Under experiment conditions, the reactions of O3/UV and O3/TiO2/UV followed first-order kinetics. The removal rate of toluene by O3/UV, TiO2/UV and O3/TiO2/UV increased with the increase of humidity until it reached the optimal humidity. Further increase of humidity would conversely decrease the removal rate. The performance of photocatalysts coated on the stainless steel mesh improved with the increase of mesh number and layers of photocatalyst. However their performance, even the one coated on the mesh with 100 meshes, was lower than that of on the aluminum foil. The removal rate of toluene irradiated by ger

分析居室空气污染特征，弄清室外大气质量与室内空气质量的关系。研制集吸附、吸热、可见/紫外光敏感的光催化薄膜，分析表面结构和表面特性对催化性能的影响；研究典型环境跫戮邮铱掌廴疚镌诒∧ど系奈焦獯呋到狻Ｎ夷诳掌柿康母纳铺峁┝艘恢中路椒ā?..................