TiO_2/膨润土光催化剂的性能及表征

Performance and characterization of TiO_2/bentonite photocatalyst

以膨润土为载体,用溶胶-凝胶法制备了一系列TiO2/膨润土光催化剂,考察了TiO2负载量、焙烧温度对光催化剂性能的影响.结果表明,当TiO2负载量为50 wt%、焙烧温度为400℃时,该光催化剂处理罗丹明-B染料废水的效果最好,其脱色率和COD去除率分别高达96.8%和91.3%.通过XRD、FT-IR、BET技术对光催化剂结构进行表征发现,TiO2粒子进入了蒙脱石层间置换出了蒙脱石层间的水合钙离子,形成了新的Ti-O-Si键,实现了TiO2胶粒与膨润土的复合;适当的焙烧温度可使膨润土中Al2O3微晶中的结构水及蒙脱石层间水分子减少,促使光催化剂中空隙数目增多、催化剂比表面积增大.光催化剂比表面积越大越有利于其活性的提高.

A series of TiOa modified bentonite photocatalysts are prepared by sol-gel method. The effect of TiO2 loadings and calcination temperatures on the performance of TiO2 bentonite photocatalysts is investigated. The results reveal that the photocatalyst calcined at 400℃ with 50wt % loading show optimum catalytic performance for the treatment of Rhodamine B dye wastewater. The percentage of decolorization and the ratio of chemical oxygen demand （COD） for the dye wastewater are 96.8 % and 91.3 %, respectively. All the catalysts are further characterized by XRD, FT-IR and BET techniques. It is found that the hydrated calcium ions in interlayer of the raw bentonite are exchanged by those entered TiO2 particles and the new Ti-O-Si bond is formed, resulting in the composition of TiO2 colloidal particles with bentonite. At the appropriate temperature, both the configuration water of the Al2O3 micro-crystal and the water molecules in the interlayer of the raw bentonite are decreased, while the pukas and the surface area of the catalyst are increased. Moreover, the larger the surface area is, the better the activity is.