Preparation Of TiO₂ Film Doped With Metal Ion And Their Application In Photocatalytic Degradation Of Organic Wastewater

a new promising catalyst. However, there are still a lot of problems in TiO₂-based photocatalysis such as low quantum efficiency and little utilization of solar energy and so on. To improve the quantum yield and broaden the absorbing spectrum range becomes a very important problem in the research field of photocatalysis.Metal ions doping is considered to be an efficient way in respect of enhancing the photocatalytic activity. In this paper, nanosized TiO₂ film doped with La, Ce, Co were prepared from Ti(OC4H9) in alcohol by sol-gel and dip-coating method. The composition, morphology, optical and photocatalysis of film were characterized by XRD, SEM, UV-Vis spectrophotometer, contact angle instrument and photocatalytic reactor instrument.The results revealed that: (1) The particles forming the TiO₂ film which are in anatase structure are homogeneous in size . Whatmore, the surface of TiO₂ film are flat and uniform. The average grain size are in the size of 40nm of the pure TiO₂ films and in the size of 28～37nm of the doped TiO₂ films, that shows the growth of grain is restrained, the crystal lattice of TiO₂ film is changed by doping. (2) Energy band of TiO₂ are shifted to visible region because of transition metal dopants. Comparing with pure TiO₂ films, doped TiO₂ films exhibit obvious red-shift. (3) Through the photocatalytic degradation of 20mg/L methyl orange, all TiO₂ film exhibit higher photocatalytic activity that the degradation efficiency of TiO₂ film from one to six coating cycle times can arrive to 96% in 40 minutes comparing with deionized water. At the same time, photocatalytic activity is improved in virtue of metal ions doping, as a result, there is the best doping amout which help to increase the photocatalytic activity of the shorter coating cycle times of film. In our experiment condition, for the photocatalytec properties, among 0.05%, 0.2%, 0.5% La doped TiO₂ films the best doping is 0.05% TiO₂ film with a thickness of 70nm, among 0.05%, 0.15%, 0.2% Ce doped TiO₂ films the best doping is 0.15% TiO₂ film with a thickness of 140nm, among 0.03%, 0.1%, 0.3% Co doped TiO₂ films the best doping is 0.03% TiO₂ film with a thickness of 70nm. (4) Using the photocatalytic reaction instrument which is designed and assembled by oneself degrades organic wastewater of the sugar factory. After six hours of TiO₂ films photocatalytic Degradation, the degradation rate arrived to 78.75% which acquired initial effect.