Study On The Preparation And Photocatalytic Degradation Of Benzoic Acid Of TiO₂ And N/TiO₂ Composit Catalytic Film

The use of aqueous suspensions of TiO₂ has many disadvantages in practical applications because of deactivation, agglomeration and the problems of separation in order to recycle the photocatalyst. So the immobilization of nano-TiO₂ on solide supports to eliminate this problem becomes necessary in practice.The preparation of P25-PTFE composit catalytic film was proposed in this thesis. The composit catalytic film was mainly composed of nickel and nano-TiO₂ which is fixed on the surface of the film. The befitting preparation of the film is studided. And the pH,intensity of light,the concentration of the benzoic acid solution is also researched. It is indicated that pH=4.0, intensity of light is 2500μw/cm², the concentration is 20mg/L, the best photocatalytic activity can be obtained.In this paper, the preparation of N/TiO₂-PTFE composit catalytic film was also researched as well as the pH,intensity of light,the concentration of the benzoic acid solution. It is indicated that pH=2.50, intensity of light is 2500μw/cm2, the concentration is 10mg/L, the best photocatalytic activity can be obtained. Based on the results of the main influence factor of the photocatalytic degradation of organic pollution, a kinetics equation which accorded with L-H equation is got about N/TiO₂ composit catalytic film.The life time of TiO₂ and N/TiO₂ composit catalytic film was also researched. The fresh and the deactivated TiO₂ and N/TiO₂ composit catalytic films were characterized by XRD,XPS and SEM. It was found that there were two main reasons leading to the deactivation, one was the surface activity sites of the film was taken up by benzoic acid and/or the by-products which absorbed and accumulate on the surface of the catalyst, the other reason was the agglomeration of the photocatalyst during the photocatalytic oxidation so that the size of particles got larger, the comparative surface area declined and the adsorption ability of photocatalyst descended.The deactivated TiO₂ and N/TiO₂ composit catalytic film was regenerated by UV illumination, surging with ultrasonic and washing with acid, respectively. At last, the activation of the regenerated composit catalytic films were also...