Studies On Preparation And Application Of TiO₂ Porous Film Photocatalyst Supported On Metal Substrate

TiO2 photocatalytic process is a green environmental technology with high efficiency and saving energy. TiO2 porous film photocatalyst supported on metal substrate was prepared by sol-gel technique with butyl titanate (Ti(OC4H9)4) as precursor, polyethylene glycol (PEG) as template and stainless steel mesh as carrier in the article. The sol stability of TiO2-PEG sol system for the preparation of TiO2 porous film was investigated by using dynamic viscosity method. TiO2 porous film was characterized by means of TG-DSC, IR, SEM, BET, XRD and Raman spectrum. Applying performance of TiO2 porous film was evaluated by the experiments of photocatalytic degradation of gas-phase formaldehyde and photocatalytic sterilization. In addition, the effects of the changes of the preparation method and the carrier on the applying performance of TiO2 porous film were explored. Experimental results showed that the solstability of TiO2-PEG sol system was affected by the changes of the dosing ratios of materials and the preparation conditions of TiO2-PEG sol system. The stoichiometric ratio of all the ingridients in TiO2-PEG sol system was Ti(OC4H9)4:H2O:C2H5OH:NH(C2H4OH)2:PEG800 = 1:2.5:70:0.5:0.1 in the study. TiO2 film with anatase crystallite and porous structure was available by controlling the preparation conditions. The photocatalytic performance of TiO2 porous film was close related to the experiment conditions including the carrier of the photocatalyst, the illumination source and the initial concentration of formaldehyde, and related to the preparation conditions including the coating cycle, the calcining temperature and the viscosity of TiO2-PEG sol system. TiO2 porous film showed higher activity and better stability when TiO2 film was coated for 4 cycles and the heat treatment temperature was 450℃ and the viscosity of the sol was in the range of 10 - 20mPa · s. The degradation efficiency of gas-phase formaldehyde on TiO2 porous film was 28.8% higher than that on the film without porosity. The degradation efficiency of formaldehyde still achieved more than 80.0% after TiO2 porous film was continually used for 4 times. The degradation efficiency of formaldehyde with TiO2 porous film packed well for 6 months was 19.5% higher than that with TiO2 porous film exposed to the open air for the same time. TiO2 porous film possessed good bactericidal performance. The average sterilization efficiency of bacteria in air could reach 89.9% when photocatalytic sterilization process took place...