Synergistic Photocatalytic Oxidation Of VOCs In Cooking Oil Fumes By TiO₂ With Ozone

With the development of catering industry, the pollution of the cooking oil fume has become increasingly serious, which has become the third biggest source of air pollution following motor vehicle pollution and industrial pollution. In particular, the pollution of the VOCs in cooking oil fume has attracted more and more concern However, the present research on the purification of the cooking oil fume mainly aims at the removal of soot particulate matter, and there is little study of the removal of VOCs. Therefore, this study takes a typical VOCs butyral as the target contaminant to study the effects of the removal of VOCs in cooking oil fume with the ozone collaborate photocatalytic technology on the basis of electrostatic air purifier.The study of the removal of butyral was carried out by the method of ozone collaborate with photocatalytic fluidized bed, investigating the effects of water vapor, ozone concentration, butyral initial concentration, temperature and other parameters on degrading the catalytic activity with this method. Additionally, the degradation of other VOCs in cooking oil fume was also explored in this research. The results showed that there was an obvious effect of the method of ozone collaborate with photocatalytic fluidized bed on the removal of butyral. The effect of water vapor, ozone concentration, the initial concentration and reaction temperature on the removal activity was also obvious. With ozone concentration of 10 ppm, 21% oxygen concentration, 2% water vapor, initial concentration of 100 ppm and, the reaction temperature of 60 ℃, the degradation rate and mineralization rate of butyraldehyde were 95.1% and 61.8% respectively. The sequence in degradation difficulty for the six typical VOCs in catering fumes was trichlorethylene > acetic acid> ethanol> butyral> hexanal> toluene.With the collecting aluminum mesh in the electrostatic air purifier as the carrier, the immobilized photocatalyst was studied and different methods, such as the direct coating method, the sol-gel method, the binder method and the paste method were compared. At the same time, the type and content of dispersant, together with the content of Ti O2 were optimized. The results showed that the paste method has good photocatalytic activity and fastness, and its activity is related with the immobilization method, the type of dispersant, the amount of dispersant and Ti O2 concentration. With aluminum mesh as the carrier and water-borne silicone-acrylate resin as adhesives and Ti O2 immobilized by the paste method, it has the higher photocatalytic activity when Ti O2 is 20% and the amount of dispersant sodium hexametaphosphate is 0.2%.The immobilized photocatalysts on the aluminum mesh was used to study the removal of butyral by ozone collaborate with immobilized photocatal yts, and the effects of the flow rate, temperature, concentration of butyral, water vapor and other parameters on the removal activity of butyral were investigated. At the same time, the life of the catalyst and the removal activity of several other VOCs were also assessed. The results showed that the effect of the method of ozone collaborate with immobilized photocatalysts on the removal of butyral was obvious, and the catalyst has good photocatalytic life. Its effect was related with flow rate, temperatu re, the initial concentration of butyral, water vapor and other parameters. The sequence in degradation difficulty for the six typical VOCs in catering fumes was trichlorethylene> acetic acid>ethanol>butyral>hexanal>toluene. The trichloroethylene has the h ighest catalytic activity per unit area, which is 13.63 μmol /(m2?s). While the catalytic activity per unit area is the lowest when degradating toluene, which was 3.25 μmol/(m2?s), and its average catalytic activity per unit area is 7.84 μmol/(m2?s).