The photocatalytic reactor used in the packed bed photocatalytic reactor is two sets of Pyrex glass double-tube annular reactors with a height of 300 mm, an inner tube outer diameter of 45 mm, and an outer tube inner diameter of 65 mm and 105 mm, respectively. 10 mm and 30 mm, respectively, filled with different supported photocatalysts to form a packed bed photocatalytic reactor in the annulus between the inner and outer tubes. The concentration of 1210mg / L methylene blue (AR, Shanghai Reagent III) solution as a model pollutant, after reaching the adsorption equilibrium, turn on the UV lamp, start the photocatalytic reaction under a certain air flow, with a spectrophotometer (760CRT, Shanghai The analytical instrument factory) determined the maximum absorbance of methylene blue at 667 nm (in accordance with the Beer-Lambert law in the experimental concentration range). The photocatalytic reaction efficiency of the reactor is indicated by the amount of methylene blue reaction per unit volume of reactor over 15 minutes. The mass transfer characteristics of different photocatalyst packed beds were investigated by changing the air flow rate. The TiO2 photocatalyst was supported on the inner wall of the outer tube of the above-mentioned ring type reactor by the above dip coating-sintering method to constitute a fixed film photocatalytic reactor. The light distribution was measured by a 250 watt high pressure mercury lamp (main wavelength 365 nm, Shanghai Yaming Bulb Factory), ultraviolet radiation meter (Beijing Normal University Photoelectric Instrument Factory) and a flat bottom container to measure the light distribution and light distribution measuring device. Fixing the position of the high-pressure mercury lamp, the ultraviolet irradiance meter and the container, changing the amount and filling thickness of the supported photocatalyst in the container, and measuring the intensity of the light radiation transmitted through the packed bed, the distribution of light in different photocatalyst beds can be obtained. . Carrier Design Ideas Effective photocatalytic reaction space should have both light, reaction substrates and photocatalysts. If light is considered as an electromagnetic wave phase, the photocatalytic process of passing air can be used as a gas (air) liquid-solid (photocatalyst) electromagnetic wave four-phase complex chemical reaction engineering analysis. The relationship between the photocatalytic reaction rate and the substrate concentration generally satisfies the Lawrmumu-Hinshelwood law. The relationship between the photocatalytic reaction rate and the electromagnetic wave phase is converted into a relationship with the directly measureable light intensity. When the light irradiates the photocatalytic reaction system, due to the strong absorption of light by the photocatalyst (although there are sometimes scattering and reflection and the absorption of light by the solution, the absorption of light by the catalyst still dominates), In the incident direction of light, the light intensity generally decays exponentially, so that the number of photons available in the local volume is also exponentially decreasing along the direction of the incident light. If only the absorption of light by the photocatalyst is considered, it can be considered that the local volume photon absorption rate also decays exponentially along the incident direction. Near the light entrance, the light intensity is the strongest, the local volume of the bed absorbs the most photons, the most carriers are generated, and the speed of recombination between carriers is also the fastest. At this time, the control step of photocatalytic reaction speed is carrier. Migration ‰ capture and corresponding heterogeneous catalytic reaction processes (such as adsorption enthalpy desorption and surface reaction), the reaction speed is independent of the light intensity. In this case, most of the light is depleted in the form of heat radiation due to the recombination of carriers. Drop, resulting in the lowest light quantum efficiency; when the light propagates along the incident direction to a certain intensity, the amount of photogenerated carriers is small, the recombination velocity between carriers is slowed, and the generated carriers can migrate to the composite before The surface of the catalyst is trapped and an effective photocatalytic reaction is initiated. At this time, the photon efficiency is the highest, and the reaction speed is proportional to the light intensity. There is a transition region between the two, and the reaction speed is proportional to the square root of the light intensity. The change rate of the recovery rate R and the light intensity I, and H is the dimensionless thickness of the reactor along the incident light direction. Although the division of the boundary line is related to the specific system, Ra can be divided into four regions according to the relationship between the reaction speed and the light intensity. 106cm Pvc Vinyl Wallpaper Vigour New Designs
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