Study On The Application Of Photocatalysis In Indoor Air Purifier

Indoor air purifier has been widely used in various places. Most of the traditional purifiers employ filtration and adsorption device as core unit which can be easily saturated by pollutants and might cause secondary-pollution during the desorption process. Photocatalysis has become one of the current topics in indoor air control, with a remarkable effeciency and ability of complete degradation of VOCs. In this paper, the photocatalytic device was assembled as a part of the air pollution control unit of the indoor air purifier, forming a model machine. Furthermore, several main influence parameters were evaluated for its operation, as well as the overall performance. Detailed contents are as follows:(1) The photocatalytic metarials and photocatalytic device were prepared and their performance were investigated by the oxidation rate of low concentration toluene in a continuous flow reactor. TiO2nanoparticles photocatalyst were synthesized via sol-gel process, and supported onto the surface of SiC foam ceramics by wet impregnation method. The results showed that the addition of PEG400and P25could highly improve the activity and extend the service life of photocatalytic device. The optimized content of PEG and P25were10%and50%, respectively. The cooperation of light and O2could promote the decomposition and desorption of the adsorbed toluene, leading to effective regeneration of the photocatalyst.(2) The practicable performance of the photocatalytic device was systematically studied, especially under the conditions of high flow rates, low concentration of pollutance, and low light intensity. A3m3chamber was used to investigate the influences of gas flow rate, initial concentration and light intensity. The photocatalytic degradation efficiency decreased when the gas flow rate increased or the concentration of toluene decreased. While the light intensity was below25μW/cm2, the degradation rate increased perpendicularly with the light intensity, and then the increase gradually slowed down. After the light intensity was higher than31μW/cm2, the efficiency remained the same.(3) The function of the model machine as a whole was tested. The photocatalytic device was combined with activated carbon, HEPA, negative-ion generator, and fan, forming a model machine of air purifier. The results showed that its ability of decomposing toluene was obviously higher as compared to several other purifiers sold in the market.