The Photocatalytic Purification Of Formaldehyde In Indoor Air

In the experiment, using tetrabutylorthotitanate [Ti(OBu)4] as the precursor, the TiO2 was supported on the glass fibers by the sol-gel method and then was used as the catalysts to photocatalytic oxidation of the gaseous formaldehyde. The TiO2 powder that was prepared by the sol-gel method in the experiment was analyzed by the XRD method. The results showed that the crystalline phase of TiO2 was anatase and the crystal size of TiO2 range from 9nm to 11nm. When the gas flow rate was 20L/h and the concentration of gaseous formaldehyde was 168 u g/L, the quality of TiO2 supported on the glass fibers which area was 158.4 cm2 was increased from 0 to 0.32 g, so the percentage of degrading gaseous formaldehyde increased with the increase of quality of TiO2, and the best efficiency was 87.0%. When the quality of TiO2 kept increasing, the efficiency maintained the constant. When the effectual reaction time in the photoreactor increased, the percentage of degrading gaseous formaldehyde increased. When the effectual reaction time increased from 11.9 s to 23.8 s, the efficiency can arrive at 87.0%, and then the efficiency maintained the constant. When the concentration of Fe3+ doped in TiO2 increased from 0 to 0.2%, the efficiency increased from 87.0% to 95.2%. The reason was that the Fe3+ doped in TiO2 can decrease the percent of photogenerated electron reuniting with photogenerated hole, so the efficiency of TiO2 was increased. The Langmuir-Hinshewood equation was fitted to the process of the photocatalytic oxidation and the modeling results matched with the experimental results well.