Investination Of Photocatalytic Degradation Of Typical Indoor Air Pollutants With Titanium Dioxide Film

The interior decoration materials can produce pollution gas, and destroy indoor airenvironment, endangers human health. Among the numerous pollution gas, formaldehyde,ammonia and benzene have been considered to be harmful. Because of its high energyefficiency and pollution-free advantages, the nanometer photocatalysis technology iswidely used for the removal of indoor air pollutants. Titania is the most effectivephotocatalyst with the characterics of resizing erosion, low cost, and nontoxicity. However,due to its high-energy band gap, titania photocatalysis reacts only under ultraviolet light.So, in this study, the glass was used as a carrier to preparat pure TiO₂films, andFe（Ⅲ）-doped TiO₂thin films. And the photocatalytic efficiency of doped TiO₂photocatalyst was investigated with indoor formaldehyde, ammonia and benzene gas asthe degradation pollutants.The TiO₂film was prepared by sol-gel method with tetrabutyl titanate （TBOT） as theprecursor, glacial acetic acid （CH3COOH） as the catalyst and ethanol as the solvent. Theeffects of sol aging time, molar ratio of H2O to Ti, coating layers, calcination time, andcalcination temperature on the photocatalytic activity were investigated. The results showthat TiO₂films prepared in16:1of mole ratio of H2O to Ti,2h of calcination time,500℃of calcination temperature had performed best photocatalytic activity. UV-Visabsorption spectrum, SEM, XRD and EDS chemical analysis were carried out on theoptimum TiO₂photocatalyst.In order to develop TiO₂photocatalyst in visible light response range, the metal ionFe3+doping TiO₂photocatalyst performance was studied. First, the TiO₂films of differentiron doping concentration were prepared using sol-gel method. Then Fe（III）-doped TiO₂thin films photocatalytic was used to degradate formaldehyde, ammonia and benzene inhomemade environment test chamber. The results show that when the iron dopingproportion （mole ratio） is1%, the TiO₂films has the best photocatalytic activity; thedegradation effect of Fe（III）-TiO₂film on the target of gas pollution is significantly higherthan pure TiO₂film; the degradation effect of formaldehyde, ammonia and benzene eachsingle gas by photocatalytic is significantly higher than that of their three mixed gas. Formaldehyde is chosen as the research object. The formaldehyde photocatalyticdegradation dynamics research shows that TiO₂film light catalytic process fit well withfirst order kinetic model. The relationship of initial concentration of formaldehyde and therate constants is linear. With the increase of initial concentration of formaldehyde,formaldehyde photocatalytic degradation rate constant decreased.Finally, the reason of TiO₂film photocatalytic activity deactivation was discussed inthis paper. The results show that chemical cleaning, ultraviolet radiation and heattreatment methods can restore TiO₂film photocatalytic activity effectively.Among them,the ultraviolet irradiation has the best effect.