Search

Understanding the removal nature of the indoor volatile organic compounds under realistic environment conditions would give clear guidance for the development of air purification devices. The study investigated the removal of indoor acetaldehyde using visible-light-responsive N-doped TiO2 (N-TiO2) photocatalyst under visible-light irradiation (light) and in the absence of light (dark). The adsorption kinetics of acetaldehyde onto N-TiO2 followed a pseudo-second-order model. The magnitude of acetaldehyde adsorption is proportional to temperature, and the results were fitted to the Langmuir isotherm model. Moreover, the effect of initial acetaldehyde concentration and visible-light intensity on the photooxidation of acetaldehyde was well described by the Langmuir-Hinshelwood model. Results show that the mesoporous N-TiO2 catalyst had a high ability to absorb acetaldehyde in the dark condition, and then acetaldehyde was subsequently photooxidized under visible-light irradiation. The adsorption capacity was found to increase with decreasing temperature. The negative value of ΔG° and the positive value of ΔS° indicate that the adsorption of acetaldehyde onto N-TiO2 was a spontaneous process. Finally, a reaction scheme for removal process of indoor acetaldehyde by N-TiO2 was proposed. [ABSTRACT FROM AUTHOR]

A facile wet chemical method was adopted for preparing highly photoactive nitrogen doped TiO2 (N-TiO2) powders with visible responsive capability, which could be achieved by the hydrolysis of titanium isopropoxide (TTIP) in the ammonium hydroxide precursor solution in various concentrations and then calcined at different temperatures. The N-TiO2 powders were characterized, and the photocatalytic activity was evaluated for the photocatalytic oxidation of ethylene gas under visible light irradiation to optimize the synthesizing conditions of N-TiO2 catalyst. The N-TiO2 photocatalytic powders were calcined in a range of temperatures from 300 to 600°C and obviously found to have greater photocatalytic activities than commercial TiO2 P25. The strong absorption in the visible light region could be ascribed to good crystallization and adapted sinter temperature of as prepared sample. XPS test demonstrated that the N was doped into TiO2 lattice and made an interstitial formation (Ti-O-N), and N doping also retarded the phase transformation from anatase to rutile as well. The N-TiO2 catalyst prepared with 150 mL ammonium hydroxide added and calcined at 500°C showed the best photocatalytic activity. The experimental results also proved the enhanced photoactivity of N-TiO2 material depends on the synthesizing conditions. [ABSTRACT FROM AUTHOR]