Electrostatic Adsorption-visible Light Photocatalytic Oxidation Treatment Of Indoor Dust-landen Volatile Organic Compounds

Indoor air pollution is complicated,and the pollutiants also have a series of cross actions in ambient air.An efficient air purifier with electrostatic adsorption-visible light photocatalysis oxidation was designed to remove the indoor suspended particulate matter and low concentration volatile organic compounds（VOCs）simultaneously without any secondary pollution.The uniform and transparent TiO₂ films were prepared on different substrates by a simple sol-gel method,and the photocatalysts prepared with different mole ratios of H₂O and Ti was studied.The results showed that the optimal mole ratio of H₂O and Ti was 8:1,and the glass was taken as the optimal substrate.The Mn and N element were not only employed to degrade ozone,which was a by-product of the electrostatic adsorption,but also to enhance the photocatalytic activity of pure TiO₂ under visible light irradiation by the means of metal elements doping TiO₂,non-metal doping TiO₂ and co-doping TiO₂ with metal and non-metal elements.The results showed that 0.1 %Mn-TiO₂ glass film performed the highest photocatalytic activity.All kinds of phocatalysts were characterized by XRD,UV-Vis,TEM and SEM.The results showed that all of Ti O₂ samples had an anatase crystallite structure,and the absorption edge were shifted to visible light region.Meanwhile,the TiO₂ nano-photocatalysts were not only in small particle size,but also well dispersed.In addition,a series of factors influencing the visible light photocatalytic activity of Mn-TiO₂ glass film were explored;meanwhile the formaldehyde was taken as the target pollution,which was a kind of typical volatile organic compounds.The results indicated that the removal rate of formaldehyde increased with temperature,light intensity and the amount of phocatalysts,whereas decreased with larger formaldehyde concentration.The photocatalytic degradation of formaldehyde and benzene when they exist separate or mixed in the indoor air was studied in best condition.The results indicated that the Mn-TiO₂ thin film had a good performance on disposing of formaldehyde and benzene,the removal rate of mixed formaldehyde and benzene were lower than which existed in air separately;meanwhile the removal rate of formaldehyde were greater than benzene whether in separately or mixed condition.The degradation reaction kinetics of formaldehyde and benzene were described by Langmuir-Hinshelwood first-order kinetics model.An electrostatic adsorption-visible light photocatalytic air purifier was designed and manufactured The clean air delivery rate（CADR）test results indicated that the purification efficiency grades on those pollutants were class A.In addition,the continuous flow experiments were conducted in this study;the results showed that the concentrations of those pollutants(formaldehyde,benzene and PM_2.5)and the by-product of electrostatic cleaner（ozone）,which were disposed by electrostatic adsorption-photocatalysis air purifier,met the indoor air quality standard（GB/T 18883-2002）.