Research Of Preparation And Photocatalytic Application Of Modified Amorphous TiO₂

Formaldehyde was a major pollutant in indoor air,which seriously affects people's physical and mental health.It reported that TiO2 can remove formaldehyde by photocataly effectively without secondary pollution.However,TiO2 has low utilization ratio of visible light,so under visible light irradiation the photocatalytic efficiency of formaldehyde is low.In this paper,amorphous TiO2 as the research object,was improved the photocatalytic activity under visible light by changing the amount of silver nitrate,the heat treatment temperature and the amount of nitric acid.Then,the non-woven wallpaper was used as base material coated with modified Ti02 to prepare the green wallpaper.The modified amorphous TiO2 was prepared by the sol-gel method,and exploring the degradation efficiency of formaldehyde in aqueous solution by modified TiO2 which made in different modifying condition,the amount of silver nitrate,the heat treatment temperature and the amount of nitric acid.Combining with experimental results and cost,the best modified conditions of amorphous TiO2 were that the ratio of silver nitrate was 0.1,the heat treatment temperature was 150 ?,and the ratio of nitric acid was 1.The degradation rate of formaldehyde by the modified TiO2 was 74.9%under fluorescent lamp for 5 hours.SEM and EDS analysis showed that the size of the modified TiO2 particles was uniform and has good dispersion,and the Ag+ was doped successfully.The modified TiO2 belonged to the porous mesoporous materials,and the specific surface area was 188.445 m2/g.The light response range of the modified TiO2 was improved,which had good absorption of light in the range of 400?800 nm.The results of disperse experiment showed that the catalyst can be fully dispersed and the degradation rate of formaldehyde was increased by 17.7%compared with before dispersion when the mass ratio of polyacrylamide and the modified TiO2 was 0.2 and the ultrasonic dispersion time was 1 hour.Then the formaldehyde gas was degraded by non-woven wallpaper which coated with modified TiO2,combining with experimental results and cost,the formaldehyde degradation rate can reach 80%under the fluorescent lamp for 8 hours when the modified TiO2 coating quantity was 120 mg,the mass ratio of ?-cyclodextrin and the modified TiO2 was 2,initial concentration of formaldehyde was 0.5?0.55 ppm and the relative humidity was 55?56%.The formaldehyde degradation rate of P25 was only 25%under the same conditions.The coating modified TiO2 on non-woven wallpaper was repeatedly used,and the formaldehyde degradation rate was 72.7%after 5 times repeated degradation experiment,which proved that the performance of the continuous use is good.Dynamic analysis results showed that the reactions of photocatalytic oxidation of formaldehyde by modified TiO2 accord with first-order kinetic equation and the reaction rate can be described by Langmuir-Hinshelwood model when the initial concentration of formaldehyde was 0.5-0.55 ppm,and the reactions of photocatalytic oxidation of formaldehyde followed the first-order kinetic equation when the relative humidity was 55?56%.In summary,the modified amorphous TiO2 had a good photocatalytic performance,and its preparation was simple,economic and environment friendly.Its photocatalytic performance was good under visible light,which has strong practicability.The research lays the foundation for application of modified amorphous TiO2 in the photocatalytic degradation of indoor formaldehyde gas.