The Tests Researching On The Degradation Of Indoor Formaldehyde By Modified Photo-catalysis Of Solid Superacid

Indoor formaldehyde creating by architectural materials and furnitures affected the health of human being a lot, especially as the indoor decoration was popularized nowadays, the pollution of indoor formaldehyde brought public attention significantly. nanometer TiO₂ photocatalysis technology was an efficient way which possess quite developmental potential in recent year, but it still had two problems to solve, one was the high recombination rate of carriers and the other was the lower rate of sunlight utilization. In order to make breakthrough from these fields, this theme mainly researched on modified solid super-acid.In this paper, firstly, the pure TiO₂ photo-catalysis powder was made based on the ratio researched by our team for a long time, adding HNO3 as catalysis, shortening the condensation time of sol, and optimizing the ratio using simplex optimization method. Secondly, the crystalline properties was characterized by X-ray diffraction (XRD). Thirdly, introducing rare earth element, La, and super-acid to create modified solid super-acid photo-catalysis and degrade indoor formaldehyde. Meanwhile, comparing the crystalline properties between the pure TiO₂ photo-catalysis powder and the modified TiO₂ photo-catalysis powder. Then, loading the best removal rate of TiO₂-photo-catalysis powder in the coating to degrade indoor formaldehyde. At last, getting the kinetic equation of modified solid superacid photo-catalysis with different initial concentration and different degradation process under the incandescent lamp.The results indicated that:â‘ By adding catalysis HNO3 to shorten the condensation time, in this paper, different addition amounts were introduced to prepare the tests, and the ratio of n(Ti):n(HNO3) were1:0.25;1:0.5;1:0.75;1:1 respectively. The result showed 1:0.25 was the best one.â‘¡Using simplex optimization method to optimize the ratio, when it was n(H2O)/n[Ti(OC4H9)4]=3.46,n(C2H5OH)/n[Ti(OC4H9)4]=26.49,n(HNO3)/n[Ti(OC4H9)4]=0.34,n(NH(C2H5OH)2)/n[Ti(OC4H9)4]=1.21, the removal rate of formaldehyde could reach 34%.â‘¢Orthogonal tests were used to make SO42--TiO₂ solid super-acid, which selected three factors, impregnation time, impregnation concentration and calcination temperature. After variance analysis, the result indicated the most important factor was impregnation concentration, following with calcination temperature. And the sequence was impregnation concentration>calcination temperature>impregnation time.â‘£Average particle size of La3+-SO42--TiO₂(500℃) was 21.3nm, comparing with average particle size of pure TiO₂ photo-catalysis powder, the modified solid superacid photo-catalysis has smaller particle size and larger specific surface area.⑤Using ultraviolet lamp as light sources, when the rate of n(La):n(Ti) was 0.25, the La3+-SO42--TiO₂ photo-catalyst properties was best. While under the incandescent lamp, the rate of sunlight utilization of SO42--TiO₂ photo-catalyst was 27.08%, and La3+-SO42--TiO₂ photo-catalyst was 39.22%.â‘¥Combine the organic binding agent and photo-catalyst uniformly, then spraying it into the glass plate painting coating already to degrade indoor formaldehyde researching on the different loading amount and different light sources. When the loading amount reach 1:0.75, the removal rate was the highest. However, the ultraviolet lamp would harm the coating, so furthering research under incandescent lamp was carried, and the removal rate reach 37.25% after spraying La3+-SO42--TiO₂ photo-catalyst on the surface of painted coating in three hours.⑦Due to different initial formaldehyde concentration, the removal rate was total different. During this process, incandescent lamp was light source, La3+-SO42--TiO₂ photo-catalyst was carried on the surface of painted coating. Assuming that the degradation of formaldehyde process accord with first order kinetic equation. And the tests proofed it was right. At last, the degradation rate constant was 0.0036mg/m3, and apparent adsorbed balance constant was 0.9769m3/mg.