Preparation Of WO₃ Composite Coating And Photocatalytic Degradation Of Formaldehyde Under Visible Light Irradiation

As the improvement of people's living standards,their demands of indoor environment and comfort have become higher.But the various decoration materials of indoors are now the main pollutant source.For example,the coating,paint,decoration and daily necessities can give out volatile organic compounds.This project studies on the photocatalysts P25 and WO3,and combines them with coating to prepare composite photocatalytic coating for the research of degradation of formaldehyde,focusing on WO3 photocatalytic coating that can respond to visible light.It has certain practical value.The main contents of this paper are as follows:1.A device for photocatalytic degradation of formaldehyde was designed and prepared.Tests show that the device is well airtight,under the only light.For a long period of time,we did not detect a significant degradation of formaldehyde gas.The following kinds of composite coatings were tested for formaldehyde degradation.1)The non-dispersed P25 was combined with the coating directly for the photocatalytic degradation of formaldehyde gas.When the amount of P25 is 7%,the degradation effect of formaldehyde is the best.When the initial concentration of formaldehyde is about 0.8 mg/m3,the photocatalytic effect is the best,which is about 16.9%.Under the light of 32 w UV light,the P25 for the degradation of formaldehyde gas is better than the same wattage under the visible light.2)The P25 was dispersed by the dispersion polyacrylamide,which was combined with the coating,for the photocatalytic degradation of formaldehyde gas.The degradation effect of P25 combined with paint for the degradation of formaldehyde gas is better than that of the direct compound,and the degradation rate is about 25%.Under the irradiation of 32w UV light,the degradation effect of four kinds of coatings on formaldehyde gas is nearly the same.It indicated that the coating has little effect on the degradation of formaldehyde,and the photocatalyst mainly play a role.3)When the initial formaldehyde concentration is 0.80 mg/m3,under the irradiation of 32 w fluorescent light.We prepared WO3 by H2W04 at the calcination temperature of 300 ?.When the addition amount is 11%,there is the highest degradation rate of formaldehyde,and it is about 8%.The four kinds of ordinary coatings purchased from the market have little change for the degradation rate of formaldehyde,and the degradation rate of the four coatings is about 8%after 8 h.2.The degradation of methyl orange was studied by homemade TiO2 and WO3.It was found that the degradation efficiency increased when the degree of crystallinity was improved by hydrothermal method.The degradation rate of methyl orange is the highest,which is about 96%.The initial concentration of methyl orange in the range of(5-20)mg/L,the degradation rate gradually increased with the initial concentration of methyl orange increasing.3.The degradation performance of WO3 to methyl orange was studied.The experiments showed that the degradation rate of methylbenzene WO3 prepared by H2WO4 at calcination temperature of 300 ?was 63%.The effect of WO3 modified by organic alkali immersion modified H2WO4 on the degradation performance of methyl orange was studied.The results showed that the degradation rate of methyl orange was 67%when the WO3 was prepared by methylamine solution soaked with H2WO4,and 4%higher than the non-immersion pretreatment.