Preparation And Degradation Of Formaldehyde In Indoor Air By Ag/AgBr/BiVO₄ Photocatalyst

Formaldehyde is a typical representative of indoor air pollutants,which has been listed as a class of carcinogens by the World Health Organization.Formaldehyde can be emitted for a long time in the decorated room,and may cause the indoor air formaldehyde concentration to exceed the standard continuously.How to control formaldehyde pollution in indoor air and effectively purify and remove formaldehyde in indoor air is a hot issue concerned by scholars and engineering circles engaged in indoor air quality assurance in recent years.Formaldehyde is a typical representative of indoor air pollutants,which has been listed as a class of carcinogens by the World Health Organization.Formaldehyde can be emitted for a long time in the decorated room,and may cause the indoor air formaldehyde concentration to exceed the standard continuously.How to control formaldehyde pollution in indoor air and effectively purify and remove formaldehyde in indoor air is a hot issue concerned by scholars and engineering circles engaged in indoor air quality assurance in recent years.The purpose of this study is to develop bismuth vanadate based photocatalyst Ag/AgBr/BiVO₄ with good light response,reduce the recombination rate of photogenerated electrons through modification,and further use it to purify indoor formaldehyde,so as to create a good indoor air environment.Firstly,BiVO₄ was prepared by hydrothermal method,then BiVO₄ was modified,and Ag/AgBr particles were loaded on BiVO₄ surface by precipitation photoreduction method to prepare Ag/AgBr/BiVO₄.The crystal phase,morphology and optical absorption properties of Ag/AgBr/BiVO₄ were characterized by XRD,SEM and XPS.The characterization results show that the Ag/AgBr/BiVO₄ photocatalyst prepared in this study has good crystallinity and is the monoclinic scheelite phase with the best photocatalytic activity,and Ag/AgBr is uniformly distributed on the surface of BiVO₄;In the range of 500-780 nm,the optical absorption capacity is significantly enhanced,and the electron hole recombination is inhibited.Then,this paper carried out the preparation of Ag/AgBr/BiVO₄ main preparation conditions and the main influence parameters of the optimal ratio of experimental research.The effects of hydrothermal reaction temperature,amount of silver nitrate and hydrothermal reaction time on the photocatalytic performance of Ag/AgBr/BiVO₄ were investigated by single factor control variable method.The optimal preparation conditions of Ag/AgBr/BiVO₄ photocatalyst were summarized as follows:hydrothermal reaction temperature was 170℃,amount of silver nitrate was 30%,and hydrothermal reaction time was 16 h.Finally,based on the investigation results of formaldehyde concentration in indoor air,the degradation efficiency of Ag/AgBr/BiVO₄ photocatalyst was studied by setting the initial concentration of formaldehyde.The degradation rate of formaldehyde was investigated by adjusting the initial concentration of formaldehyde,the dosage of Ag/AgBr/BiVO₄ and the light intensity.The results showed that in a certain range,the degradation rate of formaldehyde increased with the increase of illumination,the initial concentration of formaldehyde and the dosage of Ag/AgBr/BiVO₄.The degradation rate of formaldehyde in indoor air by Ag/AgBr/BiVO₄ photocatalyst was more than 90%in180 min.The results show that Ag/AgBr/BiVO₄ has better response to visible light,low photogenerated electron hole composite rate,high degradation efficiency for formaldehyde in simulated indoor air,effective purification of formaldehyde and building a healthy and safe indoor air environment.