Research On Photocatalytic Degradation Of Gas Phase Toluene By Metal-oxide/Titanium Dioxide Composite

In recent years,the environmental pollution problem caused by haze become more and more serious.As one of the most important constituent,the volatile organic pollutants(VOCs)has been widely studied.Photocatalytic degradation of VOCs is considered to be one of the most prospective method of green environmental purification technology.Among many catalysts,TiO2 due to its non-toxic,light stability,and the thoroughly degrading ability,has become the most common photocatalyst.However,TiO2 as photocatalyst still exist the following problems:(1)In the process of photocatalytic,quantum usage efficiency is low,the electron-hole recombination normally;(2)Since TiO2 is a kind of wide bandgap semiconductor(3.2 eV),it can only use the ultraviolet part of the sunlight,so the utilization rate of visible light is low.Therefore,How to improve the electron-hole separation efficiency of the TiO2 and expand TiO2 response to visible light are the focus in the study of photocatalytic technology.In this paper,the efficiency of the photocatalytic efficiency of titanium dioxide will improve by the composite of hydrotalcite and cuprous oxide.The main research results are as follows:(1)The study put forward detect the concentration of the gas phase toluene using ultraviolet spectrophotometry.This method is simple,less cost,fast,high sensitivily.On the basis of drawing standard curve and the precision and stability test of the method,the result determine the uv-vis spectrophotometry is a feasible method to measure the concentration of toluene;(2)The preparetion method of composite TiO2-LDHs was coprecipitation combined hydrolysis.According to the result of characterization,TiO2,LDHs were combined well during the experiment.Under simulate light irradiation,the degradation rate of gas phase toluene(171.6 mg/m3)reached 86%;under the actual sunlight,the rate reached 92%.And in repeated experiments,degradation rate of toluene by TiO2-LDHs remain above 60%after fouth use.(3)The preparetion of composite catalyst TiO2-Cu2O was the hydrolysis combined reduction method.According to the result of characterization,there is a formation of p-n heterojunction between the TiO2 and Cu2O,therefore,the the light response range of the catalyst extend to the visible light region.In photocatalytic degradation of toluene experiment,Under simulate light irradiation,the degradation rate of gas phase toluene(171.6 mg/m3)reached 79%,under simulate visible light irradiation,the rate reached 70%.