Photocatalytic Degradation Of VOCs By TiO₂-GO/LDHs Composite

With firmly winning the battle of pollution prevention and control becoming a national key strategic task,the social awareness of strengthening the construction of ecological civilization has been further improved.Focusing on the prevention and control of air pollutants,volatile organic pollutants(VOCs),as a kind of indoor air pollutants closely related to human beings,are getting more and more attention because of their harm to human body and environment.The degradation of toluene,methanol,ethyl acetate and other representative VOCs has practical significance for the understanding of VOCs system.Photocatalysis is a kind of green technology which uses solar energy to realize pollutant degradation.It is widely used because of its high efficiency,convenience and no pollution.Among many common oxide photocatalysts,TiO2 is the most widely used one.However,the wide band gap of TiO2 is about 3.2 eV,which leads to the low utilization of visible light.In addition,the high recombination rate of photogenerated electron hole pair and other defects limit the application of TiO2.In this study,TiO2,GO and MgAl LDH were combined to improve the performance of TiO2,and the photocatalytic activity of TiO2 was significantly improvedThe main results of this study are as follows:(1)TiO2-GO/LDHs photocatalyst was prepared by hydrothermal method and characterized by XRD,SEM and HRTEM.The results show that TiO2,GO and LDHs are in good condition.The addition of go significantly reduces the recombination rate of charge carriers,and LDHs makes more oxidation free radicals exist(2)In the experiment of photocatalytic degradation,the concentration of gaseous pollutants was measured in real time by ultraviolet spectrophotometer.Compared with TiO2 alone,the photocatalytic performance of TiO2-GO and TiO2-GO/LDHs was improved significantly,the proportion of GO/LDHs in the composite was changed,and the optimal value of 2wt%was obtained.After comparison,the degradation process of photocatalytic experiment accords with pseudo first-order kinetic model,that is,the reaction rate is directly proportional to the concentration of reactants.(3)Under the synergism of TiO2,GO and LDHs,VOCs degradation was accelerated.The removal efficiency of VOCs by photocatalyst is alcohol>ester>arene,which is related to the photocatalytic conversion and degradation process of different organics.In the repeated experiments,photocatalysts show excellent recyclability.