Deactivation And Regeneration Of Supported TiO₂ In Sunlight Inducing Degradation Of Acrylonitrile

Photocatalytic oxidation technology is a new type of environmental pollution control technology.It has no secondary pollution and can degrade almost all organic pollutants.At present,the application of photocatalytic oxidation technology in degradation of acrylonitrile has been confirmed,and has attracted extensive attention both at home and abroad.However,in the process of photocatalytic degradation of acrylonitrile pollutants,N-F-TiO2 /SiO2 photocatalyst will be poisoned and lose its activity,and the efficiency of degrading organic compounds will decrease.The deactivation and regeneration of N-F-TiO2 /SiO2 photocatalyst limits the practical application and promotion of photocatalytic oxidation technology.The problem of photocatalytic poisoning in acrylonitrile degradation by N-F-TiO2 /SiO2 photocatalyst was studied in this paper.On the basis of in-depth analysis of its photocatalytic mechanism and toxic mechanism,kinetics and deactivation kinetics of acrylonitrile degradation by N-F-TiO2 /SiO2 photocatalytic oxidation were investigated,and the factors affecting the degradation process,the mechanism of poisoning and the deactivation and regeneration of poisoning N-F-TiO2 /SiO2 photocatalyst were studied.The effect of initial concentration of acrylonitrile,simulated light intensity,applied oxidant and initial p H value on the degradation of acrylonitrile by N-F-TiO2 /SiO2 photocatalyst was investigated by single factor experimental design.The kinetic analysis showed that the photocatalytic degradation of acrylonitrile by N-F-TiO2 /SiO2 was in accordance with the quasi first order reaction kinetics.The lifetime of N-F-TiO2 /SiO2 photocatalyst under various factors was studied.SEM,XPS,BET,XRD and other surface analysis techniques were used to characterize the poisoning N-F-TiO2 /SiO2 photocatalyst and the regenerated N-F-TiO2 /SiO2 photocatalyst.According to the result analysis,the main cause of the poisoning of N-F-TiO2 /SiO2 photocatalyst is: on the one hand,in the process of degradation of acrylonitrile by N-F-TiO2 /SiO2 photocatalyst,the N-F-TiO2 /SiO2 photocatalyst will agglomerate in different degrees,resulting in the decrease of the specific surface area of the catalyst and the decrease of the adsorption capacity of the pollutants;finally,N-F-TiO2 /SiO2 photocatalyst was not strong in water resistance,and the active sites were continuously lost under hydraulic shear.In view of the above inactivation reasons,the N-F-TiO2 /SiO2 photocatalyst was regenerated by high temperature roasting,ultrasonic cleaning and reloading.The experimental results show that the high temperature calcination can remove the carbon deposition on the catalyst surface and expose the active sites,so that the activity can be partially recovered;reloading can make the loss of active component supplement,so the activity recovery is more.But because of the existence of deactivated catalyst,the activity can not be completely restored.