Photocatalytic Degradation Of Formaldehyde And Deactivation-regeneration Of Supported TiO₂

With the frequent occurrence of indoor formaldehyde exceeding standard,photocatalytic oxidation technology has become the focus of current research due to its high oxidation and low cost.In this paper,TiO₂was prepared by sol-gel method and coated on ceramic surface to prepare supported photocatalyst.The effects of calcination temperature,the addition amount of Triton X-100 and deionized water on the crystal structure,surface morphology and catalytic activity of TiO₂were studied by XRD,SEM and TG.The results showed that the TiO₂/ceramic photocatalytic material had the best performance when the volume ratio of tetrabutyl titanate,Triton X-100 and deionized water was 20:5:2 and calcined at 550℃for 2 h in air atmosphere.it could completely degrade 1 mg/m³formaldehyde within 10 min.The formaldehyde degradation experiments of TiO₂/ceramic photocatalyst under static conditions were carried out to compare the degradation rate and service life under different initial formaldehyde concentrations,wind velocity,UV light intensities and wavelengths.The photocatalytic activity of TiO₂decreases with the increase of initial formaldehyde concentration,and the service life of the catalyst is significantly shortened at high formaldehyde concentration.At low wind speed,the wind speed is proportional to the degradation rate of photocatalyst.When the wind speed exceeds 3.5 m/s,the wind speed is inversely proportional to the degradation rate of photocatalyst,and the wind speed has little effect on the service life of catalyst.When the light intensity is 14 W,the activity and service life of the catalyst are higher.However,increasing the light intensity at high light intensities has little effect on the service life of the catalyst.UV wavelength is negatively correlated with the efficiency and service life of the catalyst.In order to explore the effect and mechanism of deactivation on photocatalyst,the catalysts before and after deactivation were characterized by XRD,SEM,BET,and FTIR.The results showed that the crystal structure of the catalyst did not change significantly after deactivation.,but the agglomeration of TiO₂appeared and the specific surface area decreased.The intermediate product of TiO₂photocatalytic degradation of formaldehyde are formate and carbonate.Based on the above reasons for deactivation,calcination regeneration and ultrasonic regeneration were used for the regeneration of TiO₂/ceramic photocatalyst.The experimental show ultrasonic regeneration method has the highest regeneration rate,the degradation rate reached 97%after regeneration.After four deactivation-regeneration cycles,degradation rate of formaldehyde on calcination regenerated decreased only 10%,better than ultrasonic regeneration.