Preparation Of Fe-N Doped Nano-TiO₂ And Its Photocatalytic Degradation Mechanism Of Formaldehyde

Formaldehyde is one of the main indoor pollutants,which can be removed efficiently and cleanly by photocatalytic oxidation technology.Among many photocatalysts,the selection of nano-TiO₂ with stable chemical properties has become a research hotspot,but there are many shortcomings due to its own defects.Therefore,it needs to be modified to improve its photocatalytic ability.In this paper,nano TiO₂ was prepared by sol-gel method and modified by Fe and N ions.Scanning electron microscope?SEM?was used to observe the change of internal structure before and after ion doping.X-ray diffraction?XRD?was used to analyze the change of its internal structure.The spectral response range and absorption intensity were analyzed by UV-vis spectrophotometry.Analysis of the characterization results:there are great differences in the crystal form of nano-TiO₂ at different calcination temperatures.The higher the calcination temperature is,the narrower the width of the diffraction peak,the stronger the intensity of the diffraction peak,and the more complete the anatase crystal development.When the calcination temperature is 600?,the characteristic peak of rutile type is found in the map,which shows that the anatase type of nano-TiO₂ is becoming less and the rutile type is becoming more.It can be seen from SEM that when calcination temperature is 500?,the shape of pure nano-TiO₂ is similar to that of spherical,and its distribution is relatively concentrated.After doping ions,the structure of nano-TiO₂ is still similar to that of the sphere.The doping of ions does not change the lattice shape of TiO₂.The particle size distribution of the sphere is about 10-20nm,which is nano scale.Compared with the results of XRD analysis,it shows that the crystal form of the modified nano-TiO₂ is still anatase,and the particle size is small.It can be seen from the UV-Vis absorption spectrum that the doping of Fe and N can change the spectral response range of pure nano-TiO₂,and make the wavelength of nano-TiO2 absorption light have a significant red shift,and the intensity of absorption light is enhanced.The absorption light intensity and spectral response range of Co doped nano-TiO₂ are higher than that of single doped nano-TiO₂.Taking the representative pollutant formaldehyde as the degradation material,the photocatalytic ability of modified nano-TiO₂ was analyzed by the degradation rate of formaldehyde.The influence of various factors on the photocatalytic activity of the sample was investigated by comparative test.The variable factors were calcination temperature,light intensity and ion doping ratio.The influence of various factors on the photocatalytic degradation of formaldehyde by ion doped nano-TiO₂ was analyzed by orthogonal experiment,and the best combination of conditions was determined.The results are as follows:500?is the best calcination temperature,its photocatalytic performance is the highest.The photocatalytic performance of nano-TiO₂ doped with ions has been improved significantly.The photocatalytic degradation performance of nano-TiO₂ is Fe-N double doping>N doping>Fe doping>pure nano-TiO₂.According to the orthogonal experiment,under the experimental conditions,the ratio of ion doping is the main factor affecting the photocatalytic degradation performance of modified nano-TiO₂,followed by the light intensity and calcination temperature.The best condition of photocatalytic degradation of formaldehyde by modified nano-TiO₂ is as follows:the doping ratio is 0.3%:2%:1,the light intensity is 15w/m²,the calcination temperature is 500?,and the photocatalytic degradation rate of formaldehyde reaches 46.2%within 3 hours.