Preparation Of TiO₂ Microspheres And Research On Photocatalytic Degradation Of HPAM

As a common photocatalyst,titanium dioxide?TiO₂?material has the advantages of non-toxic,stable chemical properties and high photocatalytic activity.It is widely used in coatings,photoelectric conversion,especially sewage treatment.Micro-scale monodisperse TiO₂ microspheres have a high refractive index,which can effectively increase the use of light,and the low sliding friction coefficient and high specific surface area make the mobility and catalytic performance are more greatly improved.Therefore,the use of TiO₂ microspheres for the degradation of HPAM has a greater potential for development and application prospects.In this paper,mesoporous TiO₂ microspheres were prepared by hydrolysis-reflux method.Fe3+ provided by Fe?NO3?3·9H2O was doped into TiO₂ and F-from NaF was used to surface fluoride.The structure and morphology of as-prepared samples were characterized using X-ray diffraction?XRD?,scanning electron microscopy?SEM?,Fourier transform infrared?FT-IR?,thermogravimetry-differential thermal?TG-DTA?,surface area and pore analysis?BJH?and ultraviolet visible diffuse reflectance spectroscopy?UV-Vis?.The photocatalytic performance was evaluated by degrading partially hydrolyzed polyacrylamide?HPAM?.1.In this study,the optimum micro-sized mesoporous spherical TiO₂ catalysts were synthesized by hydrolysis-reflux method using tetrabutyl titanate?TBOT?as the titanium source.The effects of surfactant type,Span-80 dosage,reaction solvent,the molar ratio of water and titanium,the reflux solvent and ultrasonic means to the microsphere morphology,structure,grain size and photocatalytic activity were investigated.The optimum conditions for the preparation of mesoporous TiO₂ microspheres were as follows: Span-80 was used as the dispersant and the mass fraction was 10%,the reaction temperature was 25 ?,isopropanol was used to as the organic solvent,the molar ratio of water titanium was R = 40,HNO3 was used as the reflux solvent and the concentration was 0.2 mol/L,ultrasonic time was 10 min.The grain size of the TiO₂ catalyst prepared under the optimum conditions is 16.1 nm,the particle size is about 1 ?m,the specific surface area can reach 58.71 m2/g,the w?rutile phase?is 22.98%,similar to P25,the monodispersity and stability was the best,and the surface of the particles was smooth.In the experiment of degradation of HPAM,the catalytic efficiency was the highest and the degradation rate was 98.56%.2.Fe-F/TiO₂ catalyst was prepared by doped with Fe3+ provided by Fe?NO3?3·9H2O,and the surface was fluorinated by Na F.Through a series of characterization,it was found that the mesoporous anatase Fe-F/TiO₂ microsphere is assembled with nanoparticles of which the diameter is 10¹5 nm and the surface is smooth.The microstructures of the microspheres were 950 nm,and the specific surface area,pore volume,average pore diameter of catalyst are 155.04 m2/g,0.25 cm3/g and 6.44 nm,respectively.The introduction of Fe and F can effectively promote the formation of anatase and inhibit the generation of rutile phase,which can result in high thermal stability;also the band gap of the catalyst is narrowed and the light absorption performance is strong in the visible region.Photocatalytic degradation of HPAM experiments show that Fe3+ and F-co-modified TiO₂ has the highest visible light catalytic activity,the COD removal rate of HPAM with the initial concentration of 500 mg/L can be up to 82% and 74% when illuminated under UV and visible light for 120 minutes using 0.1 g of catalyst.Photocatalytic property was promoted because of the synergistic effect of Fe3+ and F-.