Yb³⁺ And Ag⁺ Doped Titania/Diatomite Photocatalyst And Its Photocatalytic Activity

Among numerous semiconductor photocatalytic materials,TiO₂ has advantages such as excellent environmental friendliness,strong photo-corrosion resistance,high photocatalytic activity,and low cost,making it a representative of semiconductor photocatalytic materials,especially in organic waste water.Processing has a broad application prospects.However,on the one hand,due to the wide band gap of 3.2 eV,TiO₂ semiconductors can only absorb ultraviolet light with shorter wavelengths in the sunlight???370 nm?,and photoelectron-hole pairs are easily recombined,thus reducing the TiO₂ semiconductor's The photocatalytic activity limits its utilization of sunlight;on the other hand,TiO₂ semiconductors tend to agglomerate when used and are difficult to be recovered and reused from solid-liquid systems,affecting their use in production.In order to overcome the defects of TiO₂ itself and improve its photocatalytic efficiency,researchers have used semiconductor composites,precious metal deposition,semiconductor surface photosensitization,ion doping and mineral loading methods to modify them.The ion doping can improve the conductivity of TiO₂ and effectively reduce the recombination of photogenerated carriers.The use of mineral as a carrier can effectively reduce the agglomeration of TiO₂ particles,and it is convenient for recycling.Therefore,these two methods are effectively combined to modify TiO₂ and improve its photocatalytic performance.In this dissertation,nano-Yb³⁺-TiO₂ photocatalytic materials were synthesized by sol-gel method with butyl titanate as the source of titanium,anhydrous ethanol as the solvent and glacial acetic acid as the inhibitor.The methylene blue solution was used as the target contaminant to test its photocatalytic performance and the optimized process parameters were determined:Yb³⁺doping amount was 0.5%,the calcination temperature was 500?,and the calcination time was 2 h.It was characterized by XRD analysis and UV-visible diffuse reflection analysis.The results show that the doping of Yb³⁺can inhibit the growth of nano-TiO₂ crystals,but it will narrow the band gap and broaden the absorption range of sunlight.The increase of calcination temperature can improve the crystallinity of nano-TiO₂ crystals.When the calcination temperature is increased to 700?,the rutile phase of nano-TiO₂ will appear;the prolongation of calcination time will also increase the crystallinity of nano-TiO₂crystals,but the nano-TiO₂ particles will accumulate as the calcination time lengthens.The optimized process parameters for the preparation of nano-Ag⁺-TiO₂photocatalytic material are as follows:Ag⁺doping amount is 0.5%,calcination temperature is 600?,and calcination time is 3 h.XRD analysis,SEM,and UV-vis diffuse reflectance analysis were used to characterize it.The methane blue solution was used as the target contaminant to test its photocatalytic performance.The results show that proper amount of Ag⁺doping will improve the crystallinity of nano-TiO₂crystals,which is beneficial to the growth of crystal grains.Excessive Ag⁺doping will deteriorate the crystallinity of nano-TiO₂,which is not conducive to the growth of crystal grains;Ag⁺doping Miscellaneous can make its forbidden band width decrease and expand the use of sunlight;the increase of roasting temperature can improve the purity and crystallinity of nano-TiO₂ crystals.When the temperature rises to 600?,a small amount of nano-TiO₂ rutile phase will appear;With the prolongation of the calcination time,the purity and the crystallinity of the nano-TiO₂ crystal become better and better,but the long calcination time will cause the nano-TiO₂ particles to aggregate.With the increase of initial concentration of methylene blue solution,the degradation efficiency of nano-Ag⁺-TiO₂ photocatalytic material will be reduced.It may be that the initial concentration of methylene blue solution affects the propagation of light in the solution.With the increase of nano-Ag⁺-TiO₂photocatalytic materials,the degradation efficiency also increases.Considering the photocatalytic activity and cost factors of nano-Ag⁺-TiO₂ photocatalytic materials,the initial concentration of methylene blue solution is 5 mg/L,and the photocatalytic material dosage is 1 g/L.The nano-Ag⁺-TiO₂/diatomite composites were used as catalyst samples.Methylene blue solution was used as the target contaminant for photocatalytic degradation tests.The photocatalytic properties of the samples were investigated and their antibacterial properties were explored.The samples were characterized by XRD,scanning electron microscopy and infrared spectroscopy.The results showed that the Ag⁺-TiO₂ particles were uniformly distributed on the surface of diatomite,which effectively reduced the agglomeration and did not destroy the diatomaceous earth.Porous structure;nano-Ag-TiO₂/diatomite photocatalyst materials were repeatedly recycled and used four times.The degradation efficiency of the methylene blue solution was more than 80%,indicating that it has good recyclability;in the antibacterial experiment will be in the sample Obvious inhibition circles around it indicate that it has an antibacterial effect.