Preparation Of Bismuth Oxide-based Hollow Material And Its Application In Water Treatment

At present,researchers are paying more and more attention to organic pharmaceutical wastewater such as antibiotic wastewater,and the abuse of antibiotics has seriously damaged the environment.In recent years,photocatalytic oxidation technology has received great attention in the field of antibiotic wastewater treatment.However,the photocatalytic oxidation technology still meets the problems,such as high material preparation cost,low utilization rate of natural light,and poor material reuse in the treatment of wastewater.Bi2O3 is known as a good photocatalyst,but the preparation of its hollow spheres,prticularly by the template method,has been reported rarely.Bi2O3 hollow sphere has a unique hollow structure,a mesoporous shell and a large specific surface area,and its photocatalytic performance is much higher than that of one-dimensional and two-dimensional materials.Therefore,in this thesis,Bi2O3 hollow materials is to be repared firstly by template method and template-free solvothermal method respectively,then the construction mechanism of these hollow photocatalytic materials is to be studied,and finally the photocatalytic degradation of antibiotic wastewater is to be conducted.The research content is as follows:(1)The bismuth oxide material with hollow spherical shape was first synthesized by solvothermal method,and then the in-situ chemical etching reaction of HCl and the prepared?-Bi2O3 material was used to successfully synthesize ?-Bi2O3/BiOCl heterojunction photocatalytic material,the material is a hollow flower-shaped sphere.The crystal structure and element composition of the prepared material were characterized by XRD and XPS,and the microscopic morphology of the material was analyzed by FESEM and TEM.The optical absorption characteristics of the prepared photocatalytic material were characterized by UV-vis-DRS.From the results of PL characterization,it can be speculated that the recombination of photoinduced e-/h+ pairs inside the material is effectively suppressed by the structure of the heterojunction.(2)Visible light catalytic performance of ?-Bi2O3/BiOCl heterojunction photocatalyst was studied with tetracycline(TC)as the target pollutant.The effects of pollutant concentration,catalyst dosage,and pH of initial solution on photocatalytic performance were studied.The conclusions are as follows:the recombination of photogenerated e-and h+ is effectively suppressed by the structure of the heterojunction;Compared with pure ?-Bi2O3 and BiOCl,the photocatalytic performance of the prepared sample is better;The photocatalytic degradation of ?-Bi2O3/BiOCl(the molar content of BiOCl is 85.7%)is the best,and the degradation rate of tetracycline reaches 99.5%within 180 minutes,and the recycling performance is better.(3)Preparation of micro-nano-grade porous bismuth oxide hollow microsphere materials using rapeseed pollen as a template.The effects of processing pollen steps,the mass ratio of pollen to bismuth source,and the calcination temperature on the formation of bismuth oxide-based materials were investigated.The material synthesized by the optimal process has a hollow diameter of about 10 ?m,rich pores with a diameter of 2-5 nm,and a specific surface area of about 170.26 m2/g.By adding an appropriate amount of cerium source for doping during the preparation process,Ce doping leads to lattice distortion,the band gap of the material becomes smaller,and the absorption range of the material is shifted toward visible light.The materials were characterized by XRD,FT-IR,EDS,SEM,XPS and N2-adsorption-desorption.The effect of different doping amounts of cerium element on the photocatalytic degradation ability of the material was explored,and the best porous bismuth oxide-based biological relic photocatalytic material was prepared,the degradation rate of tetracycline reaches 89.7%within 180 minutes,and the recycling performance is better.