The Preparation Of Boron And Neodymium Doped Bismuth Oxide Photocatalyst And Its Catalytic Performance Evaluation

Dye wastewater which contains azo, aromatic compounds and heavy metals is harmful to the human and ecological environment. It has high color degree, high COD and low biodegradability, resulting in high cost and low efficiency of dye wastewater treatment.Therefore, how to develop a cost-effective technology for the treatment of dye wastewater has been paid a lot of attention.Photocatalysis is sought after by environmentalists because of its efficiency, energy convervation and no-secondary pollution. Bismuth oxide?Bi₂O₃? is p-type semiconductor which is an important functional material with wide band-gap, high refractive index,dielectric permittivity, high oxygen conductivity, remarkable photoconductivity and photoluminescence. Bismuth oxide?Bi₂O₃? is p-type semiconductor which is an important functional material with wide band-gap, high refractive index, dielectric permittivity, high oxygen conductivity, remarkable photoconductivity and photoluminescence. Bi₂O₃ is regarded as an ideal photocatalyst. We prepare boron modified Bi₂O₃, Nd³⁺ modified Bi₂O₃ and B/Nd³⁺ modified composites for obtaining more active photocatalyst. Their structures and properties had been investigated as well as their photocatalytic activities. This dissertation consists of following contents.B-Bi₂O₃ composites were prepared by sol-gel method and respectively from the boron content and sintering time inspect its effect on the catalytic activity of catalysts.Their structures and properties of the as-prepared samples were extensively characterized by TEM,HRTEM, XRD, Raman, FT-IR and UV-Vis DRS. The characterization results revealed that boron doping does not change Bi₂O₃ crystal structure, sample in the form of alpha Bi₂O₃. But due to the generated Bi4B2O9, to some extent, inhibit the growth of the crystal can be enough to promote the effective separation of electron hole, the loading effects of boron increased the activity of photocatalysts. And calcination time will not change the crystal structure of Bi₂O₃, but can affect Bi4B2O9 generated, promote the growth of crystal, make the catalyst particles increases, influence the effect of catalyst. The highest photocatalytic activity wasgotten when the ratio of n?B? : n?Bi? was 0.08 and 500? calcination 1 h.Nd modified of Bi₂O₃ coupled composites were prepared by sol-gel method and respectively from the Nd³⁺content and sintering time inspect its effect on the catalytic activity of catalysts, their structures and properties of the as-prepared samples were extensively characterized by thermal analysis, TEM, HRTEM, XRD, Raman, FT-IR and UV-Vis DRS. The characterization results revealed that The doping rate of Nd/Bi,calcination time had effects on polymorphs and photocatalytic activity. The optimum preparation conditions were: Nd/Bi rate was 0.08, Calcination temperature is 500? and calcination time was 1h. The photpcatalyst under optimum preparation conditions was tetragonal Bi₂O₃. Its adsorption edge was about 600 nm and the bandgap was 2.45 e V. After two hours degradation under visible-light, the degradation rate of methyl orange was up to89.7 %.Boron modified of Nd-Bi₂O₃ coupled composites were prepared by sol-gel method and respectively from the boron content and sintering time inspect its effect on the Nd-Bi₂O₃ catalytic activity of catalysts, and their structures and properties of the as-prepared samples were extensively characterized by TEM, HRTEM, XRD, Raman, FT-IR and UV-Vis DRS.The characterization results revealed that Nd doping inhibits cooling process of the ?-Bi₂O₃ to ?-Bi₂O₃. Lead to boron and neodymium doped bismuth oxide sample by single monoclinic ?-Bi₂O₃ or single square crystal phase ?-Bi₂O₃ into ?-Bi₂O₃ and ?-Bi₂O₃ coexistence state.At the same time, forming a series of composite oxide with ?-Bi₂O₃ and?-Bi₂O₃ form heterogeneous structure or solid solution structure, so as to inhibit the grain growth of the sample and the reunion, effectively reduce the grain size of the sample, can form the electronic capture center at the same time, effectively improve the photocatalytic activity.Taken into account when boron doping amount was 2% at 500?calcination 1 h of Nd-Bi₂O₃ composite photocatalyst has the highest photocatalytic activity.