Synthesis Of Bismuth-Based Photocatalysts And Their Property Of Photocatalytic Reduction Of Cr(Ⅵ)

Chromium is widely distributed in the natural environment,and improper treatment of hexavalent chromium ions not only causes water pollution,but also poses a great threat to public health throuth various forms of migration and enrichment.Different from of the traditional disposal,photocatalysis could provide a more feasible and durable resolution for the environmental remediation because of its clean and low operating cost.Among the numerous photocatalysts,bismuth-based materials possess their unique properties.First of all,most of them have a trend to grow along some given directions in terms of crystal structure.Therefore,researchers may utilize the feature to regulate the growth condition in order to obtain various morphologies and explore the influence on the characteristics.Secondly,most of bismuth-based materials show excellent absorption of sunlight.So,the research on bismuth-based photocatalysts has become an important area in the field of photocatalysis.In the second chaper of the thesis,BiF₃,a UV-responsive photocatalyst,was selected as a sacrificial template.Firstly,EG was used as the solvent and PVP as surfactant in this experiment.Through a simple solvothermal route,Bi³⁺coordinated with PVP could be slowly released to have a precipitation with F^-to produce BiF₃ nanospheres with good hydrophilic property and monodispersity.After that,Bi₂S₃ nanopheres with hollow hierarchical structure was fabricated via an ion exchange process under the given hydrothermal condition according to Kirkendall effect.Finally,a series of characterization and test were achieved to measure the component and morphology,meanwhile the photocatalytic activities was evaluated by the photoreduction of K₂Cr₂O₇whose concentration is 40 ppm under the visible light irradiation.In the third chapter of the thesis,sillenite Bi₁₂P_0.86O_20.14,visible-responsive material but poor photocatalytic activity,was choosen to explore how to elevate its performance.Taking the hydrophilic property of material and the feature of photoreduction of Cr（Ⅵ）into consideration,PVA was selected to modify the intrinsic material after much attempts.On account of the reduction by PVA in the given experimental condition,Bi₁₂P_0.86O_20.14/Bi with more oxygen vacancies compound could be synthesized surprisingly.Futhermore,due to the enhancement of adsorption of Cr（Ⅵ）and light absorption,the sample modified with PVA outperformd the intrinsic material in photoreduction of K₂Cr₂O₇ under the visible light irradiatin.