Study On The Photocatalytic Degradation Of Orang Ⅱ And Methylene Blue By BiOBr

Because of high chroma、high toxicity、difficult to degradation, dye wastewater poses tremendous menace to the environment. In China, there are many printing and dyeing enterpeises, and most of them are small and medium-sized enterprises which have many difficulties and problems in dye wastewater treatment, so it is necessary to find an efficient technology to solve the dye wastewater problem. There are many different methods to treat the dye wastewater, such as adsorption, coagulation, chemical oxidation, biological method, photocatalytic oxidation and so on. Photocatalytic oxidation has received an astonishing amount of attention for its no secondary pollution, low energy consumption and high degradation rate.Catalyst is the heart of photocatalytic technology, Titanium dioxide(TiO2) is one of the most commonly used catalysts in photocatalytic field, but the limitations of its structure make it can only use UV, therefore the visible light will be waste, so the research on the metal oxide photocatalysts driven by visible light has been one of the most important issues in catalyst research. Studies focused on two aspects, one is modification the catalysts and another is develop the new catalysts. Ion doping、noble metal loading、semiconductor compound、surface photosensitization were used for catalyst modification. Bismuth oxyhalide (BiOX) as one of the Bismuth compounds has unique crystal structure and high photocatalytic activity and attracted the attention of investigators.Bismuthyl bromide (BiOBr) photocatalyst was synthesized by one-step solvothermal process in this paper, the catalyst was characterized by XRD、XPS、 FESEM、TEM、UV-Vis and nitrogen adsorption techniques. The results show that the prepared samples were high-purity Bismuthyl bromide (BiOBr), the microspheres structure of Bismuthyl bromide (BiOBr) are constructed by nanoplates, and the surface has open porous structure, the aperture is between7to30nm, band gap of the sample is2.64eV and the specific surface area is7.69m2/g.In order to investigate the photocatalytic activity of the prepared samples, choose Orange Ⅱ and Methylene blue as target pollutants to test photocatalytic degradation efficiencies. The experiments indicate Bismuthyl bromide (BiOBr) have a good photocatalytic activity for both the Orange Ⅱ and the Methylene blue, the final degradation rate were99%and80%. The adsorption of Methylene blue by Bismuthyl Bromide (BiOBr) is significantly higher than the adsorption of Orange Ⅱ. By change the experiment conditions we found in a certain range, improve the amount of catalyst and increase the light intensity that would improve the degradation rate while improve the initial concentration of the reaction solution can reduce the degradation rate; Change the initial pH of the reaction solution has little effect on the degradation reaction. Experiments of free radical scavenging indicate that the hole (h+) is the main oxidative species in the photocatalytic degradation of Orange Ⅱ and Methylene blue system.