Design And Performance Of Reactor Based On BiOBr Visible Light Photocatalyst

Accompanied by the increasing attention on environmental problems from all over the world, photocatalysis utilized for the treatment of pollutants has attracted researchers’attention in the world. To improve the photocatalytic activity and the efficiency of using solar energy, more researchers addicted to explore new types of photocatalysts, powder and film photocatalysts. Although TiO2has been applied in various fields because of the advantages of its low price, nontoxic characters, and stability, its practical utilization in industry is still limited to low quantum efficiency and absorption of UV light. Besides, developing non-TiO2photocatalysts with the capacity of absorbing visible light may be an effective method to realize the wide application of photocatalysis. With high photocatlytic activity and stability, BiOBr with multi-layer structure has also drawn more research aspiration from scientists. Currently, a variety of approaches have been developed to prepare BiOBr photocatlys including hydrolysis, reverse micro-emulsion, solvothermal and microwave etc which can assist to grow photocatalysts with different structures such as flower-like microsphere and nanoparticals. However, to apply the BiOBr photocatlyst in industry is still complex because it is not easy in recycling use. Recently, issues in photocatalysis mainly include:(1) The major work focusing on powder photocatalysts which are difficult in separation and recycling use and shielding lights for colorful dye pollutants which leads to decrease of light absorption of powder photocatalysts,(2) design of photocatalysis reactor because photocatalysis process is only effective under so that it is unavailable in the evening,(3) requirements for further research on oxidation mechanism of photocatalytic degradation for organic pollutants especially cooperated with other oxidation process. To solve the above problems, three parts work in this paper done as following:(1) BiOBr photocatalytic films via ionic-liquid-assisted solvothermal preparation and its application in rotating disk reactor.We prepared the BiOBr photocatalyst film by the approach of ionic-liquid-assisted solvothermal preparation and mainly focused on the research of the mechanism of BiOBr growing on the pre-treated soda glass. BiOBr tightly combined with substrate by the Bi-O-Si bonds. In the growing process of BiOBr film,[C16mim]Br ionic liquid was the bromine source as well as structure-directing agent, which help to obtain he BiOBr film with uniformly assembled nanosheets growing on the glass substrate. XRD and FESEM were used to test its crystal structure and morphology. XPS and FTIR assisted to propose the growth mechanism and combination between film and substrate. Rhodamine B was ustilized as degradation probe. It was proved that the BiOBr film obtained with [C16mim]Br ionic liquid presented the higher visible light photcatalytic degradation rate of dyeing compounds than the BiOBr film with other bromine sources.(2) Degradation of organic pollutants on Ag/BiOBr film in fluorescence rotation reactor.Silver nanoparticals were deposited on BiOBr film by photo reduction approach. basedon the plasma effect of silver, the visible light absorption was enhanced and the absorption range was enlarged in the rage of440to500nm, which coincided with the wavelength of fluorescence light. Therefore, the photocatalytic activity of Ag/BiOBr film could be enhanced remarkably, additionally, fluorescence rotation reactor was utilized to cooperate with Ag/BiOBr film to increase the utilization efficiency of solar light in the photocatalytic system.(3) Visible-light-induced photocatalytic degradation of4-chlorophenol in BiOBr/H2O2system.Process and mechanism of photocatalytic4-chlorophenol degradation was studied in the H2O2/BiOBr system, in which pwder BiOBr catalyst was prepared according our previous work.[115] By adding different trapping agents for active radical, it was found that photo-induced holes mainly affected the degradation process of BiOBr without detected intermediate product, and·O2-was the critical radical in the system of BiOBr/H2O2with intermediate p-dihydroxy benzene and p-benzoquinone product.