| Rhodamine B(RhB),as a typical synthetic dye,cannot be completely removed by conventional wastewater treatment methods.As a result,RhB discharged into water bodies continuously accumulates in the environment,causing serious impact on the ecological environment.The photocatalytic method is very popular in the removal of RhB due to its good processing effect,simple operation,good economic benefits,and no secondary pollution.The performance of the photocatalyst is the key condition that determines the effectiveness of the method.The development of new and efficient photocatalysts has always been a hot spot for domestic and foreign scholars to study the treatment of organic polluted wastewater.The good stability and visible light catalytic activity of Bi OBr make it have potential application value in the field of organic dye degradation.However,in actual water treatment applications,powdered Bi OBr has disadvantages such as easy agglomeration,difficulty in separation and recycling.In order to improve the above shortcomings,in this thesis,Bi OBr was loaded on electrospun nanofibers,and a self-supporting Bi OBr-based nanofiber film photocatalytic material was successfully prepared;it was applied to the photocatalytic degradation of RhB in the water phase,and the photocatalytic degradation was discussed.Catalytic activity and corresponding photocatalytic mechanism.The main findings is as follows:(1)The PVA/SiO2 electrospun nanofiber membrane was used as the substrate,and Bi OBr crystals were loaded on the surface of the PVA/SiO2 electrospun nanofiber membrane by solvothermal method to construct the PVA/SiO2@Bi OBr fiber membrane material.The photocatalytic performance of the material on RhB in the water tank was studied.The results show that the PVA/SiO2 electrospun nanofibers contain uncrosslinked-OH functional groups,which can provide nucleation sites for the growth of Bi OBr crystals,thereby increasing the crystal loading rate and obtaining a uniform and dense Bi OBr film on the fiber surface.PVA/SiO2@Bi OBr fiber membrane has good light absorption ability under visible light.Compared with powdered Bi OBr,the band gap is reduced,which can better absorb and utilize visible light,and the photocatalytic activity is significantly improved.The photocatalytic reaction rate of the simulated pollutant RhB under visible light is 2.1 times higher than that of simple Bi OBr.In addition,the PVA/SiO2@Bi OBr fiber membrane has good recyclability and reusability.After 3 cycles,the photocatalytic degradation rate of RhB decreases by less than 10%.Free radical quenching experiments proved that the main role of the PVA/SiO2@Bi OBr composite film in the photocatalytic process is photogenerated electrons and·O2-.(2)Using PVA/SiO2 electrospun nanofiber membrane as the substrate,Bi OBr doped with amorphous Ti O2 is grown on the fiber surface by solvothermal method in one step to obtain PVA/SiO2@TB composite fiber membrane.The Bi OBr crystals are not damaged after doping with amorphous Ti O2,and they are uniformly loaded on the fiber membrane,and the loading rate is higher.In addition,the composite film PVA/SiO2@TB has a good capacity for light absorption in visible light.Compared with PVA/SiO2@Bi OBr fiber film,due to the reduced bandgap,it can better absorb and utilize visible light.The prepared PVA/SiO2@TB fiber membrane was used for photocatalytic degradation of RhB in the water phase.The results showed that the addition of Ti affects the photocatalytic activity of the fiber membrane.When T:B(the molar ratio of Ti to Bi)=0.75:1,The photocatalytic activity is the highest,and is significantly higher than that of powder TB,and the photocatalytic rate is 3.4 times that of powder TB.·OH and·O2-play the main role in the photocatalytic process of PVA/SiO2@TB composite film,indicating that the doping of Ti O2 can effectively inhibit the recombination of photo-generated electrons and holes.Recycling experiments show that the PVA/SiO2@TB composite film has good reusability. |
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