| As a new nonmetal semiconductor photocatalyst,g-C3N4 has attracted more and more researchers' attention,because of its visible light response,high stability and excellent energy band position.However,g-C3N4 has many disadvantages such as low visible light response,complex carrier recombination,difficult recovery,and low photocatalytic efficiency.These defects limit the development of photocatalysis.In order to solve these problems,this paper focuses on the defects of g-C3N4.On the one hand,g-C3N4 and other semiconductor materials are used to form a g-C3N4 heterojunction photocatalyst to improve the response of visible light and the photo-generated electron-hole pairs Separation efficiency,through the deposition of Ag on ?-Fe2O3/g-C3N4,the Z-Scheme Ag/?-Fe2O3/g-C3N4 catalyst material was constructed to further improve the separation and transmission of photogenerated charge and visible light response,to improve its photocatalytic degradation of pollutant activity.On the other hand,using y-Fe2O3 as a magnetic matrix,a magnetic Ag/g-C3N4/SiO2@y-Fe2O3 composite was constructed to improve the recycling performance of the catalyst.The structure and properties of the composites were characterized by XRD,FTIR,SEM,TEM,UV-VIS DRS and XPS.The photocatalytic activity and recycling of the samples were evaluated using Rhodamine B as the target degradant.The photocatalytic mechanism was explored through the capture experiment of active groups,and the wastewater was simulated with dye Rhodamine B solution to study the degradation kinetics of the catalyst.The main research contents and results are as follows;(1)Firstly,g-C3N4 was synthesized by thermal polymerization method,and?-Fe2O3/g-C3N4 composite sample was synthesized by sol-gel method.The ?-Fe2O3/g-C3N4 sample was examined for its morphology,The effect of structure and photocatalytic activity on the photocatalytic activity shows that the ?-Fe2O3/g-C3N4 composite has a visible light effect compared to g-C3N4,and ?-Fe2O3/g-C3N4 has a high photocatalytic activity.The degradation rate of Rhodamine B was 79.7%.Then,Ag nanoparticles were deposited on ?-Fe2O3/g-C3N4 by photo-deposition method.The effects of different Ag content on the morphology,structure and photocatalytic activity of Ag/?-Fe2O3/g-C3N4 samples were investigated.The results show that Ag/?-Fe2O3/g-C3N4 composites have stronger visible light response than ?-Fe2O3/g-C3N4 composites,and the degradation rate of 3%Ag/?-Fe2O3/g-C3N4 is 95%.In addition,the results of free-radical capture experiments show that 3%Ag/?-Fe2O3/g-C3N4 participates in the reaction of rhodamine under visible light,mainly O2 and OH.The kinetic analysis showed that the degradation of Rhodamine by Ag/?-Fe2O3/g-C3N4 accorded with the first-order kinetics.(2)Synthesis of ?-Fe2O3 by hydrothermal method,synthesis of SiO2@?-Fe2O3 composites by sol-gel,and then using urea as precursor to load g-C3N4 on SiO2@?-Fe2O3 by thermal polymerization method.Photo-reduction method was used to synthesize Ag supported Ag/g-C3N4/SiO2@?-Fe2O3 composite photocatalyst.The effects of different Ag content on the morphology,structure and photocatalytic activity of Ag/g-C3N4/SiO2@?-Fe2O3 were investigated.The experimental results show that the degradation rate of Rhodamine by Ag/g-C3N4/SiO2@?-Fe2O3 is 81.1%,which is higher than that of pure phase g-C3N4.The Ag/g-C3N4/SiO2@?-Fe2O3 composite has a visible light response,and the photocatalytic activity of 5%Ag/g-C3N4/SiO2@?-Fe2O3 is the highest,and the magnetic recovery performance is good.In addition,the results of active group capture experiments show that the main reactive groups participating in the reaction of Ag/g-C3N4/SiO2@?-Fe2O3 composite catalysts are·O2-and H+.in the degradation of rhodamine under visible light The kinetic analysis showed that the degradation of rhodamine by Ag/g-C3N4/SiO2@?-Fe2O3 composite catalyst conformed to the first-order kinetics. |
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