Preparation And Photocatalytic Properties Of Bi-based Photocatalysts-magnetic Particles Composites

Bi2WO6 and BiOBr are representative Bi-based photocatalysts.To separate them easily from the reaction media,we synthesized the magnetic photocatalysts using magnetic iron oxide and Bi2WO6 or BiOBr.The degradation of rhodamine B dyes by magnetic composite photocatalytic materials was improved by H2O2 oxidant-assisted method and PVP surfactant modification.The main research contents and conclusions are as follows:(1)Fe3O4 was synthesized by solvothermal method.The morphology and particle size of Fe3O4 were well controlled by adding NaAc.The magnetic material Fe3O4@SiO2-NH2 was prepared by covering the surface of Fe3O4 with SiO2 and amino-functionalizing with 3-aminopropyl trimethoxysilane(APTMS),which can prevent Fe3O4 from corrosion and improve the interface property of Fe3O4 and photocatalyst.The results showed that the uniform spherical Fe3O4 was anti-cubic spinel structure.The diameter of Fe3O4 was 600 nm,and its saturation magnetization(Ms)value was 64 emu·g-1.The thickness of the SiO2 coating is about 15-20 nm.(2)Bi2WO6 was synthesized,and its photocatalytic activity was improved by changing the reaction conditions.Magnetic Fe3O4/SiO2/Bi2WO6 composite was prepared by hydrothermal method.WO42-of Bi2WO6 was absorbed on the surface of Fe3O4 with positive charge,which enhanced the binding force between Bi2WO6 and Fe3O4.H2O2,added for modification during the degradation,acted as a Fenton-like reagent with Fe3O4,promoting the catalytic reaction effectively.Using H2O as solvent and adjusting the pH to 3,the product exhibits the best photocatalytic activity.The Ms of the composite was 16.7 emu·g-1.With the help of H2O2,the degradation rate of Fe3O4/Bi2WO6 was highly increased to 2.781 h-1.(3)BiOBr was synthesized,and its photocatalytic activity was improved by changing the reaction conditions.Magnetic Fe3O4/SiO2/BiOBr composite was prepared by solvothermal method.To overcome the problem that photocatalytic activity of the composite decreased,PVP was used for modfication during the preparation.PVP acted as a facet inhibitor and surface stabilizer,optimizing the morphology of BiOBr and enhancing the combination of Fe3O4 and BiOBr.The products fabricated using EG as the solvent at 120℃ had highest photocatalytic performance.The Ms of the composites was 18.3 emu·9-1 and the degradation rate of Fe304/SiO2/BiOBr was increased to 0.720 h-1.