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.