Comparative study of photocatalytic activities of magnetically separable WO_3/TiO_2/Fe_3O_4 nanocomposites and TiO_2, WO_3/TiO_2 and TiO_2/Fe_3O_4 under visible light irradiation

摘要

In this study WO_3/TiO_2/Fe_3O_4 nanocomposite particles with different amount of WO_3 content (1,3, 5, 8 and 10 wt.%) were prepared via sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface areas, diffuse reflectance spectra (DRS) and the vibration sample magnetometry (VSM) were used to characterize the nanocomposites. The photocatalytic activity of the nanoparticles was tested by degrading direct blue 71 dye solution under visible light irradiation. The enhanced photocatalytic activity is attributed to the electron-hole separation and transformation among the semiconductors. The effect of the initial dye concentration, catalyst dosage and the photocatalytic reaction apparent rate constant k_(app) were also investigated. On the other hand the WO_3/TiO_2/Fe_3O_4 nanocomposites could be readily recovered from the reaction solution by using a permanent magnetic bar and their photocatalytic activity was studied after six cycles of repetitive recycling. Then, this nanocomposite can be used as highly efficient and reusable photocatalyst.