Functionalization of electrospun magnetically separable TiO _2-coated SrFe_(12)O_(19) nanofibers: Strongly effective photocatalyst and magnetic separation

摘要

Magnetically separable TiO_2-coated SrFe_(12)O _(19) electrospun nanofibers were obtained successfully by means of sol-gel, electrospinning, and coating technology, followed by heat treatment at 550-650 °C for 3 h. The average diameter of the electrospun fibers was 500-600 nm. The fibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM). The optimized calcining temperature was determined by XRD and the analysis of decolorizing efficiency of methylene blue (MB) under UV-vis irradiation. The photocatalytic activity of the TiO_2-coated SrFe_(12)O_(19) fibers was investigated using ultraviolet-visible absorbance by following the photooxidative decomposition of a model pollutant dye solution, MB in a photochemical reactor. In contrast to pure TiO_2 fibers, the TiO_2-coated SrFe_(12)O _(19) fibers have higher absorption in 250-750 nm wavelength regions. The presence of SrFe_(12)O_(19) not only broadened the response region of visible-light, but also enhanced the absorbance for UV light. The decolorizing efficiency of MB under UV-vis irradiation was up to 98.19%, which was a little higher than that of Degussa P25 (97.68%). Furthermore, these fibers could be recollected easily with a magnet in a photocatalytic process and had effectively avoided secondary pollution of treated water.