Characterizations of TiO ₂ /SiO ₂ /Ni–Cu–Zn Ferrite Composite for Magnetic Photocatalysts

Abstract

The TiO 2 /SiO 2 /Ni–Cu–Zn ferrite composite for magnetic photocatalysts with high photocatalytic activity is successfully prepared in this study. The composite are composed of spherical or elliptical Ni–Cu–Zn ferrite nanoparticles about 20–60 nm as magnetic cores, silica as barrier layers with thickness of 15 nm between the magnetic cores and titania shells with thickness approximately 1.5 nm. Photodegradation examination of TiO 2 /SiO 2 / Ni–Cu–Zn ferrite composite was carried out in methylene blue ( MB ) solutions illuminated under a Xe arc lamp with 35 W and color temperature of 6000 K. The results indicated that about 47.1% of MB molecules adsorbed on the TiO 2 /SiO 2 /Ni–Cu–Zn ferrite composite within 30 min mixing due to it higher pore volume of 0.034 cm 3 /g, and after 6 h Xe lamp irradiation, 83.9% of MB 16.1% was photodegraded. Compared with the TiO 2 /Ni–Cu–Zn ferrite composite, the TiO 2 /SiO 2 /Ni–Cu–Zn ferrite composite with silica barrier layer prohibited the photodissolution and enhanced the photocatalytic ability. The magnetic photocatalyst shows high photocatalytic efficiency that the apparent first‐order rate constant k obs is 0.18427 h −1 , and good magnetic property that the saturation magnetization ( M s ) of is 37.45 emu/g, suggesting the magnetic photocatalyst can be easily recovered by the application of an external magnetic field.