Photodegradation of Methylene Blue by TiO_2-Fe_3O_4-Bentonite Magnetic Nanocomposite

Fe 3 O 4 -bentonite nanoparticles have been prepared by a coprecipitation technique under a nitrogen atmosphere. An aqueous suspension of bentonite was first modified with FeCl2 and FeCl3. TiO2 was then loaded onto the surface of the Fe 3 O 4 -bentonite by a sol-gel method. After sufficient drying, the colloidal solution was placed in a muffle furnace at 773 K to obtain the TiO 2 - Fe 3 O 4 -bentonite composite. The material has been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and vibrating sample magnetometry (VSM). Morphological observation showed that Fe 3 O 4 and TiO2 nanoparticles had been adsorbed on the surface of bentonite nanoneedles. The material was then applied for the photodegradation of the azo dye methylene blue (MB). It was found that the removal efficiency of MB exceeded 90% under UV illumination, and that only a 20% mass loss was incurred after six cycles. The composite material thus showed good photocatalytic performance and recycling properties.