Synthesis and performance of novel magnetically separable nanospheres of titanium dioxidephotocatalyst with egg-like structure

Abstract

A magnetically separable photocatalystTiO2/SiO2/NiFe2O4 (TSN) nanosphere with egg-like structure was prepared by a unique process that combineda liquid catalytic phase transformation method, reverse micelle technique and chemicalprecipitation means. The prepared photocatalyst shows high photocatalytic activity for thedegradation of methyl orange in water. The magnetic property measurements indicate thatthe photocatalyst possesses a superparamagnetic nature. It can be separated from waterwhen an external magnetic field is added and redispersed into water solution after theexternal magnetic field is eliminated. It is one of the promising photocatalystsfor wastewater treatment. A transmission electron microscope (TEM) and anx-ray diffractometer (XRD) were used to characterize the structure of the TSNphotocatalyst. The results indicate that nickel ferrite core nanoparticles were completelyencapsulated into monodisperse silica nanospheres as carrier, and titania nanoparticleaggregates were coated onto the surface of SN nanospheres, forming an imperfectTiO2 shell forphotocatalysis. The SiO2 layer between the NiFe2O4 core and the TiO2 shell effectively prevents the injection of charges fromTiO2 particlesto NiFe2O4, which gives rise to an increase in photocatalytic activity. Moreover, the recycled TSNexhibits good repeatability of the photocatalytic activity.