The Effect of Morphology on the Photocatalytic Efficiency of Magnetite-Titania Nanoparticles for Wastewater Purification

In this work, for the first time, the effect of magnetite morphology on magnetic and photocatalytic properties of magnetite-titania nanoparticles (Fe3O4-TiO2 NPs) for waste-water purification was studied. Hydrothermal method was used to synthesize magnetite and magnetite-titania nanoparticles, using ferrosulfate heptahydrate and tetraubutyl orthotitanate as magnetite and titania precursors, respectively. X-ray diffractometry and scanning electron microscopy results revealed successful synthesis of spherical (Fe3O4S), cubic (Fe3O4C) and rod-like (Fe3O4R) NPs. Fe3O4C NPs had the highest (66.36 emu.g−1) and Fe3O4R had the lowest (35.11 emu.g−1) saturated magnetism. By depositing titania on the magnetite NPs, saturated magnetism was drastically reduced in the samples. The kinetics of photocatalytic methylene blue (MB) decoloration of the samples followed the first-order model. MB removal efficiency of Fe3O4-TiO2 NPs with spherical, cubic and rod-like magnetite was more than 90, 73 and 64%, respectively, after 120 min irradiation, which shows an excellent improvement compared to similar works. It was interesting that the specific surface area of Fe3O4-TiO2 NPs had a higher influence on photocatalytic activity compared to morphology. The results revealed that Fe3O4C-TiO2 NPs had the highest magnetic saturation, while Fe3O4S-TiO2 NPs had the highest photocatalytic activity. It was found that Fe3O4S-TiO2 NPs had the optimal magnetic and photocatalytic properties, and may potentially be used for wastewater purification. GRAPHICAL ABSTRACT