High reusability of green-synthesized Fe3O4/TiO2 photocatalyst nanoparticles for efficient degradation of methylene blue dye

Abstract

This study investigates photocatalytic degradation performance of Fe 3 O 4 /TiO 2 nanoparticles (NPs) green-synthesized using Moringa oleifera leaf extract. A coprecipitation synthesis method was successfully used to synthesize NPs of various concentrations and the magnetic properties of the photocatalyst was further explored so that it could be reused. X-ray diffraction and selected area electron diffraction showed that TiO 2 has a tetragonal structure and Fe 3 O 4 has an inverse spinel cubic structure. The prepared transmission electron microscopy image of Fe 3 O 4 /TiO 2 showed that it was almost spherical, not uniform, and slightly dispersed under agglomerated conditions due to the presence of a TiO 2 boundary. Besides, the chemical elements are confirmed by energy-dispersive X-ray spectroscopy . Fourier-transform infrared spectra showed functional groups namely C–H, C=O, C=C, and C–N which indicating successful green synthesis. In addition, the presence of Fe–O functional groups at 551.8–620.3 cm −1 and Ti-O at 400–600 cm −1 also suggests the formation of NPs. A vibrating sample magnetometer showed that the Fe 3 O 4 /TiO 2 NPs exhibited saturation magnetization in the range of 11.15–30.38 emu/g, with a coercivity value of approximately 55 Oe. The degradation efficiency of methylene blue (MB) was optimal for Fe 3 O 4 :TiO 2 at a concentration of 1:7 which reached 99.9% degradation for two hours for uptake every 20 minutes. Owing to the magnetic potential of the synthesized NPs, they could be recycled up to four times without significant loss of activity. Therefore, green synthesis of Fe 3 O 4 /TiO 2 NPs is promising for effective and efficient removal of organic pollutants in various environment-related applications. • Fe3O4/TiO2 NPs were synthesized using coprecipitation method with MO extract • Green-synthesized Fe3O4/TiO2 NPs have superior photocatalytic activity up to 99.9% • kapp value between the theoretical model and the experimental data has a good match • After 4 repetitions, the photocatalyst showed excellent stability and reusability • A conceivable photocatalytic mechanism has been proposed