Effect of reaction temperature and capping agents on the structural, optical and photocatalytic properties of magnetic Fe3o4/TiO2 nanocomposites: application for the photocatalytic degradation of methylene blue

Abstract

Iron oxide/titanium oxide nanocomposites have been synthesized by the chemical precipitation method at 25 and 80 °C using polyvinylpyrrolidone (PVP) and aloe vera gel (AG) as capping agents and tested for the degradation of methylene blue (MB) dyes. Coupling TiO₂ with other oxides by optimizing reaction conditions, to form a heterojunction nanocomposite can improve on the degradation efficiencies of organic pollutants, by adjusting its structural, morphological and optical properties. The materials were characterized using powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and Brunauer–Emmett–Teller (BET) methods. FT-IR shows bands characteristic of Fe–O–Ti bonds, suggesting the formation of iron oxide/titanium oxide nanocomposites. The formation of magnetite phase for iron oxide and both anatase and rutile for titanium as major phase at low temperature and a unique titanomagnetite (Fe_2.75O₄Ti_0.25) phase at high temperature were evidenced by p-XRD. The elemental composition of the synthesized particles was confirmed by EDX analysis, which showed the presence of Fe, Ti and O. SEM analysis revealed rod-like titanium oxide particles suspended on spherical/oval magnetite particles at low temperature and irregular shapes at high temperature with sizes ranging from 11 to 100 nm. BET measurements revealed that the samples were mesoporous with low surface area (4–6 m²g⁻¹) and medium sized pores (11–18 nm). All the synthesized materials were used as catalysts for the photocatalytic degradation of methylene blue (MB) under UV-irradiation. After 180 min of irradiation using 50 mg of photocatalyst, degradation efficiencies of 54–86% were obtained, with the PVP-capped particles at low temperature showing more photocatalytic efficiencies, thus highlighting the effect of capping agent and reaction temperature on the photocatalytic properties of magnetite/titanium oxide nanocomposites as potential candidates for environmental remediation.