A novel sol–gel synthesis and characterization of MgFe₂O₄@γ–Al₂O₃ magnetic nanoparticles using tragacanth gel and its application as a magnetically separable photocatalyst for degradation of organic dyes under visible light

In the current study, for the first time, MgFe₂O₄@γ–Al₂O₃ magnetic nanoparticles (MNPs) were synthesized using tragacanth gel as biotemplate through the simple and cost effective novel sol–gel method. The sample was characterized by powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), elemental mapping and energy dispersive X-ray analysis (EDX). The nanocomposite shows ferromagnetic behavior at room temperature, with a saturation magnetization of 10.15 emu/g and a coercivity of 50 Oe. XRD results show that MgFe₂O₄@γ–Al₂O₃ nanoparticles correspond to the tetragonal phase of γ-Al₂O₃ and cubic spinel structure of MgFe₂O₄. The present photocatalyst displays notable catalytic activity for the removal of reactive red 195 and reactive orange 122 dyes in water under visible light irradiation. It was established that the catalyst could remove ca. 98% of the reactive red 195 dye and ca. 93% of the reactive orange 122 dye. The effects of initial dye concentration, photocatalyst dosage, and visible light irradiation on dye degradation were assessed. The magnetic photocatalyst can be simply separated by using an external magnet and nearly no decline in photocatalytic efficiency was observed even after recycling five times.