Magnetic Mg0.5Zn0.5FeMnO4 nanoparticles: Green sol-gel synthesis, characterization, and photocatalytic applications

Water pollution is one of the main global concerns affecting humans and numerous people die annually because of the diseases inflicted by contaminated water. Due to the toxicity and carcinogenic potential of the dyes in effluent, it is necessary to attain an efficient method for wastewater treatment using the highly active and reusable photocatalyst. This study presents a promising green approach for the preparation of heterogeneous catalytic nanoparticles by investigating the synergistic effect of metal ions in spinel structure to enhance their photocatalytic activity. Herein, Mg0.5Zn0.5FeMnO4 magnetic nanoparticles (MNPs) were prepared by a green sol-gel process and thoroughly characterized by X-ray Photoelectron Spectroscopy (XPS), powder X-ray diffraction (XRD), Electrochemical Impedance Spectroscopy (EIS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), transmission electron microscope (TEM), Brunauer Emmett Teller (BET), Fourier transform infrared spectroscopy (FT-IR), high-solution transmission electron microscopy (HRTEM) images and selected area electron diffraction (SAED), Differential reflectance spectroscopy (DRS), vibrating sample magnetometer (VSM), and elemental mapping. XRD pattern confirmed the spinel structure of Mg0.5Zn0.5FeMnO4 MNPs which displayed good photocatalytic performance for the decolorization of Reactive Blue 21 (RB21) dye under ambient conditions and at natural pH (pH = 6) wherein 96% of dye was degraded in 30 min and total organic carbon removal followed in 30, 60, and 120 min. Mechanistic aspects of the photodegradation were ascertained in presence of scavenger agents and the degradation products were studied by Gas chromatography–mass spectrometry (GC-MS) with identification of smaller ensuing fragmented molecules. Magnetic nanoparticles could be recycled by applying an external magnet, and their efficiency was maintained intact even after five cycles while retaining their structural integrity as attested by XRD, and FESEM analysis after reuse. [Display omitted] •Green synthesis of Mg0.5Zn0.5FeMnO4 MNPs by Tragacanth gel.•Mg0.5Zn0.5FeMnO4 photocatalyst has a band gap of 1.56 eV and low electron transfer resistance.•96% of RB21 dye was photo degraded after short time 30 min with 48% removal of TOC.•GC-MS results show that the RB21 dye molecules were completely degraded and break down into small molecules.