Enhancing photocatalytic potential of Mg0.5Ti0.5Fe2O4.5 NPs by optimizing the sintering temperature

Abstract

Ti⁴⁺substituted magnesium ferrite nanoparticles (Mg_0.5Ti_0.5Fe₂O_4.5) with spinel structure were synthesized using the sol-gel process and sintered at 300, 400 and 500 °C. Mg_0.5Ti_0.5Fe₂O_4.5 nanoparticles were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) with X-ray dispersive spectroscopy (EDS), High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED). Surface area of all synthesized nanoparticles was compared using BET method. The effect of sintering temperature on structure and photocatalytic activity was examined using tetracycline hydrochloride as a model pollutant under visible light irradiation. The XRD patterns confirmed the presence of spinel structure in Mg_0.5Ti_0.5Fe₂O_4.5NPs at all heat-treated temperatures and in the pure phase. TEM and SEM-EDX analyses confirmed the porosity and agglomeration in the doped ferrite nanoparticles. Infrared spectra showed absorption bands between 400 and 600 cm⁻¹, confirming the presence of the ferrite phase. Lattice constant and band gap energy were decreased due to substitution of tetravalent Ti⁴⁺ ion. Mg_0.5Ti_0.5Fe₂O_4.5 sintered at 400 °C showed a minimal band gap of 2.10 eV and highest photocatalytic potential. The combination of hydrogen peroxide and ferrites was discovered to have a synergistic effect on the photodegradation of tetracycline hydrochloride. Quenching experiments demonstrated that hydroxyl radicals and holes were dominating in the degradation of tetracycline hydrochloride under visible light. Kinetic studies of photodegradation and quenching tests were carried out using the Langmuir-Hinshelwood model.