Synthesis of magnetic graphene oxide doped with strontium titanium trioxide nanoparticles as a nanocomposite for the removal of antibiotics from aqueous media

Abstract

In this study, strontium titanium trioxide (SrTiO₃) nanoparticles were synthesized and doped onto graphene oxide (GO) based magnetic nanoparticles (MNPs) simply via ultrasound. The newly synthesized GO/MNPs–SrTiO₃ magnetic nanocomposite was characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). As prepared GO/MNPs–SrTiO₃ was applied for the removal/adsorption of antibiotics namely tetracycline and cefotaxime from water samples. The effective parameters on the adsorption process including adsorbent dosage (mg), NaCl salt (% w/v), and solution pH were studied and their optimum values were obtained. The GO/MNPs–SrTiO₃ nanocomposite showed high adsorption capacities of 65.78 mg g⁻¹ and 18.21 mg g⁻¹ toward tetracycline and cefotaxime, respectively. A comparison study of Langmuir, Freundlich and Dubinin-Radushkevich isotherm models along with a kinetic study showed that the adsorption experimental data were well fitted to the Langmuir isotherm (R² > 0.996) and pseudo-second-order rate model (R² > 0.995). An intra-particle diffusion model demonstrated that the adsorption was not controlled by diffusion process. The thermodynamic studies (+ΔH) of the antibiotics adsorption onto GO/MNPs–SrTiO₃ revealed an endothermic nature. However, adsorption isotherms, free energy, kinetic models and thermodynamic studies suggested a monolayer sorption model followed by physisorption process for the selected antibiotics.