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

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 (R-2 > 0.996) and pseudo-second-order rate model (R-2 > 0.995). An intra-particle diffusion model demonstrated that the adsorption was not controlled by diffusion process. The thermodynamic studies (+Delta H) 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.