Preparation of Fe3O4@C@TiO2 and its application for oxytetracycline hydrochloride adsorption

The magnetic Fe3O4@C@TiO2 microspheres with multilevel yolk–shell structure were successfully prepared by combining sol–gel and simple hydrothermal methods. The features of the as-obtained Fe3O4@C@TiO2 microspheres were investigated by Fourier transform infrared (FTIR) spectra, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), N2 adsorption–desorption measurements and transmission electron microscopy (TEM). Fe3O4@C@TiO2 was used as an adsorbent to explore its adsorption properties of oxytetracycline hydrochloride (OTC-HCl) by changing initial concentration and time. The results suggest that the maximum adsorption of Fe3O4@C@TiO2 is 87.3 mg·g−1, and the time reaching the absorption equilibrium is 60 min. Langmuir model fits to data better than the Freundlich model, and the kinetic properties are well described by the pseudo-second-order model. In addition, the synthesized composites’ reusability without obvious deterioration in performance is demonstrated by three cycles.