Graphene oxide supported titanium dioxide & ferroferric oxide hybrid, a magnetically separable photocatalyst with enhanced photocatalytic activity for tetracycline hydrochloride degradation

Abstract

A facile, robust approach to the synthesis of Fe₃O₄/rGO/TiO₂ nanocomposites is described. The synthesis involves two major steps: (1) preparation of Fe₃O₄/GO by an electrostatic self-assembly method; (2) deposition of TiO₂ on the surface of the Fe₃O₄/rGO nanocomposite via a hydrothermal method. The as-prepared Fe₃O₄/rGO/TiO₂ photocatalyst exhibited an enhanced photocatalytic activity for the degradation of tetracycline hydrochloride (TC-HCl) over a wide pH range from 3.0 to 11.0. At optimal conditions, a 92.6% degradation rate of TC-HCl was achieved within 330 min. The enhanced photocatalytic activity could be ascribed to the synergistic effect of the photo-Fenton reaction and electron transportation of graphene. A possible photocatalytic mechanism for TC-HCl by the Fe₃O₄/rGO/TiO₂ nanocomposite and H₂O₂ was proposed based on the quenching tests and liquid chromatography-mass spectrometry (LC-MS) analysis. Furthermore, a leaching test was also carried out and the result suggested that the leached iron from the reaction system was negligible and the catalyst still exhibited excellent photocatalytic activity after five reaction cycles, which clearly demonstrated that the Fe₃O₄/rGO/TiO₂ nanocomposite was reusable, excellently stable and highly effective.