Synthesis of reduced graphene oxide/magnetite composites and investigation of their adsorption performance of fluoroquinolone antibiotics

The reduced graphene oxide/magnetite composites (RGO-M), synthesized by an in situ reaction, have been investigated for the adsorption of fluoroquinolone, ciprofloxacin (CIP) and norfloxacin (NOR). The composites were characterized by Transmission electron microscope (TEM), Scanning electron microscope (SEM), Energy dispersive X-ray (EDX), Vibrating sample magnetometer (VSM), X-ray diffraction (XRD). The high saturation magnetization (12.0 emu g−1) made them easier and faster to be separated under an external magnetic field. Batch adsorption tests indicated that RGO-M exhibited adsorption affinity to CIP or NOR with a maximum adsorption capacity of 18.22 or 22.20 mg g−1, respectively. Langmuir, Freundlich and Temkin model were used to fit the equilibrium data on RGO-M at 298 K. The results showed that the adsorption equilibrium could be well fitted by Langmuir and Temkin model. CIP and NOR adsorption on RGO-M could be well described by the pseudo-second order kinetics model. Adsorption of CIP and NOR on RGO-M was found to be strongly dependent on pH. The thermodynamic parameters indicated that the adsorption process was a spontaneous and exothermic process in nature. This study proved that RGO-M could be utilized as an efficient and magnetically separable adsorbent for fluoroquinolone antibiotics.