Removal of tetracycline and oxytetracycline from water by magnetic Fe3O4@graphene

In this paper, Fe3O4@graphene (Fe3O4@G) magnetic nanocomposite was prepared via in situ precipitation method for the removal of oxytetracycline (OTC) and tetracycline (TC) from aqueous solution. The properties of the prepared nanocomposite were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and magnetic property measurement system (MPMS). Adsorption isotherm and kinetics of OTC and TC were studied in batch experiments. The influence of the dosage of Fe3O4@G, the solution pH, and ion strength on the adsorption process were also assessed. The results demonstrated that the Langmuir model fitted the adsorption equilibrium data better than did the Freundlich model, and the pseudo-first-order model was more suitable than the pseudo-second-order to describe the adsorption process, with a good adsorption rate constant (k = 0.974 and 0.834 g mg(-1) h(-1), respectively). The adsorption ability reached maximum at pH of 7 with no NaCl. The removal efficiency of Fe3O4@G in lake, tap, and pool water were 95.45, 96.68, and 89.82 % for OTC and 98.77, 98.23, and 89.09 % for TC, respectively. The pi-pi interaction and cation-pi bonding of the adsorbent and analytes make it suitable for the removal of OTC and TC. The present study suggests that the prepared composite can be deemed as a promising material for the removal of tetracycline antibiotics from aqueous solution.