A DFT theoretical and experimental study about tetracycline adsorption onto magnetic graphene oxide

This work reports the study of tetracycline adsorption on magnetic graphene oxide (GO·Fe3O4) from theoretical and experimental approaches. From the theoretical side, the combination of ab initio and Density Functional Theory (DFT) presents the structural and electronic properties of magnetic nanoadsorbent and tetracycline, revealing chemical adsorption between tetracycline and GO·Fe3O4. From the experimental viewpoint, the synthesis of GO·Fe3O4 was performed via co-precipitation method with control of magnetite (Fe3O4) incorporation on the GO surface. The nanoadsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The maximum tetracycline adsorption capacity was 531.93 mg g−1 using 50 mg of GO·Fe3O4 1:1, with an initial concentration of TC (1000 mg L−1), pH 7.0 at 293 K. The thermodynamic parameters showed that the process was spontaneous, exothermic, and chemical. Theoretical and experimental studies were coherent and showed that tetracycline adsorption on GO·Fe3O4 occurs by chemisorption mechanism. In summary, magnetic nanoadsorbent (GO·Fe3O4 1:1) proves to be an efficient nanomaterial for removing tetracycline from aqueous solutions, excluding subsequent process steps.