Reduced Graphene oxide-Fe3O4 hybrid nanoadsorbent for adsorption of tetracycline in aqueous medium

FLORENCIA M. ONAGA MEDINA; MARIEL MARISCAL; MARÍA E. PAROLO; MARCELO J. AVENA

Buenos Aires

Congreso; WCCE11 -11th World Congress of Chemical Engineering; 2023

Asociación Argentina de Ingenieros Químicos

Antibiotics are extensively used worldwide to treat diseases. Most of these chemical compounds are poorly absorbed, metabolized, and large fractions are excreted in form unchanged by the body. Those substances in residual water, surface, and groundwater have been widely reported [1]. Even at low concentrations, antibiotics can cause potential adverse effects on the ecosystem and human health through bioaccumulation and the emergence of resistant genes and bacteria. Tetracycline (TC) is one of the most reported due to its multiple applications in both human and veterinary health. Adsorption is an effective technique that has been largely explored due to its easy operation and low energy requirement. In this sense, graphenic carbon-based materials have been considered as promising adsorbent owing to their excellent surface properties. This work presents partial results of synthesis, characterization and adsorption capacity of graphene oxide (GO) and reduced graphene oxide-Fe3O4 hybrid nanoadsorbent (rGO_mag). TC was selected as emerging contaminant for adsorption tests. GO was obtained from powdered graphite (< 50 µm)by Tour`s Method [2]. Synthesis of rGO_mag was carried out from the reduction of GO by FeSO4 at pH 10.5 and simultaneous generation of Fe3O4 nanoparticles.The nanoadsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), Zeta potential, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Through FTIR spectroscopy, oxygenated functional groups present in GO were detected: -OH (3402 cm-1); C=O (1740 cm-1); C=C (1622 cm-1); C-OH (1420 cm-1); C-O-C (1228 cm-1) and C-O (1051cm-1). In the case of rGO_mag, the bands of the oxygenated groups decreased and the Fe-O band (575 cm-1) was observed. Potential Z results were less negative for rGO_mag which corroborates its reduction. TEM microphotographs of rGO_mag show a large amount of Fe3O4 nanoparticles between reduced graphene oxide sheets (~20nm). Regarding its structure, GO diffractogram presented a characteristic diffraction peak at 9.6º (d002= 0.95nm), corroborating the graphite oxidation and the increase of the interlaminar space while rGO_mag presented the characteristic planes of Fe3O4 (220) (311), (400) (551). The adsorption performance of GO and rGO_mag (dosage: 250 mg L-1) for the removal of TC (30 mg/L) from water was evaluated at pH5 where the antibiotic is mostly in its zwitterionic form. According to the adsorption results rGO_mag showed higher TC adsorbed capacity than GO, 96 and 62% respectively.As a conclusion of this preliminary study, when the GO is reduced and magnetized, better TC adsorption performance is achieved making rGO_mag competitive in the removal of organic pollutants from water or wastewater. In addition to presenting a significant advantage in the magnetic separation of said solid from the medium.