Síntese, caracterização e aplicação de óxido de grafeno na adsorção de antibióticos em meio aquoso

Abstract

The incidence of emerging pollutants in the environment has become increasingly frequent. Due to the uncertainty of long-term adverse effects, environmental control bodies have not yet regulated these substances. Because sewage treatment plants (STPs) do not remove these pollutants effectively, several studies have been carried out looking for alternative, low-cost, more effective methods. Thus, this work aimed to evaluate the adsorptive potential of graphene oxide (GO) in the removal of the drugs Tetracycline (TCT) and Sulfachloropyridazine (SCP) in an aqueous solution. The GO was obtained from the oxidation of commercial graphite using the adapted Hummers method. The characterization of the adsorbent material was performed using Infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and zero charge point (PCZ). For comparison purposes, prepared OG and commercial graphite were tested. The adsorption capacity of the materials was determined by subjecting them to contact with the antibiotics tetracycline (TCT) and sulfachloropyridazine (SCP) in an aqueous solution. For this, the effects of the adsorbent mass, the initial pH of the solution, the concentration of the drugs, the temperature and the contact time were evaluated. Equilibrium data were evaluated by the Langmuir, Freundlich, Redlich-Peterson and Temkin isotherm models. The adsorption kinetics was studied using pseudo-first-order, pseudo-second-order and Elovich models. The experimental data of TCT and SCP in contact with the GO had good fits to the pseudo-first order and pseudo-second order models, respectively, presenting K1 of 0.06 g mg-1.min-1 and K2 of 0 .07 to 0.10 g mg-1.min-1. The results showed that the isotherm model that best fitted the adsorption process was the Redlich-Peterson model for both drugs. Considering the Langmuir model, the maximum adsorption capacity was 59.5 mg g-1 for TCT and 33.6 mg g-1 for SCP at 45ºC. It is concluded that the synthesized graphene oxide showed a favorable potential for the removal of both drugs in an aqueous medium.