Remoção de tetraciclina e sulfametoxazol em meio aquoso empregando a resina Amberlite XAD-7

Abstract

Emerging contaminants are generally exogenous compounds originating mainly from anthropogenic actions and found in environmental compartments. Among them are drugs such as those belonging to the antibiotic group currently associated with antimicrobial resistance in organisms. Given this, there is concern about proposing methodologies for removing these compounds in sewage or water treatment systems. Thus, this research aimed to study the application of the commercial resin Amberlite XAD–7 for the removal of tetracycline (TRC) and sulfamethoxazole (SMZ) in aqueous media. PHPCZ, SEM, and EDS initially characterized the resin to verify whether the analytes were adsorbed. Kinetic and equilibrium studies were carried out using batch methodology at pHs 5.5, 7.5, and 9.5 and determining the concentrations of antibiotics in the aqueous phase by UV-Vis spectrophotometry. Kinetic data were evaluated using pseudo-first, pseudo-second-order, and Elovich equation models. The Langmuir, Freundlich, Redlich-Peterson, Temkin, and Dubinin-Radushkevich isotherm models were used for the equilibrium data. The micrographs indicated that the Amberlite XAD7 resin has a homogeneous and spherical surface. The EDS spectra revealed a variation in the percentage of carbon and oxygen before and after the contact of the resin with the TRC and SMZ, suggesting their adsorption. In the study with TRC, the Elovich chemisorption model was the best fit for the kinetic behavior, with slow adsorption rates. At the same time, for SMZ, the kinetics were described as pseudofirst order. In terms of equilibrium, for both drugs, the isotherms presented a sigmoidal shape, and the model that best fitted was the Dubinin-Radushkevich model, which suggested predominant adsorption is physical and not ion exchange, with weak Van der Waals interactions and intermolecular hydrogen bond interactions. Finally, it was concluded that the resin could remove TRC and SMZ; however, there is a need for better exploration of the pH and temperature variables to obtain better adsorption capabilities.