Compósito superparamagnético à base de quitosana para adsorção de tetraciclina

Abstract

Polymer-based magnetic composites have desirable properties for use in environmental remediation, such as high surface area and easy removal. Both chitosan and magnetite are biocompatible, biodegradable and non-toxic, in addition to being low-cost and easy to operate, which allows their use in wastewater treatment. Therefore, in this study, the chitosan-based magnetite composite (CS/Fe3O4) was obtained through the coprecipitation method, where the tetracycline adsorption capacity of the composite was investigated and the equilibrium time was identified. The adsorption studies were conducted at temperatures of 25 and 35 ± 2 °C and were monitored by readings on the UV-Vis spectrophotometer at 281 nm. The composite was characterized by infrared, X-ray diffraction, magnetic measurements, Scanning Electron Microscopy (SEM) and zeta potential, which confirmed the achievement of the composite. The results showed that the adsorption of tetracycline at all temperatures followed the Lagmuir isotherm. The thermodynamic parameters indicated that at low concentrations the negative enthalpy values refer to the attraction forces between sorbate and the sorption sites, thus consisting of a physical adsorption and at high concentrations they have positive enthalpy values, confirming that the adsorption is endothermic in nature. The CS/Fe3O4 superparamagnetic composite showed a tetracycline adsorption capacity of 49 ± 1 mg/g, which is twice as high as the adsorption capacity of pure magnetite.