Adsorption Behavior and Mechanism of Sulfonamide Antibiotics in Aqueous Solution on a Novel MIL-101(Cr)@GO Composite

The occurrence of numerous antibiotics, such as sulfonamides (SAs), in environmental water has recently heightened concerns in consideration of their potential threat to human health and aquatic ecosystems. The removal of pharmaceuticals by adsorption comprises some of the most promising techniques because of their easy regeneration, low cost, and high efficiency. In this work, MIL-101(Cr)@GO, with a high surface area, was synthesized. Its adsorption properties toward three SAs were examined in batch adsorption experiments to probe the underlying factors of adsorption behavior and the mechanism for the first time. The pronounced factors that influenced the adsorption and removal process were investigated. The adsorption kinetics and isotherms were studied in order to characterize the operation. The adsorption kinetics demonstrated that the adsorption process would match the pseudo-second-order kinetic model. Furthermore, the adsorption was spontaneous, entropy was decreased, and the process was exothermic, and the equilibrium data was more appropriate described by the Freundlich isotherm model. Moreover, the adsorptiondesorption of MIL-101(Cr)@GO could be consecutively cycled at least five times. MIL-101(Cr)@GO exhibited remarkable removal efficiency compared to MIL-100(Fe), MIL-101(Cr), and other adsorbents. These results demonstrated that MIL-101(Cr)@GO would be a promising adsorbent for the removal of sulfonamides from water samples and even for environmental protection.