Synthesis of aluminum-based MOF/graphite oxide composite and enhanced removal of methyl orange

Abstract

An aluminum-based MOF/graphite oxide composite, MIL-68(Al)/GO, was synthesized and used to explore its adsorption performance toward methyl orange (MO). The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption. Compared to parent material, the composite possessed higher total pore volume and surface area. Meanwhile, a sandwich construction for the composite, with a preserved structure of MIL-68(Al) and GO, was also observed. Considering adsorption application, some key operating factors, adsorption isotherms, kinetics, mechanism, and regeneration were investigated. The adsorption isotherm conformed to the Langmuir isotherm model and the maximum equilibrium adsorption capacity was 400 mg/g. For kinetics, the process of adsorption was more suitably described by a pseudo-second-order model. Moreover, this material can be used over a wide pH range and exhibited superior adsorption performance and regenerability for the adsorption of MO. From these results, MIL-68(Al)/GO was suggested here to be a promising adsorbent for removing MO from aqueous solution.