MOF/graphene oxide composite as an efficient adsorbent for the removal of organic dyes from aqueous solution

The metal-organic frameworks (MOFs) MIL-100(Fe) and graphene oxide (GO) composites were prepared by hydrothermal method and characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, thermal-gravimetric (TG) analysis, the Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy (SEM). The composites were used for the adsorption of methylene blue (MB) and methyl orange (MO) in aqueous solution. The results indicated that MIL-100(Fe) and GO formed a sandwich-like structure, and the crystal structure of MIL-100(Fe) was reserved in the composites. The attachment of GO layers to the MIL-100(Fe) decreased the surface area from 1690 to 1602 m²/g, and pore volume from 0.996 to 0.770 cm³/g when 5% (w/w) GO was added, due to the coating of MIL-100(Fe) by GO sheets. The addition of 5% (w/w) GO increased the adsorption capacity for MB (from 1019 to 1231 mg/g) and MO (from 667 to 1189 mg/g). The composites showed a better thermal stability than MIL-100(Fe); the decomposition temperature increased from 280 to 350 °C. The addition of GO improved the properties of MIL-100(Fe) as an adsorbent for MO/MB from aqueous solution.