Indium-based metal-organic framework/graphite oxide composite as an efficient adsorbent in the adsorption of rhodamine B from aqueous solution

MIL-68(In)-NH2/graphite oxide (GO) composites (In-MOF@GO) were prepared via a solvothermal route. The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FUR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and N-2 adsorption-desorption isotherms. The adsorption of rhodamine B (RhB) from aqueous solution by the In-MOF@GO composite was investigated; features such as adsorption isotherms, kinetics, operating pH and ionic strength, as well as regeneration of the adsorbent, were studied. The adsorption process followed the Langmuir isotherm with a pseudo-second-order kinetic model. The optimal adsorption activity was achieved at pH 6. Increasing ionic strength from 0 to 100 mM slightly improved the RhB adsorption, due to the electrostatic screening by NaCI. The In-MOF@GO composite used could be regenerated by ethanol, maintaining good performance. Furthermore, compared to MIL-68(In)-NH2, the In-MOF@GO composite exhibited enhanced adsorption performance in RhB removal from aqueous solution, highlighting its potential application in wastewater treatment. (C) 2016 Elsevier B.V. All rights reserved.