Synthesis of graphene oxide/metal-organic frameworks hybrid materials for enhanced removal of Methylene blue in acidic and alkaline solutions

BACKGROUND: Dye wastewater is causing a serious problem to the environment and to human health. A considerable amount of colored wastewater is generated from many industries. Moreover, many dyes in the wastewater are believed to be toxic and even carcinogenic. Therefore, the removal of dyes from wastewater is necessary and urgent. RESULTS: The adsorption kinetics, isotherms and intra-particle diffusion model were determined from experimental data, and the results indicated that the pseudo-second-order kinetic model and the Langmuir adsorption isotherm matched well the adsorption of MB onto GO/MOFs. Thermodynamic parameters revealed that the adsorption of MB by GO/MOFs was spontaneous and exothermic. The adsorption capacity was greatly improved in acidic or alkaline aqueous solution. The maximum adsorption capacity of GO/MOFs reached 274 mg g(-1), higher than most previously reported adsorbents. Also, the adsorbent could be used at least five times after washing with ethanol. CONCLUSION: A microwave-assisted ball milling method was used successfully to synthesize Ni-MOFs and GO/MOFs. Because of electrostatic interaction and acid-base interaction, both acidic and alkaline aqueous solutions were found to favor the adsorption of MB by GO/MOFs, this being different from previous reports. GO/MOFs also showed acceptable reusability after being regenerated by ethanol. All the results suggest that MOFs prepared by microwave-assisted ball milling give the prospect of removal of MB from aqueous solution. (C) 2017 Society of Chemical Industry