Facile preparation of MgO/graphene oxide nanocomposite for efficient removal of aqueous Congo red: adsorption performance and interaction mechanism

Aqueous dyes are important source of water pollution. In this work, a nanocomposite MgO/graphene oxide (MgO/GO) was prepared with a simple solvothermal method. The as-prepared MgO/GO was characterized and employed as a potential adsorbent to remove aqueous Congo red (CR). The interaction mechanism between MgO/GO and CR was clarified. The adsorption of CR (initial concentration 700 mg L-1) onto MgO/GO (dosage 1000 mg L-1) equilibrated in 10 min, adsorption percent and adsorption quantity were 97.84% and 684.85 mg g(-1), respectively. Compared with other adsorbents, MgO/GO was superior in adsorption efficiency due to the fast adsorption kinetics. Moreover, MgO/GO exhibited good adaptability to the fluctuations of environmental factors including CR initial concentration and coexisting electrolyte. The adsorption fits well with the Freundlich model and PSO model; chemical adsorption was the rate-controlling step. Both GO and MgO in MgO/GO contributed to CR adsorption. GO adsorbed CR via an electrostatic attraction and face-to-face pi-pi interaction, MgO adsorbed CR via weak van der Waals force. Owing to the advantages as facile preparation, high adsorption efficiency, and good environmental adaptability, MgO/GO may be a promising adsorbent for aqueous dyes.