Facile fabrication of MgO/graphene oxide composite as an efficient adsorbent for rapid removal of aqueous organic dyes: Performance evaluation and mechanistic investigation

Aqueous dyes are major environmental contaminants. Herein, a facile solvothermal method is introduced for the fabrication of an MgO/graphene oxide (MgO/GO) nanocomposite. The as-fabricated MgO/GO has been characterized and employed as an adsorbent to remove aqueous methyl blue (MB) and malachite green (MG). The removal performance has been evaluated through batch adsorptions. More importantly, interactions between MgO/GO and MB or MG have been analyzed in detail, allowing the proposal of a plausible adsorption mechanism. Adsorptions of MB (initial concentration 100 mg L-1) and MG (initial concentration 650 mg L-1) on MgO/ GO (dosage 500 mg L-1) reached equilibrium in 12 min and 10 min, respectively; the removal efficiency and adsorption capacity of MB were 85.95% and 171.90 mg g-1, and those of MG were 98.08% and 1275.00 mg g-1. Both adsorption processes conformed well to the Freundlich model and the pseudo-second-order model, whereby adsorption rate is controlled by chemical adsorption. The adsorption mechanism involves electrostatic attraction, hydrogen bonding, 7C-7C interactions, and van der Waals forces. The facile preparation and high adsorption efficiency may make MgO/GO a potential adsorbent for aqueous dyes.