Characterization and adsorption performance of graphene oxide - montmorillonite nanocomposite for the simultaneous removal of Pb2+ and p-nitrophenol

Montmorillonite-graphene oxide composite (MGC) with their own advantages was successfully fabricated for the simultaneous treatment of the combined pollution wastewater containing heavy metal ions and organic pollutants. The features of MGC were analyzed by X-ray diffraction, transmission electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy. Subsequently, a series of batch experiments were carried out to investigate the adsorption performance of Pb2+ and p-nitrophenol (PNP) onto MGC in single and binary system. The results indicated that MGC exhibited a gossamer layer with spots and a larger interlayer spacing. In single adsorption experiment, the removal of PNP by MGC reached 96.82%, while Pb2+ removal reached 98.94%, which was maintained at the same level as montmorillonite. In binary acidic system of Pb2+ and PNP, the removal of Pb2+ reached 98.23%, while PNP removal dropped to 51.06% due to their competitive adsorption. The thermodynamic study indicated that the chemisorption was predominant in the adsorption of Pb2+ onto MGC, while physisorption was for PNP. It was exactly that the strong competitiveness of Pb2+ brought the remarkable reduction in PNP adsorption capacity in the simultaneous adsorption.