A sandwich-structured graphene-based composite: Preparation, characterization, and its adsorption behaviors for Congo red

In this work, a novel sandwich-structured graphene-based composite (PPD-GO) was prepared. The graphene-based composite was prepared by amination of graphene oxide (GO) with p-phenylenediamine (PPD) with the aid of the coupling reagents. And PPD was introduced into the interlayers of graphene nanosheets. The morphology, composition, and grafted functional groups of the composite were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. And PPD-GO was used as a highly efficient adsorbent for removal of Congo red from used from aqueous solutions. The whole adsorption process was studied in depth and elucidated systematically. A maximum Congo red adsorption capacity of 892.8 mg/g was obtained for PPD-GO composite at an initial temperature of 298 K and pH of 3.0. The second-order kinetic equation could well describe the sorption kinetics. The equilibrium data were perfectly fitted by the Langmuir isotherm. The thermodynamic analysis indicated that the adsorption of Congo red onto the PPD-GO composite was a spontaneous and endothermic process. (C) 2016 Elsevier B.V. All rights reserved.