Mechanistic aspects of enhanced congo red adsorption over graphene oxide in presence of methylene blue

To elucidate the role of cationic dye for the enhanced adsorption of anionic dye over Graphene oxide(GO), we have made a novel approach to evaluate the adsorption capacity of GO for removal of Congo red (CR) from aqueous system in presence of Methylene blue (MB). Physicochemical and spectroscopic techniques have been used to assertion the interaction of dye molecules with the surface of GO. At pH = 2, GO possessed 96% adsorption capacity towards CR in presence of MB. The existing pH dependant electrostatic interaction mechanism between CR and MB dye has been explained for enhanced CR adsorption over GO surface. Fourier transform infrared spectroscopy and Raman spectrum of dye adsorbed GO also gives well support to evaluate the extent of electrostatic interaction between oxygen containing functional groups and functional moieties of dye resulting in good adsorption over GO surface. (C) 2016 Elsevier Ltd. All rights reserved.