Adsorption of methylene blue on graphene oxide prepared from amorphous graphite: Effects of pH and foreign ions

The adsorption of methylene blue (MB) on graphene oxide (GO) prepared from an economical and resourceful amorphous graphite (AG) was studied. The effects of pH, foreign ions and concentrations of KClO4 on MB removal were also evaluated. XRD, FT-IR, XPS, AFM and an Analyzer were employed to characterize the prepared GO. The results indicated that the C/O mass ratio of GO reached 1.84 and that thin layers (thickness of which less than 2 nm) accounted for 83.76%. The results of batch experiments showed that the adsorption of MB in the presence of cations decreased in the sequence Li+ approximate to Na+ > K+, while it was reduced in the order ClO4- > NO3- > Cl- in the presence of anions. MB removal in ClO4- was independent of solution pH, which may be ascribed to the synergistic effect between GO and ClO4-. The adsorption process was well described by a pseudo-second-order kinetics model, and the adsorption isotherm agreed well with the Langmuir model. (C) 2016 Elsevier B.V. All rights reserved.