Preparation of large-sized graphene from needle coke and the adsorption for malachite green with its graphene oxide

With needle coke (NC) as an initial material, large-sized graphene was successfully prepared through an oxidation–exfoliation–thermal reduction process. The prepared graphene was characterized by SEM, TEM, AFM, FTIR, XRD, Raman, and XPS, respectively. Results showed that the morphology of graphene from NC was different from that of natural graphite although the spectroscopic properties of graphene from NC are very similar to those from natural graphite. The lateral size of the prepared graphene is concentrated in 3–8 µm, which was considerably larger than that of natural graphite, multiwalled carbon nanotubes (MWCNTs) and stacked graphene nanofibers (SGNFs). In addition, the adsorption capacity of graphene oxide from NC for malachite green was investigated to confirm the size of graphene indirectly. The equilibrium adsorption capacity of 437.7 mg/g for malachite green was considerably higher than that from natural graphite whose adsorption capacity was 209.5 mg/g under identical conditions. All results confirm that NC is a better alternative for the preparation of graphene than natural graphite.