▎ 摘　　要

Exfoliation of graphite has become a popular top-down method of producing graphene. However, it is still a challenging issue to prepare purified graphene because the exfoliated graphene was usually mixed with the unexfoliated graphite. In this work, we investigated the isolation of the graphene and graphite by using supercritical CO2 through Computational Fluid Dynamics (CFD) simulation and experimental. The Eulerian multiphase and standard k-e turbulence models for CFD simulation were used to explore the influences of the pressure and the velocity of supercritical CO2, the geometry of the separation column, and the feeding amount of the mixture on the distribution of the graphene and graphite in the column. The isolation experiments were carried out based on the CFD simulation results, and the isolated graphene was characterized by Raman spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy. The results indicate that the purified graphene sheets can be obtained by supercritical CO2 elutriation approach and the optimal experimental conditions were consistent with that obtained by CFD simulation. The graphene was isolated with graphite completely when the volume fraction of the mixture of the graphene and graphite was <20%, the pressure and the flow rate of supercritical CO2 were 8 MPa and 0.2 m/s, respectively. The obtained graphene sheets mainly consisted of 3-5 layers. The CFD simulation is helpful in scale-up production of purified graphene by supercritical CO2 elutriation technique. (C) 2019 Elsevier B.V. All rights reserved.