▎ 摘　　要

This paper reports the effect of acid treatment and grinding process on the physical properties of graphene (GN)/multi-walled carbon nanotubes (MWCNTs) composite. HNO3 and H2SO4 based simple purification method and low energy ball milling in aqueous circumstance were applied on graphene and MWCNTs for getting graphene/MWCNTs nanocomposite. Field emission scanning electron microscopy (FESEM), EDS, transmission electron microscope (TEM), sedimentation, electric conductivity, thermal diffusivity, thermal conductivity enhancement and heat transfer coefficient enhancement ratio measurement were performed which expose some strong witnesses of a better synthesis of graphene and MWCNTs by purification as well as grinding process. The highest thermal conductivity enhancement (4.29% at 40 degrees C) of GN/MWCNTs based nanofluid without any surfactant treatment is achieved by applying acid treatment as well as wet grinding at 500 rpm for 2 h.