Preparation and characterization of colloidal dispersions of graphene-like structures from different ranks of coals

This paper focuses on preparation of colloidal solution of graphene-like structures from different ranks of coals: brown coal, bituminous coal, low-volatile bituminous coal, anthracite. It was found that brown coal thermo-oxidative destruction leads to formation of small d = 32 nm (V = 17%) and large d = 122 nm (V = 11%) fractions of nanoparticles. The thermo-oxidative destruction of bituminous coal leads to formation of nanoparticles d = 50 nm (V = 5.2%) and d=164 nm (V = 16%). Thermo-oxidative destruction of low-volatile bituminous coal and anthracite leads to formation of nanoparticles, predominantly, d = 122-190 nm. Carbon nanostructures obtained from coal are negatively charged at pH = 2-12. Colloidal solution of carbon nanostructures at dispersed phase concentration 0.01 mg/mL is stable for 1 month. Electron diffraction patterns and X-ray analysis of carbon nanostructures showed that nanostructure from brown coal is amorphous and nanostructure from anthracite is crystalline. Results of coal macromolecules modeling and graphene-like structures obtained from them are presented.