NMR study of the electrolyte diffusion in bituminous coal

Abstract

The transfer of the electrolyte molecules (H2SO4 or H3PO4) into bituminous coal was studied by the method of solid-state NMR spectroscopy. The kinetic dependences of the electrolytes transfer into a coal membrane from an aqueous solution have been obtained. It was shown that the transfer of H2SO4 molecules into a coal thin layer is determined by the solid phase diffusion. The process was investigated in the framework of a mathematical model of diffusion in layered media. When the flow of electrolyte is directed perpendicular to the surface of the layer the diffusion coefficient of sulfuric acid in the coal equals 1∙10-13 m2/s. The diffusion coefficient of H2SO4 in the bituminous coal is four order of less than the self-diffusion coefficient of proton in aqueous solution. The diffusion process of the electrolyte delivery may be the rate-limiting stage preceding chemical transformations with the H2SO4 participation in bituminous coal.