Discussion on micro-mechanisms for the adsorption of water on coal surfaces

摘要

Coal seam infusion is an effective method of reducing coal dust and preventing coal and gas outburst. Therefore, research on the micro-mechanisms of water adsorption in coal is very important. Using molecular thermodynamics and surface physical chemistry theory, the characteristics of coal surface free energy and micro-mechanisms of water adsorption on coal were studied. The results show that the attractions of water molecules and coal surfaces are electric attractions in molecular level which include intermolecular forces and hydrogen bonding. The adsorption of water molecules on coal is multi-layer adsorption. The first layer adsorption is mainly due to hydrogen bonding and the other layers are mainly due to long-distance attractions. Attractions between coal and water molecules were estimated and the results show that London dispersion force is the most intensive. In essence, measures increasing coal wetness can change the attraction between coal surfaces and water molecules.