Molecular dynamics simulations and experimental characterization of the effect of different concentrations of [Bmim][Cl] in aqueous solutions on the wettability of anthracite

Abstract

For the difficulty of wetting low permeability coal seams with water injection, it is valuable to investigate the factors influencing the coal seam wetting by aqueous solutions of new solvent-ionic liquids. Contact angle and surface tension studies evaluate and assess the wetting effect of different concentrations of 1-butyl-3-methyl ionic liquid [Bmim][Cl] in aqueous solutions on anthracite in this research. The different concentrations [Bmim][Cl]–H2O-Coal system are constructed from a microscopic perspective using molecular dynamics simulations to explain the parameters impacting the wetting properties of the ionic liquid [Bmim][Cl] in aqueous solutions on anthracite. The contact angle and surface tension decreased and then increased as the concentration of ionic liquid [Bmim][Cl] in aqueous solutions increased, with the lowest surface tension of 53.82 mN/m and the lowest contact angle of 19.2° at a solution concentration of 5 %, which was 74.77 % lower than the original contact angle. One of the data from the interfacial formation energy shows that the power to reduce the solution's interfacial tension is most extraordinary at this moment, and the wetting effect is best. By studying the relative concentration distribution curves of imidazolium chloride salt systems with different concentrations, we discover a correlation between the overlap range of coal and water and the starting point of water. The influence of varying concentrations of ionic liquid [Bmim][Cl] in aqueous solutions on the migration rate of water molecules in wetting coal dust is also illustrated by the water molecules' mean square displacement and self-diffusion coefficient. It is critical to combine experiments and simulations to investigate the effects of ionic liquids on coal dust wetting from both macroscopic and microscopic perspectives to optimize coal dust wetting.