Mechanisms of pore geometry and apparent morphology on the wettability of coal-ionic liquids

In order to investigate the mechanism of pore regulation on the wetting performance of coal-ionic liquids, the wetting performance and mechanism of coal-ionic liquids at different temperatures were analyzed based on the contact angle, surface tension, low-field nuclear magnetic resonance, and atomic force microscopy experiments. A method of comprehensively analyzing the wetting mechanism through pore structure and surface morphology was proposed. The findings demonstrated that the wetting properties of ionic liquids on coal showed temperature selectivity, with the ionic liquids containing Cl− preferring low temperatures and [BMIM][BF4] on the contrary. After treatment, the average pore diameter, average roughness, and porosity of coal samples increased by 0.34–18.36 nm, 2.09–9.7 nm, and 0.5929%–1.4313%, respectively, and the trend of pore parameter change aligns with the trend of wetting characteristic change. In addition, the fitting results revealed that the increase in roughness had a negative correlation with the contact angle's size and a positive correlation with the increase in porosity, indicating that ionic liquids can affect the wetting properties of coal by changing the pore structure and apparent morphology of the coal. The research results are significant in enhancing the mine dust management capability.