Wetting behavior and interaction mechanism between gas-containing coal and active water

Gas and dust were two hazardous sources for mine safety production. As mining depth increased, the methane content rose, and the difficulty of wetting gas-containing coal also increased. Although active water could improve the wettability of coal, existing research often overlooked the impact of gas, leading to unclear wetting behavior and interaction mechanisms between gas-containing coal and active water. As the gas pressure increases, the contact angle between active water and gas-containing coal increases too. In the micro-wetting system, an increase in gas pressure promoted a higher contact probability between surfactant hydrophobic groups and gas, thereby increasing the coordination number between hydrophobic groups and coal molecules. The intermolecular interactions between water molecules and surfactant molecules were weakened, thereby enhancing the dispersion. Simultaneously, the methane diffusion coefficient decreased with increasing pressure, while the interaction energy of the coal/surfactant/gas/water four-component system gradually weakened. Electrostatic potential analysis indicated that as the adsorption pressure increased, the difference between the extreme points of positive and negative electrostatic potentials diminished, and a larger potential difference was more likely to induce intermolecular interactions. The research provided some guidance for the collaborative application of injection active water technology in high coalbed methane content to achieve mine gas and dust disaster prevention.