Experimental and molecular dynamics simulation study of the effect of different surfactants on the wettability of low-rank coal

It is critical to choose suitable surfactants for water-based dust suppressant applications. However, the surfactant selection in previous research has mainly relied on experimental approaches that are inefficient and insufficient to elucidate the wetting mechanism from a microscopic point of view. In this work, we combine experimental methods with molecular dynamic simulations to investigate the wetting and adsorption effects of different surfactants on low-rank coal (LRC) and demonstrate the benefits of the combined approach. We use experimental measurements of contact angle and surface tension, scanning electron microscope analyses, and wind erosion resistance tests to assess the wetting and adsorption properties of the surfactants cocamidopropyl betaine (CAB) and coconut oil diethanolamide (CDEA). We also use Materials Studio software to perform molecular dynamics simulations to investigate the wetting and adsorption effects of the two surfactants on LRC dust at the molecular level. In so doing, we have computationally analyzed the number of hydrogen bonds, interaction energy, distribution curve of relative concentration, and mean square displacement curve formed by the two materials. The experimental results show that CAB has better wetting and adsorption performance on LRC than CDEA, which is supported by the molecular dynamics simulations. This work has identified better surfactants for the suppression of coal dust.