Experimental and molecular dynamics simulation study of the effect of composite surfactants on wetting of coal dust

•By combining macroscopic experiments and microscopic simulations, the optimal combination of composite ionic surfactant solutions is derived, which can realize the efficient enhancement of the effect of dust reduction on coal dust.•The dynamic changes of surface tension and contact angle of different solutions were observed, and the microscopic wetting principles of each surfactant were characterized from their structural features by establishing their molecular models.•By constructing adsorption models containing two different ions, it was concluded that the nonionic and anionic surfactants had the most obvious longitudinal distribution between coal and water after compounding, which could form a tighter adsorption layer and allow water molecules to penetrate into the coal molecules, thus enhancing the wetting effect on coal dust. To improve surfactant wetting action on coal dust in the process of mine spray dust reduction, this paper adopts a combination of experiments and molecular simulation to study the wetting properties and mechanism of different kinds of active agents on coal dust and selects the compounded surfactants with better dust reduction effect. The results show that: fatty alcohol polyoxyethylene ether can reduce the surface tension to 34.16 mN·m−1, which is 35.84 mN·m−1 comparatively less than that of pure water; dodecylphenol polyoxyethylene ether and poly(ethylene glycol) octyl phenyl ether have the maximum electrostatic potentials of 0.0892 a.u and 0.0908 a.u, which exceed that of water molecules, which indicate that the nonionic active agents are the most polar, and it is easy for them to form the hydrogen bonding with water, and the ability to reduce surface tension is superior to other types of active agents; molecular simulation results show that the non + anionic complex system can form a tighter adsorption layer between coal and water, so that the water molecules move more vigorously, moving from the molecules of water to those of coal, thus producing a better wetting effect than the monomer active agent. In addition, dust settling experiments and particle size experiments were conducted to verify the reasonableness of the microscopic simulation. The study’s findings can provide a reference for identifying and designing compounded surfactants with excellent wetting performance to improve the dust reduction effect.