Molecular mechanism study of nonionic surfactant enhanced anionic surfactant to improve the wetting ability of anthracite dust

Through experiments and simulations, the mechanism of the influence of the addition of a small amount of dodecyl polyoxyethylene ether (C12(EO)23) on the enhancement of the wettability of anthracite coal dust by sodium olefin sulfonate (AOS). The surface tension of seven solutions was measured to reveal their own properties and predict the possibility of solution spreading on the coal dust surface. Then, through macroscopic experiments such as the settling time of coal dust and the contact angle with coal dust, the effective anionic and nonionic surfactant ratios that can synergistically improve the wettability of anthracite dust were determined. Furthermore, mesoscopic characterization such as X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) revealed that the number of hydrophilic elements and hydrophilic functional groups increased most significantly when the anthracite dust was modified using a composite surfactant solution with an AOS:C12(EO)23 ratio of 5:1. Finally, the different systems were simulated by molecular dynamics (MD). The results indicated that the addition of the composite surfactant weakened the diffusibility of water in the system, enhanced the interaction energy of water with anthracite, and increased the number of hydrogen bonds formed between the surfactant-adsorbed coal surface and water. In conclusion, this study shows that the addition of a small amount of nonionic surfactant can greatly weaken the electrostatic repulsive force between the anionic surfactants, which makes it play a key role in the wetting process, and enhance the hydrophobic interaction between the two surfactants. This enhances the wetting effect on anthracite. This study will provide a theoretical basis for the suppression of coal dust.