Molecular dynamics study on wettability difference between lignite dust and silica dust

In this paper, the differences in the wetting mechanisms of lignite dust and silica dust were investigated using molecular dynamics simulations and quantum chemical methods. A water-surfactant-lignite coal dust/silica dust model was constructed and the interaction energy, radial distribution function (RDF), mean square displacement (MSD), self-diffusion coefficient (D) and relative number density among the components within 100 ps after equilibrium were investigated by molecular dynamics simulations. The results show that the interaction energy and self-diffusion coefficient between cetyl trimethyl ammonium bromide(CTAB) solution and lignite molecules are larger and the peak value of relative number density is higher compared to silica dust; by comparing the electrostatic potential of lignite dust with that of silica dust, the magnitude of the potential difference of SiO₂ varies widely, which shows that the size of the potential difference between the dust surface and water molecules due to active agent adsorption is one of the factors affecting the difference in surface wettability, but the functional groups in lignite increase the intermolecular interactions and play a significant role in the wetting process.