Molecular dynamics simulation of the effect of SDS / SDBS on the wettability of anthracite

In order to explore the microscopic mechanism of anionic surfactants in coal mine dust removal. Using molecular dynamics simulation methods, two commonly used anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS), were selected to study their effects on the wettability of anthracite. The surface roughness and interaction energy of the surfactant anthracite adsorption system were calculated. The relative concentration distribution and radial distribution function (RDF) of the water surfactant anthracite system were analyzed. The microscopic reasons for the wettability change of anthracite were discussed.The results show that there are two ways of adsorption of anionic surfactants on anthracite, the adsorption of the head group toward the surface of the anthracite and the adsorption toward the liquid phase; this adsorption is physical adsorption, and van der Waals interaction plays a leading role in the adsorption process; The presence of benzene ring in SDBS leads to tighter adsorption on the surface of anthracite, and the adsorption configuration is more stable. The results of RDF and coordination number further show that the hydrophobicity of SDS near the ketone group of anthracite is similar to that of SDBS; the hydrophobicity of SDBS near the hydroxyl group is stronger than that of SDS, which is the main reason for the stronger hydrophobicity and greater wettability change of anthracite after adsorption by SDBS; Benzene ring plays an important role in the change of wettability of anthracite. This provides a certain basis for the selection of surfactants in coal mine dust removal. The basic theory of wettability of anthracite has been enriched and developed. The molecular dynamics simulation evaluation of the adsorption behavior and wettability changes of these two anionic surfactants is in good agreement with the existing experimental data.