Study on the effects of surfactants on the interface characteristics and wettability of lignite

To further explore the wetting mechanism of the interface between surfactant and coal dust. By constructing a surfactant-water-coal interfacial simulation system, the microscopic interfacial wettability of four surfactants, rapid penetrant T (RPT), sodium dodecylbenzene sulfonate (SDBS), dodecyl glucoside (APG), and cocamidopropyl betaine (CAB), on coal dust is discussed. The intermolecular movement trends were observed to determine the correlation mechanism of surfactants affecting the wettability of coal dust. The results showed that the total pore volume and specific surface area after wetting coal dust in the RPT system decreased by 90.53% and 96.93%, respectively, with a median particle size distribution up to 151.29 μm; the interfacial thickness, tension and interfacial formation energy were 27.08 Å, 31.66 mN/m and − 80.91 kcal/mol, respectively, compared with SDBS, APG and CAB, corresponding to The maximum improvements were 13.40%, 6.85%, and 59.04%, respectively, which were closely related to the strength and types of interactions between different surfactants and molecules, i.e., the adsorption strength of electrostatic interactions such as hydrogen bonding was greater than van der Waals interactions, and the macroscopic experiments were consistent with molecular interface simulations, and the research results could provide a reference for efficient evaluation of the wettability of surfactants.