Experimental and molecular dynamics simulation study on the influence of SDS and JFC composite ratios on bituminous coal wettability

Dust control has always been a difficult problem in the process of safe mining. Using composite surfactants becomes a simple and effective dust suppression method. However, the micro mechanism of the effect of composite ratio on coal wettability was still unclear. In this study, the experimental combined with molecular dynamics (MD) simulations were used to research the effect of different composite ratios of SDS (Sodium dodecyl sulfate)/JFC (Fatty alcohol polyoxyethylene ether) surfactant on bituminous coal wettability. The experiment results showed that the mixed JFC and SDS solution had good wettability on bituminous coal. The contact angle and surface tension decreased as the proportion of JFC increased in the compound solution. Zeta potential experiment results indicated that adding JFC improved the aggregation ability between coal dust and promoted the settlement of coal dust in the mixed surfactant. The best synergistic wetting effect was achieved at a molar ratio of 1:3 (SDS/JFC). The simulation results showed that the thickest coal/water adsorption layer was formed at a 1:3 (SDS/JFC) mixing ratio. At this ratio, the diffusion coefficients of water molecules increased significantly, which promote the probability of coal collision with water molecules. Finally, the mechanism of the optimal synergistic ratio promoting coal wetting was explained by analyzing the distribution configuration of surfactant molecules. The whole work is of great significance to coal dust prevention and provides a new idea for exploring the synergistic composite ratio of wetting agents.