Research on the wetting mechanism of coal dust by different surfactants: combination of experimental characterization and molecular dynamics simulation

Surfactants can reduce the surface tension of water and improve the efficiency of spray dust reduction, but the synergistic mechanism of composite surfactant solutions wetting coal dust remains unclear. In this study, sodium dodecyl sulfonate (SDDS)/sodium dodecylbenzene sulfonate (SDBS) solution and SDDS/primary alcohol ethoxylate (AEO-9) solution were prepared to wet three types of coal with different deterioration degrees. The surface tension, contact angle, and functional group composition were measured. The results show that SDDS/AEO-9 solution had lower surface tension and critical micelle concentration than SDDS/SDBS solution at the same mixing ratio. When the ratio of SDDS: SDBS was 2:1, it had the best wetting effect on coal dust. It is found that for SDDS/SDBS solutions, aliphatic hydrocarbons and surface tension have a positive correlation with the contact angle, and hydroxyl groups have a negative correlation with the contact angle. For SDDS/AEO-9 solution, only the surface tension and contact angle show a significant linear relationship. The main factors that affect the wetting change with the combination of surfactants. AEO-9 has an electrostatic shielding effect on SDDS, while SDBS increases the electrostatic repulsion between SDDS solution and electronegative functional groups of coal. The synergism among these surfactants plays an important role in the process of wetting coal.

Automated summary

In this study, two surfactant solutions were prepared to wet coal dust, and the surface tension, contact angle, and functional group composition were measured. The results showed that the SDDS/AEO-9 solution had lower surface tension and critical micelle concentration compared to the SDDS/SDBS solution at the same mixing ratio. The wetting effect on coal dust was best when the ratio of SDDS:SDBS was 2:1. The study found that aliphatic hydrocarbons and surface tension had a positive correlation with contact angle in SDDS/SDBS solutions, while hydroxyl groups had a negative correlation. Only surface tension and contact angle showed a significant linear relationship in the SDDS/AEO-9 solution. The combination of surfactants played an important role in the wetting process of coal.