Correlation between surface wettability and fluid physics characteristics of lignite under compound solution regulation

The specific composition and ratio of the composite wetting agent will affect its dust reduction effect. Therefore, in order to study the effect of the composite wetting agent on the wettability and physical structure of lignite, the anionic surfactant sodium dodecyl sulfate was selected and mixed with different concentrations of sodium chloride to obtain different concentrations of the composite wetting agent. The correlation between the fluid physical properties of these composite wetting agents and the wetting of lignite surfaces was comprehensively explored by contact angle measurement, surface tension analysis, and low-temperature liquid nitrogen adsorption experiments, and the potential effects on pore structure were investigated. The results showed that as the sodium chloride concentration increased, the surface tension, contact angle, adhesion work, and surface free energy of the composite solution decreased, while the diffusion coefficient increased. There was a high linear correlation between the pore diameter of coal and the contact angle (R2 = 0.955), which revealed the close relationship between the permeability behavior of the fluid in the coal pores and the physical structure of the coal body. In addition, composite wetting agents with high sodium chloride concentrations exhibited a specific pore expansion effect, which helped optimize the coal's pore distribution and thus promoted effective coal wetting. This study not only deepens our understanding of the role of fluid physics principles in dust removal technology but also provides an important theoretical basis for selecting suitable composite wetting agents and their optimal ratios.