Experimental study of wetting effect of surfactant based on dynamic wetting process and impedance response of coal

Abstract

Surfactant can improve the wettability of water to coal, which is beneficial to reduce the production of coal dust in coal seam water injection. Through the measurement and calculation of contact angle and its decay rate, the wettability differences of SDS (C₁₂H₂₅OSO₃Na), AES (C₁₄H₂₉O₅NaS), OP-10 (C₁₈H₃₀O₁₀), and JFC (RO(CH₂CH₂O)_nH) to anthracite were compared. In addition, the wetting modification effect and infiltration rate of anthracite by water, AES, and OP-10 were studied by infrared spectroscopy and complex impedance monitoring of coal pillar immersion process. The results show that when the concentration of surfactant is 0.1%, the contact angle decay time of OP-10 is very short, and the contact angle decay rate is as high as 19°/s. The decay rate can more obviously reflect the wettability difference of surfactants. And the wetting modification effect of OP-10 on anthracite is stronger than that of AES, and the peaks of oxygen-containing functional groups such as carboxyl and hydroxyl groups are stronger. Furthermore, the capillary force between OP-10 and anthracite is much larger than that of water, which shows the characteristics of fast water absorption and wide distribution in the infiltration experiment of columnar coal. The results of complex impedance measurement indicate that the impedance decay rate of coal is well correlated with capillary rise factor F_C, contact angle decay rate, and contact angle. It is hoped that the research results can provide help for coal seam water injection and dust prevention.

Keywords: Complex impedance of coal; Contact angle; Functional group; Infiltration; Surfactant; Wettability.