Effect of water-based SiO2 nanofluid on surface wettability of raw coal

Coal seam water injection has been shown to be an effective method for controlling coal and gas outburst disasters in coal mines. However, the shortcomings, such as poor wettability of the coal seam and easy filtration loss of injected water, have resulted in low construction efficiency and uneven control effects. In this study, a method of surface wettability alteration through a water-based SiO2 nanofluid was proposed to overcome the aforementioned shortcomings, and the underlying action mechanism was elucidated. First, the sedimentation characteristics of the water-based SiO2 nanofluid were evaluated using three test methods. Then, the variations in the water content and contact angle were obtained. Finally, potential mechanisms for the application of water-based SiO2 nanofluid in coal seam water injection technology were revealed. Based on the nanofluid sedimentation characterization, the enhancement effects of SiO2 nanofluid on the surface wettability and water adsorption of raw coal were elucidated in this study, indicating that the presence of nanofluid improved the effectiveness of coal seam water injection. In addition, the SiO2 nanofluid had a similar wetting effect on samples with initial contact angles of both 80° and 90°. These results can provide new ideas for improving the effectiveness of coal seam water injection. •The effect of SiO2 nanofluid on surface wettability and water adsorption of raw coal is elaborated.•The SiO2 nanofluid can enhance control effect of coal and gas outburst in coal seam water injection.•The potential mechanism for application of SiO2 nanofluid in coal seam water injection is revealed.