Experimental and molecular dynamics study into the surfactant effect upon coal wettability

Area of Science:

• * Coal science and engineering
• * Surface chemistry
• * Materials science

Background:

• * Improving coal seam wettability is crucial for water injection efficiency, dust reduction, and preventing coal and gas outbursts.
• * Surfactants can modulate coal surface properties to address these challenges.
• * Understanding coal surface chemistry is key to effective modification.

Purpose of the Study:

• * To investigate the use of surfactants for engineering coal surface wettability.
• * To quantify the impact of surfactants on coal surface properties and water interaction.
• * To provide guidance for coal water injection and dust suppression applications.

Main Methods:

• * Contact angle measurements were used to assess coal wettability.
• * Surface free energy analysis was performed on modified coal samples.
• * The Wiser model was employed to construct surfactant-coal adsorption models.

Main Results:

• * The non-ionic surfactant Triton X-100 reduced the contact angle by 47%.
• * Surface free energy increased from 44.51 mN m^-1 to 49.52 mN m^-1 with 1.0 wt% Triton X-100.
• * Surfactant adsorption enhanced water-coal interaction and water molecule diffusion, leading to hydrophilicity.

Conclusions:

• * Surfactant application effectively transforms coal surfaces from hydrophobic to hydrophilic.
• * This modification improves coal seam wettability and permeability.
• * The findings offer valuable insights for optimizing coal water injection and dust control strategies.