High-Pressure CO 2 -Induced Regulation of Particle-Fluid Interfaces in Coal Slurry Transport Systems

This study examines how high-pressure CO2 regulates particle-fluid interfacial behavior in coal slurry systems from a molecular perspective. A representative Guozhuang coal macromolecular model was constructed and applied in molecular dynamics simulations of coal–H2O, coal–CO2, and coal–CO2/H2O systems under identical conditions. Results show pronounced surface polarity heterogeneity: oxygen-containing groups serve as primary hydration sites, while aromatic regions preferentially interact with CO2. In coal–H2O systems, strong electrostatic interactions and hydrogen bonding form a rigid, low-mobility interfacial layer dominated by bound water. The introduction of high-density CO2 redistributes interfacial species, screens coal–water interactions, weakens hydrogen-bond networks, and enhances molecular mobility. These findings provide a molecular-scale mechanism by which fluid environment modification can reduce particle-fluid coupling and improve slurry dispersion and transport.