Effect of temperature on the wetting performance of coal powder by different surfactant solutions: experimental and molecular dynamics simulation study

Current research on coal dust wettability primarily focuses on surfactant types, concentrations, and coal properties, while the role of temperature as a key parameter in practical applications has not been fully explored. This study combines experimental measurements and molecular dynamics (MD) simulations to systematically investigate the influence of temperature (291.15-308.15 K) on the wetting behavior of coal dust by three surfactants: zwitterionic BS‑12, nonionic OP‑10, and anionic SDS. Macroscopic experiments indicate that increasing temperature contributes to improved wetting performance: contact angles are reduced by 45.3% (BS‑12), 50.1% (OP‑10), and 46.8% (SDS), while coal dust settling time is shortened by 33.1%, 83.62%, and 63.44%, respectively. Molecular dynamics simulations further reveal that elevated temperature enhances the interactions between surfactants and coal and promotes structural expansion of the adsorption layer. Among them, OP‑10 exhibits relatively pronounced thermal responsiveness, with its adsorption-layer thickness increasing from 5.53 Å to 14.57 Å, consistent with the wetting behavior observed in macroscopic experiments. At the molecular level, OP‑10 primarily forms a compact and stable interfacial adsorption layer through π-π stacking interactions with aromatic structures in coal, whereas SDS and BS‑12 rely mainly on electrostatic interactions. This study provides a molecular-level reference for surfactant selection in varying temperature environments and suggests that maintaining temperatures above 298.15 K (25 °C) in practical dust suppression applications can help enhance wetting effectiveness, offering certain guidance for industrial dust control practices.