Investigation of the Wetting Mechanism of Nonionic Surfactant-Modified Bituminous Coal Surfaces

The wettability of bituminous coal surfaces in the presence of nonionic surfactants was investigated to understand the underlying mechanisms of surfactant interaction. Using raw coal from the Pingdingshan mining area, this study employed comprehensive characterization techniques, including proximate analysis, FTIR, ¹³C NMR, and XPS to explore the structural parameters of the bituminous coal. These techniques provided insights into the surface functional groups, elemental composition, and carbon skeleton, which facilitated the construction of a macromolecular structural model. Wettability experiments, such as sedimentation time, Zeta potential, and surface free energy measurements, were conducted to evaluate the effect of nonionic surfactants (JFC-E, X-100) on coal dust wettability. The combination of laboratory experiments and molecular simulations with self-developed coal macromolecular model enabled a deeper understanding of the molecular-scale interactions between the surfactants and coal. The results demonstrated that Pingdingshan bituminous coal is primarily composed of hydrophobic aromatic hydrocarbons, with benzene, naphthalene, and anthracene as the key aromatic units. Surfactant adsorption was found to significantly alter the coal's surface free energy, enhancing the polar component, with X-100 exhibiting optimal performance. Molecular simulations revealed that X-100's hydrophilic moiety contains more oxygen-containing functional groups than JFC-E, providing additional hydrophilic sites. Furthermore, X-100's benzene ring structure strengthens π-π interactions with the coal surface, leading to a more stable adsorption configuration that facilitates water molecule adsorption. This study provides technical guidance and methodological insights for scientifically efficient dust suppression in mining operations.