Study on the Compounding Optimization of Surfactants and Synergistic Effects on the Wettability of Anthracite Coal

To enhance the wettability of surfactants on anthracite coal and to investigate their wettability mechanisms, a single-factor experiment was conducted using Zhulinshan smokeless coal as a model. By employing contact angle and sedimentation experiments, the optimal formulation method and concentration were established from four surfactants, which were mixed in pairs in equal proportions. Integrating the contact angle and sedimentation experiments of both single and compound surfactants with coal samples revealed that the compound solution of the anionic surfactant SDBS and the nonionic surfactant X-100 exhibited the most effective wetting performance on coal samples from Zhulinshan. The optimal compounding solution was identified as 0.05% SDBS and 0.05% X-100, yielding a contact angle of 16.910° and a sedimentation time of merely 5.79 s. A three-phase system consisting of water, surfactant, and coal was constructed by using the Build Layer tool. Subsequently, molecular dynamics simulations were performed with the Forcite module of Materials Studio software, where the interaction energy, relative concentration distribution, and diffusion coefficients of the water/surfactant/coal system were calculated and analyzed at the molecular level. The findings from contact angle experiments, sedimentation experiments, and optimal compounding schemes derived from molecular simulations regarding the impact of surfactant compounding on the wettability of coal samples were consistent.