Experimental and kinetic analysis of the fluorocarbon structures and coal particles at the microscale

Understanding the dynamic wetting process between liquid droplets and coal dust particles is crucial. Compared to other substances, coal possesses a more intricate microscale molecular chemical structure, with coal's molecular chemical and physical structural characteristics being the primary microscale factors influencing its wetting properties. To enhance the wetting and permeability performance of coal dust, an analysis of the microstructural influences on the wetting process of coal dust through experiments and simulations with five different structured fluorocarbon solutions: perfluorooctane sulfonate sodium (A1), perfluoroisopropyl acrylate (A2), perfluorooctane sulfonic acid ammonium salt (A3), perfluorooctyl alcohol polyoxyethylene ether (N1), and perfluorohexyl ethanol polyoxyethylene ether (N2), was conducted. A wetting theory model (collision–adsorption–immersion) was proposed based on experiments with different concentrations and types of surface tension, and wetting experiments were conducted based on this theory model. The results indicate that smaller coal particle sizes facilitate solution penetration, with the N2 solution demonstrating the best wetting and permeation effects. Microstructural experimental analysis revealed that N2 has more polar functional group structures than the other four fluorocarbon solutions. To further investigate the forces of different structures on coal particles, a molecular dynamics model was employed, and the simulation results indicated that the interaction forces and the number of hydrogen bonds representing the adsorption capacity in the N2 system were the highest.