Effect of different surfactants on the wettability of coal dust based on Dmol3 module

Coal dust control has always been a real problem in underground coal mines and the addition of dust suppressants to achieve effective deposition of coal dust based on spray technology has good application prospects. However, in the preparation of dust suppressants, the selection of raw material surfactants is often carried out experimentally, which has some technical difficulties such as low efficiency, high cost and harsh experimental conditions. As the molecular simulation technology has become quite mature and been widely used in many fields such as physics, chemistry and biology as an important tool for material structure analysis and transition state search, using molecular simulation technology, with the help of the front-line orbital energy difference in quantum chemical analysis as the main criterion for surfactant wettability, and the electrostatic potential polar size and hydrogen bonding number of surfactant molecules as an auxiliary means, the coal dust wettability of fast penetrant T,sodium dodecyl benzene sulfonate(SDBS),and cocamidopropyl betaine(CAB) was discussed. The wettability of the above surfactants was macroscopically demonstrated by surface tension, surfactant capillary reverse osmosis experiments and contact angle experiments. The molecular dynamics analysis was carried out at the molecular level by establishing a three-phase kinetic model of coal/water/surfactant to observe the trend of mutual motion between the molecules under different surfactant systems, and the simulation results were analyzed in terms of relative concentration, mean square displacement and radial function distribution. The simulation results were validated at the molecular level to verify the wetting performance of different surfactants. The results show that the number of hydrogen bonds formed with water molecules by the frontline orbital energy difference of the fast penetrant T molecule is 5.077 eV,1 098,the SDBS is 4.387 eV,1 046 and the CAB is 2.077 eV,1 029.While the minimum surface tension, contact angle and coal dust penetration height of the aqueous solutions of the three to coal dust are 23.80 mN/m, 27.12°,4.1 cm; 26.83 mN/m, 32.69°,3.2 cm; 29.94 mN/m, 39.61°,1.4 cm. As the orbital energy difference decreases, the wetting effect of surfactant on coal dust also gradually decreases, the surfactant frontline orbital energy difference is directly related to its wettability, the larger the surfactant orbital energy difference, the more the number of hydrogen bonds formed with water molecules, the better the wettability of surfactant solution, which is consistent with relative concentration, and radial function. The experimental results are also consistent with the molecular simulation results table, showing the same variation pattern, which verifies the reasonableness of the simulation.