Effect of Dodecyl Trimethyl Ammonium Bromide on the Migration of Water Molecules in the Pores of Lignite: An Experimental and Molecular Simulation Study

Molecular dynamics simulations and experiments were used to study the influence of dodecyl trimethyl ammonium bromide (DTAB) on the migration of water molecules in the pores of lignite. To simulate the accuracy, 13 C NMR was used to confirm the structure of Shengli lignite. It was found through adsorption experiments that DTAB reduces the specific surface area and pore volume of lignite. Molecular simulations indicate that the lignite and water molecules are primarily connected by hydrogen bonding. DTAB impedes the movement of water molecules in the pores of lignite and the storage space of compressed water molecules. Water molecules are mainly present in the pores of lignite in a posture parallel to the XOY plane, which facilitates the formation of hydrogen-bonding networks. However, this also leads to a decrease in the mobility of water molecules. Experimental and simulation results show that DTAB can enter lignite pores, reducing the water absorption in lignite. This is highly significant for the processing and utilization of lignite.