Influence of electric field on the diffusion of water on the surface of kaolinite

In order to clarify the microscopic mechanism of the effect of electric field on the diffusion characteristics of water molecules on the surface of kaolinite, a kaolinite supercell model was constructed, and the grand canonical ensemble Monte Carlo(GCMC) and molecular dynamics(MD) simulation methods were used.The related Perl program was used to obtain the polarization conformation and adsorption morphology, diffusion coefficient, interaction energy and hydrogen bond evolution law of water molecules on the surface of kaolinite under different electric field conditions.The simulation results show that the polarization of the electric field will make the adsorption of water molecules on the surface of kaolinite into a regular upside-down “V” shape, away from the hydroxyl groups on the surface of kaolinite, and diffuse into the vacuum layer.When the electric field intensity is 10¹⁰ V/m, the included angle of the H—O—H bond of water molecules decreases by 3° under the influence of the Coulomb force.The diffusion of water molecules on the surface of kaolinite is anisotropic, and the diffusion coefficients in the X and Y directions are similar, and much larger than that in the Z direction.Water molecules diffuse more easily in the XY plane.The diffusion coefficient of water molecules increases with the increase of the electric field intensity, and the positive and negative directions of the electric field have little effect on the diffusion coefficient of water molecules.The interaction energy between water molecules and kaolinite is mainly electrostatic interaction energy and hydrogen bond interaction energy.After the electric field is applied, the electrostatic interaction energy and hydrogen bonding energy are greatly reduced, and the interaction energy is negatively correlated with the electric field strength.The electric field weakens the binding effect of water molecules on the surface of kaolinite, which is beneficial to the diffusion of water molecules on the surface of kaolinite.With the increase of the electric field intensity, the hydrogen bonding between water molecules and the surface of kaolinite weakens, the number of hydrogen bonds decreases, and the hydrophilicity of the kaolinite crystal surface decreases.