Effects of Mg(II) doping amount on the hydration characteristics of kaolinite surface: Molecular dynamics simulations and experiments

Abstract

To explore the microscopic effects of Mg(II) doping amount on the hydration characteristics of kaolinite surface, the Mg(II) ions and kaolinite were used as the subjects of research in molecular dynamics simulations and experimental verification to investigate the microscopic effects of the lattice magnesium impurity on the surface hydration of kaolinite. The results indicate that the interaction between H2O and Mg(II)-doped kaolinite (Mg(II)-Kao) surfaces, along with hydrogen bonding at the interface, gradually increase with increasing Mg(II) doping amounts, implying that Mg(II) doping significantly enhance the surface hydration of kaolinite. The hydration of the Mg(II)-doped kaolinite (001) surface (Mg(II)-Kao(001)) is stronger than that of the Mg(II)-doped kaolinite (001¯) surface (Mg(II)-Kao(001¯)) with the same Mg(II) doping amount. As the quantity of Mg(II) doping increased, the contact angle and humidity of the kaolinite surface decrease and progressively increase, respectively, signifying that the hydration level of the kaolinite surface increase. Overall, the main influence of Mg(II) doping on the surface hydration properties of kaolinite is the enhancement of hydration activity and ionic hydration. The results can provide theoretical support for further study of the real clay surface hydration mechanism, efficient treatment of clay-containing mineral processing wastewater and resource utilization of coal measure clay.