Investigating the floc formation of kaolinite with molecular dynamics: association mechanisms in salt solution and deionized water

M Lu and YY Zheng and ZY Yin, COMPUTERS AND GEOTECHNICS, 184, 107312 (2025).

DOI: 10.1016/j.compgeo.2025.107312

The focus of research in environmental geology has always been the formation mechanism and structural characteristics of clay floc. The association characteristics of kaolinite floc are mainly dominated by the ions and water in the solvent. This study explored the association behavior of kaolinite minerals in NaCl solution and deionized water through the Molecular Dynamics method. The flocculation process of kaolinite minerals was reproduced by soaking them in a solvent. Minerals would mainly form the face-face or edge-face floc in NaCl solution while contacted in an edge-edge or edge-face manner in deionized water. The bridging, weakening, and shielding effects of ion and the double layer repulsion (e.g., repulsion of clay-clay and water-water) were obtained through analyzing the association process, EDL (electric double layer) structure, as well as the electrostatic and van der Waals energies. Additionally, salt concentration, interparticle spacing, and initial configuration were taken into account. These micro factors determined the association by influencing ionic effects and double layer repulsion. This study investigated the mechanism of kaolinite association at the micro level and emphasized the role of ion and EDL, which verified and supplemented the macro experiments and theory.

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