Influence mechanism of lattice Mg(Ⅱ)impurities on the sur-face charge characteristics of kaolinite

CHEN Jun; ZHOU Chao; SUN Yu; YU Guoqiang; MIN Fanfei

doi:10.16447/j.cnki.cpt.2025.03.002

Abstract：In order to explore the influence mechanism of lattice Mg(Ⅱ)impurities on the surface charge char-acteristics of kaolinite,Mg(Ⅱ)doped kaolinite is taken as the research object.The surface charging charac-teristics of Mg(Ⅱ)doped kaolinite are systematically studied by means of Density Functional Theory(DFT)and classical Molecular Dynamics(MD).The molecular simulation results are verified by Zeta potential test-ing of Mg(Ⅱ)doped kaolinite samples.The results of DFT show that:after Mg(Ⅱ)doping,the Mg and ad-jacent oxygen atoms have formed new bonds,which makes the charge on the surface of kaolinite rearrange and present a negative charge.MD results show that the negative surface charge of kaolinite(001)surface increases and the surface potential decreases with the increase of Mg(Ⅱ)doping.The results of Zeta potential test show that the deprotonation on kaolinite basal and edge surfaces gradually increases with the increase of solution pH value,and the surface potential of kaolinite surfaces with different Mg(Ⅱ)doping amounts gradually de-creases,and the negative surface charge of Mg(Ⅱ)doped kaolinite is significantly stronger than that of pristine kaolinite.The experimental results are in good agreement with the molecular simulation results,which verifies the accuracy of the simulation.The influence mechanism of Mg(Ⅱ)doping on the charge of kaolinite is mainly that the negative charge characteristics of kaolinite surface are significantly enhanced,and the elec-trostatic repulsion between particles is enhanced,resulting in difficult agglomeration of fine kaolinite particles.The research can provide further theoretical support for the efficient sedimentation of coal slurry.