高岭石表面水化机理及电场弱化其吸附性能的分子模拟  

Molecular Simulation of Surface Hydration Mechanism and Electric Field Weakening Adsorption Properties of Kaolinite

作　　者：李天宇 柴肇云[1] 杨泽前 辛子朋 孙浩程 闫珂 LI Tianyu;CHAI Zhaoyun;YANG Zeqian;XIN Zipeng;SUN Haocheng;YAN Ke(Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学原位改性采矿教育部重点实验室,太原030024

出　　处：《材料导报》2024年第1期119-125,共7页Materials Reports

基　　金：国家自然科学基金(52274091,51974193)。

摘　　要：高岭石是泥岩黏土矿物组成中的主要成分之一,其水理特性对分析高岭石类黏土矿物遇水工程性质劣化的研究至关重要,通过密度泛函理论和分子动力学模拟研究了高岭石表面水化机理及电化学作用对高岭石表面吸附性能的影响。结果表明:水分子在高岭石(001)晶面吸附时水中的Hw、Ow原子与高岭石表面羟基的Hs、Os原子间形成了Hw-Os及Hs-Ow两种类型的氢键,并且Hw-Os氢键作用较强;水分子与高岭石(001)晶面之间形成的氢键作用导致高岭石(001)晶面具有较强的亲水性质;外加电场对体系中水分子的平衡构象及吸附形态产生显著影响,当体系无电场时,水分子通过氢键与高岭石(001)晶面结合紧密,随着电场强度不断增加,水分子逐渐从高岭石表面脱附,以氢原子朝上、氧原子朝下的“V”字型结构向体相中扩散,水分子的偶极矩沿电场方向排列;随着水-高岭石体系中电场强度的增加,吸附体系中的氢键作用逐渐被破坏,水分子脱附能力增强,高岭石表面对水分子的吸附性降低。Kaolinite is one of the main components in the composition of mudstone clay minerals and its hydrophysical characteristics are essential for the analysis of the deterioration of engineering properties of kaolinite-like clay minerals in contact with water.The surface hydration mechanism of kaolinite and the influence of electrochemical effects on the adsorption properties of kaolinite surface were investigated by density functional theory and molecular dynamics simulation.The results show that during the adsorption of water molecule on the surface of kaolinite(001),two types of hydrogen bonds,H w-O s and H s-O w,are formed between the H w and O w atoms in water and the H s and O s atoms of the hydroxyl groups on the surface of kaolinite,and the H w-O s hydrogen bonding is stronger.The hydrogen bonding between water molecule and kaolinite(001)surface results in strong hydrophilicity of the kaolinite(001)surface.The applied electric field has a significant effect on the equilibrium conformation and adsorption pattern of water molecules in the system,when there is no electric field in the system,water molecules are tightly bonded to the kaolinite(001)surface through hydrogen bonding,and with the increasing strength of the electric field,water molecules are gradually disassociated from the kaolinite surface to diffuse into the bulk phase in a‘V’structure with hydrogen atoms facing up and oxygen atoms facing down,and the dipole moments of water molecules are arranged along the electric field direction.With the increase of electric field strength in the water-kaolinite system,the hydrogen bonding in the adsorption system is gradually destroyed,the desorption ability of water molecules is enhanced,and the adsorption of water molecules on the kaolinite surface is reduced.

关 键 词：高岭石 密度泛函理论 表面水化 分子动力学 电场 扩散 

分 类 号：P574[天文地球—矿物学]