应用分子动力学模拟和拉曼光谱对钙、镁、氯离子水化现象的研究  

Application of molecular dynamics simulation and Raman spectroscopy to study the hydration phenomena of calcium,magnesium and chloride ions

作　　者：乔梦丹 李非[1,2,3,4] 王美玲 朱含钰 张宇 袁俊生[1,2,3,4] QIAO Meng-Dan;LI Fei;WANG Mei-Ling;ZHU Han-Yu;ZHANG Yu;YUAN Jun-Sheng(School of Chemical Engineering,Hebei University of Technology/Engineering Research Center for Chemical Technology of the Efficient Utilization of Seawater Resources,Tianjin 300130,China;Collaborative Innovation Center of Hebei Modern Marine Chemical Technology,Tianjin 300130,China;School of Chemical Engineering,Hebei University of Technology/Chemical Energy Conservation Process Integration and Resource Utilization National-Local Joint Engineering Laboratory,Tianjin 300130,China;Tianjin Key Laboratory of Chemical Process Safety,Tianjin 300130,China)

机构地区：[1]河北工业大学化工学院海水资源高效利用化工技术教育部工程研究中心,天津300130 [2]河北省现代海洋化工技术协同创新中心,天津300130 [3]河北工业大学化工学院化工节能过程集成与资源利用国家-地方联合工程实验室,天津300130 [4]天津市本质安全化工技术重点实验室,天津300130

出　　处：《原子与分子物理学报》2023年第1期21-30,共10页Journal of Atomic and Molecular Physics

基　　金：河北省自然科学基金(E2020202020,B2017202246);河北省高等学校科学技术研究项目(QN2019048);国家重点研究发展计划项目(2016YFB0600504);教育部创新团队发展计划项目(IRT14R14);河北省现代海洋化工技术协同创新中心项目(冀教科[2013]37号);河北省重点研发计划项目(19274003D);河北工业大学本科教育教学改革研究项目(201903020);基于工学并举的“海水提钾”一体化教学资源构建(202002046010);基于科教融合的海洋技术专业教学资源构建及应用探索(2020GJJG029)。

摘　　要：应用分子动力学方法,模拟了298 K下,密度为1.0 g/cm^(3)的水溶液中Ca^(2+),Mg^(2+),Cl^(-)的水化现象,得到了相应离子周围水分子的微观分布情况.发现在钙离子周围,水分子以其氧离子去靠近中心离子;而在氯离子周围,水分子则以其中的一个氢原子去靠近中心离子.通过分析三种离子的径向分布函数、配位数曲线、水化数、水化半径,发现Ca^(2+)的水化数和水化半径均大于Mg^(2+),即Ca^(2+)的水合能力比Mg^(2+)强.与以往研究结果相比,本文计算所得的自扩散系数更接近实验所得结果.为了使模型更好的代表真实水溶液体系,本文还应用分子动力学和拉曼光谱法研究了不同浓度的CaCl水溶液.分子动力学研究发现随着浓度的升高,CaCl溶液中Ca^(2+),Cl^(-)的配位数分别呈降低趋势.同时,随着浓度的升高,Ca,Cl^(-)的自扩散系数也呈现降低的趋势.作者推断这是由于浓度的升高,加剧了离子的微观反向运动造成的.拉曼光谱法研究发现随着水溶液中CaCl浓度的升高,溶液中的氢键网络结构受到了越来越严重的破坏,溶液中Ca^(2+)与Cl^(-)形成的直接接触离子对的数量开始大量增加.Using molecular dynamics method,the hydration phenomenon of Ca^(2+),Mg^(2+),Cl^(-)in an aqueous solution with a density of 1.0 g/cm^(3)at 298 K was simulated,and the microscopic distribution of water molecules around the corresponding ions was obtained.It was found that around calcium ions,water molecules approached the central ion by oxygen ions;around chloride ions,water molecules approached the central ion by the hydrogen atoms.By analyzing the radial distribution function,coordination number curve,hydration number,and hydration radius,it was found that the hydration number and hydration radius of Cawere greater than those of Mg^(2+).Therefore,it was speculated that the hydration capacity of Ca^(2+)was stronger than that of Mg^(2+).In order to simulate the real aqueous system,the microstructure of Ca^(2+)Claqueous solutions at different concentrations were studied by molecular dynamics and Raman spectroscopy.Molecular dynamics studies found that with the increase of concentration,the coordination number of Caand Clin Ca^(2+)Clsolution showed a decreasing trend.At the same time,as the concentration increases,the self-diffusion coefficients of Ca^(2+)and Clalso showed a decreasing trend.This may be caused by the microscopic reverse motion of the ions.The Raman results showed that with the increase of CaClconcentration,the hydrogen bond network structure in the solution was damaged severely.And there appeared more contact ion pairs formed by Caand Cl.

关 键 词：钙 镁 氯 离子水合作用 分子动力学模拟 拉曼光谱 

分 类 号：O641[理学—物理化学]