离子液体[EMIM][BF_4]/乙醇混合体系的分子动力学模拟研究

Molecular Dynamics Simulations of Structure and Properties of 1-Ethyl-3-methylimidazolium Tetrafluoroborate Ionic Liquid and Ethanol Mixtures

利用分子动力学模拟研究了298.15 K、0.1 MPa下乙醇摩尔分数为0.1～0.4的1-乙基-3-甲基咪唑四氟硼酸盐([EMIM][BF4])/乙醇混合体系.获得了体系的密度、径向分布函数、自扩散系数、粘度和电导率.模拟得到的密度值与实验值符合得较好;混合体系各组分之间的径向分布函数随乙醇摩尔分数的增加呈现有规律的变化;体系内阴阳离子的自扩散系数随着乙醇摩尔分数的增加不断增大;体系粘度随着乙醇摩尔分数的增加逐渐减小,电导率不断增大.分析空间分布函数得到体系中各组分的三维空间分布情况.研究工作揭示了有机分子对离子液体中离子的存在形式、迁移性、分子间和分子内相互作用和扩散机制的影响,对离子液体在有色金属电化学冶金与材料制备领的应用域具有重要指导作用.

Molecular dynamics simulations of the mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid and ethanol are performed at 298.15 K and 0.1 MPa with ethanol mole fraction between 0.1~0.4.Densities,radial distribution functions,self-diffusion coefficients,viscosities and conductivities of the system are obtained.The simulated densities agree well with the experimental values.The radial distribution functions of different components in the mixture present regular changes：the viscosity decreases with increasing ethanol mole fraction,whereas the conductivity and the self-diffusion coefficients of the cation and anion increase respectively.The spatial distribution functions obtained from the MD simulations are visualized to depict the microscopic structures of different components in the system.The effects of organic molecules on the forms,mobilities,inter-or intra-molecular interactions,diffusion mechanisms of ions,cations and anions in ionic liquids are revealed,which is important for application of ionic liquids in electro-winning of non-ferrous metals and material preparing.