物理化学学报 >> 2015, Vol. 31 >> Issue (6): 1045-1053.doi: 10.3866/PKU.WHXB201504071

理论与计算化学 上一篇    下一篇

氧气在碱溶液中结构与扩散系数的分子动力学模拟

吕页清1,2, 郑诗礼1, 王少娜1, 杜浩1, 张懿1   

  1. 1 中国科学院过程工程研究所, 湿法冶金清洁生产技术国家工程实验室, 绿色过程与工程重点实验室, 北京100190;
    2 中国科学院大学, 北京100049
  • 收稿日期:2014-12-24 修回日期:2015-04-07 发布日期:2015-06-05
  • 通讯作者: 杜浩 E-mail:hdu@ipe.ac.cn
  • 基金资助:

    国家自然科学基金(51274179)和国家重点基础研究发展规划项目(973)(2013CB632601)资助

Structure and Diffusivity of Oxygen in Concentrated Alkali-Metal Hydroxide Solutions: A Molecular Dynamics Simulation Study

Lü Ye-Qing1,2, ZHENG Shi-Li1, WANG Shao-Na1, DU Hao1, ZHANG Yi1   

  1. 1 National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China;
    2 University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2014-12-24 Revised:2015-04-07 Published:2015-06-05
  • Contact: DU Hao E-mail:hdu@ipe.ac.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51274179) and National Key Basic Research Program of China (973) (2013CB632601).

摘要:

采用分子动力学方法对不同温度(25-120 ℃)及碱浓度(1:100-1:5, 摩尔比)下NaOH和KOH溶液中的氧气进行了模拟. 本文考察了NaOH及KOH溶液中溶剂-溶剂、氧气-溶剂及氧气-溶质的径向分布函数, 并采用爱因斯坦方程从均方位移曲线中计算得到了氧气及溶质离子的扩散系数. 结果显示随着碱浓度的升高, 氧气扩散系数逐渐减少; 在相同条件下, 氧气在NaOH溶液中扩散系数小于在KOH溶液中的扩散系数; 溶质离子扩散系数的变化规律与氧气一致. 通过与现有实验结果对比, 发现了分子动力学方法的可靠性及用于研究实验受限领域的优越性.

关键词: 分子动力学模拟, 氧气, NaOH, KOH, 扩散系数

Abstract:

Molecular dynamics simulations of oxygen molecules in NaOH and KOH solutions at different temperatures (25-120 ℃) and concentrations (1:100-1:5, molar ratios) were performed in this study. The interactions of oxygen molecules with the surrounding solvent and solute were clarified by considering the solvent-solvent, oxygen-solvent, and oxygen-solute radial distribution functions. The self-diffusion coefficients of the oxygen molecules and the solute were both determined by analyzing the mean-squared displacement (MSD) curves, using Einstein's relationship. It was concluded that at all concentrations, the diffusion coefficient of oxygen in NaOH solution is smaller than that in the corresponding KOH solution. The diffusion coefficients for hydroxide, Na+, and K+ decrease with increasing solute concentration, following similar trends to those of oxygen. The oxygen diffusion coefficient obtained in this study is in good agreement with the reported experimental value, suggesting that MSD is an attractive approach to study the oxygen diffusion behavior in strong alkaline solutions at elevated temperatures, which are experimentally extremely challenging.

Key words: Molecular dynamics simulation, Oxygen, NaOH, KOH, Diffusion coefficient

MSC2000: 

  • O645