Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (6): 1045-1053.doi: 10.3866/PKU.WHXB201504071


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
  • 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).


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