氧气在碱溶液中结构与扩散系数的分子动力学模拟

摘要

Molecular dynamics simulations of oxygen molecules in NaOH and KOH solutions at different temperatures (25-120 ° C) 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 al concentrations, the diffusion coefficient of oxygen in NaOH solution is smal er than that in the corresponding KOH solution. The diffusion coefficients for hydroxide, Na+, and K+decrease with increasing solute concentration, fol owing 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 chal enging.%采用分子动力学方法对不同温度(25-120°C)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。