Acta Scientiarum Naturalium Universitatis Pekinensis ›› 2025, Vol. 61 ›› Issue (4): 687-696.DOI: 10.13209/j.0479-8023.2025.053

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Revised Homogeneous Nucleation Mechanism of KCl in Aqueous Solutions

ZHANG Meixi, SUN Qiang†   

  1. School of Earth and Space Sciences, Peking University, Beijing 100871
  • Received:2024-05-13 Revised:2024-05-22 Online:2025-07-20 Published:2025-07-20
  • Contact: SUN Qiang, E-mail: qiangsun(at)pku.edu.cn

水溶液中氯化钾均一成核机理修正

章美希, 孙樯†   

  1. 北京大学地球与空间科学学院, 北京 100871
  • 通讯作者: 孙樯, E-mail: qiangsun(at)pku.edu.cn
  • 基金资助:
    国家自然科学基金(8200908846)资助

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Abstract:

Molecular dynamics (MD) simulations on supersaturated KCl solutions are conducted to understand the homogeneous nucleation mechanism of ions in aqueous solution. According to the MD simulation results, dissolved K+ and Cl− ions tend to aggregate in solution. When the aggregates reach a critical size, KCl grains may crystallize inside the aggregates. The free energy surface (FES) during the nucleation process, calculated by the METAD method, demonstrates that the process of ion aggregation does not require the overcoming of a potential barrier, which is different from the two-step nucleation theory. Based on the structural analysis, the formation of aggregates may be closely related to hydrophobic effects. Therefore, the revised classical nucleation theory (rev-CNT) is proposed to understand the KCl homogeneous nucleation mechanism in aqueous solution.

Key words: potassium chloride (KCl), homogeneous nucleation, aggregates, hydrophobic effect, hydrogen bond

摘要：

为了解盐水溶液中离子的均一成核机制, 对过饱和KCl溶液进行分子动力学(MD)模拟。模拟结果表明, K+和Cl−趋向于在溶液中聚集, 形成离子聚合体。当聚合体达到临界尺寸时, 其中可能出现KCl晶核。使用METAD方法重建成核过程中的自由能表面(FES), 证明离子聚合无需克服势垒, 这与两步式(2-Step)成核机制有所不同。结构分析结果表明, 聚合体的形成可能与疏水作用相关。因此, 提出修正的经典成核理论(rev-CNT)来理解水溶液中KCl均一成核机制。

关键词: 氯化钾(KCl), 均一成核, 聚合体, 疏水作用, 氢键

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