Diffusions in Aqueous Solutions with Multivalent Cations and Especially in Cationic First Hydration Shell.
Diffusions in Aqueous Solutions with Multivalent Cations and Especially in Cationic First Hydration Shell.
复制标题
DOI：
10.1021/acs.jpcb.2c02110
复制
发表时间：
2022-05
期刊：
影响因子：
--
通讯作者：
Jinbing Zhang;Jie Cui;Fengping Wang;J. Xiang;Z. Cao;Qiang Wang
中科院分区：
文献类型：
--
作者：
Jinbing Zhang;Jie Cui;Fengping Wang;J. Xiang;Z. Cao;Qiang Wang
与单价阳离子扩散相比，多价阳离子的扩散行为知之甚少，更不用说水在其第一水化壳层中的扩散。在这里，我们表明，所有公布的平移扩散系数的多价阳离子和水在室温下测得的表现出相同的浓度依赖性时，绘制为自由水或水合溶质的质量分数的函数。这种行为一直保持到只有水合和承压水保留在溶液中，其中它们的浓度依赖性变成阳离子电荷数依赖性。我们还发现，冰山模型可以很好地描述多价阳离子的扩散随着水含量的减少，直到只有水化水存在。然而，1H-脉冲场梯度核磁共振测量证实，在室温下，第一水化壳层中的1H比Al 3+扩散得快，并且只有当温度降低到约243 K时，它们才具有相同的扩散系数。因此，冰山模型只能等价地描述强离子-水相互作用对多价阳离子扩散的影响。这些结果也将帮助我们重新认识我们目前的理解的途径水合水影响溶质的扩散行为与相对较弱的溶质-水相互作用。
Compared with univalent cationic diffusion, little is known about the diffusion behavior of multivalent cations let alone the diffusion of water in their first hydration shell. Here, we show that all published translational diffusion coefficients of multivalent cations and water measured at room temperature exhibit the same concentration dependence when plotted as a function of the mass fraction of free water or of hydrated solute. This behavior is held until only hydration and confined water remain in solutions, wherein their concentration dependences become cationic charge number-dependent. We also found that the iceberg model can well describe the diffusions of multivalent cations with decreasing water content until only hydration water is present. However, 1H-pulsed-field-gradient nuclear magnetic resonance measurements confirmed that 1H in the first hydration shell diffuses faster than Al3+ at room temperature and they have the same diffusion coefficient only with decreasing the temperature down to about 243 K. Therefore, iceberg model only equivalently describes the effect of strong ion-water interaction on multivalent cationic diffusion. These results will also help us reconceive our current understanding of the pathway for hydration water affecting the diffusion behavior of solutes with relatively weak solute-water interactions.