Charging of the Ice/Solution Interface by Deprotonation of Dangling Bonds, Ion Adsorption, and Ion Uptake in an Ice Crystal As Revealed by Zeta Potential Determination
Charging of the Ice/Solution Interface by Deprotonation of Dangling Bonds, Ion Adsorption, and Ion Uptake in an Ice Crystal As Revealed by Zeta Potential Determination
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DOI：
10.1021/acs.jpcc.8b12435
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发表时间：
2019-03-14
影响因子：
3.7
通讯作者：
Okada, Tetsuo
中科院分区：
文献类型：
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作者：
Inagawa, Arinori;Harada, Makoto;Okada, Tetsuo
我们通过测量冰的zeta电位揭示了冰/溶液界面离子的充电机制和行为。冰的zeta电位，这是计算从一个探针在冰通道在各种条件下的迁移，使用斯特恩双电层模型解释。冰的zeta电位是由悬挂OH键的去质子化、离子在冰表面上的吸附以及离子在冰晶格中的吸收产生的。冰的表面上的悬挂OH键的去质子化增强相比，在散装液态水;前者的pK（a）估计是类似于3。有趣的是，即使在pH > 6的情况下，冰表面上的总悬挂OH键中也只有1.41%被去质子化，这表明悬挂键的去质子化抑制了附近OH位点的进一步解离。这是由于在存在L-缺陷的情况下，冰中的水分子容易重新取向。离子吸附常数表明，离子的相互作用，而不是H+与冰表面主要是由悬挂键的离子的配位。因此，较小的离子比较大的离子更容易吸附在冰表面上。此外，在冰晶晶格中的吸收建议。冰/水界面性质的阐明将使我们不仅能够了解在冰中限制的纳米或微米级液相中发现的独特性质，而且还可以开发使用冷冻水介质作为平台的新型分离和反应。
We reveal the charging mechanism and behavior of ions at the ice/solution interface through measurements of the zeta potential of ice. The zeta potential of ice, which is calculated from the migration of a probe in an ice channel under various conditions, is interpreted using the Stern double layer model. The zeta potential of ice is generated by the deprotonation of dangling OH bonds, the adsorption of ions on the ice surface, and ion uptake in the ice crystal lattice. The deprotonation of the dangling OH bonds on the surface of ice is enhanced compared to that in bulk liquid water; the pK(a) of the former is estimated to be similar to 3. Interestingly, only 1.41% of the total dangling OH bonds on the ice surface are deprotonated, even at pH > 6, suggesting that the deprotonation of a dangling bond suppresses further dissociation of the nearby OH sites. This is caused by the facilitated reorientation of the water molecules in ice in the presence of L-defects. The ion adsorption constants indicate that the interaction of ions other than H+ with the ice surface is mainly driven by coordination of the dangling bonds to the ions. Therefore, smaller ions are adsorbed more readily on the ice surface than their larger counterparts. Additionally, uptake of in the ice crystal lattice is suggested. Elucidation of the ice/water interface properties will allow us not only to understand the unique properties found in nano- or micro-sized liquid phases confined in ice but also to develop novel separations and reactions using frozen aqueous media as platforms.