Insights into water-mediated ion clustering in aqueous CaSO4 solutions: pre-nucleation cluster characteristics studied by ab initio calculations and molecular dynamics simulations
Insights into water-mediated ion clustering in aqueous CaSO4 solutions: pre-nucleation cluster characteristics studied by ab initio calculations and molecular dynamics simulations
复制标题
深入了解 CaSO4 水溶液中水介导的离子簇：通过从头计算和分子动力学模拟研究成核前簇特征
DOI：
10.1039/c7cp00428a
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发表时间：
2017
影响因子：
3.3
通讯作者：
Xia Fei-Fei
中科院分区：
文献类型：
--
作者：
Li Hui-Ji;Yan Dan;Cai Hou-Qin;Yi Hai-Bo;Min Xiao-Bo;Xia Fei-Fei
构建晶体的生长单元的分子结构是水溶液结晶过程中的一个基本问题。在这项工作中，系统地研究了预成核团簇及其在CaSO4水溶液中的水化特性，采用从头计算和分子动力学（MD）模拟。从头计算和MD模拟结果表明，CaSO4水溶液中的优势组分为单齿离子相关结构。与带电离子簇相比，中性离子簇更有可能出现在CaSO4水溶液中。中性（CaSO4）m团簇可能是参与预成核或结晶过程的生长单元。同时，CaSO4水溶液中离子缔合物的水化行为在相关的相/多态性选择中起着重要作用。在离子聚集过程中，由于Ca2+和SO42−的双重作用，一些水分子在Ca2+周围的驻留被削弱，而一些桥接水分子的驻留被增强。在CaSO4水溶液中，通过控制预成核团簇周围的水化，可以实现一定的相/多态性选择。此外，钙与硫酸盐之间的关联趋势较强，这暗示了硫酸钙在水中的溶解度较低。
The molecular structure of growth units building crystals is a fundamental issue in the crystallization processes from aqueous solutions. In this work, a systematic investigation of pre-nucleation clusters and their hydration characteristics in aqueous CaSO4 solutions was performed using ab initio calculations and molecular dynamics (MD) simulations. The results of ab initio calculations and MD simulations indicate that the dominant species in aqueous CaSO4 solutions are monodentate ion-associated structures. Compared with charged ion clusters, neutral clusters are more likely to be present in an aqueous CaSO4 solution. Neutral (CaSO4)m clusters are probably the growth units involved in the pre-nucleation or crystallization processes. Meanwhile, hydration behavior around ion associated species in aqueous CaSO4 solutions plays an important role in related phase/polymorphism selections. Upon ion clustering, the residence of some water molecules around Ca2+ in ion-associated species is weakened while that of some bridging waters is enhanced due to dual interaction by Ca2+ and SO42−. Some phase/polymorphism selections can be achieved in aqueous CaSO4 solutions by controlling the hydration around pre-nucleation clusters. Moreover, the association trend between calcium and sulfate is found to be relatively strong, which hints at the low solubility of calcium sulfate in water.