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The Molecular Dynamics Study of the Molecular Structure of Highly Concentrated Aqueous Solution and the Control of Crystallization

高浓度水溶液分子结构及结晶控制的分子动力学研究

基本信息

批准号：
09650225
负责人：
HIHARA Eiji
金额：
$ 2.05万
依托单位：
the University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

The objectives of this study are to clarify the molecular structure of the highly concentrated aqueous electrolyte solution and to explain the macroscopically measured properties, such as solubility or pressure drop, on a molecular level using molecular dynamics simulation. As for liquid computer simulation, in the case of simple liquid, say liquid noble gases, where interactions between particles are well known, the results derived from the simulation deserve high degree of reliability. On the other hand, in the case of complicated liquid, which have not yet been treated analytically. They can predict the properties of liquid which cannot or not directly be measured and at the same time various tests of reliability are required. The contents and results are as follows.1. Comparison between J4D calculation and EXAFS analysis about molecular structureIn the mixture of aqueous electrolyte solutions, such as LiBr & KBr, the structure around Br was investigated. The calculation results using simplified pair potentials well agree with experimental ones. Even with a simplified potential, molecular dynamics simulation gives quantitative structural features.2. Prediction of the macroscopically measured propertiesWhen the concentration of a solution is over the solubility, the computational domain in which both vapor and liquid exist is effective. Because the pressure of the system is the same to the saturation vapor pressure, the control of pressure is not needed. The properties of a solution surface, such as density profile or surface tension, were calculated and the pressure drop was estimated.3. The MD simulation of absorption process and crystallization process The state of the solution surface during water vapor absorption and the effects of the non-equilibrium state on absorption rate were investigated. The simulation of a crystallization process is the next theme.

本研究的目的是澄清高浓度电解质水溶液的分子结构，并解释宏观测量的性能，如溶解度或压降，在分子水平上使用分子动力学模拟。至于液体计算机模拟，在简单液体的情况下，比如说液体惰性气体，其中粒子之间的相互作用是众所周知的，从模拟中得出的结果应该具有高度的可靠性。另一方面，在复杂液体的情况下，这还没有被分析处理。它们可以预测不能或不能直接测量的液体性质，同时需要进行各种可靠性试验。主要研究内容和结果如下：1. J4D计算与EXAFS分析分子结构的比较研究了LiBr和KBr混合电解质溶液中Br周围的结构。用简化的对势计算的结果与实验结果符合得很好。即使在简化势的情况下，分子动力学模拟也能给出定量的结构特征.宏观测量性质的预测当溶液浓度超过溶解度时，汽液共存的计算域是有效的。由于系统的压力与饱和蒸汽压相同，因此不需要控制压力。计算了溶液表面的性质，如密度分布和表面张力，并估算了压降.吸收过程和结晶过程的分子动力学模拟研究了水蒸气吸收过程中溶液表面的状态以及非平衡态对吸收速率的影响。结晶过程的模拟是下一个主题。