稀散元素(铷和铯)提取分离的基础溶液化学研究

The salt lake brine will be a main source for the scattered alkali metal element rubidium and cesium materials in the future. However, the deficiency of basic solution chemistry of rubidium and cesium largely restricts their development and utilization. As an extension of our investigations on the rubidium and cesium resource chemistry in the past decade, this proposal will focus on the phase equilibria and thermodynamics of rubidium and cesium. On the base of an in-depth study of the solution behaviors of rubidium and cesium salts in the organic solvent-water systems, the influences of functional groups on the salting-out effect will be discussed. The phase equilibrium of rubidium/cesium salt-lithium/sodium/potassium salt-water multicomponent systems will be investigated to simulate the composition of salt lake brine. The solubility, density, viscosity, and other basic physical and chemical data will be obtained to complete the integrate phase diagrams. With the combination of EMF and isopiestic methods, the interactions between ions and ions, and ions and the solvent will be evaluated. The interaction parameters will be calculated from the Pitzer or other related models. Finally, the experimental data coupled with the model parameters will be utilized to forecast the phase equilibria of rubidium/cesium salts – mixed solvent or multicomponent salt-water systems. Undoubtedly, the development of this proposal will lay the foundation for the separation and enrichment of rubidium and cesium resources from the salt lake brine.

盐湖卤水中稀散碱金属元素铷、铯资源的合理利用将是未来铷和铯材料的主要来源和开发重点，而铷、铯盐水体系基础溶液化学研究的匮乏很大程度上制约了铷和铯资源的开发利用。本项目拟在我们多年来研究铷、铯资源化学的基础上，以相平衡和热力学为主要内容，深入研究铷、铯盐-混合溶剂体系溶液化学，力争从官能团的角度阐明有机溶剂在铷、铯盐水体系盐析过程作用的规律性；模拟盐湖卤水组成，开展铷、铯盐-锂、钠、钾盐-水多元交互体系的溶液化学研究，测定体系多温溶解度、密度、粘度等基本理化数据，完成体系相图的绘制；结合电动势法和等压法，探究铷、铯盐水体系中离子与离子之间、离子与溶剂之间相互作用关系，采用Pitzer等电解质溶液理论模型关联计算各类相互作用参数；结合实验结果和模型参数，实现铷、铯盐-混合溶剂和铷、铯多元交互体系的相平衡理论预测，为解决盐湖卤水中铷、铯资源的提取和分离富集问题奠定溶液化学基础。

稀散元素铷/铯离子在混合溶剂/混合电解质体系中的溶液行为研究，可以为水溶液中铷、铯资源的分离富集提供重要的参考依据。本项目基于我们十余年来在溶液化学领域研究的经验，系统研究了铷、铯离子与酰胺、离子液体以及脲类等及水组成的三元体系以及铷铯与钠钾等氯化物、溴化物和硫酸盐等组成的混合电解质体系的相化学和热力学性质。获得了体系的溶解度、密度和折光率等物理化学性质，以及活度系数、过量吉布斯自由能、水化数等热力学参数。系统探讨了系列溶剂官能团、极性、介电常数等对体系溶解度等性质的影响，以及有机溶剂的性质对溶液中离子-离子以及离子-溶剂间相互作用的影响规律。水盐体系相图的获得和水盐体系热力学性质的结果，为复杂离子体系中铷铯的分离提供支持。利用获得的溶解度数据，可以获得盐类溶解的热力学参数，而利用热力学结果，可以预测水盐体系的相行为。结合实验结果和模型参数，本项目的研究结果为盐湖卤水中铷、铯资源的提取和分离富集奠定了溶液化学基础。