化工学报 ›› 2021, Vol. 72 ›› Issue (6): 3179-3187.DOI: 10.11949/0438-1157.20201473

• 青海盐湖资源综合利用专栏 • 上一篇    下一篇

四元体系LiB5O8 + NaB5O8 + KB5O8 + H2O在298.15 K实验与理论预测相平衡研究

宋江涛(),袁菲,余艳,郭亚飞(),邓天龙   

  1. 天津科技大学化工与材料学院,天津市卤水化工与资源生态化利用重点实验室,天津 300457
  • 收稿日期:2020-10-22 修回日期:2021-01-21 出版日期:2021-06-05 发布日期:2021-06-05
  • 通讯作者: 郭亚飞
  • 作者简介:宋江涛(1993—),男,硕士研究生,1838768858@qq.com
  • 基金资助:
    国家自然科学基金项目(22073068);教育部创新团队资助计划项目(IRT_17R81)

Experimental and predictive phase equilibria for the quaternary system LiB5O8 + NaB5O8 + KB5O8 + H2O at 298.15 K

SONG Jiangtao(),YUAN Fei,YU Yan,GUO Yafei(),DENG Tianlong   

  1. Tianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization, College of Chemical Engineering and Material Sciences, Tianjin University of Science and Technology, Tianjin 300457, China
  • Received:2020-10-22 Revised:2021-01-21 Online:2021-06-05 Published:2021-06-05
  • Contact: GUO Yafei

摘要:

采用等温溶解平衡法研究了四元体系LiB5O8 + NaB5O8 + KB5O8 + H2O在298.15 K下的相平衡。实验测定了该体系在298.15 K下的固液相平衡溶解度和物理性质(密度和折射率),基于实验溶解度绘制了四元体系的干盐相图、水图和物理性质组成图。在该四元体系的干基图中,有一个共饱点(LiB5O8·5H2O + NaB5O8·5H2O + KB5O8·4H2O)、3条单变量溶解度曲线和3个单盐结晶区(LiB5O8·5H2O、NaB5O8·5H2O和KB5O8·4H2O)。该体系在298.15 K下没有复盐和固溶体生成,属于简单四元水溶液体系。结合三元体系溶解度,拟合获得了3种碱金属五硼酸盐的单盐参数和三离子混合作用参数;应用Pitzer及其扩展的HW模型对溶解度进行预测,预测值与实验值吻合较好,表明获得的Pitzer参数可靠。研究结果可为碱金属五硼酸盐分离纯化提供理论基础。

关键词: 水盐体系, 相平衡, Pitzer模型, 碱金属五硼酸盐

Abstract:

The isothermal solution equilibrium method was used to study the phase equilibrium of the quaternary system LiB5O8+ NaB5O8 + KB5O8 + H2O at 298.15 K. The solid-liquid equilibrium solubility and physical properties (density and refractive index) of the system at 298.15 K were experimentally determined. Based on the experimental solubility, the dry salt phase diagram, water diagram and physical property composition diagram of the quaternary system were drawn. There are one invariant point (LiB5O8·5H2O + NaB5O8·5H2O + KB5O8·4H2O), three univariant isothermal dissolution curves, and three crystallization zones corresponding to LiB5O8·5H2O, NaB5O8·5H2O, and KB5O8·4H2O, respectively. It was found that neither double salt nor sold liquid was formed in this alkalis pentaborate system, and it belongs to the simple quaternary aqueous system. Based on the solubility data of sub-ternary systems, the single salt parameters and three-ion mixing parameters of the three pentaborates were obtained. The predictive solubility obtained by Pitzer and its extended HW model agrees well with the experimental values, indicating that the Pitzer parameters obtained in this work are reliable. The results of this study can provide the basic data of phase equilibria for the separation and purification of alkali-pentaborates.

Key words: salt-water system, phase equilibrium, Pitzer model, alkalis pentaborates

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