CIESC Journal ›› 2021, Vol. 72 ›› Issue (6): 3160-3169.DOI: 10.11949/0438-1157.20201696

• Special column for comprehensive utilization of salt lake resouces in Qinghai • Previous Articles     Next Articles

Pitzer thermodynamic model of the system HCl-NaCl-CaCl2-H3BO3-H2O at 298.15 K and its application

LI Dan1(),SUN Shuaiqi1,ZHANG Tao1,ZHAO Yihui1,MENG Lingzong1(),GUO Yafei2,DENG Tianlong2   

  1. 1.School of Chemistry and Chemical Engineering, Linyi University, Linyi 276000, Shandong, China
    2.College of Chemical Engineering and Materials Science, Tianjin University of Science and Technology, Tianjin 300457, China
  • Received:2020-11-27 Revised:2021-01-28 Online:2021-06-05 Published:2021-06-05
  • Contact: MENG Lingzong

五元体系HCl-NaCl-CaCl2-H3BO3-H2O在298.15 K的Pitzer模型及其应用研究

李丹1(),孙帅琦1,张涛1,赵一慧1,孟令宗1(),郭亚飞2,邓天龙2   

  1. 1.临沂大学化学化工学院,山东 临沂 276000
    2.天津科技大学化工与材料学院,天津 300457
  • 通讯作者: 孟令宗
  • 作者简介:李丹(1982—),女,硕士,讲师,lidan@lyu.edu.cn
  • 基金资助:
    山东省自然科学基金项目(ZR2020MB051);国家自然科学基金项目(22073068)

Abstract:

Solubility and refractive index in the ternary system CaCl2-H3BO3-H2O at 323.15 K were investigated with the dissolution equilibrium method. The phase diagram of this system consists of one invariant point, two univariant solubility curves and two single-salt crystallization regions for CaCl2·6H2O and H3BO3. The Pitzer parameters containing H3BO3 in the quinary system HCl-NaCl-CaCl2-H3BO3-H2O were fitted with the solubility data of ternary systems in this study and literatures. Combining the dissolution equilibrium constants of the solid phases in the quinary system, the Pitzer model of this system was constructed. The solubility in the quinary system and its subsystems were calculated with the Pitzer model. The phase diagrams and Pitzer model for the quaternary system were used to conduct computer simulation of H3BO3 separation from brine with NaCl and CaCl2. The order of salt precipitation and changes in concentration of the brine were obtained. The calculation results show that the separation of H3BO3 is easier to achieve under acidic conditions.

Key words: Pitzer thermodynamic model, boric acid, solid and liquid equilibrium, solubility, brine separation

摘要:

采用等温溶解法测定了三元体系CaCl2-H3BO3-H2O在298.15 K的溶解度和液相的折射率,该三元体系为简单共饱型,有1个共饱点,2条溶解度曲线和2个单盐结晶区,分别为CaCl2·6H2O和H3BO3。结合本文测定和文献中的溶解度数据,拟合了五元体系HCl-NaCl-CaCl2-H3BO3-H2O中含H3BO3的Pitzer参数,结合固相的溶解平衡常数,构建了该五元体系的Pitzer模型,并计算了该五元体系及其子体系的溶解度。根据Pitzer模型和计算相图,对氯化钠、氯化钙共存卤水中硼酸的分离进行了计算,获得了分离过程中的析盐顺序和卤水组成的变化规律。计算结果表明酸性条件下更容易实现H3BO3的分离。

关键词: Pitzer热力学模型, 硼酸, 固液相平衡, 溶解度, 卤水分离

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