NaBr-CaBr2-H2O和KBr-CaBr2-H2O三元体系273.15 K相平衡实验及计算

采用等温溶解平衡法对两个三元体系NaBr-CaBr₂-H₂O和KBr-CaBr₂-H₂O在273.15 K下的固液相平衡关系进行了研究，测定了相关盐在水溶液中的溶解度，绘制其等温相图。结果表明，两个三元体系均为水合物型，即平衡固相中未发现任何复盐及固溶体。两个三元体系在273.15 K下的等温相图均由一个共饱点、两条等温溶解度曲线、两个平衡固相结晶区组成。三元体系NaBr-CaBr₂-H₂O在273.15 K的两个结晶区的平衡固相分别为NaBr·2H₂O和CaBr₂·6H₂O，NaBr·2H₂O的结晶区远大于CaBr₂·6H₂O。三元体系KBr-CaBr₂-H₂O在273.15 K的两个结晶区的平衡固相分别为KBr和CaBr₂·6H₂O，KBr的结晶区远大于CaBr₂·6H₂O。基于Pitzer模型，运用已报道的Pitzer参数对所研究的两个三元体系在273.15 K下的等温溶解度进行模拟计算，其计算结果与实验结果基本吻合。

Experiment and calculation of phase equilibrium in ternary systems NaBr-CaBr2-H2O and KBr-CaBr2-H2O at 273.15 K

The relationship of solid-liquid phase equilibrium in the two ternary systems NaBr-CaBr₂-H₂O and KBr-CaBr₂-H₂O were conducted at 273.15 K by using the isothermal dissolution equilibrium method. The results show that the two ternary systems are of hydrate type. That is, there is absence for double salt and solid solution identified in the equilibrium solid phase. The isothermal phase diagrams of the two ternary systems NaBr-CaBr₂-H₂O and KBr-CaBr₂-H₂O at 273.15 K are composed of an invariant point, two isothermal dissolution curves, and two equilibrium solid phase crystallization regions. The equilibrium solid phases of the ternary system NaBr-CaBr₂-H₂O in the two crystallization regions at 273.15 K are NaBr·2H₂O and CaBr₂·6H₂O, respectively, and the crystallization region of NaBr·2H₂O is much larger than that of CaBr₂·6H₂O. The equilibrium solid phases of the ternary system KBr-CaBr₂-H₂O in the two crystalline regions at 273.15 K are KBr and CaBr₂·6H₂O, respectively, and the crystalline region of KBr is much larger than CaBr₂·6H₂O. Based on the Pitzer model, the reported Pitzer parameters are used to calculate the isothermal solubility of the two ternary systems studied at 273.15 K, and the calculated results are basically consistent with the experimental results.