中文摘要：

不同温度下的Na^＋//CI^-，SO4-^2，H2O体系液固平衡是芒硝和盐生产过程重要的理论基础，其应用方面的研究工作进行得较多，而多温下热力学的研究尚未见报道。本文采用Pizter离子相互作用模型理论，建立了上述体系热力学模型；利用该模型对上述体系在不同温度下的溶解度进行了预测，并与实验数据对比，研究了Pizter离子相互作用模型理论对于本体系多温情况的适用性。本文利用Pizter理论中的温度系数以及不同温度下该体系的溶解度实验数据，通过Matlab优化函数获得不同温度下各盐的活度积和两离子、三离子混合作用参数，并利用Matlab非线性方程求解函数，预测该体系0-150℃范围内的液固平衡数据，并与实验数据对比。研究结果表明Pizter模型的多温适用性良好，预测结果与实验数据基本一致，对生产实践有一定指导意义。

英文摘要：

The liquid-solid equilibrium of the system Na^＋//CI^- ,SO4^-2 - H2O is the important theory basis of industry of NaC1 and Na2S04, which has been studied on application for industry but not on its thermodynamics at different temperatures. In this paper, on the basis of Pitzer＇s ion interaction model of electrolyte solution, the thermodynamic model of this system has been established. As a resuit, the solubilities of the quaternary system Na^＋//CI^- ,SO4^-2 -H2O at 0 -150 ℃ were calculated. All the energy parameters were obtained from experimental solubilities data of the binary and ternary systems. The results showed that the solubilities predicted were in agreement well with experimental data, and Pitzer＇s model is well suitable for the system Na^＋//CI^- ,SO4^-2-H2O at different tempera tures.