The phase equilibria for CsCl in three polyethylene glycols (PEG) with molecular weights of 1000, 4000, 6000 g⋅mol −1 and water (H 2 O) mixed solvent were investigated at 288.15 and 308.15 K. The isothermal dissolution equilibrium method was applied for the solid–liquid equilibria experiments; the turbidimetric method was used for the liquid–liquid equilibria experiments. Results show that there is only solid–liquid equilibrium for the ternary system CsCl–PEG1000–H 2 O at 288.15 K, both solid–liquid and liquid–liquid equilibria coexist in ternary systems CsCl–PEG1000–H 2 O at 308.15 K and CsCl–PEG4000/6000–H 2 O at 288.15 and 308.15 K. For liquid–liquid equilibrium, the binodal curve and compositions of the tie-lines were obtained experimentally, and the effect of temperature and molecular weight of PEG on liquid–liquid equilibrium was discussed. It shows that the liquid–liquid equilibrium formed easily at higher temperature and larger molecular weight of PEG. Moreover, three nonlinear expressions were applied to correlate the binodal curve, and the experimental values of tie-line were correlated with a good agreement by using Othmer–Tobias, Bancroft and NRTL models.

中文翻译：

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由氯化铯、聚乙二醇 (PEG1000/4000/6000) 和水在 288.15 和 308.15 K 组成的系统的固-液和液-液平衡

在288.15和308.15 K下研究了CsCl在分子量为1000、4000、6000 g·mol -1 和水（H 2 O）混合溶剂的三种聚乙二醇（PEG）中的相平衡。应用等温溶解平衡法用于固液平衡实验；浊度法用于液-液平衡实验。结果表明三元体系CsCl-PEG1000-H 2 O在288.15 K时仅存在固-液平衡，在308.15 K和CsCl三元体系CsCl-PEG1000-H 2 O中固-液和液-液平衡共存–PEG4000/6000–H 2 O at 288.15 and 308.15 K. 对于液-液平衡，通过实验获得双节点曲线和连接线的组成，温度和 PEG 分子量对液-液平衡的影响为讨论。这表明在较高温度和较大分子量的 PEG 下容易形成液-液平衡。此外，应用三个非线性表达式来关联双节点曲线，并且通过使用 Othmer-Tobias、Bancroft 和 NRTL 模型，连接线的实验值与良好的一致性相关。