CsCl-PEG8000-H_(2)O三元体系288.2、298.2、308.2 K相平衡测定

Phase equilibria for ternary system CsCl-PEG8000-H_(2)O at 288.2,298.2 and 308.2 K

采用等温溶解法和浊点法研究了288.2、298.2、308.2 K下三元体系CsCl-PEG8000-H_(2)O的相平衡关系,采用经验方程分别对双液线和结线数据进行了拟合,绘制了完整相图。研究发现CsCl-PEG8000-H_(2)O体系在288.2、298.2、308.2 K下同时存在固液平衡与液液平衡关系,其完整相图均由不饱和液相区(L)、两个一液一固区(L+S)、双液相区(2L)、两液一固区(2L+S)和两固一液区(2S+L)构成;随着温度升高,不饱和液相区(L)、双液相区(2L)、一液一固区(L+S)、两液一固区(2L+S)均增大,两固一液区(2S+L)减小。对比288.2、298.2、308.2 K下三元体系CsCl-PEG1000/4000/6000/8000-H_(2)O完整相图,结果表明:288.2、298.2 K时,仅CsCl-PEG1000-H_(2)O体系存在固液平衡关系,CsCl-PEG4000/6000/8000-H_(2)O体系同时存在固液和液液平衡关系;308.2 K时,CsCl-PEG1000/4000/6000/8000-H_(2)O体系同时存在固液和液液平衡关系;双液相区(2L)随聚乙二醇分子量增大而增大。

The phase equilibrium relationship of the ternary system CsCl-PEG8000-H 2 O at 288.2,298.2 and 308.2 K was studied by isothermal dissolution method and turbidimetric method.Meanwhile,the empirical equations were used to fit the data of binodal curve and tie line.Based on the experimental data,the completed phase diagrams at 288.2,298.2 and 308.2 K were plotted.According to the experimental results,both solid-liquid equilibrium and liquid-liquid equilibrium coexisted in the ternary systems CsCl-PEG8000-H_(2)O at T=288.2,298.2 and 308.2 K.The corresponding phase diagrams at three temperature all composed of 6 regions:unsaturated liquid phase(L),two regions of one liquid and one solid phase CsCl(L+S),region of two-liquids phase(2L),two liquids with one solid CsCl(2L+S),and region of one liquid with two solids of CsCl and PEG8000(L+2S).Comparing the phase diagrams CsCl-PEG8000-H_(2)O at T=288.2,298.2 and 308.2 K,it can be concluded that with the temperature increase,the areas of(L),(2L),(L+S)and(2L+S)increased,while the area of(2S+L)decreased.Comparing the phase diagrams CsCl-PEG1000/4000/6000/8000-H_(2)O at T=288.2,298.2 and 308.2 K,it can be found that there is only solid-liquid equilibrium in the ternary system CsCl-PEG1000-H_(2)O at 288.2 and 298.2 K,while the solid-liquid and liquid-liquid equilibria were found in the systems CsCl-PEG4000/6000/8000-H_(2)O at 288.2 and 298.2 K.Both solid-liquid and liquid-liquid equilibria were found in ternary systems CsCl-PEG1000/4000/6000/8000-H_(2)O at 308.2 K.And the region of two-liquids phase increase with the increase of molecular weight of PEG.