Na~+,K~+//Br~-,B_4O_7~(2-)-H_2O交互四元体系348K相平衡研究

采用等温溶解平衡法研究了348 K时交互四元体系Na+,K+//Br-,B4O27--H2O的相平衡及平衡液相,测定了平衡液相的溶解度以及密度,补充了该体系在348 K下的溶解度和密度数据。研究结果发现,该体系属于简单共饱和体系,无复盐和固溶体生成。根据实验数据绘制了相应的相图、密度-质量分数图和含水量图,相图中有2个共饱点,5条单变量曲线,4个结晶区。4个结晶区的平衡固相分别为:Na2B4O7.5H2O,K2B4O7.4H2O,KBr和NaBr。从相图上可以看出,该体系在348 K时Na2B4O7.5H2O的结晶区最大,NaBr的结晶区最小。

Phase equilibria of reciprocal quaternary system Na~+,K~+//Br~-,B_4O_7~(2-)-H_2O at 345 K

Phase equilibria of the reciprocal quaternary system Na+,K+//Br-,B4O2-7-H2O at 348 K were studied by the isothermal equilibrium method.The solubilities and densities of equilibrium solution were determined,so the solubilitise and densities of the system at 348 K were supplemented.The experimental results show that the reciprocal quaternary system is a simple common saturation and without complex salt and solid solution.According to the experimental data,the phase diagram,density-composition diagram and water content diagram of the reciprocal quaternary system at 348 K were plotted,and the phase diagram consists of two invariant points,five univariant curves,and four crystallization fields.The equilibrium solid phases of the four crystallization fields were Na2B4O7·5H2O,K2B4O7·4H2O,KBr and NaBr,respectively.From the phase diagram of the system at 348 K,it reveals that the crystallization field of Na2B4O7·5H2O is the biggest and the counterpart of NaBr is the smallest.