NaBr-Na_2SO_4-H_2O三元体系323K相平衡研究

Phase equilibrium of ternary system of NaBr-Na_2SO_4-H_2O at 323 K

采用等温溶解平衡法研究了三元体系NaBr-Na2SO4-H2O在323 K的相平衡关系,测定了平衡溶液的溶解度及密度。研究发现,该三元体系为简单共饱和型,无复盐及固溶体形成。根据溶解度数据绘制了相图,相图中有1个共饱点E,2条单变量曲线EF,ED所对应的平衡固相分别为NaBr.2H2O和Na2SO4。在共饱点E处的液相组成(质量分数)分别为NaBr 54.37%,Na2SO40.70%。实验结果表明,NaBr对Na2SO4有较强的盐析作用。简要讨论了密度变化规律,对比了三元体系NaBr-Na2SO4-H2O在不同温度条件下共饱点的液相组成。

Phase equilibrium relationship of the ternary system of NaBr-Na2SO4-H2O at 323 K was studied by isothermal equilibrium method. The solubilities and densities of equilibrium solution were determined. The experimental results show that the ternary system is a type of simple common saturation and without complex salt and solid solution. On the basis of solubility data, the phase diagram of the temary system at 323 K was plotted, which consists of one invariant point E, two univariant curves EF, ED and two crystallization fields corresponding to NaBr·2H2O and Na2SO4. The composition （mass fraction ） of equilibrium solution at the invariant point E is 54.37% for NaBr and 0.70% for Na2SO4. It shows that NaBr has a better salting-out effect on Na2SO4. The density relationship was discussed briefly and the liquid components of NaBr-Na2SO4-H2O ternary system at the invariant point were compared at different temperatures.