Na^+、K^+//SO^4^(2-)-H_2O三元体系273K介稳相平衡研究

Study on Metastable Phase Equilibrium of Na^+,K^+//SO_4^(2-)—H_2O Ternary System at 273 K

采用等温蒸发法研究了三元体系Na+、K+//SO42--H2O 273 K时介稳相平衡,测定了该体系的溶解度和液相密度。根据溶解度数据绘制了相图。该体系的介稳相图由2条单变量曲线、2个结晶相区和1个共饱点组成。2个结晶区分别对应于盐K2SO4和Na2SO4.10H2O的结晶区;共饱点液相组成为w(K2SO4)7.56%、w(Na2SO4)5.14%。该体系属简单共饱型,无复盐及固溶体形成。

The metastable phase equilibrium of Na^＋,K＋//SO4^2--H2O ternary system was studied by isothermal evaporation method at 273 K, and the solubilities and densities of this system were measured. Phase dia- gram was plotted according to the solubility data. There exist two univariant curves, two crystallization fields and one co-saturation point in the isothermal metastable diagram. The two crystallization fields are corresponding to K2SO4 and Na2SO4·10H2O respectively, and the composition of the co-saturation point is w（K2SO4） 7.56% and w（Na2SO4）5.14%. This ternary system was simple evtonic type, without double-salt or solid solution formed.