三元体系Li2SO4-MgSO4-H2O在273.15K时介稳相平衡

Metastable equilibria of ternary system Li_2SO_4-MgSO_4-H_2O at 273. 15 K

采用等温蒸发法,测定了三元体系Li2SO4-MgSO4-H2O在273.15 K时介稳平衡的溶解度和液相的物化性质(密度和折光率)。根据实验数据绘制了相应的介稳相图和物化性质-组成图。研究结果表明:该三元体系有1个共饱点(Li2SO4·H2O+MgSO4·7H2O),2条单变量溶解度曲线,2个单盐结晶区:Li2SO4·H2O,MgSO4·7H2O,其中MgSO4·7H2O的结晶区域较大。该体系属简单共饱型,无复盐及固溶体产生。介稳平衡溶液的物化性质密度、折光率随溶液中MgSO4含量的变化而有规律变化,并且在共饱点处有最大值。采用经验公式预测了该体系介稳平衡溶液的密度和折光率,预测值与实验值吻合较好。

The solubilities and the physicochemical properties （density and refractive index） of the ternary system Li2SOa-MgSOn-H20 at 273.15 K were determined by isothermal evaporation method. According to the experimental data, the metastable equilibrium phase diagram and the physicochemical properties vs. composition diagram were plotted. The experimental results of the metastable equilibria show that there is one eutectic point for （Li2SO4 ·H20 ＋ MgSO4· 7H20）, two univariant curves, and two crystallization regions corresponding to the large area of epsomite （MgSO4·7H20） and the relative small area of lithium sulphate monohydrate （Li2SO4 · H20）. The system belongs to a simple co- saturated type, and neither double salt nor solid solution was found. It also indicates that the physieochemical properties of the metastable equilibrium solution are in regular changes with the change of sulfate ion concentration, and achieve the maximum values at the invariant point in the system. The calculated values of densities and refractive indices in the quaternary system by the empirical equations agree well with the experimental values.