Li＋, Na＋//SO42－, CO32－-H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li^＋, Na^＋// SO₄^2－, CO₃^2－-H₂O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na₃Li(SO₄)₂?6H₂O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li₂SO₄?H₂O, Na₂SO₄, Na₃Li(SO₄)₂?6H₂O, Li₂CO₃, Na₂CO₃?10H₂O. 复盐Na₃Li(SO₄)₂?6H₂O和一水硫酸锂(Li₂SO₄?H₂O)的结晶区较小, 而Li₂CO₃的结晶区最大; 该四元体系介稳平衡条件下未发现Na₂SO₄?10H₂O的结晶区.

Study on Metastable Equilibria in Quaternary System Li+, Na+//SO42-, CO32--H2O at 288 K

An experimental study on metastable equilibria at 288 K in the quaternary system Li^＋, Na^＋//SO₄^2－, CO₃^2－-H₂O was done by isothermal evaporation method. Metastable equilibrium solubilities and physico-chemical properties such as density, conductivity, pH, refractive index and viscosity of the solution were determined experimentally. The experimental results of the metastable equilibria show that the double salt Na₃Li(SO₄)₂?6H₂O] forms in the quaternary system Li^＋, Na^＋//SO₄^2－, CO₃^2－-H₂O at 288 K. According to the experimental data, the metastable equilibrium phase diagram and the physico-chemical composition diagram were plotted. In the metastable phase diagram, the quaternary system has three invariant points, seven univariant curves, five fields of crystallization Li₂SO₄?H₂O, Na₂SO₄, Li₂CO₃, Na₂CO₃?10H₂O, Na₃Li(SO₄)₂?6H₂O]. The double salt Na₃Li(SO₄)₂?6H₂O and Li₂SO₄?H₂O have smaller crystallization fields than the others. The crystallization field of Na₂SO₄?10H₂O was not found in the metastable equilibria.