K+,Mg2+//SO42-,B4O72--H2O四元体系288K时的固液相平衡

摘要

Solid-Liquid equilibria of the reciprocal quaternary system K+, Mg2+∥SO2-4, B402-7 - H20 at 288 K were studied by isothermal solution equilibrium method. Solubilities and densities of each single salts in the solution of the reciprocal quaternary system were determined experimentally. According to the experimental data, the equilibrium phase diagram and water content diagram of the quaternary system were plotted,respectively. The experimental results show that the double salt K2SO4· MgSO4·4H20 forms in the quaternary system K+, Mg2+∥SO2-4, B402-7-H20 at 288 K. The phase diagram of the quaternary system at 288 K has three invariant points F1, F2 and F3, seven univariant curves E1-F1, E2-F1, E4-F3, E5-F3, E3-F2, F1-F2 and F2-F3, and five fields of crystallization [K2SO4·MgSO4·6H2O, K2B4O7·4H20, K2SO4, MgSO4·7H20 and MgB4O7·9H20].%采用等温溶解平衡法研究了288 K时K+,Mg+//SO42- B4O72- -H2O四元体系的固液相平衡关系,测定了该四元体系在288 K时平衡液相的溶解度和密度.依据实验测定的平衡溶解度数据及对应的平衡固相,绘制了该四元体系的平衡相图和水图.研究结果表明:交互四元体系K+,Mg2+//SO42-,B4O72-H2O 288 K时的相平衡关系中,有复盐软钾镁矾(K2SO4·MgSO4·6H2O)生成,平衡相图中有3个共饱点,7条单变量曲线,5个结晶区,对应的平衡固相分别为K2B4O7·4H2O,MgB4O7·9H2O,K2SO4,MgSO4·7H2O和K2SO4·MgSO4·6H2O.