Na^+,Mg^(2+)//SO_4^(2-),B_4O_7^(2-)-H_2O交互四元体系288K时相平衡研究

Study on Phase Equilibria of the Quaternary System Na^+,Mg^(2+)//SO_4^(2-),B_4O_7^(2-)-H_2O at 288 K

采用等温溶解平衡法研究了288K时Na+,Mg2+//SO42-,B4O72--H2O四元交互体系的相平衡关系,测定该体系在288K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以及其密度-组成图。研究结果表明:交互四元体系Na+,Mg2+//SO42-,B4O72--H2O288K时的相平衡实验中,有复盐Na2SO4·MgSO4·4H2O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Na2B4O7·10H2O,MgB4O7·9H2O,Na2SO4·10H2O,MgSO4·7H2O和Na2SO4·MgSO4·4H2O。

Phase equilibria of reciprocal quaternary system Na^ ＋ ,Mg^2＋ / /SO42,B4O72H2O at 288K were studied by isothermal solution equilibrium method.Solubilities and densities of each single salts in the solution of reciprocal quaternary system were determined experimentally.According to the experimental data,the equilibrium phase diagram and density composition diagram of the quaternary system were plotted.The experimental results showed that the double salt Na2SO4·MgSO4·4H2O forms in the quaternary system Na^ ＋ ,Mg2 ^＋ / /SO42 ,B4O72 H2O at 288K.The quaternary system has three invariant points F1,F2,and F3,seven univariant curves E1 F1,E2 F1,E4 F3,E5 F3,E3 F2,F1 F2,F2 F3,and five fields of crystallization [Na2SO4 ·MgSO4 ·4H2O,Na2B4O7·10H2O,Na2SO4·10H2O,MgSO4·7H2O,MgB4O7·9H2O].