Na_2B_4O_7-Na_2SO_4-NaCl-H_2O四元体系323K相平衡研究

Phase equilibrium for quaternary system of Na_2B_4O_7-Na_2SO_4-NaCl-H_2O at 323 K

采用等温溶解平衡法研究了四元体系Na2B4O7-Na2SO4-NaC l-H2O在323 K的相平衡及平衡液相,测定了平衡液相的溶解度及密度。研究发现,该体系属于简单共饱和体系,无复盐和固溶体生成。根据实验数据绘制了相应的相图,相图中有一个共饱点E,3条单变曲线E1E,E2E和E3E;3个结晶区平衡固相分别为:NaC l,Na2B4O7.10H2O和Na2SO4。实验结果表明,NaC l对Na2B4O7.10H2O和Na2SO4有盐析作用,并简要讨论了密度变化规律。

The solubilities and densities of solution in the quaternary system of Na2B4O7-Na2SO4-NaCl-H2O at 323 K were determined by isothermal equilibrium method. The experimental results indicate that the system is of simple eutectic type and no double salt and solid solution are formed. Based on the experimental data, the phase diagram of the system was plotted, which consists of one invariant point E, three univariant curves E1E, E2E and E3E and three crystallization fields： NaCl, Na2B4O7 · 10H2O and Na2SO4. The experimental results show that the sodium chloride has the salting-out effect on Na2B4O7 ·10H2O 和 Na2SO4. The densities transformation rules were discussed.