Phase Equilibria of Quaternary System NaCl-NaBr-Na2B4O7-H2O at 348 K

The phase equilibria of quaternary system NaCl-NaBr-Na2B4O7-H2O at 348 K were studied by the iso- thermal equilibrium method. The solubilities and densities of the equilibrium solution were determined. According to the experimental data, the phase diagram, density-composition diagrams and water content diagram of the quaternary system at 348 K were plotted respectively. And the phase diagram consists of one univariant curve, two crystalliza- tion fields and without any invariant point of the quaternary system. The equilibrium solid phases of the two crysta- llization fields were Na（C1, Br） and Na2B4OT＇5H20, The experimental results show that the quaternary system contained solid solution. The densities of the solution decrease with increasing NaC1 concentration and increase with increasing NaBr concentration.