Solid-liquid equilibrium for quaternary system Na2SO4-NaCl-H2O2-H2O at 283.15 K

The solid-liquid phase equilibrium for the quaternary system Na2SO4-NaCl-H2O2-H2O was studied at 283.15 K by Schreinemaker's wet residues method. The solubility data for the quaternary system were measured, and the phase diagram was constructed. When the concentration of hydrogen peroxide employed in the experiments was below 50 mass%, four solid phases were present in the quaternary system, which corresponded to NaCl, Na2SO4 center dot 10H(2)O, Na2SO4 center dot 0.5H(2)O(2)center dot H2O, and 4Na(2)SO(4)center dot 2H(2)O(2)center dot NaCl. The phase diagram of the quaternary system included two invariant points and four crystalline zones. The crystalline region of 4Na(2)SO(4)center dot 2H(2)O(2)center dot NaCl was larger than those of NaCl, Na2SO4 center dot 10H(2)O, or Na2SO4 center dot 0.5H(2)O(2)center dot H2O.