Phase Equilibria of the Na⁺, NH₄⁺//SO₄^2–, NO₃^––H₂O Quaternary System at 303.15 and 323.15 K

Abstract

The equilibrium solubility of the quaternary system Na + , NH 4 + //SO 4 2−, NO 3 − −H 2 O at 303.15 and 323.15 K was determined by an isothermal dissolution equilibrium method. The weighing bottle method and Abbe refractometer were adopted to measure the density and refractive index of the aqueous liquid phase. The solid-phase invariant points at equilibrium were confirmed by Xray diffractometry. The complete diagrams of equilibrium phase, water content vs J(NO 3 − ) 2 of this quaternary system at 303.15 and 323.15 K were constructed based on experimental data. The phase diagrams demonstrated that the system was a complicated quaternary system at 303.15 and 323.15 K. Five single-salt crystallization zones and four double-salt crystallization zones were found in this system at 303.15 K. Four single-salt crystallization zones and four double-salt crystallization zones were found in this system at 323.15 K.

Study on the Phase Equilibrium of the Quaternary Na2SO4–NaBr–NH4Br–(NH4)2SO4–H2O System at 298.15 and 323.15 K

“…In known reports, the phase diagram of the ternary NH 4 Br–NaBr–H 2 O system at 298.15 K has only one invariant point and three crystallization regions . Sang et al reported the phase diagram of the ternary NaBr–Na 2 SO 4 –H 2 O system at 298.15 to 373.15 K and found that NaBr existed in the form of NaBr·2H 2 O at 298.15 to 323.15 K. When the temperature was between 348.15 and 373.15 K, NaBr·2H 2 O is converted to NaBr. − Rivett and Zhang et al measured the phase equilibrium data of the quaternary Na 2 SO 4 –NaCl–(NH 4 ) 2 SO 4 –NH 4 Cl–H 2 O system at 273.15 to 373.15 K and found that the double salt appeared at 273.15 to 323.15 K, and the crystallization region of the double salt disappeared at 333.15 K. The ternary subsystems of this quaternary system (Na + , NH 4 + //SO 4 2– –H 2 O, Na + , NH 4 + //Br – –H 2 O, and Na + //Br – , SO 4 2– –H 2 O) have been reported at 298.15 and 323.15 K. ,,− There are no reports on the ternary NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system and the quaternary Na 2 SO 4 –NaBr–NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system. In view of this, the phase equilibrium data of the quaternary Na 2 SO 4 –NaBr–NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system and its ternary NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system at 298.15 and 323.15 K were determined using the isothermal method.…”