Phase Equilibria of the Ternary Systems ((NH₄)₂SO₄–MNSO₄–H₂O) and ((NH₄)₂SO₄–MGSO₄–H₂O) at 303.15 K

Abstract

In this work, the solid–liquid phase equilibria and physicochemical properties of ((NH4)2SO4–MnSO4–H2O) and ((NH4)2SO4–MgSO4–H2O) systems at T = 303.15 K have been determined by the isothermal solution saturation method. Also we used the Schreinemaker wet residue method to determine the equilibria solid phase. The experimental results show that there are two double-salts, (NH4)2Mn(SO4)2·6H2O and (NH4)2Mg(SO4)2·6H2O, in both systems. At the same time, there are two common points ((MnSO4·H2O+(NH4)2Mn(SO4)2·6H2O) and ((NH4)2SO4+(NH4)2Mn(SO4)2·6H2O) in the (NH4)2SO4–MnSO4–H2O system, (MgSO4·6H2O+(NH4)2Mg(SO4)2·6H2O) and ((NH4)2SO4+(NH4)2Mg(SO4)2·6H2O) in the (NH4)2Mg(SO4)2·6H2O system) and five crystalline regions. The density and refractive index of the two systems are calculated and compared with the experimental values. According to means of the through and intermediate translation techniques together, we predicted the phase diagram of the (NH4)2SO4–MnSO4–MgSO4–H2O quaternion system. Thus, the study of solid–liquid phase equilibrium at 303.15 K is of great theoretical significance to the crystallization process of manganese sulfate.