Phase equilibria and critical phenomena in the Li2SO4-K2SO4-H2O system at 380-400°C: Specifics of ternary phase diagrams with type 2 (p-Q) boundary subsystems

Abstract

Phase equilibria in Li2SO4-KLiSO4-H2O and K2SO4-KLiSO4-H2O ternary systems, which contain type 2 salts (Li2SO4, KLiSO4, and K2SO4), were studied at temperature of 380 to 400°C and pressures up to 90 MPa. Homogeneous supercritical (SC) fluids, which propagate from type 2 water-salt subsystems into a three-component region, change to heterogeneous liquid-phase equilibria as a result of the transformation of metastable immiscibility regions into stable equilibria. The heterogenization of SC fluids starts with critical phenomena in saturated solutions. In the K2SO4-KLiSO4-H2O system, the monovariant critical curve $(l_1 = l_2 - s_{KLiSO_4 } )$ reveals a temperature maximum at the invariant double critical end point (DCE).