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2017, N1, pp. 69-79

M.A. Urusova, V.M. Valyashko

Solubility and Critical Phenomena in Ternary Aqueous Solutions, Containing the Salt of the Type 2 and Alkali

Supercritical phase equilibria in ternary system K2SO4KOHH2O at 420500 °C and up to 130 MPa pressure with binary boundary subsystems of different types are studied. The binary subsystem of type 1 do not have any critical phenomena in saturated (l = g s) aqueous solution as well as the immiscibility equilibrium (l1l2) (͗2O), the second binary subsystem of type 2 (K2SO4H2O) has two critical end-points p (g = l sK2SO4) and Q (l1 = l2sK2SO4) with saturated aqueous solution and the liquid-liquid immiscibility equilibria. The ternary system has two three-phase equilibria (g l sK2SO4) and (l1 l2 sNa2SO4), separated by a two-phase supercritical fluid region (flsK2SO4) and two types of monovariant critical curves (g = l sK2SO4) and (l1 = l2 sK2SO4). The three?phase regions approach each other at temperature increased up to the point where the two-phase supercritical equilibrium disappeares, and the two mentioned monovariant critical curves are joined into a double homogeneous critical point (g = l s ↔ l1 = l2 s) at maximum temperature ∼ 445 °C and 5152 MPa.

Key words: ternary water-salts systems, supercritical phase equilibria, phase diagrams


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