Aqueous solutions at pressures up to 2 GPa: gas–gas equilibria, closed loops, high-pressure immiscibility, salt effects and related phenomena

Abstract

It is the aim of the present article to review the immiscibility phenomena found in our experiments on aqueous solutions of organic substances up to 2 GPa. The pressure dependence of liquid–liquid phase equilibria of systems exhibiting upper and lower critical solution temperatures, the complicated phase behavior of closed loop systems under pressure and the influence of a third substance (mixed solvent, mixed solute, added salt) on mutual miscibility are considered. The thermodynamic conditions that hold for the critical phenomena found are summarized. The interference with gas–liquid critical phenomena is also briefly discussed from a phase-theoretical point of view, including the exhibition of gas–gas equilibria.