Topological transformation of the phase diagram of a potassium perchlorate-water-tetrahydrofuran ternary system in the temperature range of 40 to 140°C

Abstract

Phase equilibria and critical phenomena in a potassium perchlorate-water-tetrahydrofuran ternary system are studied by visual polythermal means in the range of 40 to 140°C; the solubility diagram of the liquid subsystem is characterized by the presence of isolated binodal curve. The temperature of formation for the critical node of the monotectic state (107.3°C) and the dependences of the composition that corresponds to the critical points of solubility in the delayering field vs. temperature in the ranges of 70.3 to 107.3°C and 137.1 to 140.2°C are determined. The topological transformation of the investigated ternary system’s phase diagram upon a change in temperature is studied using isothermal sections of the system’s temperature concentration prism, plotted at nine temperatures. It is found that potassium perchlorate has only a salting-in effect on mixtures of water and tetrahydrofuran at temperatures below 107.3°C; at higher temperatures, it has both a salting-in and a salting-out effect, depending on its concentration and the composition of mixed solvent. It is shown that potassium perchlorate’s effect of salting tetrahydrofuran out of aqueous solutions grows slightly with an increase in temperature.