Solid-Liquid and Solid-Liquid-Liquid Equilibria in the KI+H2O+i-C3H7OH Ternary System within 10-120°C

The solubility of components, phase equilibria, and critical phenomena in the ternary potassium iodide (KI) +water (H2O) +isopropyl alcohol (i-C3H7OH) system were studied in the range of 10-120 degrees C by the visual polythermal method. Potassium iodide was found to have a salting-out effect at temperatures above 97.0 degrees C, and homogeneous water-isopropanol solutions were delaminated. The formation temperature of the critical tie line of the monotectic state (97.0 degrees C) and the compositions of the solutions corresponding to the critical liquid-liquid solubility points at 104.2, 110.1, 115.6, and 120.1 degrees C were determined. The distribution coefficients of isopropyl alcohol between the organic and aqueous phases in the monotectic state at 100.0, 110.0, and 120.0 degrees C were calculated. The salting-out effect of potassium iodide relative to isopropyl alcohol from aqueous solution is small (the distribution coefficient K-d of isopropanol is 1.8 at 100.0 degrees C) and slightly increases with temperature (K-d is 3.4 at 120.0 degrees C).