Phase equilibria and salting out of butyric acid in the ternary system potassium nitrate + water + 2-(2-butoxyethoxy)ethanol

Visual polythermal method in the bynary system of water-2-(2-butoxyethoxy) ethanol in the range of –25÷0° C the ice melting line is determined and the phase equilibria in the ternary system potassium nitrate–water–2-(2-butoxyethoxy) ethanol are studied in the range of 10.0–90.0° C. The ice melting line in the water–2-(2-butoxyethoxy) ethanol binary system is a flat, smooth line. This form of the melting line shows a hidden separation in liquid mixtures. It has been found that potassium nitrate salts out 2-(2-butoxyethoxy)ethanol from water-organic mixtures, and at 31.7° C in the ternary system of potassium nitrate–water–2-(2-butoxyethoxy)ethanol, separation begins. The compositions of the solutions corresponding to the critical solubility points at several temperatures have been determined. The isothermal phase diagrams of the ternary system at 10.0, 25.0, 30.0, 31.7, 35.0, 50.0, 90.0° С have been plotted. The distribution coefficients of 2-(2-butoxyethoxy) ethanol between the liquid phases of monotectic state have been calculated. It is shown that the effect of salting-out 2-(2-butoxyethoxy) ethanol from aqueous solutions with potassium nitrate increases with increasing temperature. The concentration of 2-(2-butoxyethoxy) ethanol in the organic phase of monotectics at 90.0° C is 90 wt.% with a distribution coefficient of 897.