Effect of Addition of Calcium Chloride on the Liquid−Liquid Equilibria of the Water + Propionic Acid + 1-Butanol System at 303.15 K

Abstract

The influence of the addition of CaCl 2 to the water + propionic acid + 1-butanol ternary system was studied at (303.15 ± 0.05) K. The quaternary system was represented projecting four sectional quaternary planes corresponding to 4.3%, 9.3%, 15.1%, and 20.3% CaCl 2 in aqueous solution onto the face of the tetrahedron containing the ternary system water + propionic acid + 1-butanol. Therefore, all compositions are given on a salt-free basis for the solubility curves and for tie-line data. The addition of salt always enhances significantly the distribution coefficients and selectivities, while the region of heterogeneity increases as compared to the no-salt condition. Band type curves were obtained for solubility curves above 4.3% CaCl 2 , and no salt precipitation was observed. The experimental results show that CaCl 2 is not distributed in the same proportion between the phases at equilibrium and that 1-butanol appears to be a good solvent for extraction purposes. A comparison between the influence of CaCl 2 and NaCl on this ternary system is also made using these experimental results with earlier data. A high value of the Sestchenow's constant was obtained by a linear regression method, which is an indication that a great salting-out effect is produced by the addition of CaCl 2 , which is more important than for NaCl.