Effect of trivalent, bivalent, and univalent cation inorganic salts on the isothermal vapor-liquid equilibria of propionic acid-water system

The effect of five dissolved inorganic salts, namely; aluminum chloride, calcium chloride, potassium chloride, potassium nitrate, and potassium bromide, on the vapor liquid equilibria (VLE) of the binary system propionic acid-water was investigated at 60 degreesC using the headspace gas chromatography technique (HSGC). For various salt concentrations, the influence of the salting out of propionic acid was noted. For a concentration of 1.0 molality (m) it was found that the trivalent cation salt (AlCl3) had the greatest effect on the salting out followed by the bivalent cation salt (CaCl2) and lastly the univalent cation salts (KCl, KNO3, KBr). Greater salting-out was achieved when the concentration of AlCl3 or CaCl2 was increased from 0.2 to 1.5 m. The experimental VILE data was fitted into the modified Furter's equation, recently proposed by Wu et al., and a correlation proposed by Subbaiah. Deviations and parameters are reported. (C) 2002 Elsevier Science B.V. All rights reserved.