Salting-Out Effect of NaCl and KCl on the Liquid-Liquid Equilibrium of Water+2-Methylpropanoic Acid + (1-Methylethyl)-benzene System at Several Temperatures

The salting-out effect of NaCl and KCl on the liquid liquid equilibrium (LLE) of the ternary system of {water (1) + 2-methylpropanoic acid (2) + (1-methylethyl)-benzene (3)}, a recommended system for liquid liquid extraction investigations, was studied at temperatures of (288.15, 298.15, and 313.15) K. The generated data for salt-free system have been used to estimate the binary molecular interaction parameters for the nonrandom two-liquid (NRTL) activity coefficient model. Results show that this model reproduces very good tie lines by estimated binary molecular interaction coefficients. The distribution coefficient of 2-methylpropanoic acid between organic/aqueous phases increases with its concentration, both in salt-free and in the presence of salt cases; however, it decreases moderately with temperature, within the range used. Adding a 0.05 mass fraction (based on mass of initial water) NaCl leads to an average enhancement of about 44% in distribution coefficient, and hence, it reaches to about 124% by adding 0.10 mass fraction of this salt. The appropriate enhancement achievement with KCl are about (38 and 121) %, respectively. The Othmer-Tobias equation was used to examine the reliability of the experimental results, and an excellent agreement was revealed.