Solubility of benzoic acid in acetone, 2-propanol, acetic acid and cyclohexane: Experimental measurement and thermodynamic modeling

In this study the solubility of benzoic acid in acetone, 2-propanol, acetic acid and cyclohexane was experimentally determined over the temperature range of (277–346) K at around 5 K intervals by employing a gravimetric method. The experimental results showed that acetone had the best solubility for benzoic acid followed by 2-propanol, acetic acid and cyclohexane and the solubility in acetic acid had the strongest positive temperature dependency. The newly measured solubility data was also compared with the available literature data. Several commonly used thermodynamic models, including the empirical Van’t Hoff equation, the λh equation, the Wilson, NRTL and UNIQUAC equations, were applied to correlate the experimental solubility data. The adjustable parameters for each model were optimized by fitting the solubility data measured in this work. It was found that the three-parameter NRTL equation could give the best correlation results. Better predictions of the solubility of benzoic acid in acetic acid at higher temperature were observed using the Wilson and UNIQUAC equations than the other three equations which all gave underestimations.