Separation of Formic Acid from Aqueous Solutions by Liquid Extraction Technique at Different Temperatures

In this study, the separation of formic acid from aqueous solutions was investigated. Liquid-liquid equilibrium (LLE) data including tie-lines was reported for water + formic acid + 2-methylpropyl ethanoate ternary mixture at (293.15 to 323.15) K and atmospheric pressure. The system shows type-I phase behavior based on Treybal’s classification because only one partially miscible binary mixture (water + 2-methylpropyl ethanoate) was observed. The composition of tie-lines was determined by cloud point method and refractive index measurements. The results show that the solubility of formic acid in the water-rich phase is more than in the solvent-rich phase. The extracting capability of the solvent was ascertained by determining the distribution coefficients and separation factors. The reliability of tie-line data was checked by Othmer–Tobias and Hand equations. The experimental data were correlated with NRTL and UNIQUAC models and the binary interaction parameters were determined. The values of the root-mean-square deviation (RMSD) were confirmed the quality of the correlations.