Liquid–liquid equilibrium data for systems containing of formic acid, water, and primary normal alcohols at T = 298.2 K

• Liquid phase equilibrium data of (water + formic acid + alcohols) systems were measured.
• Experimental LLE data were correlated using NRTL and UNIQUAC models.
• Distribution coefficients and separation factors were evaluated.

Solubility and tie-line data for the ternary systems of (water + formic acid + aliphatic alcohols) were measured at T = 298.2 K and atmospheric pressure. The organic solvents were four primary normal alcohols, i.e. 1-butanol, 1-pentanol, 1-hexanol, and 1-heptanol. The phase diagrams for all these ternary systems are of type-1. The immiscibility region was found to be larger for the ternary system containing 1-heptanol. The experimental LLE data were correlated using the NRTL and the UNIQUAC models, and the binary interaction parameters were calculated. The Othmer–Tobias correlation equation was used to ascertain the quality of the LLE data for each system. Distribution coefficients and separation factors were evaluated over the immiscibility regions. The experimental results indicate the advantage of 1-heptanol as the preferred solvent for the recovery of formic acid from water.

Binodal curves diagram for water + FA + normal alcohols T = 298.2 K: (○) 1-butanol, (▴) 1-pentanol, (♢) 1-hexanol, and (■) 1-heptanol.Figure optionsDownload as PowerPoint slide