Liquid–liquid equilibria of water + 2,3-butanediol + isobutanol at several temperatures

(Liquid–liquid) equilibrium (LLE) data for the ternary system of water + 2,3-butanediol + isobutanol have been determined at 298.2, 308.2 and 318.2 K and atmospheric pressure. Solubility curves were obtained by the cloud point method, while compositions of tie-lines were obtained by gas chromatography. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer–Tobias correlation. The LLE data of the ternary systems have been correlated by both the NRTL model and UNIQUAC model. Root mean square deviations between experimental and calculated compositions were considered satisfactory.

► LLE for water + 2,3-butanediol + isobutanol has been determined.
► The reliability of the experimental tie-lines has been confirmed by using Othmer–Tobias correlation.
► The interaction parameters in the thermodynamic models NRTL and UNIQUAC were calculated.