Liquid-Liquid Equilibria for the System Composed by Water, Acetic Acid, and 1-Hexanol at 293.15 K and Under Atmospheric Pressure Using Refractometry and Densitometry

Abstract

-In order to evaluate the accuracy of an indirect quantification method, the liquid-liquid equilibrium for the ternary system composed by water, acetic acid and 1-hexanol at 293.15 K and at atmospheric pressure was determined by means of refractometry and densitometry. The binodal curve was measured using the cloud point method, while the tie-lines were obtained in a cell-glass where the mixture was vigorously stirred and maintained at constant temperature. After the completeness of phase separation, samples were collected using simple syringe needles and the concentration of all components were satisfactorily obtained using the relation between the refraction index and density with the binodal curve sample concentrations. Generated data were correlated using NRTL model, and their quality were verified by Othmer-Tobias and Hand tests. All the results were compared with a previous work which quantified the equilibrium phases by means of a direct method (gas-chromatographic analysis). The indirect method were very efficient, resulting in two equations that related the physical properties with sample concentrations with an average relative deviations between the experimental and calculated physical properties lower than 0.01%. NRTL model parameters were regressed and the mean deviation was 0.61. Othmer-Tobias and Hand tests presented coefficients of determination of 0.9984 and 0.9975, indicating the high quality of these data.