Binary mixtures of known compositions were shaken in a glass stoppered cell ( Figure 1) equipped with a magnetic stirrer and jacketed for circulating water from a constant temperature bath at 298.15± 0.20, 303.15± 0.20 and 308.15± 0.20 K. The binodal curve for the water-acetic acid-butyl acetate ternary system was determined by the cloud-point method. The measured physical properties are listed in Table 2, along with some values from the literature (Weast, 1990). The estimated uncertainties in the density and boiling point measurements were ☐.0001 g.cm -3 and 0.1 K, respectively. Densities were measured with an Anton Paar densimeter (model 4500)_Boiling point measurements were obtained by using a Fischer boiling point apparatus. Refractive indexes were measured with an Abbé-Hilger refractometer its stated accuracy was ± 0.0005. Deionized water was further distilled before use. Acetic acid and butyl acetate were used without further purification. Dependence on temperature was studied by evaluating distribution coefficients and separation factors for each case.Īcetic acid and butyl acetate with purities of 99.98 % (W/W) and 99.50 % (W/W), respectively, were purchased from Merck. In this paper, to be able to evaluate butyl acetate as an agent for the extraction of acetic acid from dilute aqueous solutions, we herein report liquid-liquid equilibrium results at temperatures of 298.15± 0.20, 303.15± 0.20 and 308.15± 0.20 K for the ternary system of water-acetic acid-butyl acetate. This study is part of a research program on the recovery of carboxylic acids from dilute aqueous solutions using solvents with high boiling points. The structural units in the calculation method are called subgroups (Higashiuchi et al. It has the advantage of being able to form a very large number of molecules from a relatively small set of structural units. This type of approach is known as the group contribution method. The UNIFAC method for estimation of activity coefficients works on the concept that a liquid mixture may be considered a solution of structural units from which the molecules are formed, rather than a solution of the molecules themselves.
It is one of the best methods used in estimating activity coefficients. The UNIFAC method (UNIFAC Functional-group Activity Coefficient) was developed by Fredenslund et al. A precise description of the dependence on temperature, pressure and composition in multicomponent systems requires reliable thermodynamic models that allow calculation of these properties from available experimental data. The real behavior of fluid mixtures can be calculated with the help of activity coefficients or fugacity coefficients. Because there is little change in the distribution ratio for moderate variations in the acid concentration of dilute solutions, the acetic acid concentrations are not shown in Table 1. Selected distribution ratios (D 2) and selectivities taken from several papers are shown in Table 1.
2001).Ī lot of solvents have been examined for extraction of acetic acid. Recovery of organic acids from dilute solutions resulting from fermentation processes is important, and many solvents have been tried in attempts to improve recovery (Upchurch and Van Winkle, 1952 Correa et al., 1989 Sayar et al., 1991 Kirk and Othmer, 1992 Dramur and Tatlı, 1993 Briones et al., 1994 Arce et al., 1995 Fahim et al., 1996 Fahim et al., 1997 Sólimo et al., 1997 Colombo et al., 1999 Aljimaz et al., 2000 Taghikhani et al. Keywords: acetic acid, butyl acetate, liquid-liquid equilibria. Distribution coefficients and separation factors were evaluated for the immiscibility region. It was found that UNIFAC group interaction parameters used for LLE did not provide a good prediction. The UNIFAC group contribution method was used to predict the observed ternary liquid-liquid equilibrium (LLE) data. The reliability of the experimental tie-line data was ascertained by using the Othmer and Tobias correlation.
Complete phase diagrams were obtained by determining solubility and tie-line data. Abstract - Experimental liquid-liquid equilibria of the water-acetic acid-butyl acetate system were studied at temperatures of 298.15± 0.20, 303.15± 0.20 and 308.15± 0.20 K.