Fluid Phase Equilibria 291 (2010) 90–94 Contents lists available at ScienceDirect Fluid Phase Equilibria journal homepage: www.elsevier.com/locate/fluid Phase equilibria in ternary aqueous mixtures of 1,3-butanediol with 2-ethyl-1-hexanol at T = (298.2, 303.2 and 308.2) K A. Ghanadzadeh a , H. Ghanadzadeh a,b,∗ , S. Abbasnejad a , Kh. Bahrpaima a a Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran b Department of Chemical Engineering, University of Guilan, Rasht, Iran article info Article history: Received 24 October 2009 Received in revised form 24 December 2009 Accepted 31 December 2009 Available online 11 January 2010 Keywords: Liquid–liquid equilibria 1,3-Butanediol 2-Ethyl-1-hexanol NRTL model abstract Experimental tie-line data for ternary system of (water + 1,3-butanediol (1,3-BD) + 2-ethyl-1-hexanol (2EH)) were determined at T = (298.2, 303.2 and 308.2) K under atmospheric conditions. This ternary sys- tem exhibits type-1 behavior of LLE. The experimental ternary LLE data were correlated using the NRTL model, and the binary interaction parameters were obtained. The average root-mean-square deviation between the observed and calculated mole fractions was 1.38%. Distribution coefficient and separation factor were measured to evaluate the extracting capability of the solvent. The separation factor values for the solvent used in this work were then compared with literature values obtained in our previous works for other butanediols. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Liquid–liquid equilibrium (LLE) investigations for ternary mix- tures are important in the evaluation of industrial units for solvent extraction processes. The accurate interpretation of phase equilib- ria for the different ternary mixtures is a key to improve solvent extraction techniques [1–8]. We have recently reported the LLE data for aqueous mixtures of 1,4-butanediol with alcohols at 298.2 K [9]. The LLE data for the (water + 2,3-butanediol + 2-ethyl-1-hexanol) system have also been reported by one of the authors [10]. For both the ternary systems, type-1 liquid–liquid phase diagram was obtained. As a continuation of that previous works, we present the LLE data for the ternary aqueous mixtures of 1,3-BD with 2EH at T = (298.2, 303.2 and 308.2) K. The LLE data for the system studied here have not been reported in any literature. 1,3-BD is a four carbon glycol (diol) that has many industrial and biological applications [11]. It is a clear viscous liquid that is miscible with water and most polar organic solvents. It is one of four stable isomers of butanediol with a sweet flavor. The physical and chemical properties of this diol make it suitable as an organic solvent and a useful chemical intermediate in the manufacture of many other chemical products. It is used industrially as an inter- mediate in manufacturing polyester resins and other products. It is ∗ Corresponding author at: Department of Chemical Engineering, University of Guilan, 41335 Rasht, Iran. Tel.: +98 131 3233262; fax: +98 131 3233262. E-mail address: hggilani@guilan.ac.ir (H. Ghanadzadeh). an excellent humectant in pet foods, tobacco and cosmetic formu- lation. The separation of diols from aqueous solutions using the liquid–liquid extraction technique is industrially and scientifically important. In this study, 2-ethyl-1-hexanol was chosen as organic solvent for recovering 1,3-BD from aqueous solution, which has low cost, high boiling point and very low solubility in water. These sol- vents have already been used as extractants to determine LLE data for many ternary mixtures [12–14]. As a detailed evaluation of solvents for the extraction of 1,3-BD from aqueous solution is not available in the literature, this work presents a useful LLE data for the extraction of 1,3-BD from aqueous solution. Complete phase diagrams are obtained by tie-line data for each temperature. Distribution coefficient (D) and separation factor (S) were deter- mined from the tie-line data to establish the extracting capability of the solvent and the possibility of using this solvent for the separa- tion of (water + 1,3-BD) binary mixture. The experimental LLE data were correlated with the non-random two-liquid (NRTL) models [15], and the values of the interaction parameter were obtained. This model has been successfully applied for the correlation of sev- eral ternary systems. 2. Experimental 2.1. Materials All chemicals used in this work (mass fraction purity > 99%) were obtained from Merck. The chemicals were used without further 0378-3812/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.fluid.2009.12.033