Liquid−Liquid Equilibrium of the Water + Citric Acid + 2-Butanol + Sodium Chloride System at 298.15 K

Abstract

Liquid-liquid equilibrium data for water + citric acid + 2-butanol + NaCl at three different salt concentrations (5, 10, and 15 mass %) and at 298.15 K were determined. The parameters for the NRTL and UNIQUAC models were obtained by fitting the thermodynamic models to the experimental data.

Properties of Citric Acid and Its Solutions

“…An exception is 2-butanol, where due to a large mutual solubility of components, the two-phase system disappears and the region of total miscibility is formed. On the other hand, as was shown by Lintomen et al [257,258], by adding sodium chloride or tricaprylin, the heterogeneous two-phase region can be considerably enlarged without a significant decrease of extracted amount of citric acid (Fig. 2.49).…”

“…Systematic distribution studies of citric acid, alcohol and water between aqueous and organic phases were performed by Apelblat and Manzurola [211], in the ternary system with 1-hexanol and 1-octanol, Apelblat et al [212] with 2-pentanol and Grinberg et al [213] with 2-butanol. Lintomen et al [257,258] determined partition of citric acid and water in systems with 1-butanol and 2-butanol and also extended their measurements by adding the fourth component -sodium chloride or tricaprylin. Kasprzycka-Guttman et al [214] investigated mutual solubilities in the citric acid-cyclohexanone water system and Tvetkova and Povitskii [215] in the citric acid-water-tributyl phosphatecarbon tetrachloride system.…”

Extended NRTL model for PEG + salt based aqueous two‐phase system

“…Stragevitch and d'Ávila [11] and Lintomen et al . [12] also followed the same approach for using the NRTL model. With the nomenclature of mass fractions, the NRTL model can be represented as follows:…”

Liquid-liquid equilibrium of water + PEG 8000 + magnesium sulfate or sodium sulfate aqueous two-phase systems at 35°C: experimental determination and thermodynamic modeling

“…Instead, mass fraction, as originally proposed by Oishi and Prausnitz (1978) can be used for the calculation of the activity coefficient of a solvent in polymeric solutions with the UNIQUAC and the UNIFAC methods. Stragevitch (1997), Velezmoro-Sánchez (1999), Batista et al (1999), Lintomen et al (2000) and Sé andAznar (2002a, 2002b) …”