Phase equilibria for ternary liquid systems of (water + levulinic acid + cyclic solvent) at T = 298.2 K: Thermodynamic modeling
Introduction
In the chemical industry, various selective solvent systems have been tested to improve the efficient separation of carboxylic acids from aqueous fermentation solutions [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]. Especially, extractive recovery of acetic acid from fermentation broth and wastewater including lower than 10% (w/w) acid concentrations has received increasing interest [7], [8]. However, it is desirable to use a low boiling solvent that have to be distilled so long as no azeotropes appear. The physical extraction of hydrophilic acids through hydrogen bonding is still challenging because such systems show extremely nonideal behaviour.
Regarding the technical and economic merits of low boiling solvents during the regeneration by distillation, the selection of C6 ring-included extracting agents from various classes of polar, protic or nonprotic type was made. They all have higher boiling temperatures than water and lower in comparison with levulinic (4-oxopentanoic) acid. As continuation of the previous study [9], [10], the present work aims to produce new (liquid + liquid) equilibrium (LLE) data for the extraction of levulinic acid from water using methylcyclohexanol, cyclohexanone, and cyclohexyl acetate (cyclohexyl ethanoate) as proton-donating and -accepting cyclic solvents of lower vapor pressure than water and higher than levulinic acid. LLE data for extraction of a carboxylic acid from water through a cyclic solvent are scarce in the literature [3], [9], [10], [11]. It has not been found dependable LLE results for the present ternaries in the literature.
In this study, the properties and (liquid + liquid) equilibria of associated ternary mixtures have been estimated through a solvation energy relation (SERLAS) [9]. The model incorporates the solvatochromic parameters [12], [13] with the thermodynamic factors derived from the UNIFAC-Dortmund model [14] in a relation including expansion terms and two correction factors. The LLE data have been determined for each of the systems (water + levulinic acid + methylcyclohexanol, or cyclohexanone, or cyclohexyl acetate) at T = 298.2 K. The distribution data were also correlated using the UNIFAC-original model [15], [16], and compared with the predictions through SERLAS.
Section snippets
Experimental
Methylcyclohexanol, cyclohexanone, and cyclohexyl acetate (99.5%, g.c.), as well as levulinic acid of analytical grade were supplied by Fluka. All the chemicals were used as received without further purification. Mass-fractions of impurities detectable by g.c. were found to be <0.002.
The binodal (solubility) curves and the mutual solubility of the (water + cyclic solvent) binaries were determined by the cloud point method in an equilibrium glass cell with a water jacket to maintain isothermal
Distribution behaviour of levulinic acid
The compositions of mixtures on the binodal curve and the mutual binary solubilities of water and cyclic solvent at T = 298.2 K are given in FIGURE 1, FIGURE 2, FIGURE 3, in which wi denotes the mass-fraction of the ith component. Table 1 tabulates the experimental tie-line compositions of the equilibrium phases, for which refer to the mass fractions of the ith component in the aqueous and solvent phases, respectively. The experimental and calculated tie-lines through UNIFAC-original
Correlation of LLE data by SERLAS
In the previous study [9], the properties (Pr) of ternary liquid systems, such as the separation factor and the modified distribution ratio , were estimated using a SERLAS. x″ and x′ designate solvent-rich and water-rich compositions of water (1), acid (2) and solvent (3), respectively. The model includes a part accounting for the properties at the composition limit of acid x2 = 0 (Pr0), and an expansion term with respect to the
Conclusions
LLE data for the three ternary mixtures {water (1) + levulinic acid (2) + cyclic solvent (3)} were determined at T = 298.2 K. It is apparent from the distribution data that the separation of levulinic acid from water by extraction with a C6 ring-containing cyclic solvent is feasible (table 2 and FIGURE 1, FIGURE 2, FIGURE 3, FIGURE 4, FIGURE 5). The distribution of levulinic acid in the (water + cyclic solvent) two-phase system is better for methylcyclohexanol and cyclohexyl acetate than cyclohexanone.
Acknowledgments
This work was supported by the Research Fund of Istanbul University. The author is also grateful to Meric Senol.
References (24)
- et al.
Fluid Phase Equilibr.
(2002) - et al.
Fluid Phase Equilibr.
(2002) - et al.
J. Chem. Thermodyn.
(2001) J. Chem. Thermodyn.
(2004)- et al.
Fluid Phase Equilibr.
(1995) - et al.
Fluid Phase Equilibr.
(1980) - et al.
J. Chem. Eng. Data
(1993) - et al.
Ind. Eng. Chem. Res.
(1994) - et al.
J. Chem. Eng. Data
(1994) - et al.
J. Chem. Eng. Data
(1999)
Ind. Eng. Chem. Res.
J. Chem. Eng. Data
Cited by (15)
Liquid + liquid equilibrium and thermodynamic modeling of water + cyclohexanone + ethyl acetate at different temperatures
2021, Journal of Chemical ThermodynamicsLiquid-liquid equilibria for the aqueous mixture of C <inf>5</inf> carboxylic acids and heavier than water solvents at T = 298.2 K
2018, Journal of Chemical ThermodynamicsCitation Excerpt :Physical extraction of levulinic acid using 2-methyltetrahydrofuran was also recently reported [20]. Cyclohexanone, cyclohexyl acetate, dimethyl succinate, dimethyl glutarate and dimethyl adipate were tested for extraction of LA from dilute aqueous solution as well [21,22]. Methylcyclohexanol, 1-Octanol and supercritical carbon dioxide are the solvents that have been exploited for both the acids VA and LA [10,23–25].
Liquid-liquid equilibria study of the (water + phosphoric acid + hexyl or cyclohexyl acetate) systems at T = (298.15, 308.15, and 318.15) K: Measurement and thermodynamic modelling
2016, Journal of Chemical ThermodynamicsCitation Excerpt :Among the organic solvents, esters are predicted to be good candidate as proton-accepting extractant for recovery of the acid from water [23–25]. Esters have been used in several ternary systems, in particular systems containing organic acids, as extracting agents [26–28]. However, further studies in this section are always important and required for various industrial purposes.
Distribution of cyclohexanol and cyclohexanone between water and cyclohexane
2015, Fluid Phase EquilibriaCitation Excerpt :Unfortunately, from the literature survey, there is no complete literature data for the system of water + cyclohexane + cyclohexanol + cyclohexanone, only part of ternary and binary data could be referenced. For the binary water + cyclohexane system, the temperature ranges at (287.15–523.11) K [8–22], and for the binary system of water + cyclohexanol, the temperature ranges at (273–457.87) K [23–32], and for the binary system water + cyclohexanone, the temperature ranges at (292.99–368.34) K [33–42]. For the ternary system, the work of Steyer and Sundmacher [43] reported the LLE data of ternary system water + cyclohexane + cyclohexanol at 295 K, however, the LLE data at other temperatures were unavailable.
Phase equilibria of (water + levulinic acid + dibasic esters) ternary systems
2009, Fluid Phase Equilibria