Isobaric vapor–liquid equilibria for acetone + methanol + lithium nitrate at 100 kPa

doi:10.1016/j.fluid.2006.09.007

Fluid Phase Equilibria

Volume 250, Issues 1–2, 20 December 2006, Pages 131-137

https://doi.org/10.1016/j.fluid.2006.09.007 Get rights and content

Abstract

Isobaric vapor–liquid equilibria for the ternary system acetone + methanol + lithium nitrate have been measured at 100 kPa using a recirculating still. The addition of lithium nitrate to the solvent mixture produced an important salting-out effect and the azeotrope tended to disappear for small contents of salt. The experimental data sets were fitted with the electrolyte NRTL model and the parameters of the Mock's model were estimated. These parameters were used to predict the ternary vapor–liquid equilibrium which agreed well with the experimental one.

Introduction

Phase equilibria of salt-containing systems is a field of researching which finds large applications in industrial processes as important as extractive distillation, extractive crystallization or liquid–liquid extraction of mixtures including salts.

In azeotropic systems, or in those the relative volatility of which is very similar, the separation of the components is very difficult by conventional distillation techniques. In this way, addition of charged species coming from a soluble salt can modify the relative volatility and the components can be more easily separated. When there is a salt-out effect the azeotrope shifts towards higher molar fraction of the most volatile component and it may be broken.

Considerable effort has been extended in determining the effect of salts on water vapor pressure. However, there is no much information about salts in organic solvents or in mixtures of them, and therefore more researching in this area is necessary.

In this publication, experimental data corresponding to the influence of lithium nitrate at different salt level on the vapor–liquid equilibrium of a mixture of acetone + methanol are reported. In most cases, the information available in the literature about the acetone + methanol + salt systems is referred to saturated solutions at atmospheric pressure [1], [2], [3], [4], [5], [6]. The influence of salt concentration on the isobaric vapor–liquid equilibria of acetone + methanol system has been studied by Tatsievskaya et al. (CdAc₂, MgAc₂) [7], Iliuta et al. (KI, NaI, NaSCN, KSCN, LiCl) [8], [9], [10], [11], Yan et al. (ZnCl₂) [12], and Al-Asheh and Banat (CaBr₂) [13]. Yan et al. obtained isothermal vapor–liquid equilibrium data of acetone + methanol system with LiBr [14] at different salt concentrations as well.

Only one paper concerning experimental values for acetone + methanol + lithium nitrate system has been found in the literature. Yan et al. [15] have studied this system at isothermal conditions (312.65, 328.15, and 343.75 K) and at four salt molalities (0.5, 1.0, 2.0, and 3.0 mol kg⁻¹), but they reported only x–y data. From their calculations, the azeotropic point was concluded to have disappeared at a salt molality higher than 0.5 mol kg⁻¹.

The aim of this work is to experimentally determine the effect of lithium nitrate on the isobaric vapor–liquid equilibrium of the acetone + methanol system at different salt concentrations, check the results with the predicted ones using the electrolyte NRTL model of Mock et al. [16] and confirm the Yan's prediction [15].

Section snippets

Materials

Methanol (Riedel-de Haën, Analytica Reagent) with a stated minimum purity of 99.8 wt.%, acetone (Merck, GR grade, minimum 99.5 wt.%) and lithium nitrate (Fluka, purum, >98.0 wt.%) were used in this study. The lithium nitrate was kept at 393 K in an oven until no water was detected with an automatic water detector, whereas the solvents were directly used without further manipulation.

Apparatus and procedure

An all-glass dynamic recirculating still manufactured by Fischer was used so as to obtain the experimental data. The

Experimental data

To test the equilibrium apparatus and dispose of suitable data for pure solvents, the acetone and methanol vapor pressures were measured in the 314–345 K range. The Antoine coefficients for both solvents, obtained from our experimental data, and mean absolute deviations between experimental and calculated vapor pressure data are shown in Table 1.

Furthermore, vapor–liquid equilibria for the binary systems acetone (1) + methanol (2), methanol (2) + lithium nitrate (3) as well as the vapor–liquid

Conclusions

The addition of lithium nitrate to acetone + methanol system produces an important salting-out effect on the acetone, and the azeotrope disappears at salt mole fractions higher than 0.022. This effect is stronger than that produced by sodium iodide [8], sodium thiocyanate [9], and calcium bromide [13] on this system.

The electrolyte NRTL model [28], [16] has proved to be suitable to predict the vapor–liquid equilibrium of the acetone + methanol + lithium nitrate system, using the parameters obtained

Acknowledgement

Financial support by Spain Ministry of Education and Culture (Grant CTQ2004-02977/PPQ) is gratefully acknowledged.

References (29)

M.C. Iliuta et al.
Fluid Phase Equilib.
(1995)
M.C. Iliuta et al.
Fluid Phase Equilib.
(1996)
M.C. Iliuta et al.
Fluid Phase Equilib.
(1997)
M.C. Iliuta et al.
Fluid Phase Equilib.
(1998)
C.H. Tu et al.
Fluid Phase Equilib.
(1997)
S. Ohe et al.
J. Chem. Eng. Jpn.
(1969)
S. Dernini et al.
J. Chem. Eng. Data
(1976)
T.S. Natarajan et al.
J. Chem. Eng. Data
(1980)
P. Rath et al.
Indian Chem. Eng.
(1984)
U. Avciata et al.
Chim. Acta Turc.
(1993)

U. Avciata et al.

Model. Meas. Control C

(1994)

G.I. Tatsievskaya et al.

Zh. Fiz. Khim.

(1982)

W. Yan et al.

J. Chem. Eng. Data

(1999)

S. Al-Asheh et al.

J. Chem. Eng. Data

(2005)

Cited by (34)

Comprehensive analysis on the economy and energy demand of pressure-swing distillation and pervaporation for separating waste liquid containing multiple components
2023, Chinese Journal of Chemical Engineering
A large amount of waste liquids containing methanol/acetone/water mixtures are produced in the synthesis of methyl methacrylate (MMA). Under the advocacy of green chemical industry, it is urgent to develop an efficient, economic and energy-saving mixture separation process. Through thermodynamic azeotropic behavior and pressure sensitivity analysis, pressure-swing distillation was determined and the optimal separation pressure of each column in the process was obtained. Due to the composition of waste liquids produced were quite different in MMA production, the pressure-swing distillation separation process was designed to fully achieve the accurate waste liquids treatment. Taking the total annual cost (TAC) as the target, the sequential iteration method was used to optimize the process, and the impact of composition on economy was compared. In order to further realize the energy-saving of the separation process, the pervaporation membrane module was introduced to pretreat the waste liquid in the pressure-swing distillation. The results showed that the TAC of the coupling process was 46% higher than that of the pressure-swing distillation process, and the thermodynamic efficiency was 30% higher. This study provides waste liquid treatment technology for enterprises and analyzes its economic and energy efficiency, which has reference significance for the development of coupled separation technology.
Reaction-assisted separation of acetone from the azeotrope of methanol and acetone
2023, Chemical Engineering Research and Design
The separation of methanol–acetone azeotrope has been a challenging issue. Methanol in the azeotrope was selectively transformed and removed in this paper. Under mild conditions, 95.5% of methanol was transformed into methyl phenylcarbonate (MPC), phenol and dimethyl carbonate (DMC), while acetone was not converted. The separation process of reaction products was simulated, and 99% of acetone with purity of 99.3 wt% was recovered. The byproducts phenol and DMC were also recovered with purity of 93 and 76 wt%, respectively. Compared to the typical pressure-swing and extractive-distillation schemes, the total number of theoretical stages and heat duty could be reduced by 27.7–38.3% and 48.6–58.4%, approximately. The results of thermodynamic experiments showed that the apparent equilibrium constant (124.4 at 23.1 °C) in the first step was much larger than that (12.9) in the second step, indicating that the intermediate MPC was very stable, and thermodynamic factors originating from the specific coplanar structure of substrate contributed to the high methanol conversion. The transesterification reactions were endothermic and spontaneous due to the positive ΔH and negative ΔG values. The spontaneity of reactions was attributed to the increase of entropy, for which the reason was the more possible spatial distributions of atoms in the products. This paper is beneficial for the separation of alcohols from various aprotic solvents.
Separation of azeotrope 2,2,3,3-tetrafluoro-1-propanol and water: Liquid-liquid equilibrium measurements and interaction exploration
2020, Journal of Chemical Thermodynamics
Citation Excerpt :
So, it is impossible to recover TFP from its aqueous solution by conventional distillation. Generally, some special distillations, for instance, extractive distillation [8–12], salt distillation [13,14] and azeotropic distillation [15,16] are usually required to separate azeotropic mixtures. Compared with these special distillations, liquid–liquid extraction was adopted to extract TFP from its aqueous solution due to its advantages of energy-saving and good selectivity.
Due to the existence of azeotropic point for the mixture 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, liquid-liquid extraction was adopted to separate TFP from its aqueous mixture with cyclohexanone as extractant in this work. The liquid-liquid phase behaviour for the mixture (TFP + water + cyclohexanone) was investigated at T = (293.15, 303.15 and 313.15) K and p = 101.3 kPa. Both selectivity and partition ratio were used for evaluating the extraction performance of cyclohexanone. Also, the NRTL activity coefficient model was applied to fit the measured LLE data with the regressed the parameters. Meanwhile, the binary interaction parameters were validated to be coherent with the measured LLE data based on the mixing surface analysis of Gibbs energy topology. The calculated values of root-mean-square deviation are 0.024, 0.017 and 0.018 at three temperatures, respectively, which indicates the correlated results agree well with the experimental values. Furthermore, the interaction energies between the components were investigated using DMol³ module to explore the molecular interactions between the components in the mixture.
Phase equilibria calculation of binary and ternary mixtures of associating fluids applying PC-SAFT equation of state
2015, Journal of Supercritical Fluids
Using the PC-SAFT equation of state to the correlation and prediction of the phase equilibria of associating systems, the vapor–liquid, the liquid–liquid and the vapor–liquid–liquid equilibria of binary and ternary mixtures were investigated. In this equation of state five pure-component parameters are required for each associating substance, two of which characterize the association interactions. Pure-component parameters for 23 self-associating and 6 non-associating substances are identified by correlating vapor pressure and liquid density data. A comparison of calculated values to literature data shows a good agreement for pure fluids. Binary systems with two self-associating compounds and others with one self-associating component and another non-self associating but can have cross-associating interactions with the first component are investigated. Binary parameters correcting the cross-dispersive interactions, k_ij, and the cross-associating interactions, υ_ij and λ_ij, are fitted to the phase equilibrium data. In addition, when a simple non-self associating pure fluid is a part of a binary system and can have cross-associating interactions with the other component, its association fictive volume and energy are regressed simultaneously with the binary interaction parameters to the phase equilibrium data. The found results have shown that the PC-SAFT equation of state demonstrates high potential of correlation and prediction of vapor–liquid, liquid–liquid and vapor–liquid–liquid phase equilibria of 38 binary systems of associating fluids. The same observations are made for the phase behavior prediction of 22 ternary mixtures of associating fluids. The PC-SAFT equation of state with its theoretical base represents a great tool for modeling and prediction of phase equilibria and thermodynamic properties of mixtures of associating fluids.
LSER-based modeling vapor pressures of (solvent + salt) systems by application of Xiang-Tan equation
2015, Chinese Journal of Chemical Engineering
Citation Excerpt :
The reliability analysis of existing vapor pressure models has been performed against fourteen (solvent + salt) systems covering different types of salts with univalent and divalent species capable of dipole–dipole interaction with the solvent. Table 1 presents a brief summary of the properties of the tested fourteen systems being selected from various classes [37–43]. Table 1 also reports the concentration (Cs) range of the salt to which the model reliability results pertain.
The study deals with modeling the vapor pressures of (solvent + salt) systems depending on the linear solvation energy relation (LSER) principles. The LSER-based vapor pressure model clarifies the simultaneous impact of the vapor pressure of a pure solvent estimated by the Xiang-Tan equation, the solubility and solvatochromic parameters of the solvent and the physical properties of the ionic salt. It has been performed independently two structural forms of the generalized solvation model, i.e. the unified solvation model with the integrated properties (USMIP) containing nine physical descriptors and the reduced property-basis solvation model. The vapor pressure data of fourteen (solvent + salt) systems have been processed to analyze statistically the reliability of existing models in terms of a log-ratio objective function. The proposed vapor pressure approaches reproduce the observed performance relatively accurately, yielding the overall design factors of 1.0643 and 1.0702 for the integrated property-basis and reduced property-basis solvation models.
Modeling vapor pressures of solvent systems with and without a salt effect: An extension of the LSER approach
2015, Journal of Chemical Thermodynamics
Citation Excerpt :
Characterization of the vapor pressure of a solvent (or a solvent mixture) is dependent strongly on the nature of the salt. The experimental findings reveal that the reduced (or enhanced) magnitude of vapor pressure is very sensitive to the physical characteristics of the ionic salt species like the ionic strength, radius and valence of the ions [13,16,17,30,68–75,77]. Regarding table 2, univalent ionic salts, especially lithium salts, are selected as favorable candidates for testing the solvation-based model framework.
A new polynomial vapor pressure approach for pure solvents is presented. The model is incorporated into the LSER (linear solvation energy relation) based solvation model framework and checked for consistency in reproducing experimental vapor pressures of salt-containing solvent systems. The developed two structural forms of the generalized solvation model (Senol, 2013) provide a relatively accurate description of the salting effect on vapor pressure of (solvent + salt) systems. The equilibrium data spanning vapor pressures of eighteen (solvent + salt) and three (solvent (1) + solvent (2) + salt) systems have been subjected to establish the basis for the model reliability analysis using a log-ratio objective function.
The examined vapor pressure relations reproduce the observed performance relatively accurately, yielding the overall design factors of 1.084, 1.091 and 1.052 for the integrated property-basis solvation model (USMIP), reduced property-basis solvation model and concentration-dependent model, respectively. Both the integrated property-basis and reduced property-basis solvation models were able to simulate satisfactorily the vapor pressure data of a binary solvent mixture involving a salt, yielding an overall mean error of 5.2%.

View all citing articles on Scopus

View full text

Isobaric vapor–liquid equilibria for acetone + methanol + lithium nitrate at 100 kPa

Abstract

Introduction

Section snippets

Materials

Apparatus and procedure

Experimental data

Conclusions

Acknowledgement

Fluid Phase Equilib.

Fluid Phase Equilib.

Fluid Phase Equilib.

Fluid Phase Equilib.

Fluid Phase Equilib.

J. Chem. Eng. Jpn.

J. Chem. Eng. Data

J. Chem. Eng. Data

Indian Chem. Eng.

Chim. Acta Turc.

Model. Meas. Control C

Zh. Fiz. Khim.

J. Chem. Eng. Data

J. Chem. Eng. Data