Phase Equilibria In Ternary Systems Research Articles

Phase equilibria of ternary systems: LiCl–MClx (M = Na+, Mg2+, Sr2+)–H2O systems at 1 bar and volume properties investigating from 1 to 1000 bar (T = 298.2 K)

There are abundant lithium resources in seawater and brines. The thermodynamic phase equilibria of salt-water systems containing lithium have significant advantages to separation lithium from brines. Consequently, measurement and prediction of phase equilibria of LiCl–MClx (M = Na+, Mg2+, Sr2+)–H2O ternary systems are investigated at 298.2 K and 1 bar. The phase equilibria are determined using the isothermal dissolution equilibrium method and the solubilities of salts in the ternary systems are predicted using the Pitzer model. The predicted solubilities agree well with experimental data at 298.2 K and 1 bar.Then, the changes of volume properties (ΔV¯dis0) and compressibility (Δκ¯dis0) of three ternary solutions at high pressure of 1–1000 bars were obtained in this work. The solubility product constants Ksp of salts at high pressure are calculated in detail. The thermodynamic prediction model of the phase equilibria is developed at high pressure of 1–1000 bar accordingly. The predicted phase equilibria at high pressure of 1–1000 bar are discussed and compared detailly.

Fine-tune simultaneous dearomatization, desulfurization and denitrogenation of liquid fuels with CO2-derived cyclic carbonates

In this work, eight CO2-derived cyclic carbonates, namely ethylene carbonate (Eth-C), propylene carbonate (Pro-C), butylene carbonate (But-C), hexylene carbonate (Hex-C), cyclohexene carbonate (Cyc-C), styrene carbonate (Sty-C), glycerol carbonate (Gly-C) and (Chloromethyl)ethylene carbonate (Chl-C) were evaluated as solvents to mitigate residual aromatic content in liquid fuels by envisioning an efficient liquid–liquid extraction process, using benzene, thiophene and pyrrole as benchmark compounds for dearomatization, desulfurization and denitrogenation processes. After evaluating at molecular scale by COSMO-RS method (activity coefficients and excess enthalpies of aromatic-cyclic carbonate mixtures), predictions of phase equilibria of ternary systems involving n-heptane are carried out by COSMO-based/Aspen methodology for evaluating the extractive properties of studied cyclic carbonates. Then, computational findings are experimentally validated for the representative Pro-C case through multicomponent liquid–liquid equilibria. Finally, the complete separation process was simulated by COSMO-based/Aspen methodology to evaluate solvent losses in extraction and distillation units, energy consumption, and aromatic purity for process specifications aimed at enhancing gasoline purity and recovery. Main results suggest that Pro-C provides promising process performance at a very competitive solvent to feed (S/F) ratio and specific energy consumption, positioning cyclic carbonates for studied separation.

Solid-liquid equilibria and thermodynamic correlation for the ternary system (KCl + PEG10000/20000 + H2O) at 288.2 K and 298.2 K

This work finished measuring the phase equilibria of ternary systems {KCl + polyethylene glycol (PEG) 10000/20000 + H2O} at 288.2 and 298.2 K. The solubility, density and refractive index were determined and corresponding diagrams were plotted in this work. There was only solid–liquid phase equilibrium existing in the ternary systems {KCl + PEG10000/20000 + H2O} at 288.2 K and 298.2 K. All of the phase diagrams of four systems are divided into three parts which respectively are the regions of unsaturated homogeneous liquid (L), one liquid and one solid KCl (L + S), and one liquid and two solids KCl and PEG (L + 2S). In addition, the effects of molar mass of PEG (PEG1000/4000/10000/20000) and temperature (288.2 K and 298.2 K) on phase equilibria were discussed. Results show that the sizes of regions of (L) and (L + S) increased and that of (L + 2S) decreased with the increase of temperature, and the regions of (L) and (L + S) decreased and that of (L + 2S) increased with the increase of the molar mass of PEG. The modified Pitzer model was adopted as the equilibrium thermodynamics model to correlate the experimental data. Comparing the experimental data and calculated dada, it can give a precise result with small error.

Determination and Calculation of Phase Equilibrium for Aqueous Ternary System (NH2)2CO+KCl+H2O at 283.15K

The solid-liquid phase equilibrium for ternary system (NH2)2CO+KCl+H2O was determined by isothermal saturation method at 283.15K under atmosphere pressure. The isothermal phase diagrams was drawn in according to the measured solubility data. There are one co-saturated point and two pure solids occurred in this ternary system. The solid phases were confirmed by Schreinemaker’s wet residue method and X-ray powder diffraction. Two thermodynamic models, Wilson model and NRTL model, were used to calculate the solubility data. The value of root mean-square deviation in Wilson model and NRTL model for this ternary system was 0.22 and 0.66 respectively, and the value of relative average deviation was 0.61% and 2.33% respectively, which indicated that the calculated data and the experimental results are nearly consistent.

Investigation of the Phase Equilibrium in Ternary Systems Formed by 2,2,2-Trifluoroethanol, Water, and Organic Alcohols

The phase equilibrium in binary constituents of ternary systems formed by 2,2,2-trifluoroethanol, water, and an organic alcohol (methanol, ethanol, or isopropanol) was experimentally investigated. It was shown that the methanol–2,2,2-trifluoroethanol, 2,2,2-trifluoroethanol–ethanol, and 2,2,2-trifluoroethanol–isopropanol systems at atmospheric pressure are characterized by the presence of binary maximum-boiling azeotropes. The phase equilibrium in the 2,2,2-trifluoroethanol–methanol–water, 2,2,2-trifluoroethanol–ethanol–water, and 2,2,2-trifluoroethanol–isopropanol–water ternary systems was calculated by mathematical modeling using Aspen Plus® V. 9.0 software.

Understanding and Prediction of the Clouding Phenomenon by Spontaneous and Effective Packing Concepts

AbstractIn this work, we show by which mechanism branching of the hydrocarbon chains influences the cloud point of nonionic, ethoxylated surfactants. The temperature‐induced separation into a dilute and a concentrated liquid phase is of liquid–gas type and can be explained by the relative probability of endcaps and branching points of the cylindrical micelles in both phases. The influence of branches on the hydrocarbon chains can be easily understood by means of spontaneous and effective packing concepts, while quantification via hydrophilic/lipophilic balance (HLB), hydrophilic‐lipophilic difference (HLD), and HLD‐Net Average Curvature requires parametrization. The phase equilibrium above the cloud point phenomenon is equivalent to the Winsor I type phase equilibrium, one of the five known phase equilibria in ternary systems.

Liquid–Vapor Phase Equilibria in Ternary Systems Formed by n-Alcohols and n-Alkyl Ethanoates

The boiling points of solutions of ternary systems formed by ethanol, n-propanol, n-butanol, and esters of ethanoic acid are measured via ebulliometry at different pressures. Coefficients of the activity of the solutions’ components are calculated using Wilson equations and the NRTL. The calculation results are verified experimentally.

Solubility of oleic acid, triacylglycerol and their mixtures in supercritical carbon dioxide and thermodynamic modeling of phase equilibrium

To evaluate the selectivity of supercritical carbon dioxide (scCO2) as a solvent to deacidify vegetable oils, the solubility of oleic acid and of a mixture of oleic acid and refined sunflower oil in scCO2 was measured. Sunflower oil was adopted as a pseudo-pure component and the phase equilibrium of ternary and binary systems were thermodynamically modeled by the Peng-Robinson equation of state with classical mixing rule. The values of the estimated and/or adopted critical properties in modeling thermodynamics were shown to be of great influence on the quality of data correlation. Although correlating data from binary systems is possible, the modeling was incapable of satisfactorily predicting the behavior of the phase equilibrium of the ternary system. The large deviations observed may derive from the presence of specific intermolecular interactions between the components of these systems that were not considered in this type of modeling.

Solid-liquid phase equilibria of ternary system Na2S2O3-Na2SO4-H2O in a wide range of temperatures: Measurement and application

Abstract In order to provide a fundamental basis for treatment of wastewater from desulfurization of coke oven gas to recover pure salt, solid-liquid equilibrium data of Na2S2O3-Na2SO4-H2O system at T = (278.15, 283.15, 291.15, 333.15 or 353.15) K were measured. The experimental data was obtained using the isothermal solution saturation method and Schreinemaker’s wet residue method. The solid-liquid phase diagrams of the ternary system were constructed. The ternary phase diagrams turned out to be simple eutectic type containing one invariant point, two univariant curves, and two single-salt crystallization regions. It was found that the crystallization region of Na2SO4 is larger than that of Na2S2O3 and expands with the increasing of temperature. But the crystallization region of Na2S2O3 decreases with the increasing of temperature. Through analyzing the thermodynamic characteristics of Na2S2O3 and Na2SO4, two crystallization methods for separating the mixture of Na2S2O3-Na2SO4 were put forward. A simple comparison of the two crystallization methods was carried out.

Extraction of 2-Phenylethanol (PEA) from Aqueous Solution Using Ionic Liquids: Synthesis, Phase Equilibrium Investigation, Selectivity in Separation, and Thermodynamic Models.

This study assessed the effect of ionic liquids (ILs) on extraction of 2-phenylethanol (PEA) from aqueous phase. It consists the synthesis of four new ILs, their physicochemical properties, and experimental solubility measurements in water as well as liquid-liquid phase equilibrium in ternary systems. ILs are an important new media for imaging and sensing applications because of their solvation property, thermal stability, and negligible vapor pressure. However, complex procedures and nonmiscibility with water are often required in PEA extraction. Herein, a facile and general strategy using four ILs as extraction media including the synthesis of new bis(fluorosulfonyl)imide-based ILs, 1-hexyl-methylmorpholinium bis(fluorosulfonyl)imide, [HMMOR][FSI], N-octylisoquinolinium bis(fluorosulfonyl)imide, [OiQuin][FSI], 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, [BMPYR][FSI], and N-triethyl-N-octylammonium bis(fluorosulfonyl)imide, [N2228][FSI], were investigated. The thermal properties, density, viscosity, and surface tension of new ILs were measured. Calorimetric measurements (DSC) were used to determine the melting point and the enthalpy of melting as well as the glass transition temperature and heat capacity at glass transition of the ILs. The phase equilibrium in binary systems (IL + PEA, or water) and in ternary systems {IL (1) + PEA (2) + water (3)} at temperature T = 308.15 K and ambient pressure are reported. All systems present liquid-liquid equilibrium with the upper critical solution temperature (UCST). All ILs revealed complete miscibility with PEA. In all ternary systems immiscibility gap was observed, which classified measured systems as Treybal's type II. The two partially miscible binaries (IL + water) and (PEA + water) exist in these systems. The discussion contains the specific selectivity and the solute distribution ratio of separation for the used ILs. The commonly used NRTL model was used for the correlation of the experimental binary and ternary systems with acceptable root-mean-square deviation. The prediction of binary and ternary compositions was provided with acceptable deviations using COSMO RS. The data of ternary LLE show the possible use of [HMMOR][FSI] as a good entrainer for the separation of PEA from water using solvent extraction.

Determination and correlation of solid-liquid phase equilibrium and phase diagram for multicomponent system of mixed dibasic acids. (III) Ternary system of succinic acid + glutaric acid + ethanol system

The solid-liquid phase equilibrium for ternary system of succinic acid+glutaric acid+ethanol was determined by an isothermal saturation method at the three temperatures of (283.15, 303.15 and 313.15)K under atmosphere pressure. Three isothermal phase diagrams were built based on the measured mutual solubility data. There were two pure solids formed in the ternary system at a certain temperature, which corresponded to pure succinic acid and pure glutaric acid and were confirmed by Schreinemaker’s method of wet residue and X-ray powder diffraction. The ternary phase diagram included one co-saturated point, two boundary curves, and three crystalline regions. The crystallization region of glutaric acid was smaller than that of succinic acid at each temperature. In addition, two thermodynamic models, NRTL and Wilson were employed to correlate and calculate the mutual solubility data for the ternary succinic acid+glutaric acid+ethanol system. The largest RMSD value for the ternary system of succinic acid+glutaric acid+ethanol was 0.43, and the maximum value of RAD was 3.0%. The Wilson model and NRTL model may all be employed to describe the mutual solubility behavior for the ternary system of succinic acid+glutaric acid+ethanol at various temperatures. Furthermore, the densities of the equilibrium liquid phase were obtained and correlated with an empirical equation.

Phase equilibria of ternary systems of carbon dioxide + ethanol, dimethyl sulfoxide, or N,N-dimethyl formamide + water at elevated pressures including near critical regions

A visual and volume-variable high-pressure phase equilibrium analyzer was used for measuring the isothermal vapor-liquid equilibrium (or vapor-liquid-liquid) phase boundaries of CO2 with the mixed solvents of ethanol/water = 9/1, dimethyl sulfoxide (DMSO)/water = 9/1, and N,N-dimethyl formamide (DMF)/water = 7.5/2.5 in molar ratio at temperatures from 298.2 K to 348.2 K over wide composition range, including near critical regions. The isothermal phase equilibrium data obtained from this work are compared with those of water-free binary systems to investigate the effect of phase boundary shifts caused by introducing the phase modifier, water, into the organic solvents. The comparison shows that the bubble, dew, and critical pressures substantially increase in the presence of water for each system, especially for DMSO-containing system. The Peng-Robinson equation of state with Mathias-Copemen alpha function and the Wong-Sandler mixing rule is employed to the phase equilibrium calculation. While the UNIFAC model estimates the excess Helmholtz free energy at infinite pressure, the binary interaction parameters for calculating the second virial coefficient are determined by the phase equilibrium data of constituent binaries. The obtained parameters are directly adopted to the phase boundary predictions for the investigated ternary systems.

Measurement and correlation of phase equilibria for ternary systems of water + (ethanol/1-propanol) + 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide at 298.15 K

Liquid-liquid phase equilibria for ternary systems of water + (ethanol/1-propanol) + 1-decyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([Dmim][NTf2]) were measured at T = 298.15 K and atmospheric pressure. Influences of alcohols with different length of alkyl chain on the liquid-liquid equilibria were revealed by the distribution coefficient and selectivity of the alcohols. The phase diagrams for the ternary systems were classified as Treybal's Type I behavior. The experimental data of ternary liquid-liquid equilibria were correlated by the nonrandom two liquid (NRTL) and the universal quasi-chemical (UNIQUAC) models, in which the interaction parameters were optimized. The values of root-mean-square deviation between the experimental and the calculated data show that those models can correlate the experimental data of the studied systems with good accuracy.

Phase equilibrium investigation with ionic liquids and selectivity in separation of 2-phenylethanol from water

This work presents some important issues and topics related to possible extraction of 2-phenylethanol (PEA) from aqueous phase “in situ” during the biosynthesis with ionic liquids (ILs). It consists of a series of experimental phase equilibrium measurements in binary and ternary systems. Three ILs as extraction media are proposed for the extraction process based on phase equilibria in ternary systems {IL (1)+PEA (2)+water (3)} at temperature T=308.15K and ambient pressure. The systems are composed of the following ILs: 1-hexyl-1-methylmorpholinium bis{(trifluoromethyl)sulfonyl}imide, [HMMOR][NTf2], 1-allyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [AMIM][NTf2], and diethylmethylsulfonium bis{(trifluoromethyl)sulfonyl}imide, [S221][NTf2]. A differential scanning calorimetry (DSC) was used to determine the thermal properties of the ILs. The synthesis of new [HMMOR][NTf2] IL and its thermal and physicochemical properties as density, viscosity, surface tension were presented. The volume expansivity, as well as the surface thermodynamic functions, such as surface entropy and enthalpy have been derived from the temperature dependence of the surface tension values, as well as the critical temperature, parachor and speed of sound for all ILs were presented. The correlation of the liquidus curves in binary systems and tie-lines in ternary systems was undertaken with the NRTL equation. These results of solubility can be used to design future alternative technological processes of the extraction of PEA from fermentation broth.

Measurement and calculation of solid–liquid equilibrium for ternary systems of 3,4-dichloronitrobenzene + 2,3-dichloronitrobenzene + ethanol/n-propanol

The stable (solid+liquid) phase equilibrium in ternary systems of 3,4-dichloronitrobenzene+2,3-dichloronitrobenzene+ethanol and 3,4-dichloronitrobenzene+2,3-dichloronitrobenzene+n-propanol at three temperatures was determined by means of an isothermal solution saturation method under pressure p=101.2kPa. The isothermal phase diagrams of the two ternary systems were plotted on the basis of the experimental mutual solubility data. The equilibrium solids formed in the two systems were identified by Schreinemakers’ method of wet residues. It was found that each phase diagram included one co-saturated point, two co-saturated curves and three crystallization zones in the ternary systems of 3,4-dichloronitrobenzene+2,3-dichloronitrobenzene+ethanol and 3,4-dichloronitrobenzene+2,3-dichloronitrobenzene+n-propanol. Two pure solid phases were formed in the studied systems, which were pure 2,3-dichloronitrobenzene and pure 3,4-dichloronitrobenzene. The crystallization zone of 3,4-dichloronitrobenzene was smaller than that of 2,3-dichloronitrobenzene at a given temperature, which showed that 2,3-dichloronitrobenzene could be easily separated from the solution. Furthermore, the solid–liquid phase diagrams were calculated by using NRTL model. The calculated phase diagrams agreed well with the experimental ones. Knowledge of (solid+liquid) phase equilibrium and ternary phase diagrams would be very valuable to design and optimize the solvent crystallization process of 2,3-dichloronitrobenzene and other crystallization processes involving the two ternary systems.

Determination and modeling of solid–liquid equilibrium for ternary system of 3,4-dichloronitrobenzene + 2,3-dichloronitrobenzene + methanol

The solid–liquid phase equilibrium for ternary system of 3,4-dichloronitrobenzene + 2,3-dichloronitrobenzene + methanol were determined experimentally by the method of isothermal solution saturation at temperatures of 283.15 K, 293.15 K and 303.15 K under pressure of 101.3 kPa. According to the obtained solubility data, the isothermal phase diagrams of the system were constructed. At each temperature, there were two pure solid phases formed, which were confirmed by Schreinemakers' wet residue method and corresponded to pure 3,4-dichloronitrobenzene and pure 2,3-dichloronitrobenzene. The crystallization regions of pure 3,4-dichloronitrobenzene and pure 2,3-dichloronitrobenzene increased with decreasing in temperature. The crystalline region of 2,3-dichloronitrobenzene was larger than that of 3,4-dichloronitrobenzene at the same temperature, and increased rapidly as the temperature increase. The data of solid–liquid phase equilibrium were correlated with NRTL model and Wilson model. The calculated solubility data with NRTL model agreed well with the experimental values. The mutual solubility data and ternary phase diagrams for the system were of great significance for optimizing the purification procedure of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene.

Liquid–liquid phase equilibria for ternary systems of several polyethers with NaCl and H2O

Liquid–liquid extraction using polymers followed by induced phase separation is a potential energy reducing technology for water–salt separation. Ternary equilibrium data have been determined and reported for the (block co)poly ethers–sodium chloride–water systems at two different temperatures at 298.15K and 313.15K and atmospheric pressure. The experimental data were correlated with the NRTL model, and the obtained binary interaction parameters to describe the ternary liquid–liquid systems at different temperatures are presented. The model predictions are in good agreement with the experimental data.

Critical end line topologies for ternary systems

A ternary critical end line (T-CEL) is a line of Ternary critical end points (T-CEPs). T-CELs provide key information on the phase behavior of ternary systems, i.e., they are boundaries for the ternary three-phase equilibrium. A ternary system may have several T-CELs. It is desirable to have available a robust algorithm for computing complete ternary CELs, thus minimizing the need for user intervention. It is also important to reliably detect the key points where T-CELs originate or terminate. In this work, we propose to apply a numerical continuation method (NCM) for the fast and robust computation of T-CELs. We present calculated T-CELs for highly asymmetric systems showing the topologies that these lines define. We consider a model of the equation of state (EOS) type and use it over wide ranges of conditions. Such ranges are much wider than those previously considered in the literature. Our main conclusion is that models for the fluid phase equilibria of ternary systems may predict, for a given system, several T-CELs of varying types and topologies. Some of such topologies have been observed for the first time in this work.

Generation of characteristic maps of the fluid phase behavior of ternary systems

The main features of the fluid phase behavior of a given binary system can be grasped at a glance by looking at its (binary) characteristic map (B-CM), which is made of unary and binary univariant lines, i.e., by geometrical objects having only one degree of freedom. Binary univariant lines are critical and azeotropic lines and liquid–liquid–vapor equilibrium lines. These lines are customary shown in the pressure–temperature plane together with the pure-compound vapor–liquid equilibrium lines (unary lines). Similarly, ternary systems also have characteristic maps for their phase equilibrium behavior. Such ternary characteristic maps (T-CMs) are made of unary, binary and ternary univariant lines. Possible ternary univariant lines are the following: ternary four-phase equilibrium lines (T-4PLs), ternary critical end lines (T-CELs) and ternary homogeneous azeotropy lines (T-ALs). T-CMs also present invariant points as the following: pure compound critical points, binary critical endpoints (B-CEPs), ternary critical endpoints of four-phase equilibrium lines (T-CEP-4PLs), ternary tricritical endpoints (T-TCEP), and all possible endpoints of binary and ternary homogeneous azeotropy lines. Analogously to B-CMs for binary systems, T-CMs make possible to quickly identify the main features of the phase behavior of a given ternary system. In other words, T-CMs provide key information on the fluid phase equilibria of ternary systems. When dealing with models for the fluid phase behavior of ternary systems, it would be useful to generate the T-CMs, in a way as automated as possible, once a ternary system and a model are chosen, and the model parameter values are set. This would make possible, among other outcomes, to quickly evaluate the main features of the model performance. B-CMs can be efficiently generated, when using a model of the equation of state (EOS) type, by applying available algorithms. In this work we show how the univariant lines of T-CMs can be efficiently computed for a given ternary system, given EOS and EOS parameter values. In general, a ternary univariant line (T-UVL) is generated in this work by using a numerical continuation method (NCM). NCMs are able to build, in their full extent, highly non linear T-UVLs, with minimum user intervention. In particular, we describe in this work how T-TCEPs and T-CEP-4PLs are detected and computed, and how the calculation of T-4PLs is started off. Finally, an algorithm for the generation of computed T-CMs is presented. The algorithm relies on previously computed critical endpoints of the binary subsystems of the ternary system under study. We have not considered yet the detection and computation of T-ALs and of closed loop T-CELs. We provide examples of T-CMs computed over wide ranges of conditions. The results of this work show that relatively simple models can generate highly complex topologies for the phase behavior of ternary systems.

Measurement and calculation of solid–liquid phase equilibrium for ternary 4-chlorophthalic anhydride + 3-chlorophthalic anhydride + acetone system

The solid–liquid phase equilibrium for ternary system of 4-chlorophthalic anhydride+3-chlorophthalic anhydride+acetone was measured at different temperatures and the mutual solubility was obtained. Four isothermal phase diagrams were constructed according to the experimental solubility. There existed two pure solid phases at each temperature in the studied system, pure 4-chlorophthalic anhydride and pure 3-chlorophthalic anhydride, which were identified by the wet residue method of Schreinemakers’. The crystallization regions of the pure two solids increase with the decrease in temperature. The experimental solid–liquid phase equilibrium for ternary system was calculated using the Wilson and NRTL models, and the corresponding binary interaction parameters were obtained according to the solubility of binary system. The calculated results agree well with the experimental data at different temperature. Both the models give acceptable results for the investigated systems.