Isothermal Ternary Phase Diagrams Research Articles

Determination and molecular simulation of ternary solid–liquid phase equilibrium of succinic acid + maleic acid + water from 283.15 K to 333.15 K

This study used the isothermal saturation gravimetric method to examine the solid–liquid phase equilibrium relationships composed of succinic acid + maleic acid + water spanning from 283.15 K to 333.15 K. The experimental data were utilized for the purpose of plotting the equilibrium phase diagrams of ternary systems in the studied temperature range. There were three crystalline regions in each isothermal ternary phase diagram, two saturation boundary curves, and a co-saturation point. To broaden the use of data from binary and ternary phase equilibrium measurements, Wilson and NRTL models were utilized for correlation and expectation, while relative average deviation (RAD) and root mean square deviation (RMSD) were utilized to evaluate the computational exactness. The results show that the theoretically calculated values were found to be in near agreement with the experimental values, and both models were able to obtain more precise theoretical data under different experimental conditions. In addition, molecular simulation was employed to elucidate the interaction between succinic acid, maleic acid, and water. This study provides accurate and reliable data for the separation of succinic acid and maleic acid mixture in water. These findings can be utilized to make sense of the dissolvability conduct of succinic acid and maleic acid in aqueous solution.

Phase boundary mapping for high thermoelectric performance β-Zn4Sb3 in Zn–In–Sb ternary system

Zn4Sb3 with complex structure shows excellent thermoelectric performance in the low temperature region. Herein, three batches of In doped Zn4Sb3 were synthesized and the influence of In dopant and Zn content on the thermoelectric properties of Zn4Sb3 was systematically investigated by using a phase boundary method. The isothermal ternary phase diagram of Zn–In–Sb is explored at 623 K. The solubility limit of In in the single phase region with β-Zn4Sb3 structure is strongly related to the ratio between Zn + In and Sb. In atoms preferentially occupy C interstitial of 48f site in the crystallographic Wyckoff position and Zn deficiency increases the concentration of Zn vacancies on this site, enhancing the solubility limit of In in the system. The modification of structure via doping with In hinders the movement and diffusion of Zn interstitial in Zn4Sb3, accompanying with the disappearance of the low temperature phase transitions from α′ to α phase and from α to β phase. The regulation of Zn and In contents in single phase region with β-Zn4Sb3 structure effectively optimizes the thermoelectric performance. A maximum ZT value of 1.43 is attained at 673 K for (Zn0·96In0.04)4.15Sb3 compound, which demonstrates a 47% improvement in comparison with that of Zn4·15Sb3 compound. This work provides a new avenue to further improve thermoelectric properties of Zn4Sb3 compounds.

Solid-liquid phase equilibrium for the hexamethylenetetramine–NH4Cl–H2O system: Solubility determination, model correlation and molecular simulation

The phase equilibrium of the hexamethylenetetramine (HMTA)–NH4Cl–H2O ternary system was investigated to optimize the crystallization separation process for HMTA in industrial wastewater treatment. The solubility of HMTA and NH4Cl in water was measured by the dynamic dissolution equilibrium method. Four isothermal ternary system phase diagrams were generated at 293.15, 303.15, 313.15, and 323.15 K. The solubility data were correlated by the Extended UNIQUAC model, which showed that the model predictions fit well with experimental values. Intermolecular interactions were analyzed by molecular simulations to describe the solubility behavior of the solute in the solvent from a microscopic perspective.

High temperature thermal stability study of SrUF6(s) in SrF2-UF4 system

Fission of U(233) leads to produce number of fission products and among them Sr is one of the high yield fission product which form stable fluoride, SrF2. High temperature interaction of SrF2 and UF4 leads to formation of single ternary compound, SrUF6(s). The Gibbs energy formation of SrUF6(s) has been experimentally measured using two different calcium fluoride solid electrolyte Galvanic cell setup with common sample electrode and different reference electrode:Cell 1: (−)Pt, U3O8(s) ​+ ​UO2F2(s) ​+ ​SrUF6(s) ​+ ​SrF2(s) = CaF2(s) = NiO(s) ​+ ​NiF2(s), Pt (+)Cell 2: (−)Pt, SrO(s) ​+ ​SrF2(s) = CaF2(s) = U3O8(s) ​+ ​UO2F2(s) ​+ ​SrUF6(s) ​+ ​SraF2(s), Pt (+)Heat capacity and enthalpy increment has been experimentally measured with Differential Scanning Calorimeter and high temperature Calvet type drop calorimeter, respectively. The pseudo-binary phase diagram of SrF2-UF4 system was calculated by minimization of Gibbs energies of the phases present in the system. Before phase diagram calculation the experimental thermodynamic data were optimized. The stability domain of SrUF6(s) has been calculated from the chemical potential diagram of Sr–U–F–O system at 873 ​K as oxygen is present as an impurity in molten fluoride salts. The isothermal ternary phase diagram of Sr–U–F2 system has also been calculated in order to determine the coexisting phases of SrUF6(s) at 873 ​K.

Thermodynamic and Molecular Recognition Mechanism of Diastereomeric Salt/Cocrystal-Induced Chiral Separation

To better understand the thermodynamics and molecular self-assembly mechanism of diastereomeric salt/cocrystal-induced chiral separation, a series of 1:1 cocrystals and salts consisting of chiral valines (VAL) and tartaric acid derivatives were synthesized via different methods. Powders of these as-screened cocrystals/salts were characterized by PXRD, TGA, DSC, FT-IR, and Raman spectroscopy. The crystal structures of the five cocrystals/salts were determined and analyzed. It was found that both DBTA and DTTA form diastereomeric salt pairs with VAL enantiomers. Interestingly, l-DMTA cocrystallizes with d-VAL and l-VAL via hydrogen bonding and proton transfer, respectively. Considering this particularity, the differential isothermal (10 °C) ternary phase diagrams (TPDs) of d-DMTA and l-VAL (d-VAL) cocrystals (salt) were constructed in the mixed solvent of MeOH/H2O. Moreover, a pure l-VAL:d-DMTA cocrystal and d-VAL:d-DMTA:0.5CH4O:0.25H2O salt were prepared via equimolar slurry conversion at 10 °C. In situ Raman spectroscopy was applied to monitor the molecular assembly process during the incubation of the cocrystal/salt. Molecular dynamics simulation was employed to rationalize the molecular recognition mechanism, demonstrating the excellent chirality preference of l-DMTA toward l-VAL instead of d-VAL. Calculations of density functional theory approved the synergistic instead of antagonistic effects of binding energy and solvation free energy toward chiral separation.

Ternary solid–liquid phase equilibrium and phase diagram for DL-malic acid+fumaric acid+water system and molecular simulation

Solubility of DL-malic acid and fumaric acid in water for binary and ternary systems was determined through high-performance liquid chromatography (HPLC) at atmospheric pressure in this study. Six isothermal ternary phase diagrams were established at temperatures of 283.15, 293.15, 303.15, 313.15, 323.15, and 333.15 K. Every isothermal ternary phase diagram contains three crystalline regions (pure DL-malic acid, pure fumaric acid, and mixture of DL-malic acid and fumaric acid), two co-saturated boundary curves, and one invariant co-saturated point. All diagrams show that the crystalline region of fumaric acid (III) is significantly larger than that of DL-malic acid (II) at six temperatures. Wilson, NRTL, and Margules models were used to correlate and predict binary and ternary system data and the corresponding calculation precision was assessed using relative average deviation (RAD) and root-mean-square deviation (RMSD). The calculated results of Wilson and NRTL models were consistent with experimental data, and maximum values of RAD and RMSD were 2.93 × 10−2 and 3.67 × 10−3, respectively. Margules model can be used to fit solubility data of DL-malic acid unlike those of fumaric acid. Interaction energy and hydrogen bond length of DL-malic acid and fumaric acid with water were calculated via molecular simulation, and the results can be used to explain solubility behavior of DL-malic acid and fumaric acid in water.

Measurement and modelling of ternary solid–liquid phase equilibrium of (DL-malic acid + maleic acid + water) from 283.15 K to 333.15 K

The solid–liquid phase equilibrium data of (DL-malic acid + maleic acid + water) in binary and ternary systems were measured by high performance liquid chromatography (HPLC) method at 283.15 K, 293.15 K, 303.15 K, 313.15 K, 323.15 K and 333.15 K under atmospheric pressure, and then six isothermal ternary phase diagrams were established. Each isothermal ternary phase diagram included one co-saturated point (invariant), two saturated boundary curves, and three crystallization regions (DL-malic acid, maleic acid, and mixture of both). For extending the application of measured solid–liquid phase equilibrium data, the Wilson model and NRTL model were used for correlation and prediction, and the relative average deviation (RAD) and root-mean-square deviation (RMSD) were applied to assess the calculation precision. The maximum values of RAD and RMSD were 2.61 × 10−2 and 1.87 × 10−3 with Wilson model, 3.31 × 10−2 and 1.86 × 10−3 with NRTL model, respectively, which demonstrated that the calculated data were close to the experimental data, and accurate theoretical data under other experimental conditions were able to acquire through the two models in DL-malic acid + maleic acid + water system. The study provided reliable and accurate data for separating the mixture of DL-malic acid and maleic acid in water.

Research and comparison of solid-liquid phase equilibrium and ternary phase diagrams of 1-(3-nitrophenyl)ethanone + 1-(4-nitrophenyl)ethanone in different solvents

The ternary phase equilibrium for 1-(3-nitrophenyl)ethanone and 1-(4-nitrophenyl)ethanone in methanol or n-propanol were determined at 298.15, 308.15 K and 318.15 K under atmospheric pressure in this work. Based on the measured mutual solubility data, the isothermal ternary phase diagrams were constructed. In each ternary phase diagram, there were one co-saturated point, two boundary curves, and three crystalline regions. The crystallization region of 1-(3-nitrophenyl)ethanone was about the same as 1-(4-nitrophenyl)ethanone at all researched temperatures. The NRTL model was used to correlate the solubility of the ternary 1-(3-nitrophenyl)ethanone + 1-(4-nitrophenyl)ethanone + solvents. The correlation results were evaluated by the values of relative average deviation (RAD) and root-mean-square deviation (RMSD), and their values were 4.18 × 10−2 and 3.60 × 10−3, respectively. The calculated results via this model were all acceptable for ternary solid-liquid phase equilibrium. The ternary phase diagram obtained will play an important part in separating the mixture of 1-(3-nitrophenyl)ethanone and 1-(4-nitrophenyl)ethanone.

Formation and crystallographic orientation study of quasicrystal, 2/1 and 1/1 approximants in Cd–Mg–Y system using electron backscatter diffraction (EBSD)

ABSTRACT A partial isothermal ternary phase diagram of the Cd–Mg–Y system including icosahedral quasicrystal (i-QC) and 1/1 approximant (APP) was obtained at 673 K. The stability of the i-QC and APPs in terms of composition and temperature was studied, as a result of which the 2/1 APP phase was discovered at 773 K. Moreover, the i-QC phase was found to be stable at lower Y concentrations of ∼12–13 at.%, as compared to the 1/1 APP, which showed ∼15–16 at.% Y. Single i-QC, 2/1 and 1/1 APP grains were also synthesized applying centrifuging system. Electron backscatter diffraction (EBSD) characterization of the obtained i-QC and APPs revealed almost the same Kikuchi patterns for the i-QC and 2/1 APP, indicating high resemblance of their structures. However, the Kikuchi pattern acquired from the 1/1 APP was distinguishable from the one obtained from the i-QC as it showed split bands. The occurrence of the split bands was associated with significant deviation from a perfect icosahedral symmetry. This was also confirmed by analysing calculated electron diffraction and Kikuchi patterns along pseudo-five-fold axes of the 2/1 and 1/1 APPs. Finally, orientation relationships between the i-QC, 1/1 APP and α-Mg were investigated by analysing acquired EBSD Kikuchi patterns from the respective domains. Accordingly, three perpendicular two-fold axes of the i-QC and {100} axes of the 1/1 APP occur along three mutually orthogonal {0001}, {10-10} and {11-20} axes of the α-Mg.

Characterisation of Intermetallic Phases in Fusion Welded Commercially Pure Titanium and Stainless Steel 304

A series of trials to fusion weld commercially pure titanium (CPTi) to stainless steel 304 (SS304) have been conducted using laser beam welding (LBW) and gas tungsten arc welding (GTAW). Neither technique produced adequate weld joints with LBW showing a more promising result, while GTAW yielded separation of the workpieces immediately after welding. Cracking and fracturing took place mainly on the SS304 side, which was explained by the differences in the materials’ thermal properties. Various intermetallic phases formed during welding that were identified using energy dispersive X-ray spectroscopy (EDS) and electron backscattered diffraction (EBSD) technique and were compared with an isothermal ternary phase diagram of Fe-Cr-Ti. Their corresponding hardness values are reported and correlated with alloy compositions.

Thermal stabilities and properties of equilibrium phases in the Pt-Te-O system

Oxides and intermetallic phases in the platinum-tellurium-oxygen system have been studied. Thermal stabilities, thermodynamics, and structures of the phases reported in the literature, including the conditions under which PtOx form and decompose, have been compiled and critically evaluated. Heat capacities of the binary phases have been estimated, and compared with the scarcely available experimental literature data. The estimated values are generally in agreement with the few available literature data.The intermetallic phase PtTe was synthesized, and thermally analysed by the differential scanning calorimetry and thermogravimetry techniques, under both inert and oxidizing conditions. Based on the calorimetric measurements, the solidus and liquidus temperatures, and enthalpy of melting of PtTe in the phase region PtTe-Pt have been determined. For the first time, the maximum thermal stability of PtTe in an oxidizing atmosphere, close to the partial pressure of oxygen in air, is experimentally determined to be T=(603±1)K, above which it oxidizes to form TeO2 and Pt. Based on experimental observations in this work combined with the literature review, isothermal ternary phase diagram of the Pt-Te-O system is proposed.

Determination and modeling of binary and ternary solid-liquid phase equilibrium for the systems formed by 3,5-dinitrobenzoic acid, m-nitrobenzoic acid and acetone

The solubility of 3,5-dinitrobenzoic acid in acetone at the temperatures ranging from (283.15 to 318.15)K and the mutual solubility of the ternary m-nitrobenzoic acid+3,5-dinitrobenzoic acid+acetone system at (283.15, 298.15 and 313.15)K were determined experimentally by using the isothermal saturation method under atmosphere pressure (101.2kPa). Three isothermal ternary phase diagrams were constructed according to the measured mutual solubility data. In each ternary phase diagram, there was one co-saturated point, two boundary curves, and three crystalline regions. The modified Apelblat equation, λh equation, NRTL model and Wilson model were used to correlate the solubility of 3,5-dinitrobenzoic acid in acetone; and the NRTL and Wilson models, the mutual solubility for the ternary m-nitrobenzoic acid+3,5-dinitrobenzoic acid+acetone system. The value of root-mean-square deviation (RMSD) was 8.53×10−4 for the binary system of 3,5-dinitrobenzoic acid+acetone; and the largest value of RMSD was 81.08×10−4 for the ternary system.

Determination and modeling of binary and ternary solid-liquid phase equilibrium for the systems formed by 1,8-dinitronaphthalene and 1,5-dinitronaphthalene and N-methyl-2-pyrrolidone

The solubility of 1,8-dinitronaphthalene and 1,5-dinitronaphthalene in N-methyl-2-pyrrolidone at (293.15–343.15)K and the mutual solubility of the ternary 1,5-dinitronaphthalene+1,8-dinitronaphthalene+N-methyl-2-pyrrolidone mixture at (313.15, 328.15 and 343.15)K were determined experimentally using the isothermal saturation method under atmospheric pressure (101.2kPa). The solubility of 1,8-dinitronaphthalene in N-methyl-2-pyrrolidone is larger than that of 1,5-dinitronaphthalene. Three isothermal ternary phase diagrams were built according to the measured mutual solubility data. In each ternary phase diagram, there were one co-saturated point, two boundary curves, and three crystalline regions. Two pure solids (pure 1,8-dinitronaphthalene and pure 1,5-dinitronaphthalene) were formed in the ternary system at a given temperature, which were identified by Schreinemaker’s method of wet residue and powder X-ray diffraction (PXRD) pattern. The crystallization region of 1,8-dinitronaphthalene was smaller than that of 1,5-dinitronaphthalene at each temperature. The modified Apelblat equation, λh equation, NRTL model and Wilson model were used to correlate the solubility of 1,8-dinitronaphthalene and 1,5-dinitronaphthalene in N-methyl-2-pyrrolidone; and the NRTL and Wilson models were employed to correlate and calculate the mutual solubility for the ternary 1,5-dinitronaphthalene+1,8-dinitronaphthalene+N-methyl-2-pyrrolidone system. The largest value of root-mean-square deviation (RMSD) was 20.34×10−4 for the binary systems; and 7.38×10−3 for ternary system. The calculated results via these models are all acceptable for the binary and ternary solid-liquid phase equilibrium.

Phase equilibria study of Cu–O–ZnO system in various oxygen partial pressures

Phase relationships of the Cu–O–ZnO system in equilibrium with air (PO2=0.21atm) and metallic copper (in pure argon) have been studied for the first time using equilibration/quenching/EPMA techniques. In this study, we quantified the phases in equilibrium with air in the temperature range 1095–1500°C and represented the equilibria by the pseudo-binary phase diagram (Cu2O–ZnO). The diagram has one simple eutectic reaction with two primary phases of cuprite (Cu2O) and zincite (ZnO), and the binary eutectic point was found to be 1098±2°C with 0.10±0.01mol fraction of ZnO. There were three phases Cu2O+ZnO+liquid copper or ZnO (Cu2O)+liquid oxide+liquid copper coexisting with each other in the temperature range 1205–1300°C, when the system was equilibrated with metallic copper. Isothermal ternary phase diagrams (Cu–O–ZnO) were used to present the results of the experiments at Cu saturation. The eutectic point of the Cu saturated system was determined to be 1208±2°C and 0.03±0.01mol fraction of ZnO. Results were compared with the phase diagrams calculated by MTDATA 5.10 and its Mtox 7.0 database. The differences between the experimental data and the computational phase boundaries were significant and the system properties require a re-assessment.

Interdiffusion and reactions between U–Mo and Zr at 650 °C as a function of time

Development of monolithic U–Mo alloy fuel (typically U–10wt.%Mo) for the Reduced Enrichment for Research and Test Reactors (RERTR) program entails a use of Zr diffusion barrier to eliminate the interdiffusion–reactions between the fuel alloy and Al-alloy cladding. The application of Zr barrier to the U–Mo fuel system requires a co-rolling process that utilizes a soaking temperature of 650°C, which represents the highest temperature the fuel system is exposed to during both fuel manufacturing and reactor application. Therefore, in this study, development of phase constituents, microstructure and diffusion kinetics of U–10wt.%Mo and Zr was examined using solid-to-solid diffusion couples annealed at 650°C for 240, 480 and 720h. Phase constituents and microstructural development were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Concentration profiles were mapped as diffusion paths on the isothermal ternary phase diagram. Within the diffusion zone, single-phase layers of β-Zr and β-U were observed along with a discontinuous layer of Mo2Zr between the β-Zr and β-U layers. In the vicinity of Mo2Zr phase, islands of α-Zr phases were also found. In addition, acicular α-Zr and U6Zr3Mo phases were observed within the γ-U(Mo) terminal alloy. Growth rate of the interdiffusion–reaction zone was determined to be 7.75(±5.84)×10−16m2/s at 650°C, however with an assumption of a certain incubation period.

Design of novel ultrafiltration systems based on robust polyphenylsulfone hollow fiber membranes for treatment of contaminated surface water

Abstract This work focuses on development of robust but economical hollow fiber ultrafiltration systems that could be operated with or without electric power to treat polluted surface water. A diverse experimental study was carried out to synthesize novel hollow fiber membranes based on polyphenylsulfone (PPSu) and polyvinylidenefluoride (PVDF) fibers for surface water treatment. A manual hollow fiber spinning machine incorporated with an inexpensive spinneret was designed to fabricate hollow fibers from dope compositions of 20 wt% PVDF in DMAc and 20 wt% PPSu in NMP by phase inversion technique. Isothermal ternary phase diagrams of PVDF or PPSu/solvent/non-solvent systems were established using three different solvents such as N,N- dimethylacetamide (DMAc), 1-methyl-2-pyrrolidinone (NMP) and N,N -dimethylformamide (DMF) with water being the non-solvent. The indigenous fibers had an approximate outer diameter of 1.5 mm and the wall thickness of 0.25 mm and were housed in inexpensive PVC and UPVC tubes using epoxy resin and nylon end connectors. PVDF hollow fibers (HF) exhibited 94.8% turbidity rejection, whereas PPSu fibers exhibited 91% rejection with 5 log E-Coliform reduction from surface water at a low hydraulic pressure of 1 bar with high flux values of 125 L m − 2 h − 1 and 73 L m − 2 h − 1 , respectively at a substantial water recovery of 80%. A water purification device capable of generating 25 L h − 1 purified water flow at an overhead tank pressure of 0.5 bar was designed and fabricated for households along with a hand pump operated submerged ultrafiltration (UF) system for treatment of surface water in flood prone regions. Detailed economic estimation of the indigenously designed water purification device for household purpose is presented which shows a low operating cost of 0.02 US $ per liter of purified water obtained.

Effect of nanoclay dispersion on liquid–liquid phase separation in a ternary system of segmented polyurethane/dimethylformamide/water system

AbstractThis paper reports a study on liquid‐liquid phase separation in an isothermal ternary system of segmented polyurethane/dimethylformamide/water system with and without the presence of nanoclay dispersion in the system. Isothermal ternary phase diagrams for three different grades with varying shore A hardness of thermoplastic polyurethane (TPU)/solvent/nonsolvent system were constructed based on the cloud point measurement that was carried out by the titration method. The effect of temperature on phase diagrams has also been studied. The binary interaction parameters between TPUs and water were estimated by water sorption experiments. The effect of organoclay dispersion concentration in the TPU solution on isothermal ternary phase diagrams has also been studied. This understanding of phase separation characteristics would be very helpful in correlating the final morphology developed in wet‐spun TPU as well as polyurethane/clay nanocomposite fibres. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Separation of CO 2 and H 2S using room-temperature ionic liquid [bmim][PF 6

We have developed a ternary equation of state (EOS) model for the CO 2/H 2S/1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]) system in order to understand the separation of these gases using room-temperature ionic liquids (RTILs). The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical interaction parameters for each binary system. These interaction parameters have been determined using our previously measured VLE (vapor–liquid equilibrium) data for CO 2/[bmim][PF 6] and literature data for H 2S/[bmim][PF 6] and CO 2/H 2S. VLLE (vapor–liquid–liquid equilibrium) measurements have been made and validate EOS model predictions which suggest that the CO 2/[bmim][PF 6] and H 2S/[bmim][PF 6] systems are Type V phase behavior, according to the classification of van Konynenburg and Scott. The validity of the ternary EOS model calculations has also been checked by conducting VLE experiments for the CO 2/H 2S/[bmim][PF 6] system. With this EOS model, isothermal ternary phase diagrams and solubility (VLE) behavior have been calculated for various ( T, P, and feed compositions) conditions. The CO 2/H 2S gas selectivity is nearly independent of the amount of ionic liquid addition and ranged from about 3.2 to 4.0. For large CO 2/H 2S mole ratios (9/1) at 298.15 K, the addition of the ionic liquid increases the CO 2/H 2S gas selectivity from about 1.2 to 3.7. For high temperature (333.15 K) and high CO 2/H 2S feed ratios, the addition of the ionic liquid provides the only means of separation because no VLE exists for the CO 2/H 2S binary system without the ionic liquid.

Separation of Carbon Dioxide and Sulfur Dioxide Using Room-Temperature Ionic Liquid [bmim][MeSO4

A ternary equation of state (EOS) model for the CO2/SO2/1-butyl-3-methylimidazolium methyl sulfate ([bmim][MeSO4]) system has been developed in order to gain further our understanding of capturing and enhanced gaseous selectivity of industrial flue gases containing CO2 and SO2 using room-temperature ionic liquids. The present model is based on a generic Redlich−Kwong (RK) EOS. The empirical binary interaction parameters have been determined using our measured vapor−liquid-equilibrium (VLE) data for SO2/[bmim][MeSO4] and literature data for CO2/[bmim][MeSO4] and CO2/SO2. The validity of the present EOS has been checked by conducting ternary VLE experiments for the present system. With this EOS, an isothermal ternary phase diagram and solubility (VLE) behaviors have been calculated for various (T, P, and feed compositions) conditions. The addition of the [bmim][MeSO4] for small and equimolar CO2/SO2 mole ratios significantly increased the selectivity. For large CO2/SO2 mole ratios, the selectivity was high for even a small addition of ionic liquid and in certain cases showed a maximum selectivity due to preferential chemical absorption of SO2. The enhancement in CO2/SO2 selectivity using [bmim][MeSO4] was significantly higher than using 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]) from our previous work and may make the simultaneous capture and separation of these acid gases practical.

Separation of Carbon Dioxide and Sulfur Dioxide Gases Using Room-Temperature Ionic Liquid [hmim][Tf2N

To understand capturing and/or enhanced gaseous selectivity of industrial flue gases containing CO2 and SO2 using room-temperature ionic liquids, we have developed a ternary equation of state (EOS) model for a CO2/SO2/1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]) system. The present model is based on a generic RK (Redlich−Kwong) EOS, with empirical binary interaction parameters of each binary system. These interaction parameters have been determined using our measured VLE (vapor−liquid-equilibrium) data for SO2/[hmim][Tf2N] and CO2/[hmim][Tf2N] and literature data for CO2/SO2. The validity of the present EOS has been checked by conducting ternary VLE experiments for the present system. With this EOS, isothermal ternary phase diagrams and solubility (VLE) behaviors have been calculated for various (T, P, and feed compositions) conditions. For large and equimolar CO2/SO2 mole ratios, the gaseous selectivity is nearly independent of the amount of the ionic liquid addition. Howe...