Experimental Vapor Pressure Research Articles

Vaporisation Thermodynamics: Are Triazolium Ionic Liquids a Real Alternative to Popular Imidazolium-Based Ionic Liquids?

New experimental vapour pressures and vaporisation enthalpies of the ionic liquids [2,4-dimethyl-1,2,4-triazolium][NTf2], [2-methyl-4-ethyl-1,2,4-triazolium][NTf2], and [2-ethyl-4-methyl-1,2,4-triazolium][NTf2] were measured using the Langmuir method in combination with the quartz crystal microbalance. New experimental vapour pressures and vaporisation enthalpies of the molecular liquids 1H-1,2,4-triazole, 1-methyl-1,2,4-triazole, 1-ethyl-1,2,4-triazole, and 1H-1,2,3-triazole were measured using the transpiration method. Structure–property relationships between molecular and ionic liquids were studied. These results will facilitate chemical engineering calculations of processes involving ILs.

Enthalpy of Formation of Calcium and Magnesium Oxide Obtained by Knudsen Effusion Mass Spectrometry

Calcium and magnesium oxide are important components of metallurgical slag systems. However, the literature values for the standard enthalpy of formation ΔfH298∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\Delta }_{f}H}_{298}^{^\\circ }$$\\end{document} of both oxides exhibit large variations in some cases. Since ΔfH298∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\Delta }_{f}H}_{298}^{^\\circ }$$\\end{document} is crucial for the modeling and prediction of equilibrium states and, thus, also for process optimization; it was determined by Knudsen effusion mass spectrometry (KEMS). Pure CaO as well as MgO were investigated in an iridium Knudsen cell. For this purpose, the intensities of the main species present in the gas phase were recorded in a temperature range between 1825 K to 2125 K and 1675 K to 2075 K, respectively, and their partial pressures were obtained. It was observed that CaO and MgO evaporated congruently with the main species in the gas phase, Ca, Mg, O, and O2. The experimental vapor pressures of the gas species in the study of MgO are in good agreement with the calculated values using FactSageTM 7.3 and the FactPS database, while those for the evaporation of CaO show significant differences. These calculations are based on available thermodynamic information, including the Gibbs energy functions of CaO(s), Ca(g), MgO(s), Mg(g), O(g), and O2(g). After calculating the partial pressures and equilibrium constants of reactions, an average formation enthalpy of ΔfH298∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\Delta }_{f}H}_{298}^{^\\circ }$$\\end{document} = − 624.5 ± 3.5 kJ/mol for CaO(s) and ΔfH298∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\Delta }_{f}H}_{298}^{^\\circ }$$\\end{document} = − 598 ± 10 kJ/mol for MgO(s) based on the third law method of thermodynamics were obtained. The deviation of ΔfH298∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\Delta }_{f}H}_{298}^{^\\circ }$$\\end{document} for MgO from the previous literature values can be attributed to the use of different ionization cross sections, temperature calibration, and variation of tabulated Gibbs energy functions.

QSPR predicting the vapor pressure of pesticides into high/low volatility classes.

In this work, the vapor pressure of pesticides is employed as an indicator of their volatility potential. Quantitative Structure-Property Relationship models are established to predict the classification of compounds according to their volatility, into the high and low binary classes separated by the 1-mPa limit. A large dataset of 1005 structurally diverse pesticides with known experimental vapor pressure data at 20 °C is compiled from the publicly available Pesticide Properties DataBase (PPDB) and used for model development. The freely available PaDEL-Descriptor and ISIDA/Fragmentor molecular descriptor programs provide a large number of 19,947 non-conformational molecular descriptors that are analyzed through multivariable linear regressions and the Replacement Method technique. Through the selection of appropriate molecular descriptors of the substructure fragment type and the use of different standard classification metrics of model's quality, the classification of the structure-property relationship achieves acceptable results for discerning between the high and low volatility classes. Finally, an application of the obtained QSPR model is performed to predict the classes for 504 pesticides not having experimentally measured vapor pressures.

Thermochemistry of formation and phase transitions of substituted thiophenes at 298.15 K

This study presented experimental vapour pressure data and thermochemical properties of phase transitions for five substituted thiophenes. Using the transpiration technique, the temperature dependencies of vapour pressure and corresponding enthalpies of vaporisation were determined. Additionally, fusion enthalpies and melting temperatures for 3-acetylthiophene and 2,2′-di-thiophene were measured with differential scanning calorimetry. The solution enthalpies of the substituted thiophenes in benzene were used to evaluate the vaporisation and sublimation enthalpies at 298.15 K. The results of this study were found to be consistent with the literature data, allowing for reliable data on the vapour pressure and enthalpies of vaporisation and sublimation to be evaluated. Furthermore, the evaluated vaporisation and sublimation enthalpies were applied to validate the literature values of condense and gas state formation enthalpies for the studied substituted thiophenes. Additionally, quantum-chemical computations of the gas-phase enthalpies of formation were carried out.

Thermodynamic Behavior of (2-Propanol + 1,8-Cineole) Mixtures: Isothermal Vapor-Liquid Equilibria, Densities, Enthalpies of Mixing, and Modeling.

Vapor pressures and other thermodynamic properties of liquids, such as density and enthalpy of mixtures, are the key parameters in chemical engineering for designing new process units, and are also essential for understanding the physical chemistry, macroscopic and molecular behavior of fluid systems. In this work, vapor pressures between 278.15 and 323.15 K, densities and enthalpies of mixtures between 288.15 and 318.15 K for the binary mixture (2-propanol + 1,8-cineole) have been measured. From the vapor pressure data, activity coefficients and excess Gibbs energies were calculated via the Barker's method and the Wilson equation. Excess molar volumes and excess molar enthalpies were also obtained from the density and calorimetric measurements. Thermodynamic consistency test between excess molar Gibbs energies and excess molar enthalpies has been carried out using the Gibbs-Helmholtz equation. Robinson-Mathias, and Peng-Robinson-Stryjek-Vera together with volume translation of Peneloux equations of state (EoS) are considered, as well as the statistical associating fluid theory that offers a molecular vision quite suitable for systems having highly non-spherical or associated molecules. Of these three models, the first two fit the experimental vapor pressure results quite adequately; in contrast, only the last one approaches the volumetric behavior of the system. A brief comparison of the thermodynamic excess molar functions for binary mixtures of short-chain alcohol + 1,8-cineole (cyclic ether), or +di-n-propylether (lineal ether) is also included.

Thermochemical properties of oxepane

In this work, the vapor pressures of oxepane (CAS 592-90-5) have been determined for the first time within the temperature range 276.2–303.2 K using the transpiration method. The enthalpy of vaporization of hexamethylene oxide was evaluated from the experimental vapor pressure data measured by using this method. Values of the enthalpies of combustion and formation have been determined for the first time by combustion calorimetry in a static bomb. A conformational analysis of oxepane in the gas has been performed using methods of molecular mechanics and ab initio computations; the structure of the most stable conformer has been identified. The enthalpy of formation of oxepane in the gaseous state was calculated with the composite G4 method. The thermodynamic functions of oxepane in the ideal gas state over wide temperature range (298.15–1500 K) have been evaluated. Values of the strain energies in a series of cyclic and heterocyclic compounds have been estimated.

Phase Transitions Equilibria of Five Dichlorinated Substituted Benzenes.

This work reports an experimental study aiming to determine the thermodynamic properties of five chlorinated compounds with environmental impact. The vapor pressures of the crystalline phases of three isomers of dichlorobenzoic acid (2,4-, 2,5-, and 2,6-) and 2,6-dichlorobenzonitrile were measured at several temperatures using the Knudsen effusion technique. Another technique (a static method based on capacitance diaphragm manometers) allowed the measurement of the vapor pressures of both the crystalline and liquid phases of 2,4-dichlorobenzonitrile between 303.0 and 380.0 K. This latter technique also enabled the measurement of sublimation vapor pressures of 2,6-dichlorobenzonitrile over a larger range interval of temperatures, T = 328.7 and 391.8 K. The standard molar enthalpy, entropy, and Gibbs energy of sublimation (for all the compounds studied) and vaporization (for 2,4-dichlorobenzonitrile) were derived, at reference temperatures, from the experimental vapor pressure results. The temperatures and enthalpies of fusion and the isobaric heat capacities of the five crystalline-substituted benzenes were determined using differential scanning calorimetry. The contributions of the three substituents (-COOH, -CN, and -Cl) to the sublimation thermodynamic properties of the compounds studied were discussed.

Vapor-liquid equilibrium of acid gases with imidazolium-based ionic liquids using the UMR-PRU model

The UMR-PRU group contribution equation of state (EoS), which couples the Peng-Robinson EoS with UNIFAC via the Universal Mixing Rules, is extended to pure imidazolium-based ionic liquids (ILs), as well as to their mixtures with CO2 and H2S. The studied ILs consist of alkyl-methylimidazolium cations and tetrafluoroborate, hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anions. The EoS parameters of pure ionic liquids, are determined by fitting experimental vapor pressure and liquid density data. For the extension of UMR-PRU to binary CO2/IL and H2S/IL mixtures, the model parameters are determined by fitting experimental binary vapor-liquid equilibrium data of acid gases with ionic liquids. For comparison, the Peng-Robinson coupled with the conventional van der Waals one-fluid mixing rules (vdW1f) is also applied to the same systems, using adjustable attractive and co-volume cross interaction parameter. It is shown that Peng-Robinson accurately describes pure ionic liquid vapor pressures and liquid densities, while UMR-PRU yields very satisfactory vapor-liquid equilibrium results for binary and ternary mixtures containing ILs and acid gases. Overall, UMR-PRU yields much better results than Peng-Robinson coupled with the vdW1f mixing rules, which indicates the superiority of the UMR mixing rules over the vdW1f ones.

Thermochemical Investigation of Tetrazole-Based Green Explosive Motifs: Experimental Vapor Pressures of N-(Fluoro)methylated Aminotetrazoles

The experimental vapor pressures of thermally modified energetic materials 2-(fluoromethyl)-1H-tetrazol-5-amine and its isomer 1-(fluoromethyl)-1H-tetrazol-5-amine were measured for the first time with the chromatography-assisted transpiration method and compared with the unsubstituted 1H-tetrazol-5-amine as well as with the methylated analogues. The resulting p–T fitting equations based on the Clausius–Clapeyron equation and the enthalpy of sublimation at the reference temperature of 298.15 K were determined for the five compounds under study, and the results are as follows: (93.8 ± 1.0) kJ·mol–1 for 2-(fluoromethyl)-1H-tetrazol-5-amine, (88.7 ± 1.3) kJ·mol–1 for 2-methyl-1H-tetrazol-5-amine, (112.6 ± 2.6) kJ·mol–1 for 1-(fluoromethyl)-1H-tetrazol-5-amine, (118.1 ± 2.0) kJ·mol–1 for 1-methyl-1H-tetrazol-5-amine, and (116.6 ± 2.2) kJ·mol–1 for 1H-tetrazol-5-amine. The p–T fitting equations were used to extrapolate to 298.15 K, and the corresponding vapor pressure results were reported in this work.

Crystal Structures of the Commonly Used Plasticizers Ethylene Glycol Dinitrate, Diethylene Glycol Dinitrate, and Triethylene Glycol Dinitrate─Characterization and Discussion of Their Structural Behavior

Ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (DEGDN), and triethylene glycol dinitrate (TEGDN) are used as plasticizers in propellant mixtures and have been known for more than 100 years. Despite the industrial application and the long history of these compounds, the crystal structures of all three compounds, which are liquids at room temperature, have not been determined. Therefore, in this work, the crystal structures were examined by low-temperature X-ray diffraction, and thus, the bonding properties and crystal packing in the solid state could be compared and discussed for the first time. Furthermore, the compounds were characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy. The thermal properties were investigated by DTA (differential thermal analysis) measurements, and the experimental vapor pressures were measured with the chromatography-assisted transpiration method. The densities at room temperature (for the liquids) were measured by gas pycnometry, and the energetic properties were calculated using the EXPLO5 code. Moreover, a more in-depth analysis of the different sensitivities through discussion of the Hirshfeld surfaces, created based on their crystal structures, was performed to compare their sensitivities in the solid state.

Vapor pressure curves and isobaric vapor–liquid equilibrium for binary systems with compounds obtained from glycerol to be used as components of a bio-diesel mixture

The search of new renewable fuels and the interest of finding new uses for the abundant subproducts of many industrial processes have prompt Eni S.p.A to develop a technology for producing biofuels from glycerol. One of the compounds involved in this process is 2-ethyl-4-ethoxymethyl-1,3‑dioxolane (PrEDO). In this paper their temperature - vapor pressure curve has been determined experimentally as well as binary vapor–liquid equilibrium data at different pressures of systems where this compound is involved.The experimental vapor pressure data of PrEDO have been fitted with the Antoine equation. The vapor liquid equilibrium data have been correlated and calculated with UNIFAC, UNIQUAC, NRTL and Wilson to analyze their use when designing distillation processes.

A short note on the application of the Cisternas-Lam vapor pressure model for liquid desiccant dehumidifier systems

Desiccants are an important part of dehumidifier systems, contributing to absorbing the humidity of the air. The vapor pressure is one of the most important properties in the dehumidification process. For this reason, the application of the Cisternas–Lam model can overcome difficulties such as the lack of experimental vapor pressure measurements. In this work, this model is applied to aqueous solution of several desiccants such as CH3COONa, CH3COOK, NaClO4, and KClO4, including ionic liquids such as [EMIM][OMs], [EMIM][OAc], [EMIM][OTf], [E3MPy][OMs], [EMIM]Cl, [BMIM]Br, [BMIM]Cl, [BMIM]I, [EMIM][ES], [EMIM][MS], [BMIM][DBP], [EMIM][DEP], [MMIM][DMP], [EMIM][DMP], [EEMI][DEP], [EMIM][Tf2N], [EMIM][DCA], [DMIM][BF4], and [MMIM][MS], estimating their K value in binary aqueous systems. In addition, the prediction capacity of the model is tested in interpolation and extrapolation examples and shows good results. Finally, this model is used to predict the vapor pressures of aqueous ternary systems that contain ionic liquids. The results showed that the Cisternas-Lam model is appropriate to correlate and predict vapor pressure in the systems studied.

Experimental and Computational Study of the Properties of Imidazole Compounds with Branched and Cycloalkyl Substituents

N-functionalized imidazole compounds with linear alkyl groups have been widely utilized precursors for imidazolium ionic liquids (ILs) while the effects of branched and cycloalkyl substituents on properties of imidazole compounds have not been studied; however, such compounds are just as synthetically accessible as those with linear alkyl groups. In this work, two fundamental properties, density and viscosity, of selected N-functionalized imidazoles bearing iso-propyl, iso-butyl, sec-butyl methylcyclopropyl, cyclopentyl, and methylcyclohexyl groups have been measured in the temperature range of 293.15–353.15 K for the guidance of molecular design for future applications. A linear and parabolic model were used for temperature-density correlation while temperature dependence of viscosity was summarized using the Andrade Equation and the Vogel-Fulcher-Tammann equation. In addition to experimental data, density, viscosity, vapor pressure and vaporization of enthalpies of target imidazole compounds were predicted using COSMOtherm calculations and compared with experimental data. It was found that the calculated densities were quite close to the experimental data, while viscosity data, obtained from COSMOtherm, underestimated experimental measurements and a scaling factor provided agreement with experiments. Predictions of vapor pressure were relatively reliable at low temperature, although the difference between experiment and prediction tended to expand with increasing temperature. Variances of vaporization enthalpies were small upon temperature change and a maximum error of ~12.3% was observed for all compounds studied.

Comparison of saturation vapor pressures of <i>α</i>-pinene + O<sub>3</sub> oxidation products derived from COSMO-RS computations and thermal desorption experiments

Abstract. Accurate information on gas-to-particle partitioning is needed to model secondary organic aerosol formation. However, determining reliable saturation vapor pressures of atmospherically relevant multifunctional organic compounds is extremely difficult. We estimated saturation vapor pressures of α-pinene-ozonolysis-derived secondary organic aerosol constituents using Filter Inlet for Gases and AEROsols (FIGAERO)–chemical ionization mass spectrometer (CIMS) experiments and conductor-like screening model for real solvents (COSMO-RS). We found a good agreement between experimental and computational saturation vapor pressures for molecules with molar masses around 190 g mol−1 and higher, most within a factor of 3 comparing the average of the experimental vapor pressures and the COSMO-RS estimate of the isomer closest to the experiments. Smaller molecules likely have saturation vapor pressures that are too high to be measured using our experimental setup. The molecules with molar masses below 190 g mol−1 that have differences of several orders of magnitude between the computational and experimental saturation vapor pressures observed in our experiments are likely products of thermal decomposition occurring during thermal desorption. For example, dehydration and decarboxylation reactions are able to explain some of the discrepancies between experimental and computational saturation vapor pressures. Based on our estimates, FIGAERO–CIMS can best be used to determine saturation vapor pressures of compounds with low and extremely low volatilities at least down to 10−10 Pa in saturation vapor pressure.

Predicting the phase equilibria of binary mixtures containing carbon dioxide + n-alkanols from a quadrupolar SAFT-VR approach

The vapor–liquid equilibria of binary mixtures containing carbon dioxide + n-alkanols is studied in the framework of the statistical associating fluid theory for potentials of variable range (SAFT-VR). The effect of the quadrupole moment of carbon dioxide on the phase equilibria is considered into the original SAFT-VR approach by incorporating an additional contribution to the Helmholtz free energy due to quadrupole–quadrupole interactions. The carbon dioxide is modeled as two spherical segments tangentially bonded with an axial quadrupolar moment. The n-alkanol molecules are represented as chains of spherical monomer segments with three associating sites to describe the hydrogen bonding interactions between the molecules. The association effects are taken into consideration by using the first-order thermodynamic perturbation theory of Wertheim. The attractive interactions between monomer segments and site-site associative interactions have been accounted for by using a square-well intermolecular potential. The pure component parameters for carbon dioxide and n-alkanols (from methanol to 1-decanol) are obtained by fitting the SAFT-VR approach to experimental saturated liquid density and vapor pressure. These optimized parameters are used to determine the vapor–liquid equilibria of the mixtures. The pressure-composition and density-composition projections predicted by SAFT-VR for the carbon dioxide + n-alkanols are in good agreement with the experimental data. A significant improvement in the description of the vapor–liquid equilibria of binary mixtures containing carbon dioxide + n-alkanols is obtained with the quadrupolar contribution compared with the results obtained from the original SAFT-VR. The optimized molecular parameters are rescaled in order to determine critical lines and the types of phase behavior. The critical lines and critical points are predicted by the original SAFT-VR approach and the quadrupolar version of the SAFT-VR in good agreement with experimental data. The inclusion of the quadrupolar interactions, present in the carbon dioxide, avoids the treatment of these interactions in an effective way via the square-well potential of variable range. The results of the present work are useful for further exploration of adsorption-extraction of n-alkanols in supercritical fluids.

Vaporization Thermodynamics of Pyrrolidinium, Pyridinium, and Imidazolium-Based Ionic Liquids Bearing the Bis(fluorosulfonyl)imide [FSI] and the Bis(trifluoromethylsulfonyl)imide [NTf2] Anions

New experimental vapor pressures in the range 407 K to 460 K and vaporization enthalpy of the ionic liquids (IL) N-alkyl-N-methyl-pyrrolidinium bis(fluorosulfonyl)imide ionic liquids have been measured using quartz crystal microbalance. The absolute vapor pressures and vaporization enthalpies were compared with analogous pyrrolidinium-based ILs with the bis(trifluoromethanesulfonyl)imide anion. The evaluated difference in vaporization enthalpy of ILs with bis(fluorosulfonyl)imide and bis(trifluoromethanesulfonyl)imide anions allowed for estimation of corresponding property for a wide set of ILs with bis(fluorosulfonyl)imide anion. The results are relevant to chemical engineering calculations of processes involving ILs as reaction and separation media.

Molecular Simulations of Vapor-Liquid Equilibrium of Isocyanates.

The wide range of applications of the isocyanates across multiple industries sparks the interest in the study of their phase behavior. A molecular simulation is a powerful tool that can go beyond experimental investigations relying on a molecular structure of a chemical. The success of a molecular simulation relies on a description of the system, namely, force field, and its parameterization on reproducing properties of interest. In this work, we propose a united-atom force field based on the transferable potentials for phase equilibria (TraPPE) to model the vapor-liquid phase behavior of isocyanates. With Monte Carlo and molecular dynamics simulation methods and the introduced force field, we modeled vapor-liquid equilibrium for a family of linear mono-isocyanates, from methyl isocyanate to hexyl isocyanate, and hexamethylene diisocyanate. Additionally, we performed similar calculations for methyl, ethyl, and butyl isocyanates based on the all-atom GAFF-IC force field available in the literature for modeling isocyanate viscosities. We showed that the developed TraPPE-based force field generally overperformed the GAFF-IC force field and overall showed excellent performance in modeling phase behavior of isocyanates. Based on the simulated vapor pressures for the considered compounds, we estimated the Antoine equation parameters to calculate the vapor pressure in a range of temperatures. The predictions are of particular use in the investigation of thermodynamic properties for those isocyanates lacking experimental vapor pressure data. Results can also be employed in modeling the phase behavior of isocyanate mixtures to investigate their sensing and capturing. Furthermore, from the vapor-liquid equilibrium binodals, we predicted the critical properties of isocyanates which can be used in thermodynamic models based on an equation of state.

Thermodynamics of organic azides: Experimental vapor pressures of organic polyazido compounds measured with the transpiration method

In this study experimental vapor pressures of several organic azides including 1,3-diazidopropan-2-ol (1,3-DAP, CAS: 57011-48-0), 2,3-diazidopropan-2-ol (2,3-DAP, CAS: 67880-10-8) and geminal diazido group containing 1,3‑diethyl-2,2-diazidomalonate (DE-DAM, CAS: 168207-98-5) were measured for the first time using the transpiration method. The study provides p-T fitting equations and corresponding molar enthalpies of vaporization, adjusted to 298.15 K: (72.6 ± 0.5) kJ mol−1 for 1,3-DAP, (75.2 ± 0.6) kJ mol−1 for 2,3-DAP and (76.0 ± 1.1) kJ mol−1 for DE-DAM.

Thermochemistry of Polonium Evaporation from LBE

Polonium is formed in relatively large quantities in lead-bismuth eutectic (LBE) cooled nuclear systems. Because of its radiotoxicity and volatility, a good understanding of the chemical equilibria governing polonium release from LBE is required. In this work, a set of thermochemical data is derived for the chemical species involved in the equilibrium between a solution of polonium in LBE and its vapor in inert conditions. The data were obtained by matching thermochemical models with experimental vapor pressure measurements and ab initio results. The dilute-limit activity coefficient of dissolved polonium in LBE is estimated, as well as the solubility of solid lead polonide in LBE. The results indicate that polonium evaporates from LBE according to the experimentally determined Henry’s law, up to dissolved polonium concentrations well above that expected in LBE cooled nuclear systems.

Modeling of H2S absorption in some ionic liquids with carboxylate anions using modified HKM plus association EoS together with RETM

In current work, mHKM-CPA EoS together with the RETM was employed to correlate H2S absorption into five carboxylate ionic liquids, including 1-ethyl-3-methylimidazolium acetate ([emim][Ace]), 1-butyl-3-methylimidazolium acetate ([bmim][Ace]), 1-hexyl-3-methylimidazolium acetate ([hmim][Ace]), 1-ethyl-3-methylimidazolium lactate ([emim][Lac]) and 1-ethyl-3-methylimidazolium propionate ([emim][Pro]). The RETM proposes a chemical reaction between IL and H2S so that the liquid phase concentrations may be obtained by solving the model. Moreover, mHKM-CPA EoS contributes to VLE calculations. In the model, H2S considered as associating component with 4 association sites while the ILs assumed as non-self-associating compounds with one electron donor/acceptor sites.Fourteen adjustable variables of mHKM-CPA EoS for pure components were calculated using experimental liquid density and vapor pressure data. Afterward, binary systems were correlated by applying RETM. Indeed, two nested loops calculate the liquid phase, total pressure, and vapor phase concentrations, respectively.The parameters of the pure ILs were calculated with maximum AAD% below 0.3. Moreover, the binary results present 4.41 as the overall AAD% for 317 data points. Furthermore, a comparison between the results of the used model with those of the SRK-CPA was performed to show the capability of the mHKM-CPA EoS. As the outputs show, the model has a good ability to correlate the H2S solubility in the ILs concerning the classic SRK-CPA EoS.