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Highlights • Measurement solubility of single gases CO 2 and H 2 S in [C 2 mim][BF 4 ] ionic liquid. • Critical assessment of literature data for CO 2 + [C 2 mim][BF 4 ] binary system. • Measurement of volumetric data and Henry's constants for CO 2 /H 2 S + [C 2 mim][BF 4 ]. • Correlation of experimental data by Pitzer's model and Generic Redlich-Kwong EoS. • Comparison of [C 2 mim][BF 4 ] with other ILs for acid gas enrichment process. Abstract The absorption capacity of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ([C 2 mim][BF 4 ]) for the single gases carbon dioxide and hydrogen sulfide was measured at temperatures from (298 to 353) K and pressures up to about 2.0 MPa. The corresponding molar volumes of CO 2 /H 2 S-saturated liquid phase were also measured in the above temperature and pressure ranges. At the same temperature and pressure, the solubility of hydrogen sulfide in [C 2 mim][BF 4 ], expressed on the molality scale, is more than three times that of CO 2. The Henry's law constants were determined from the new experimental data, which in turn were used to derive the change of some thermodynamic functions for dissolution of the gases in that particular ionic liquid. The partial molar volume at infinite dilution for CO 2 /H 2 S + [C 2 mim][BF 4 ] mixtures was estimated from the measured molar volumes. The new experimental data were correlated by using two models: (a) a model comprised of the extended Henry's law and Pitzer's virial expansion for the excess Gibbs energy, and (b) a generic Redlich-Kwong (GRK) type of cubic equation of state. Both models adequately good correlate the experimental data; however, the first model shows a slightly higher correlative accuracy than the second one. The selectivity of [C 2 mim][BF 4 ] to separate CO 2 and H 2 S is also discussed on the basis of correlation results. [ABSTRACT FROM AUTHOR]

Solubility of the single gases CO 2 and H 2 S in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C 4 mim][OTf]) was measured at temperatures from (303.15–343.15) K and pressures up to about 3.2 MPa for CO 2 and 1.6 MPa for H 2 S. A modified isochoric saturation technique was developed in this study to determine the volume of the gas saturated liquid phase in the solubility measurements. The reliability of the experimental setup and measurement method was assessed through detailed comparison of generated data for CO 2 + [C 6 mim][Tf 2 N] binary mixture with the most reliable data reported in the literature. The average of percent absolute relative deviation (AARD%) of pTx and specific volume data (in cm 3 ·kg −1 ) measured in this work from the corresponding data in the literature is 3.7% and 0.23%, respectively. Comparison of the obtained solubility data shows that H 2 S is more than 4 times as soluble as CO 2 in [C 4 mim][OTf]. The solubility of both gases in [C 4 mim][OTf] is higher than in the lower homologue [C 2 mim][OTf]. Furthermore, [C 4 mim][OTf] shows the highest absorption capacity for H 2 S and high H 2 S over CO 2 selectivity relative to other [C 4 mim]/[C 2 mim] – based ionic liquids with different anions. The experimental data were correlated by using the extended Henry's law combined with a simplified Pitzer's model. The values of AARD% of correlated molalities from experimental data are 1.1% for CO 2 + [C 4 mim][OTf] and H 2 S + [C 4 mim][OTf] binary mixtures. The Henry's law constants, partial molar volume at infinite dilution and thermodynamic functions for dissolution of CO 2 and H 2 S gases in [C 4 mim][OTf], as a function of temperature, were calculated from the experimental data. [ABSTRACT FROM AUTHOR]

The solubility of carbon dioxide and hydrogen sulfide gases in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([C 2 mim][OTf]) was measured at temperatures from (303.15–353.15) K and pressures up to about 3.0 MPa. The Henry's law constants were determined from the new experimental data, which in turn were used to derive the change of some thermodynamic functions of dissolution of the gases in that particular ionic liquid. The new experimental data were correlated by a combination of the extended Henry's law and Pitzer's model for the excess Gibbs energy. The average relative percent deviation (ARD%) of correlated molality values from experimental data are within experimental uncertainties, which indicate quite good correlative accuracy of the Pitzer's model for the systems under investigation. Results show that at the same temperature and pressure, the solubility of H 2 S in [C 2 mim][OTf], expressed on the molality scale, is more than four times that of CO 2 . Comparison of the obtained experimental data indicates that the solubility of H 2 S, expressed on the molality scale, in [C 2 mim][OTf] is much more than its magnitude in the high-capacity ionic liquids 1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([C 2 mim][eFAP]) and 1-ethyl-3-methylimidazolium bis(trifluoromethyl) sulfonylimide ([C 2 mim][Tf 2 N]). For example the molality of H 2 S at 303.15 K and 2.0 MPa is 2.5 times and 1.3 times that of [C 2 mim][eFAP] and [C 2 mim][Tf 2 N], respectively. Solubility of CO 2 in the ionic liquids follows the order [C 2 mim][OTf] < [C 2 mim][Tf 2 N] < [C 2 mim][eFAP]. Compared with other ionic liquids, [C 2 mim][OTf] could potentially be used for separation of CO 2 and H 2 S gases from each other. [ABSTRACT FROM AUTHOR]

[Display omitted] • Measurement solubility of CO 2 and H 2 S in the ionic liquid [Bzmim][Tf 2 N]. • Simultaneous measurement of molar volume of CO 2 / H 2 S saturated [Bzmim][Tf 2 N]. • Evaluation of Henry's constants for solubility of CO 2 and H 2 S in [Bzmim][Tf 2 N]. • Correlation of experimental data by the Pitzer's model and Generic Redlich-Kwong EoS. • Solubility of CO 2 /H 2 S in [Bzmim][Tf 2 N] is compared with [C n mim][Tf 2 N] at molecular level. The solubility of CO 2 and H 2 S in 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bzmim][Tf 2 N]) ionic liquid has been measured at temperatures from (303.15 to 343.15) K and pressures of up to about 3.1 and 1.6 MPa, respectively. The molar volume of the gas saturated liquid phase has also been measured. It was found that the solubility of H 2 S in [Bzmim][Tf 2 N] is>2 times that of CO 2. Henry's constants, partial molar volumes and partial molar thermodynamic functions at infinite dilution for dissolution of CO 2 and H 2 S in [Bzmim][Tf 2 N] were evaluated from the experimental data. The experimental data was correlated using the extended Henry's law combined with a simplified Pitzer's model. The experimental data was further correlated by a generic Redlich-Kwong equation of state (GRK EoS). Both models show quite good correlative accuracy for CO 2 /H 2 S + [Bzmim][Tf 2 N] mixtures. However, the former model was superior to that of the GRK EoS for H 2 S + [Bzmim][Tf 2 N]. [ABSTRACT FROM AUTHOR]

Highlights: [•] Measurement solubility of single gases CO2 and H2S in [C2mim][eFAP] ionic liquid. [•] Evaluation of Henry’s constants for solubility of CO2 and H2S in [C2mim][eFAP]. [•] Correlation of experimental data by the Redlich–Kwong equation of State. [•] Correlation of experimental data by the extended Henry’s law and Pitzer model. [•] Comparison of [C2mim][eFAP] with other ILs for gas sweetening and separation. [ABSTRACT FROM AUTHOR]

Gaseous solubilities of carbon dioxide (1), hydrogensulfide (2),and their binary mixture (x2≈0.2, 0.5, 0.8) have been measured in the ionic liquid 1-octyl-3-methylimidazoliumbis(trifluoromethyl)sulfonylimide ([C8mim][Tf2N]) at temperatures ranging from (303.15 to 353.15) K and at pressuresunder 2 MPa. The observed PTxsolubility data wereused to obtain Henry's law constants and correlated by three models:(1) the simple Krichevsky–Kasarnovsky (KK) equation, (2) amodel comprised of the extended Henry's law and the Pitzer's virialexpansion for the excess Gibbs free energy, and (3) the generic Redlich–Kwong(RK) cubic equation of state proposed for gas–ionic liquidsystems. The correlations from the three models show quite good consistencywith the experimental data for IL/CO2and IL/H2S binary mixtures within experimental uncertainties. For IL/CO2/H2S ternary mixtures, the RK model shows the bestcorrelation with the experimental data. The comparison showed thatthe solubility of H2S is about two times as great as thatof CO2in the ionic liquid studied in this work. It wasfurther found, by comparison of the experimental data of this studywith those of previous reports, that the solubility of H2S in [Cnmim][Tf2N] ILs increasesas the number of carbon atoms in the alkyl substituent of methylimidazoliumcation, n, increases. In addition, quantum chemicalcalculations at DFT/B3LYP level of theory using 6-311(d) and 6-311(2d,2p)basis sets were performed on the isolated systems studied in thiswork to provide explanations from a molecular point of view for theobserved experimental trends. [ABSTRACT FROM AUTHOR]

Abstract: The solubility and diffusion coefficient were determined for carbon dioxide and hydrogen sulfide gases in the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) at temperatures ranging from (303.15 to 353.15)K and pressures up to 1.6MPa. The Krichevsky–Kasarnovsky equation was used to correlate solubility data and Henry’s law constants at different temperatures were obtained. The partial molar thermodynamic functions of solution such as Gibbs free energy, enthalpy, and entropy were calculated using the solubility data. A semi-infinite volume approach is used to obtain the diffusion coefficients for CO2 and H2S and a correlation equation with temperature is presented for each gas. Comparison showed that H2S is more soluble than CO2 and its diffusion coefficient is about two orders of magnitude as that of CO2 in the ionic liquid studied in this work. [Copyright &y& Elsevier]

Abstract: The solubility of carbon dioxide in a series of 1-(2-hydroxyethyl)-3-methylimidazolium ([hemim]+) based ionic liquids (ILs) with different anions, viz. hexafluorophosphate ([PF6]−), trifluoromethanesulfonate ([OTf]−), and bis-(trifluoromethyl)sulfonylimide ([Tf2N]−) at temperatures ranging from 303.15K to 353.15K and pressures up to 1.3MPa were determined. The solubility data were correlated using the Krichevsky–Kasarnovsky equation and Henry’s law constants were obtained at different temperatures. Using the solubility data, the partial molar thermodynamic functions of solution such as Gibbs free energy, enthalpy, and entropy were calculated. Comparison showed that the solubility of CO2 in the ILs studied follows the same behaviour as the corresponding conventional 1-ethyl-3-methylimidazolium ([emim]+) based ILs with the same anions, i.e. [hemim][NTf2]>[hemim][OTf]>[hemim][PF6]>[hemim][BF4]. [Copyright &y& Elsevier]

• Measurement solubility of CH 3 SH in four [C 4 mim] – based ionic liquids. • Evaluation of Henry's constants for solubility of CH 3 SH in the ionic liquids. • Correlation of experimental data by the extended Henry's law and Pitzer model. • Correlation of experimental data by the Redlich-Kwong equation of State. • The surprisingly higher solubility of CH 3 SH compared to H 2 S is discussed in molecular level using DFT calculations. In this work, the absorption capacity of four 1-butyl-3-methylimidazolium ([C 4 mim]+) ionic liquids containing tetrafluoroborate ([BF 4 ]–), hexafluorophosphate ([PF 6 ]–), trifluoromethanesulfonate ([OTf]–), and bis(trifluoromethyl)sulfonylimide ([Tf 2 N]–) anions for methanethiol has been experimentally and theoretically studied. The experimental measurements were conducted below 100 kPa and temperatures ranging from (303.15 to 343.15) K. Henry's law constants, as well as the thermodynamic functions for dissolution of methanethiol in the ionic liquids were evaluated using the experimental solubility data and compared with the corresponding data for the solubility of hydrogen sulfide reported in the literature. The solubility of CH 3 SH was found to be unexpectedly higher (1.3 to 2.9 times) than that of H 2 S in the ionic liquids studied in this work. The comparison of Henry's constants showed that the solubility of CH 3 SH in the ionic liquids follows the order: [C 4 mim][Tf 2 N] > [C 4 mim][PF 6 ] ≈ [C 4 mim][BF 4 ] > [C 4 mim][OTf]. The measured data for the solubility of CH 3 SH in the ionic liquids were correlated using both the γ – φ approach, based on the Pitzer's activity coefficient model, and the φ – φ approach, on the basis of the generalized Redlich-Kwong cubic equation of state (GRK EoS). Surprisingly, the GRK EoS indicated a better correlative accuracy compared to the Pitzer's model for the four CH 3 SH + IL mixtures studied in this work. Quantum chemical density functional theory (DFT) as well as atoms-in-molecules (AIM) calculations, based on M06-2X level of theory, using the 6–311++G(2d,2p) basis set, was employed to explore the irregularly high solubility behavior of CH 3 SH compared to H 2 S in the ionic liquids studied in this work. According to DFT calculations CH 3 SH establishes a stronger interaction with the ionic liquids compared to H 2 S. In addition, the interaction of the cation with the anions diminishes in the presence of CH 3 SH compared with H 2 S, which results in greater void volume available to CH 3 SH guest molecules compared to H 2 S. [ABSTRACT FROM AUTHOR]

Highlights • Measuring the diffusion coefficient of H 2 S and CO 2 in some (emim)-based and (hemim)-based RTILs. • Investigation of the influence of viscosity and Henry's constant on diffusivity. • Correlating of the experimental diffusion coefficient of H 2 S and CO 2 with Wilke-Chang semi-empirical equation. Abstract The diffusivity of carbon dioxide and hydrogen sulfide was studied in five ionic liquids containing two different cations and four anions, namely, 1-ethyl-3-methylimidazolium (emim) based ionic liquids with bis-(trifluoromethyl)sulfonylimide (NTf 2) anion and 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, (eFPT) as well as 1-(2-hydroxyethyl)-3-methylimidazolium (hemim) based ionic liquids (ILs) with different anions, viz. hexafluorophosphate (PF 6), trifluoromethanesulfonate (OTf) and bis-(trifluoromethyl)sulfonylimide (NTf 2). Experimental trials were carried out at temperatures of 303.15, 313.15 and 323.15 K and low initial pressures by means of semi-infinite volume method. The results show that the diffusion coefficients of CO 2 and H 2 S in RTILs increase with increasing temperature, but with different orders, and the diffusivity of CO 2 and H 2 S in (emim) based ILs is greater than that in (hemim) based ILs. In addition, the measured diffusion coefficients of CO 2 and H 2 S have been fitted through Wilke-Chang empirical equation. [ABSTRACT FROM AUTHOR]

Abstract: The solubility of hydrogen sulfide in a series of 1-(2-hydroxyethyl)-3-methylimidazolium ([HOemim]+)-based ionic liquids (ILs) containing different anions, viz. hexafluorophosphate ([PF6]−), trifluoromethanesulfonate ([OTf]−), and bis-(trifluoromethyl)sulfonylimide ([Tf2N]−) at temperatures ranging from 303.15 to 353.15K and pressures of up to about 1.8MPa was measured by a volumetric based static apparatus. The solubility data were correlated using two models: (1) the Krichevsky–Kasarnovsky equation and (2) the extended Henry''s law combined with the Pitzer''s virial expansion for the excess Gibbs energy. Henry''s law constants (at zero pressure) in mole-fraction and molality scales were obtained at different temperatures by means of these two models. Using the solubility data, the partial molar thermodynamic functions of solution, i.e. Gibbs energy, enthalpy, and entropy were calculated. Comparison showed that the solubility of H2S is greater than that of CO2 in the corresponding ILs studied in this work and that the solubility of both gases increases as the number of trifluoromethyl (–CF3) groups in the anion increases, i.e. the solubility behavior of both gases follows the order [HOemim][Tf2N]≥[HOemim][OTf]>[HOemim][PF6]>[HOemim][BF4]. [Copyright &y& Elsevier]

New experimental data for CO2 solubility in the aqueous solutions of N-methyldiethanolamine (MDEA) and 1-butylpyridinium tetrafluoroborate ([Bpy][BF4]) ionic liquid (IL) are reported. The experiments were conducted in a static high pressure equilibrium cell. Solubility measurement of CO2 was performed in various solution compositions of IL and MDEA in a wide temperature range of 298.15-343.15 K and pressures up to 4 MPa. The experimental results revealed that, by increasing the weight percent of IL, the absorption capacity of aqueous mixtures diminishes. It was also observed that the main capacity of CO2 loading in the absorbent solutions belonged to MDEA through chemical absorption, whereas its concentration was more effective than IL in gas solubility. The experimental results are correlated using a semiempirical model with good accuracy. [ABSTRACT FROM AUTHOR]

Highlights: [•] New experimental results for the solubility of carbon dioxide in C8mim PF6 ionic liquid. [•] New experimental results for the solubility of hydrogen sulfide in C8mim PF6 Ionic liquid. [•] New experimental results for the solubility of the mixed CO2 and H2S in C8mim PF6. [•] Correlating obtained experimental data using different models [16,84]. [Copyright &y& Elsevier]

Abstract: The solubility of hydrogen sulphide in three ionic liquids, viz. 1-hexyl-3-methylilmidazolium hexafluorophosphate ([hmim][PF6]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF4]), and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([hmim][Tf2N]), at temperatures ranging from 303.15K to 343.15K and pressures up to 1.1MPa were determined. The solubility values were correlated using the Krichevsky–Kasarnovsky equation and Henry’s constants were obtained at different temperatures. Partial molar thermodynamic functions of solvation such as standard Gibbs free energy, enthalpy, and entropy were calculated from the solubility results. Comparison of the values obtained show that the solubility of H2S in these three ionic liquids was in the sequence: [hmim][BF4]>[hmim][PF6]≈[hmim][Tf2N]. [Copyright &y& Elsevier]