Mean Molal Activity Coefficients Research Articles

Binary aqueous solutions of choline salts: Determination and modelling of liquid density (298.15 or 313.15 K) and Vapour Pressure Osmometry (313.15 K)

Salts composed of the cholinium cation (such as choline hydroxide and choline chloride) have become one of the main reactants for the synthesis of greener ionic liquids, but, for a proper description of the aqueous solutions of these strong electrolytes by thermodynamic modelling, reliable data on liquid density (ρ) and vapour pressure (p) are needed, which are often unavailable. So, in this work, the liquid density (ρ) of binary aqueous solutions of choline bicarbonate ([Ch][Bic]), choline (2R,3R)-bitartrate ([Ch][Bit]), choline chloride ([Ch]Cl), choline dihydrogen citrate ([Ch][H2Cit]) and choline hydroxide ([Ch]OH) were measured at 298.15 or 313.15 K and 0.1 MPa and correlated using second-degree polynomials with salt molality (m), obtaining determination coefficients (R2) higher than 0.9974. Furthermore, the osmotic coefficients (ϕ) of these binaries were determined using vapour pressure osmometry (VPO), at 313.15 K and 0.1 MPa, being satisfactorily described by the Extended Pitzer Model of Archer, which yielded low values of standard deviation (3.58<σϕ·103<12.86). Then, the mean molal activity coefficients (γ±) and excess Gibbs free energies (GE/RT) were calculated, following the order [Ch][H2Cit] > [Ch][Bit] > [Ch][Bic] > [Ch]OH > [Ch]Cl, which corresponds to the decreasing polarity of the choline salts and agrees with the empirical law of matching water affinities (LMWA).

Measurement and modelling of liquid density (298.15 and 313.15 K) and vapour pressure osmometry (313.15 K) for binary aqueous solutions of organic salts

Due to the eco-friendliness of organic salts, they have been gradually replacing other electrolytes in different fields of chemistry. For example, they provide biocompatible salting-out agents for liquid–liquid extractions and earth-abundant materials for flow batteries. Nevertheless, reliable liquid density and vapour pressure data, which are paramount for a proper parameterisation of thermodynamic models, are often hard to find for aqueous solutions of organic salts, delaying the development of these technologies.In this work, the liquid density (ρ) of five binary aqueous solutions of organic salts (disodium tartrate, sodium potassium tartrate, dipotassium tartrate, trisodium citrate and tripotassium citrate) were measured and correlated at 298.15 and 313.15 K and 0.1 MPa. In these assays, second-degree polynomials provided determination coefficients (R2) larger than 0.9982 in the correlation of liquid density with salt molality, for which a very accurate description of this property was accomplished. Moreover, vapour pressure osmometry (VPO) studies were carried out for these solutions at 313.15 K and 0.1 MPa. Then, the obtained osmotic coefficients (ϕ) were successfully modelled using the Extended Pitzer Model of Archer, yielding standard deviations (σϕ) lower than 8.61·10-3. Finally, the mean molal activity coefficients (γ±) and excess Gibbs free energies (GE/RT) of the binary aqueous solutions of organic salts were effectively calculated, with potassium- and tartrate-based salts attaining significantly higher values than the ones composed of sodium and citrate, hinting at a more ideal solution behaviour of the former.

Extension of the AIOMFAC model by iodine and carbonate species: applications for aerosol acidity and cloud droplet activation

Abstract. Iodine and carbonate species are important components in marine and dust aerosols, respectively. The non-ideal interactions between these species and other inorganic and organic compounds within aqueous particle phases affect hygroscopicity, acidity, and gas–particle partitioning of semivolatile components. In this work, we present an extended version of the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model by incorporating the ions I−, IO3-, HCO3-, CO32-, OH−, and CO2(aq) as new species. First, AIOMFAC ion interaction parameters for aqueous solutions were determined based on available thermodynamic data, such as water activity, mean molal activity coefficients, solubility, and vapor–liquid equilibrium measurements. Second, the interaction parameters for the new ions and various organic functional groups were optimized based on experimental data or, where data are scarce, alternative estimation methods such as multiple linear regression or a simple substitution by analogy approach. Additional bulk water activity and electrodynamic balance measurements were carried out to augment the database for the AIOMFAC parameter fit. While not optimal, we show that the use of alternative parameter estimation methods enables physically sound predictions and offers the benefit of a more broadly applicable model. Our implementation of the aqueous carbonate–bicarbonate–CO2(aq) system accounts for the associated temperature-dependent dissociation equilibria explicitly and enables closed- or open-system computations with respect to carbon dioxide equilibration with the gas phase. We discuss different numerical approaches for solving the coupled equilibrium conditions and highlight critical considerations when extremely acidic or basic mixtures are encountered. The fitted AIOMFAC model performance for inorganic aqueous systems is considered excellent over the whole range of mixture compositions where reference data are available. Moreover, the model provides physically meaningful predictions of water activity under highly concentrated conditions. For organic–inorganic mixtures involving new species, the model–measurement agreement is found to be good in most cases, especially at equilibrium relative humidities above ∼ 70 %; reasons for deviations are discussed. Several applications of the extended model are shown and discussed, including the effects of ignoring the auto-dissociation of water in carbonate systems, the effects of mixing bisulfate and bicarbonate compounds in closed- or open-system scenarios on pH and solution speciation, and the prediction of critical cloud condensation nucleus activation of NaI or Na2CO3 particles mixed with suberic acid.

Thermodynamic study of interaction effects in aqueous solutions of purine and pyrimidine nucleobases ionic liquids at 298.15 K

We report herewith experimental density and osmotic pressure measurements for aqueous 1-ethyl-3-methylimidazolium ([Emim]), and 1-n-butyl-3-metylimidazolium ([Bmim]) based nucleobases ionic liquids [NBILs] at 298.15 K to gain thermodynamic understanding of NBIL – water mixtures. Molar volumes Vm, standard entropies S0 and lattice potential energies UPOT are reported at 298.15 K using density data of pure state NBILs. Large values of S0 and small UPOT explains the existence of NBILs in liquid state at ambient conditions. Experimental density data of aqueous NBIL solutions were used to obtain apparent, partial and electrostricted volumes from which electrostricted hydration numbers were obtained. It was found that observed hydration numbers are solely due to anion hydration as cation shows negligibly small hydration. Negative magnitudes of excess molar volumes confirm the hydrophobic nature of NBILs. Using experimental osmotic coefficients, water activity (aW), mean molal activity coefficient γ± of NBILs, excess Gibbs free energy change ΔGE due to mixing etc. were obtained and found that these aqueous systems show negative deviation from limiting law. At low concentration hydrophobic hydration is dominant whereas hydrophobic ion-association occurs at higher concentration revealed from minimum in osmotic coefficients. Application of McMillan–Mayer theory of solutions yielded osmotic second virial coefficients which are found to be negative indicating attractive type of ion-ion – ion-pair interactions.

Thermodynamic behaviour of binary mixture of 1,3-dimethoxyimidazolium bis(trifluoromethyl-sulfonyl)imide and water

The osmotic coefficient value of binary aqueous solution containing ionic liquid was obtained by using vapour-pressure osmometry technique. The change in activity and vapour pressure depression of solvent on addition of 1,3-dimethoxyimidazolium bis(trifluoromethylsulfonyl) imide ((OMe)2Im:NTf2) to water have been estimated at two different temperatures (T =313 K and 323 K). The experimental osmotic coefficient values of (OMe)2Im:NTf2 at different molality were correlated by extended Pitzer model of Archer and the ion interaction parameters were evaluated. The correlation coefficients obtained from this model were used to estimate the mean molal activity coefficient, and excess Gibbs free energy of this mixture. The osmotic coefficient values were decreased with increase in molality of the ionic liquid within the solution. The osmotic coefficient values were found to be increased with increase in temperature of the system.

Studies of osmotic and activity coefficient properties of aqueous solutions of triethylammonium formate and triethylammonium glycolate protic ionic liquids at 298.15 K

The triethylammonium-based carboxylate protic ionic liquids (PILs) are called as truly bio-ionic liquids. They can be used as green solvent, additives (biphasic catalysis) and for other considerable effects involving nano-material specially related to biomolecules. In this work, osmotic coefficient (φ) measurements using vapor pressure osmometry technique for aqueous solutions of two PILs, namely, triethylammonium formate [TEAF] (0.01290–0.55988 mol·kg−1) and triethylammonium glycolate [TEAG] (0.00989–0.53176 mol·kg−1) have been reported at 298.15 K. The water activity (aw) and solvent activity coefficient (γ1), mean molal activity coefficient (γ±) of PILs and osmotic pressure (π) of solutions properties in a binary mixture, were determined using experimentally measured φ data. The analysis of osmotic pressure data revealed that the studied PILs are electrolytes in the limit of infinite dilution and yield correct molecular weights as well as show negative values for virial coefficients. The variations of osmotic coefficient and mean molal activity coefficient of studied PILs with concentration indicate positive deviations from Debye-Hückel limiting law similar to that of ammonium ions. Further, Gibbs free energy changes due to mixing (ΔGm) and excess Gibbs free energy changes (ΔGE) for the studied binary systems are estimated. The solute-solute virial coefficient (NB22∗0) for the studied PILs in aqueous solutions were estimated by an application of the McMillan−Mayer theory of solutions. The results indicate that the hydration effect is dominant in PILs through the cooperative H–bonding with water-structure making effect suggesting the significance of hydrophobic hydration as observed in tetraalkylammonium salts and aprotic ionic liquids. A need to study the water molecule splitting at nitrogen charge centre and possible attenuation of water structural effects due to hydrophobic moieties present in the molecule is emphasized.

Thermodynamic studies of phosphonium and imidazolium based ionic liquids in water at 298.15 K: Application of McMillan-Mayer theory and Pitzer model

Experimental results of the osmotic coefficients of aqueous solutions of 1-ethyl-3-methylimidazolium ethylsulfate [EMIM][EtSO4], 1-ethyl-3-methylimidazolium methylsulfate [EMIM][MeSO4], 1-ethyl-3-methylimidazolium tosylate [EMIM][Tos], 1,3-dimethylimidazolium methylsulfate [MMIM][MeSO4], tributylmethylphosphonium methylsulfate [TBMP][MeSO4] and triisobutylmethylphosphonium tosylate [(iBu)3MP][Tos] obtained by vapor pressure osmometry (VPO) at 298.15 K and at atmospheric pressure are reported in this work. From this data water activity (aw), vapor pressure (p), mean molal activity coefficients (γ±), Gibbs free energy due to mixing (ΔGmix) and excess Gibbs free energy change (ΔGE) are calculated. The activity coefficient data obtained are correlated with McMillan-Mayer theory and Pitzer model. The results obtained are elucidated in terms of ion association and structural characteristics of ILs.

Effect of hydrophobicity and H-bonding abilities of ions on osmotic coefficients of aqueous diethylammonium based protic ionic liquid solutions at 298.15 K

The osmotic and activity coefficients of aqueous solutions of diethylammonium based protic ionic liquids (PILs) were determined experimentally using vapor pressure osmometry in the concentration range of (~0.02 to ~0.5) mol·kg−1 at 298.15 K. Osmotic coefficient data show positive deviation from Debye-Hückel limiting law for all the studied PILs. Also a minimum in osmotic coefficient data was observed at higher concentrations and is explained in terms of ion-pair formation. Data of experimental osmotic coefficient were used to obtain activities (aw) and activity coefficients (γ1) of water, mean molal activity coefficient (γ±) of PILs and excess Gibbs free energy change (ΔGE) due to mixing. Observed variations in osmotic coefficients data were explained in terms of hydrophobicity as well as H-bonding. The data of osmotic and activity coefficients were further subjected to analysis through Pitzer ion-interaction model to get an information of ion-ion and ion-solvent interaction to understand ion-pairing, ion hydration and hydrophobic effects in aqueous solutions of PILs. For this, Pitzer ion interaction parameters β(0) and β(1) were estimated and compared with literature data available for other relevant systems. Finally, the results are interpreted in terms ion-ion, ion-solvent interaction along with effect of hydrophobicity on ion-pairing and further discussed the effect of alkyl chain length of anions on solvation behavior of protic ionic liquids in aqueous solutions.

Specific ion effects in non-aqueous solvents: The case of glycerol carbonate

The effect of eight potassium salts (KF, K3PO4, KOCN, K2CO3, KCl, K2SO4, KBr and KI) on glycerol carbonate (GC) is studied through NMR, DSC, solubility and ATR-FTIR experiments. From the solubility data, the main thermodynamic functions of solution and solvation are estimated, and the mean molal activity coefficients are calculated. The results suggest that the capability of an anion to establish hydrogen bonds with the solvent molecules (or behave as a base, as in the case of fluoride, phosphate, cyanate and carbonate) is the most important structural feature that determines its effects on the solvent structure. On the other hand potassium iodide behaves in an anomalous way, due to the large polarizability of the anion that can form non-electrostatic, van der Waals dispersive intermolecular interactions.

(Vapor + liquid) equilibria of alcohol + 1-methyl-1-propylpiperidinium triflate ionic liquid: VPO measurements and modeling

In this work the vapor pressure osmometry technique (VPO) has been used for the determination of osmotic and activity coefficients, at T=323.15K, of the binary mixtures containing 1-methyl-1-propylpiperidinium triflate ionic liquid, PMpipTFO, and alcohols, primary or secondary, 1-propanol, 2-propanol, 1-butanol, 2-butanol, or 1-pentanol. Using the vapor pressures experimentally obtained, the vapor pressure depressions were calculated. For the data correlation, the Extended Pitzer model of Archer (srd⩽0.015) and the MNRTL model (srd⩽0.044) have been adopted. Mean molal activity coefficients and the excess Gibbs free energy were obtained using parameters of the Extended Pitzer model of Archer. The results of this work were considered in terms of the (solute+solvent) and (ion+ion) interactions.

Aqueous Binary Lanthanide(III) Nitrate Ln(NO3)3 Electrolytes Revisited: Extended Pitzer and Bromley Treatments

To date, only limited thermodynamic models describing activity coefficients of the aqueous solutions of lanthanide ions are available. This work expands the existing experimental osmotic coefficient data obtained by classical isopiestic technique for the aqueous binary trivalent lanthanide nitrate Ln(NO3)3 solutions using a combination of water activity and vapor pressure osmometry measurements. The combined osmotic coefficient database for each aqueous lanthanide nitrate at 25 °C, consisting of literature available data as well as data obtained in this work, was used to test the validity of Pitzer and Bromley thermodynamic models for the accurate prediction of mean molal activity coefficients of the Ln(NO3)3 solutions in wide concentration ranges. The new and improved Pitzer and Bromley parameters were calculated. It was established that the Ln(NO3)3 activity coefficients in the solutions with ionic strength up to 12 mol kg–1 can be estimated by both Pitzer and single-parameter Bromley models, even thoug...

Thermodynamic Behavior of Binary Mixtures of 1-Butyl-1-methylpyrrolidinium Iodide and Alcohols

In this work, the osmotic properties of the binary mixtures of 1-butyl-1-methylpyrrolidinium iodide ([BmPr][I]) with isopropanol and n-butanol were studied by using vapor pressure osmometry (VPO) technique at 323.15 K at atmospheric pressure. It was found that the values of osmotic coefficient, mean molal activity coefficient, and vapor pressure decrease with increasing molality. We observed that the change in vapor pressure of ionic liquid in n-butanol is smaller compared to ionic liquid in isopropanol. The excess Gibbs free energy of ionic liquid in isopropanol has a higher value as compared to an ionic liquid + n-butanol mixture. The binary mixture of ionic liquid with alcohols shows noticeable deviation from the Debye–Huckel limiting law. We have used the pseudophase separation model on the experimental osmotic coefficient value to estimate the critical aggregation concentration of ionic liquid in alcohols. We have showed the structural effect of the solvent on the preceding thermodynamic parameters a...

Study of Activity Coefficient of Hydrochloric Acid in 2-Propanol-Water Mixture by Electromotive Force Measurement Method

This paper is mainly focusing on the determination of mean molal activity coefficient of HCl in aqueous acidic medium. The present investigations have been carried out to determine the activity coefficients of hydrochloric acid in 2-propanol water mixture solutions under various conditions to study the ion solvent interactions in different temperatures. The standard molar potential Em0 of the cell; Pt; H2(g) /HCl(m) x% 2-propanol; Hg2Cl2(S)/Hg have been determined in 10%; 20% and 30% (w/w) of 2-Propanol-water mixture solution at three different temperatures 308K, 313K and 318K and molality ranging from 0.005 to 0.1 mol Kg-1. Eo of the cell can be computed by modified Davies equation as below, where K= 2.3026(RT/F), A΄ = appropriate Debye-Huckel constant and Mean molal activity coefficient, The mean molal activity coefficients of hydrochloric acid in aqua organic media and temperature are also computed. The primary ion-solvent effects and the secondary ion-solvent effects are also reported.

Vapor Pressure Osmometry Determination of the Osmotic and Activity Coefficients of Dilute Aqueous Solutions of Symmetrical Tetraalkyl Ammonium Halides at 308.15 K

Osmotic coefficients were measured by the vapor pressure osmometry technique for dilute aqueous solutions of Me4NBr, Et4NBr, Pr4NBr, Bu4NBr, Me4NCl, and Me4NI at 308.15 K. From the experimental osmotic coefficient data, the water activity, water activity coefficient and vapor pressure values were evaluated. The experimental osmotic coefficient data were fitted to the Pitzer equation from which the values of the mean molal activity coefficients were calculated. The values of the obtained osmotic and mean molal activity coefficient data for the bromides decreased with the size of the cation: Bu4N+ < Pr4N+ < Et4N+ < Me4N+. The results for the tetramethylammoniums show that the osmotic and mean molal activity coefficient varies in the following way: Me4NCl > Me4NBr > Me4NI. However the values of the water activity, vapor pressure depression, and the water activity coefficient data follow the order Me4NBr < Et4NBr < Pr4NBr < Bu4NBr and Me4NCl < Me4NBr < Me4NI, which implies that the smaller ions hydrate more water molecules than the ions with larger size.

Osmotic coefficients of alcoholic mixtures containing BMpyrDCA: Experimental determination and correlation

The vapour pressure osmometry technique (VPO) has been used to obtain the osmotic coefficients of the binary mixtures of the primary and secondary alcohols 1-propanol, 2-propanol, 1-butanol, 2-butanol and 1-pentanol with the ionic liquid 1-butyl-1-methylpyrrolidinium dicyanamide, BMpyrDCA. From these coefficients, the corresponding activity coefficients and vapour pressures of the mixtures have been also determined. The results have been discussed in terms of solute–solvent and ion–ion interactions and have been compared with those taken from literature in order to analyse the influence of the anion or cation constituting the ionic liquid. For the treatment of the experimental data, the Extended Pitzer model of Archer and the MNRTL model have been applied, obtaining standard deviations from the experimental osmotic coefficients lower than 0.015 and 0.065, respectively. From the parameters obtained with the Extended Pitzer model or Archer, the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures have been calculated.

Osmotic coefficients and apparent molar volumes of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid in alcohols

In this work, density for the binary mixtures of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate in alcohols (1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol) was measured at T=323.15K and atmospheric pressure. From this property, the corresponding apparent molar volumes were calculated and fitted to a Redlich–Meyer type equation. For these mixtures, the osmotic and activity coefficients, and vapor pressures of these binary systems were also determined at the same temperature using the vapor pressure osmometry technique. The experimental osmotic coefficients were modeled by the Extended Pitzer model of Archer. The parameters obtained in this correlation were used to calculate the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures.

Vapour pressures and osmotic coefficients of binary mixtures containing alcohol and pyrrolidinium-based ionic liquids

The osmotic and activity coefficients and vapour pressures of mixtures containing primary (1-propanol, 1-butanol and 1-pentanol) and secondary (2-propanol and 2-butanol) alcohols with pyrrolidinium-based ionic liquids (1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide, C4MpyrNTf2, and 1-butyl-1-methyl pyrrolidinium trifluoromethanesulfonate, C4MpyrTFO) have been experimentally determined at T=323.15K. For the experimental measurements, the vapour pressure osmometry technique has been used. The results on the influence of the structure of the alcohol and of the anion of the ionic liquid on the determined properties have been discussed and compared with literature data. For the correlation of the osmotic coefficients obtained, the Extended Pitzer model of Archer and the Modified Non-Random Two Liquids model were applied. The mean molal activity coefficients and the excess Gibbs energy for the studied mixtures were calculated from the parameters obtained in the correlation.

Osmotic and apparent molar properties of binary mixtures alcohol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid

In this work, physical properties (densities and speeds of sound) for the binary systems {1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol+1-butyl-3-methylimidazolium trifluoromethanesulfonate} were experimentally measured from T=(293.15 to 323.15)K and at atmospheric pressure. These data were used to calculate the apparent molar volume and apparent molar isentropic compression which were fitted to a Redlich–Meyer type equation. This fit was used to obtain the corresponding apparent molar properties at infinite dilution. On the other hand, the osmotic and activity coefficients and vapor pressures of these binary mixtures were also determined at T=323.15K using the vapor pressure osmometry technique. The Extended Pitzer model of Archer was employed to correlate the experimental osmotic coefficients. From the parameters obtained in the correlation, the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated.

Thermodynamic Studies of Ionic Hydration and Interactions for Amino Acid Ionic Liquids in Aqueous Solutions at 298.15 K

Amino acid ionic liquids are a special class of ionic liquids due to their unique acid-base behavior, biological significance, and applications in different fields such as templates in synthetic chemistry, stabilizers for biological macromolecules, etc. The physicochemical properties of these ionic liquids can easily be altered by making the different combinations of amino acids as anion along with possible cation modification which makes amino acid ionic liquids more suitable to understand the different kinds of molecular and ionic interactions with sufficient depth so that they can provide fruitful information for a molecular level understanding of more complicated biological processes. In this context, volumetric and osmotic coefficient measurements for aqueous solutions containing 1-ethyl-3-methylimidazolium ([Emim]) based amino acid ionic liquids of glycine, alanine, valine, leucine, and isoleucine are reported at 298.15 K. From experimental osmotic coefficient data, mean molal activity coefficients of ionic liquids were estimated and analyzed using the Debye-Hückel and Pitzer models. The hydration numbers of ionic liquids in aqueous solutions were obtained using activity data. Pitzer ion interaction parameters are estimated and compared with other electrolytes reported in the literature. The nonelectrolyte contribution to the aqueous solutions containing ionic liquids was studied by calculating the osmotic second virial coefficient through an application of the McMillan-Mayer theory of solution. It has been found that the second osmotic virial coefficient which includes volume effects correlates linearly with the Pitzer ion interaction parameter estimated independently from osmotic data as well as the hydrophobicity of ionic liquids. The enthalpy-entropy compensation effect, explained using the Starikov-Nordén model of enthalpy-entropy compensation, and partial molar entropy analysis for aqueous [Emim][Gly] solutions are made by using experimental Gibb's free energy data and literature enthalpy data. This study highlights that the hydrophobic interaction persists even in the limit of infinite dilution where the hydration effects are usually dominant, implying importance of hydrophobic hydration. Analysis of the results further shows that the hydration of amino acid ionic liquids occurs through the cooperative H-bond formation with the kosmotropic effect in contrast to the usual inorganic salts or hydrophobic salts like tetraalkylammonium halides.

Thermodynamic behavior of binary mixtures CnMpyNTf2 ionic liquids with primary and secondary alcohols

In this paper, the osmotic and activity coefficients and vapor pressures of the binary mixtures containing the ionic liquids 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, C2MpyNTf2, and 1-methyl-3-propylpyridinium bis(trifluoromethylsulfonyl)imide, C3MpyNTf2, with 1-propanol, or 2-propanol and the ionic liquid 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, C4MpyNTf2, with 1-propanol or 2-propanol or 1-butanol or 2-butanol were determined at T=323.15K using the vapor pressure osmometry technique. The influence of the structure of the alcohol and of the ionic liquid on both coefficients and vapor pressures is discussed and a comparison with literature data on binary mixtures containing ionic liquids with different cations and anion is also performed. Besides, the results have been interpreted in terms of solute–solvent and ion–ion interactions. The experimental osmotic coefficients were correlated using the Extended Pitzer model of Archer and the Modified Non-Random Two Liquids model obtaining standard deviations lower than 0.059 and 0.102 respectively, and the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated.