NRTL Equation Research Articles

Phase equilibria and energetics of binary mixtures of water with highly hydrophilic [EMIM]-based ionic liquids: Methanesulfonate, methylsulfate, and dimethylphosphate

As a follow-up to our systematic studies on the aqueous solutions of 1-ethyl-3-methylimidazolium-based ([EMIM]) ILs, this work deals with phase equilibria and energetics of other three aqueous [EMIM] ILs whose anion is methanesulfonate ([MeSO3]), methylsulfate ([MeSO4]), and dimethylphosphate ([DMP]). We present here new and extensive experimental VLE, SLE and excess enthalpy data, our aim being to provide truly reliable information that would substantially upgrade that existing in the literature. After investigations of the phase behavior and properties of the pure ILs, we performed for the IL solutions systematic measurements of the water activity in the span from 0.05 to 1 and excess enthalpy in the highly dilute IL region (xIL < 0.003) as functions of composition and temperature in the range of 30 K. The freezing temperatures of solutions were further measured in the water-rich region and, in case of [EMIM][DMP], also in the IL-rich region. The VLE and excess enthalpy data were then simultaneously correlated by a modified NRTL equation whose ability to reliably capture VLE, SLE and the energetic properties of the systems was subsequently demonstrated in detail. This also comprised due comparison and analysis of the available literature information which lead to the identification of some incorrect literature data. The calculated excess Gibbs energy and excess enthalpy of the systems revealed for all three systems large negative deviations from ideality that increase in the sequence [EMIM][MeSO3] < [EMIM][MeSO3] < [EMIM][DMP], the values exhibited by the (water + [EMIM][DMP]) belonging to the largest negative deviations from the ideal mixture behavior ever observed. In contrast to other aqueous [EMIM] ILs, the aqueous [EMIM][DMP] exhibits an enormously negative excess entropy which at xw > 0.5 corresponds to an entropy loss upon mixing and indicates thus an unprecedented structuring effect of the system. The excess Gibbs energy and enthalpy values at extrema for aqueous solutions of five hydrophilic [EMIM] ILs studied here and in our previous work were further found to closely correlate with the solvatochromic H-bond basicity parameters of the ILs anions, which proved that the water – IL affinity is governed by the H-bonding of the water to the anions of the ILs. Finally, simple MD simulations gave insight into the way and the number of H-bonds between the water molecules and the anion of the IL in the water-rich region.

Comparative analysis of phase diagrams of organochlorosilane/organoalkoxysilane—solvent—water systems

The phase diagrams of the liquid systems RnSi(OR’)4−n-Me2CO-H2O and RnSiCl4−n-Me2CO-H2O, where R = Me, Ph; R’ = Me, Et; n = 0–2, were compared. Mathematical modeling of the phase equilibrium in these systems was performed on the basis of the UNIFAC and NRTL equations. The heterogeneous regions, conodes of phase equilibrium, and compositions of the coexisting phases are determined. A satisfactory description of the experimental data by the parameters of the models of phase equilibrium obtained on the basis of the NRTL equations is shown for the phase diagrams of the MeSi(OEt)3/Si(OEt)4-Me2CO-H2O systems. The heterophase character due to the mutual insolubility of the monomers and water is common for both systems. The heterogeneous region of the RnSi(OR’)4−n-Me2CO-H2O system is smaller than that of RnSiCl4−n-Me2CO-H2O (calculation by the UNIFAC method). At the same acetone concentration, the water concentration in the organic phases of the “alkoxy” systems is higher than that in the “chlorosilane” systems. The replacement of acetone with ethanol and AcOH leads to a sharp reduction of the heterogeneous region.

Effect of Mixed Solvents Containing Ethylene Glycol and Various Salts on the Vapor–Liquid Equilibrium of Water + Methanol + Ethanol

The mixture of water, methanol, and ethanol is frequently produced in the pharmaceutical industry. To separate the mixture by extractive distillation, the selection of entrainer is a crucial step. Entrainer performances of ethylene glycol (EG) and some mixed solvents were evaluated in this work, including EG + KOAc, EG + CaCl2, EG + LiCl, and EG + choline chloride (ChCl). Isobaric vapor–liquid equilibrium data were measured for the quaternary and quinary systems at 101.3 kPa and were modeled by use of the NRTL equation. The effects of EG and the mixed solvents on the relative volatilities of the volatile key components are discussed in relation to the effects on the activity coefficients. Results showed that adding salts into ethylene glycol results in significant improvement of solvent performance. A more rapid decrease in the activity coefficient of water, as well as an increase in the activity coefficient of ethanol, can be observed with the addition of the mixed solvents, resulting in a more rapid increase in the relative volatility of ethanol to water. The mixed solvent EG + ChCl 4:3 showed the best performance, having a value of 5.85 for the relative volatility of ethanol to water at a solvent mass fraction of 0.8.

Experimental study and thermodynamic modeling of a novel heat-resistant explosive in different mono solvents

In this paper, the solubility of 5,5′-bis(2,4,6-trinitrophenyl)-2,2′-bis(1,3,4-oxadiazole) (TKX-55) was first determined by a dynamic laser monitoring at T = (293.15, 298.15, 303.15, 308.15, 313.15, 318.15, 323.15, 328.15 and 333.15) K in fourteen pure solvents, including nitrobenzene (NB), methylethylketone (MEK), dimethyl carbonate (DMC), N,N-dimethylformamide (DMF), methoxybenzene (MOB), ethenyl acetate (VAC), 1,2-propanediol (PDO), cyclohexanone (CYC), epichlorohydrin (ECH), 1-butanol (NBA), n-butyl acrylate (BA), dimethyl sulfoxide (DMSO), tributyl phosphate (TBP) and 2-butanol (IBA), under atmospheric pressure (P = 0.1 MPa). Besides, supersolubility as well as the metastable zone width of TKX-55 in PDO, BA, DMSO and IBA was determined by the dynamic laser monitoring method. The experimental results showed that the solubility of TKX-55 in fourteen pure solvents increases with increasing temperature and the metastable zone width decreases with increasing temperature. The metastable zone width is approximately 2.49 K–43.26 K. In addition, in order to improve the applicability of the solubility, the modified Apelblat equation, λh equation, the polynomial empirical equation, van't Hoff equation and NRTL equation were used to correlate the solubility data of TKX-55, and the results showed that all models can give a satisfactory correlation. The average root-mean-square deviation (102RMSD) values were 1.71, 8.91, 2.33, 6.12 and 3.30, respectively. Moreover, Hansen solubility parameter was used for explaining the solubility order of TKX-55 in selected solvents, the consequences showed that solubility order of TKX-55 resulted from the comprehensive function of several solubility parameters. The solubility parameter of Δδt between TKX-55 and solvents reached from 1.27 MPa0.5 to 15.28 MPa0.5. Furthermore, three kinds of thermodynamic properties of the mixing enthalpy (ΔmixH), the mixing entropy (ΔmixS) and the mixing Gibbs energy (ΔmixG) of TKX-55 in selected solvents were calculated by NRTL equation and the results turned out that the dissolution process was spontaneous. Besides, thermal properties of TKX-55 were measured by differential scanning calorimetry (DSC). The results showed that the melting temperature and the fusion enthalpy were 640.65 K and 19.60 kJ·mol−1, respectively. Finally, solubility values and thermodynamic relations of TKX-55 in fourteen pure solvents would be invoked as fundamental data and models regarding the purification process.

Tert-Butanol–water mixture separation by extractive distillation: Application of experimental data in process simulations

Effect of two solvents on the tert-butanol–water azeotropic mixture separation efficiency and economy has been studied. As solvents, two imidazolium ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium bromide [EMim]Br and 1-butyl-3-methylimidazolium bromide [BMim]Br, were selected. For the original diluted tert-butanol (TBA) mixture separation, a separation unit composed of pre-concentration and extractive distillation columns was proposed. Simulations of separation equipment were carried out based on the equilibrium stage model of a distillation column implemented in ASPEN+. Regarding phase equilibrium description, the original NRTL excess Gibbs energy equation was used for the components’ activity coefficients calculation. Phase equilibrium data of IL-containing binaries were measured experimentally in a broad range of ILs’ concentrations and original binary parameters of the NRTL equation were evaluated from these data. To avoid ILs decomposition, regeneration of extraction solvents, ILs, in a vacuum film evaporator was considered. The effect of temperature and pressure in the vacuum film evaporator on the purity of the recovered ILs was tested experimentally in laboratory equipment and the results were applied in separation unit design simulations. For the proposed separation unit, operation costs were evaluated using the ASPEN+ software. Influence of the state of feed entering the extractive distillation column on operation costs was also investigated. By replacing the total condenser at the pre-concentration column head for a partial one, overall operation costs of the separation unit were reduced by about 20%.

Separation of organosulfur compounds from heptane by liquid–liquid extraction with tricyanomethanide based ionic liquids. Experimental data and NRTL correlation

This work is an attempt to determine appropriate solvents for extractive desulfurization, which is the dominant alternative to the risky and expensive solution, which is hydrodesulfurization (HDS). The main part of this research is the study on (liquid + liquid) phase equilibria in {IL (1) + heptane, or thiophene, or 2-methylthiophene, or benzothiophene (2) binary systems and {IL (1) + thiophene/2-methylthiophene/benzothiophene (2) + heptane (3)} ternary system. In this work, five new synthesized tricyanomethanide – based ILs that is: N-(3-cyanopropyl)-N-methylmorpholinium tricyanomethanide, [Mo1,3CN][TCM], N-(3-hydroxypropyl)-N-methylmorpholinium tricyanomethanide, [Mo1,3OH][TCM], N-(3-cyanopropyl)pyridinium tricyanomethanide, [Py3CN][TCM], N-(3-hydroxypropyl)pyridinium tricyanomethanide, [Py3OH][TCM], N-(2-hydroxyethyl)pyridinium tricyanomethanide, [Py2OH][TCM] are analyzed as an extractant in desulfurization of model fuel. Based on the experimental ternary LLE data, the selectivity and solute distribution ratio are calculated and used to determine the efficiency of the tested ILs as solvents for the extraction of sulfur compounds from model fuel. The experimental results have been compared to literature data for other tricyanomethanide-based ILs and were discussed in terms of the selectivity and solute distribution ratio of separation of related systems. The NRTL equation was successfully used to correlate the LLE in binary systems as well as the experimental tie-lines.

The Effects of NaI, KBr, and KI Salts on the Vapor-Liquid Equilibrium of the H2O+CH3OH System.

The vapor–liquid equilibrium (VLE) in chemical engineering is indispensable for the design of equilibrium separation processes such as distillation, absorption, extraction, and crystallization. VLE data were measured for H2O+CH3OH+NaI, H2O+CH3OH+KBr, and H2O+CH3OH+KI systems. By analyzing and summarizing the results of H2O+Methanol+Alkali metal halide systems, the salt effects of NaI, KBr, and KI on the vapor–liquid equilibrium were obtained. Simultaneously, a model based on the NRTL equation (non-random two liquid) was proposed to correlate and calculate the VLE for the systems. In addition, the assumption of solvation based on hydration was introduced in this model. The proposed model can be successfully used to calculate the VLE for H2O+Methanol+Alkali metal halide systems.

Physicochemical Properties of Terebic Acid, MBTCA, Diaterpenylic Acid Acetate, and Pinanediol as Relevant α-Pinene Oxidation Products.

The physicochemical properties and the synthesis of four α-pinene oxidation products, terebic acid, 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), diaterpenylic acid acetate (DTAA), and pinanediol, are presented in this study. The physicochemical properties encompass thermal properties, solubility in water, and dissociation constant (pKa) for the investigated compounds. It was found that terebic acid exhibits a relatively high melting temperature of 449.29 K, whereas pinanediol revealed a low melting temperature of 329.26 K. The solubility in water was determined with the dynamic method and the experimental results were correlated using three different mathematical models: Wilson, NRTL, and UNIQUAC equations. The results of the correlation indicate that the Wilson equation appears to work the best for terebic acid and pinanediol. The calculated standard deviation was for 3.79 for terebic acid and 1.25 for pinanediol. In contrast, UNIQUAC was the best mathematical model for DTAA and MBTCA. The calculated standard deviation was 0.57 for DTAA and 2.21 for MBTCA. The measured water solubility increased in the following order: pinanediol > DTAA ≥ MBTCA > terebic acid, which affects their multiphase aging chemistry in the atmosphere. Moreover, acidity constants (pKa) at 298, 303, and 308 K were determined for DTAA with the Bates–Schwarzenbach spectrophotometric method. The pKa values obtained at 298, 303, and 308 K were found to be 3.76, 3.85, and 3.88, respectively.

Vapor pressures and activity coefficients of 2,2,2-trifluoroethanol in binary mixtures with 1,3-dimethyl-2-imidazolidinone and 2-pyrrolidone

The vapor pressures of two binary mixtures containing 2-trifluoroethanol (TFE) + 1,3-dimethyl-2-imidazolidinone (DMI) and TFE + 2-pyrrolidone (PYR), were investigated at temperatures T = (274.15 to 423.15) K using two different static method installations. Both combinations were modelled using an extended Clausius-Clapeyron equation with concentration dependent parameters and the NRTL equation with temperature dependent parameters. The best fit was obtained using the NRTL equation. • Two high-accuracy static experimental set ups were used. • An extended Clausius–Clapeyron type equation has been developed. • The NRTL activity coefficient model was developed.

Solid-liquid phase equilibrium and solution thermodynamics of 2-chlorobenzenesulfonamide in 16 mono solvents at temperature ranging from 273.15 K to 324.65 K

Abstract The synthesis and separation processes of chemical intermediate is based on the knowledge of its solid-liquid phase equilibrium with solvents in industry. In this work, the solubility of 2-chlorobenzenesulfonamide in 16 single pure solvents including methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, acetone, 2-butanone, 2-pentanone, cyclohexanone, cyclopentanone, ethyl acetate, methyl acetate, ethyl formate, acetonitrile and tetrahydrofuran was determined at temperature range from 273.15 to 324.65 K and atmospheric pressure. The mole fraction solubility of 2-chlorobenzenesulfonamide in all selected mono solvents was enhanced by an increase in temperature. In addition, the experimental data were further correlated by the modified Apelblat equation, λh equation, NRTL model and Wilson model. The values of RAD with NRTL equation were smaller than those with other three models, and thus the NRTL model offered the best fitting performance. The thermodynamic functions of dissolution including enthalpy, entropy, and Gibbs energy were derived, and the results expectedly suggested a spontaneous and entropy-driven mixing process. All the crystallographic and thermodynamic data reported in this study provides the fundamental data for designing and optimizing of the reaction and crystallization processes of 2-chlorobenzenesulfonamide.

Measurement and correlation of the solubility of estradiol and estradiol-urea co-crystal in fourteen pure solvents at temperatures from 273.15 K to 318.15 K

Abstract The solubility of estradiol and estradiol-urea co-crystal in fourteen pure solvents had been measured at temperatures from 273.15 K to 318.15 K. The solubility of estradiol and estradiol-urea co-crystal in fourteen pure solvents increased with increasing temperature. The solubility data of estradiol in fourteen solvents were fitted by the modified Apelblat equation, Van't Hoff equation, λh equation, NRTL equation, and Wilson equation. The solubility data of estradiol-urea co-crystal in fourteen solvents were fitted by the modified Apelblat equation, Van't Hoff equation, λh equation. The solubility values obtained by the correlation of the above thermodynamic models are in agree with the experimental values. The experimental data is very useful for the application of estradiol.

Solubility measurement and correlation of 2-phenyl-1H-indole in fourteen mono organic solvents from 289.05K to 338.55K

2-Phenyl-1H-indole is an important chemical intermediate in organic syntheses. The solubility of 2-phenyl-1H-indole in fourteen pure organic solvents was measured using the gravimetric method from 289.05 to 338.55 K at normal pressure. The results show that the solubility of 2-phenyl-1H-indole in all the solvents increases as temperature rising. The melting point and fusion enthalpy of 2-phenyl-1H-indole were measured with differential scanning calorimeter. The experimental solubility data were correlated with four thermodynamic models, including modified Apelblat equation, λh equation, Wilson equation and NRTL equation. The best correlation results were found with modified Apelblat equation. The mixing thermodynamic functions (Gibbs free energy, enthalpy and entropy) were calculated based on the Wilson equation. The results showed that the entire mixing process is spontaneous.

Vapor-liquid equilibria of the binary systems (cyclohexanone + 2-heptanone) and (cyclohexanone + hexanal) at different temperatures

Isothermal VLE data for (cyclohexanone + 2-heptanone) and (cyclohexanone + hexanal) mixtures are reported at T = (313.15, 333.15, 353.15, 393.15) K, which were measured using a static technique. Equilibrium properties are measured directly, and their expanded uncertainties (k = 2) are: injected volume 0.06 mL, temperature 20 mK, and total pressure 0.1%. The non-ideality of the vapor phase was taken into account using the virial equation of state. VLE data were correlated using Margules, Wilson, NRTL and UNIQUAC equations obtaining good results. The binary mixture (cyclohexanone + 2-heptanone) presents a maximum pressure azeotrope which is broken at 393.15 K.

Effects of imidazolium-based ionic liquids on the isobaric vapor–liquid equilibria of methanol + dimethyl carbonate azeotropic systems

Abstract The separation of methanol (MeOH) and dimethyl carbonate (DMC) is important but difficult due to the formation of an azeotropic mixture. In this work, isobaric vapor–liquid equilibrium (VLE) data for the ternary systems containing different imidazolium–based ionic liquids (ILs), i.e. MeOH + DMC + 1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmim][Tf2N]), MeOH + DMC + 1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][Tf2N]), and MeOH + DMC + 1-ethyl-3-methylimidazolium hexafluorophosphate ([Emim][PF6])) were measured at 101.3 kPa. The mole fraction of IL was varied from 0.05 to 0.20. The experimental data were correlated with the NRTL and Wilson equations, respectively. The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC, and [Bmim][Tf2N] showed a much more excellent performance on the activity coefficient of MeOH. The interaction energies of system components were calculated using Gaussian program, and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.

Measurement and Correlation of the Solubility of Aminocaproic Acid in Some Pure and Binary Solvents

The solubilities of aminocaproic acid in four monosolvents (isopropanol, methyl acetate, ethyl acetate, and water) and three binary solvents (methanol–water, ethanol–water, and dimethylformamide–water) were measured by the static analytical method from 283.15 to 323.15 K at atmospheric pressure. In monosolvents, the solubility increases with the increase of temperature. Also, the solubility of aminocaproic acid in water is much higher than that in other organic solvents. In binary solvents, the solubility increases with the increase of the temperature and the mole fraction of water. The solubility data was well correlated by the Apelblat equation, λh equation, and NRTL equation, and the mixing properties of enthalpy, Gibbs energy, and entropy have also been discussed.

Separation of azeotropic mixtures using protic ionic liquids as extraction solvents

The aim of this work is to evaluate the separation of hydrocarbons (hexane and heptane) from their azeotropic mixtures with ethanol using protic ionic liquid (PIL) as extraction solvents. With this goal in mind, PILs were synthesized and their thermal and physical characterization were carried out. Experimental determination of the phase equilibrium for the ternary systems hydrocarbons + ethanol + PIL at 298.15 K and 101.2 kPa were also carried out in order to evaluate the feasibility of this application. The solute distribution ratio and the selectivity were also determined to compare the solvent capacity of these PILs. The NRTL equation was used to correlate the experimental data. Furthermore, this paper provides a comparison of the solvent capacity of these PILs with different extraction solvents (ionic liquids (ILs), ILs mixtures and deep eutectic solvents) available in the literature. Then, a critical review for the separation of these azeotropic mixtures was carried out using the extraction processes data obtained through the simulation using a conventional software.

Measurement and Correlation of the Solubility of Dienogest in Twelve Pure and Water + Methanol Binary Solvents at Temperatures from 273.15 to 318.15 K

In this paper, the measured solubility data for Dienogest in common solvents are presented. The solubility of Dienogest in twelve pure and binary solvents of water + methanol has been tested at temperatures from 273.15 to 318.15 K by using the experimental method of high-performance liquid chromatography (HPLC). The solubility results in twelve pure solvents were correlated by the modified Apelblat, van’t Hoff, λh, NRTL, UNIQUAC, and Wilson equations. The solubility results in the binary solvents of water + methanol were correlated by the modified Apelblat, van’t Hoff, λh, NRTL, UNIQUAC, Jouyban–van’t and Jouyban–Apelblat equations. The solubility of the Dienogest in twelve pure solvents and binary solvents increased with increasing temperature. The calculated results by using the above equations are consistent with the experimental results. The experimental values of Dienogest in the binary solvents of water + methanol, compared with the linear summation of solubility of Dienogest in water + methanol, showed a strong effect of reducing the solubility of Dienogest in the mixed solvent. The experimental data and calculated data are very meaningful in the separation and production process of Dienogest.

Solid–Liquid Phase Equilibrium for Ternary Systems of p-Nitroacetophenone plus m-Nitroacetophenone plus Methanol/Toluene/Ethyl Acetate

The mutual solubilities for ternary systems of p-nitroacetophenone (1) + m-nitroacetophenone (2) + methanol (3), p-nitroacetophenone (1) + m-nitroacetophenone (2) + toluene (3), and p-nitroacetophenone (1) + m-nitroacetophenone (2) + ethyl acetate (3) were investigated through a steady method at 283.15, 298.15, and 313.15 K, respectively, under a local ambient pressure of 101.2 kPa. The isothermal phase diagrams of the three systems were constructed in terms of the obtained mutual solubilities. At a fixed temperature, there were two neat solids formed, namely neat p-nitroacetophenone and neat m-nitroacetophenone, which were recognized through Schreinemakers’ wet residue method. The crystallization regions of neat p-nitroacetophenone and neat m-nitroacetophenone increased with decreasing temperature. The mutual solubility was correlated through the Wilson and NRTL equations. The relative average deviations for p-nitroacetophenone + m-nitroacetophenone + methanol/toluene/ethyl acetate systems were, respectively, 4.44 × 10–2, 3.86 × 10–2, and 3.35 × 10–2 for the NRTL equation and 4.33 × 10–2, 2.51 × 10–2, and 2.29 × 10–2 for the Wilson equation. The acquired solubility data and the ternary phase diagrams for the three systems were very significant for designing and optimizing the purification process of p-nitroacetophenone and m-nitroacetophenone mixtures.

Solubility of lamotrigine in acetonitrile + water mixtures at various temperatures

ABSTRACT The solubility of lamotrigine (LTG) was reported in full concentration range of acetonitrile + water at T = 293.15–313.15 K. The solubility data were correlated by the Jouyban-Acree, Jouyban-Acree-van’t Hoff, NRTL, UNIQUAC and Wilson equations in addition to modified Wilson and Machatha. With respect to the obtained %ARDs, Jouyban-Acree is superior to Jouyban-Acree-van’t Hoff and the order of %ARDs for non-linear models is NRTL < UNIQUAC < Wilson. Moreover, the Machatha non-linear is more consistent with experimental data rather than modified Wilson for correlating the data with regard to the solvent composition. Finally, apparent standard Gibbs energy, enthalpy and entropy of dissolution and mixing, , , , , , of LTG in aqueous mixtures of acetonitrile were computed at mean harmonic temperature Thm = 303.0 K. The positive variable of suggesting the favourability of dissolution in acetonitrile-rich mixtures and ‘entropy-driven’ nature of it in only four cases.

Vapour-liquid equilibrium study of tertiary amines, single and in blend with 3-(methylamino)propylamine, for post-combustion CO2 capture

This work studies the potential of using the tertiary amines 3-dimethylamino-1-propanol (3DMA1P), 3-diethylamino-1-propanol (3DEA1P) and 1-(2-hydroxyethyl)pyrrolidine (1-(2HE)PRLD) as an alternative to 2-(diethylamino)ethanol (DEEA) in the blend with 3-(methylamino)propylamine (MAPA). Vapour pressure of the three tertiary amines and vapour-liquid equilibrium (VLE) of the binary mixtures 3DMA1P/H2O, 3DEA1P/H2O and 1-(2HE)PRLD/H2O at T = (353, 363 and 373) K were measured in a modified Swietoslawski ebulliometer. The vapour pressure of the pure amines was fitted to the Antoine equation, and the P-T-x-y data were fitted to NRTL equations. VLE of the CO2 loaded blended amines were measured in the temperature range of T = 313 to 393 K, and speciation data of equilibrated samples at different CO2 loadings were obtained by NMR spectroscopy.The study showed that the tertiary amines 3DMA1P, 3DEA1P and 1-(2HE)PRLD in the binary amine/H2O system were less volatile than DEEA in aqueous solution. The CO2 loaded blended amines showed comparable VLE behaviour, as well as speciation, and obtained a cyclic capacity higher than that of 30 wt% MEA but similar to most of the blended amines studied in the literature. The overall results indicated that the tertiary amines studied in this work can be used as an alternative to DEEA.