A (vapor + liquid) equilibria of the {carbon dioxide + isopropoxyethanol (iC3E1)} and the {carbon dioxide + isobutoxyethanol (iC4E1)} systems

Binary (vapor + liquid) equilibrium data were measured for the {carbon dioxide + isopropoxyethanol (iC₃E₁)} and the {carbon dioxide + isobutoxyethanol (iC₄E₁)} systems at temperatures ranging from (313.15 to 333.15) K. These experiments were performed with a circulating-type apparatus with on-line gas chromatography. The experimental data correlated well with the Peng–Robinson equation of state using the Wong–Sandler mixing rules.     

Critical behaviour of { water + n-nonane + sodium di(2-ethyl-1-hexyl)sulphosuccinate } microemulsions

Coexistence curves of ( T, n), ( T, ϕ), and ( T, Ψ), where n, ϕ, and Ψ are the refractive index, volume fraction and effective volume fraction ψ = ϕ / {ϕ +  [(1  − ϕ )ϕ_c / (1  − ϕ_c )]}, respectively, for ternary microemulsion systems of {water  + n -nonane  +  sodium di(2-ethyl-1-hexyl)sulphosuccinate} have been determined at temperatures within 8.7 K above the critical temperature by measurements of refractive index at constant pressure and a constant molar ratio of water to sodium di(2-ethyl-1-hexyl)sulphosuccinate. The critical exponent β deduced from ( T,n ), ( T, ϕ), and ( T, Ψ) coexistence curves was found consistent with nonmonotonic crossover observed in all aqueous ionic solutions. The values of β deduced from the experimental data in the range of 1 K above T_cwere consistent with the universality class of three-dimensional Ising-like systems. The coexistence curves have been interpreted by a combination of the Wegner expansion and the rectilinear diameter. The present results indicate that the molar mass dependence of critical amplitudes, we proposed recently, is valid for microemulsion systems.     

Pitzer ion-interaction parameters for Fe(II) and Fe(III) in the quinary {Na + K + Mg + Cl + SO4 + H2O} system at T=298.15 K

This paper describes a chemical model that calculates (solid + liquid) equilibria in the {m₁FeCl₂ + m₂FeCl₃}(aq), {m₁FeSO₄ + m₂Fe₂(SO₄)₃}(aq), {m₁NaCl + m₂FeCl₃}(aq), {m₁Na₂SO₄ + m₂FeSO₄}(aq), {m₁NaCl + m₂FeCl₂}(aq), {m₁KCl + m₂FeCl₃}(aq), {m₁K₂SO₄ + m₂Fe₂(SO₄)₃}(aq), {m₁KCl + m₂FeCl₂}(aq), {m₁K₂SO₄ + m₂FeSO₄}(aq), and {m₁MgCl₂ + m₂FeCl₂}(aq) systems, where m denotes molality at T=298.15 K. The Pitzer ion-interaction model has been used for thermodynamic analysis of the experimental activity data in binary FeCl₂(aq) and FeCl₃(aq) solutions, and ternary solubility data, presented in the literature. The thermodynamic functions needed (binary and ternary parameters of ionic interaction, thermodynamic solubility products) have been calculated and the theoretical solubility isotherms have been plotted. The mixed solution model parameters {θ(MN) and ψ(MNX)} have been chosen on the basis of the compositions of saturated ternary solutions and data on the pure water solubility of the K₂SO₄ · FeSO₄ · 6H₂O double salt. The standard chemical potentials of four ferrous {FeCl₂ · 4H₂O, Na₂SO₄ · FeSO₄ · 4H₂O, K₂SO₄ · FeSO₄ · 6H₂O, and MgCl₂ · FeCl₂ · 8H₂O} and three ferric {FeCl₃ · 6H₂O, 2KCl · FeCl₃ · H₂O, and 2K₂SO₄ · Fe₂(SO₄)₃ · 14H₂O} solid phases have been determined. Comparison of solubility predictions with experimental data not used in model parameterization is given. The component activities of the saturated {m₁MgSO₄ + m₂FeSO₄}(aq) and in the mixed crystalline phase were determined and the change of the molar Gibbs free energy of mixing Δ_mixG^∘_m(s) of crystals was determined as a function of the solid phase composition. It is established that at T=298.15 K the mixed (Mg,Fe)SO₄ · 7H₂O and (Fe,Mg)SO₄ · 7H₂O crystals show small positive deviations from the ideal mixed crystals. Limitations of the {Fe(II) + Fe(III)} model due to data insufficiencies are discussed.     

Phase equilibria for mixtures containing nonionic surfactant systems: Modeling and experiments

Surfactants are important materials with numerous applications in the cosmetic, pharmaceutical, and food industries due to inter-associating and intra-associating bond. We present a lattice fluid equation-of-state that combines the quasi-chemical nonrandom lattice fluid model with Veytsman statistics for (intra + inter) molecular association to calculate phase behavior for mixtures containing nonionic surfactants. We also measured binary (vapor + liquid) equilibrium data for {2-butoxyethanol (C₄E₁) + n-hexane} and {2-butoxyethanol (C₄E₁) + n-heptane} systems at temperatures ranging from (303.15 to 323.15) K. A static apparatus was used in this study. The presented equation-of-state correlated well with the measured and published data for mixtures containing nonionic surfactant systems.     

Isopiestic studies on the saturated systems {H2O + BaCl2(sat) + NaCl + NH4Cl} and {H2O + BaCl2(sat) + mannitol(sat) + NaCl + NH4Cl} at the temperature 298.15 K: Comparison with the ideal-like solution model

Isopiestic measurements have been carried out at the temperature 298.15 K for two saturated aqueous solutions: {H₂O + BaCl₂(sat) + NaCl + NH₄Cl} saturated with barium chloride and {H₂O + BaCl₂(sat) + mannitol(sat) + NaCl + NH₄Cl} saturated with barium chloride and mannitol. Taking sodium chloride (aq) as reference solutions, osmotic coefficients of the aqueous solutions were determined. The experimental results are well represented by the ideal-like solution model.     

Excess properties and vapour pressure of (3-diethylaminopropylamine + n-alkanes)

The vapour pressures of liquid (3-diethylaminopropylamine (3-DEPA) + n-heptane) mixtures were measured by a static method between T = (303.15 and 343.15) K at 10 K intervals. The molar excess enthalpies H^E at T = 303.15 K were measured for the systems {3-DEPA + C_nH_2n+2 (n = 6, 7, 12)}. The molar excess Gibbs free energies G^E were obtained with Barker’s method and fitted to the Redlich–Kister equation. The Wilson equation was also used. Deviations between experimental and predicted G^E and H^E, by using group contribution UNIFAC (Gmehling version) model, were evaluated.     

Hot band spectroscopy of CCO in the C–O stretching region: The (ν1 + 2ν3) − 2ν3 and (2ν1 + ν3) − (ν1 + ν3) bands

Two C–O stretching hot bands, (ν₁ + 2ν₃) − 2ν₃ and (2ν₁ + ν₃) − (ν₁ + ν₃), of the CCO radical in the ground electronic state were measured. These hot bands are red shifted by approximately 70 cm⁻¹ compared to the C–O stretching fundamental. CCO was produced in a discharge through a flowing mixture of carbon suboxide and helium. The spectra were recorded using a diode laser spectrometer. The band origins were determined to be 1904.32512(62) and 1902.69130(56) cm⁻¹ for (ν₁ + 2ν₃) − 2ν₃ and (2ν₁ + ν₃) − (ν₁ + ν₃), respectively. The measurements in this band together with previously reported frequencies in the C–C and C–O stretching regions were analysed to determine harmonic frequencies and anharmonicity constants.     

Energetic characterisation of the system (water + 1-propoxypropan-2-ol) at T = 298.15 K

Given the importance that enthalpic and entropic contributions have in the interplay between thermodynamics and self-assembly of aqueous amphiphile systems, the energetic characterisation of the system {water + 1-propoxypropan-2-ol (1-pp-2-ol)} at T = 298.15 K was made by directly measuring excess partial molar enthalpies of 1-pp-2-ol and water, over the entire composition range, at T = 298.15 K and atmospheric pressure. Derivatives of the partial molar properties with respect to the composition are used to improve the understanding of molecular interactions in the water-rich region. The present results were compared with those for the well-studied system {water + 2-butoxyethanol (nC₄E₁)}, the two amphiphiles being structural isomers.     

Phase behavior of ternary mixtures {aliphatic hydrocarbon + aromatic hydrocarbon + ionic liquid}: Experimental LLE data and their modeling by COSMO-RS

Separation of aromatic and aliphatic hydrocarbons is a complex process in the petrochemical industry due to overlapping boiling points and azeotrope formation. In this paper, liquid extraction of aromatic compounds (toluene and ethylbenzene) from aliphatic compounds (hexane and cyclohexene) using ionic liquids (1-butyl-3-methylimidazolium methylsulfate, BMimMSO₄, 1-propyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide, PMimNTf₂, and 1-butyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide, BMimNTf₂) as solvent was studied. (Liquid + liquid) equilibrium (ELL) data for the ternary systems {hexane (1) + ethylbenzene (2) + BMimMSO₄, or BMimNTf₂, or PMimNTf₂ (3)}, {hexane (1) + toluene (2) + BMimMSO₄ (3)} and {cyclohexene (1) + ethylbenzene (2) + BMimMSO₄ (3)} were experimentally determined at T = 298.15 K and atmospheric pressure. Moreover, an analysis of the influence of the structure of each compound on the phase behavior was also carried out. The ability of the studied ILs to separate aromatic from aliphatic compounds was evaluated in terms of the solute distribution ratio, β, and the selectivity, S. The Non Random Two-Liquid (NRTL) and UNIversal QUAsiChemical (UNIQUAC) thermodynamic models were used to correlate the experimental LLE data. Furthermore, the COnductor-like Screening MOdel for Real Solvents (COSMO-RS) was applied to predict the (liquid + liquid) equilibrium. The suitability of this model to describe the phase behavior of the studied mixtures was evaluated comparing the experimental and calculated data.     

Quaternary (liquid + liquid) equilibria for (water + 2-propanol + 1,1-dimethylethyl methyl ether + diisopropyl ether) at the temperature 298.15 K

(Liquid + liquid) equilibrium tie-lines were measured for one ternary system {x₁H₂O + x₂(CH₃)₂CHOH + (1 − x₁ − x₂)CH₃C(CH₃)₂OCH₃} and one quaternary system {x₁H₂O + x₂(CH₃)₂CHOH + x₃CH₃C(CH₃)₂OCH₃ + (1 − x₁ − x₂ − x₃)(CH₃)₂CHOCH(CH₃)₂} at T = 298.15 K and P^∘ = 101.3 kPa. The experimental (liquid + liquid) equilibrium results were satisfactorily correlated by modified and extended UNIQUAC models both with ternary and quaternary parameters in addition to binary ones.     

Near critical measurements of HmE andVmE for (ethane + sulphur hexafluoride)

A flow mixing calorimeter and a vibrating-tube densimeter have been used to measure excess molar enthalpies H_m^E and excess molar volumes V_m^E of {xC₂H₆ +  (1  − x)SF₆ }. Measurements over a range of mole fractions x have been made at T =  305.65 K and T =  312.15 K and at the pressures (3.76, 4.32, 4.88 and 6.0) MPa. The pressure 3.76 MPa is close to the critical pressure of SF₆, the pressure 4.88 MPa is close to the critical pressure of C₂H₆, and the pressure 4.32 MPa is midway between these values. The measurements are compared with the Patel–Teja equation of state which reproduces the main features of the excess function curves as well as it does for similar measurements on {xCO₂ +  (1  − x)C₂H₆ }, {xCO₂ +  (1  − x)C₂H₄ } and {xCO₂ +  (1  − x)SF₆ }.     

Effect of ionic liquid 1-methylimidazolium chloride on the vapour liquid equilibrium of water,methanol, ethanol,and {water + ethanol} mixture

Measurements of vapour pressure data were conducted using a quasi-static ebulliometer for systems containing water, methanol, ethanol, and a mixture of {water + ethanol} in the presence of an ionic liquid (IL), namely, 1-methylimidazolium chloride ([MIm]Cl), wherein the IL-content ranged from w₂ = (0.10 to 0.50). The vapour pressure data of IL-containing binary systems were correlated by the NRTL model with an overall average absolute relative deviation (AARD) of 0.0103, and the resulting binary parameters were used to predict the vapour pressures of a ternary system {water + ethanol + [MIm]Cl} with an AARD less than 0.0077. Further, the isobaric vapour liquid equilibria (VLE) for the ternary system {water + ethanol + IL} with IL-content of w₃ = (0.10, 0.30, and 0.50) for [MIm]Cl and x₃ = 0.15 for [MIm]Cl, [C₄MIm]Cl, and [C₆MIm]Cl were predicted at 101.3 kPa, respectively. It is indicated that [MIm]Cl presents the strongest ability to enhance the relative volatility of ethanol to water in the mixture of {water + ethanol} than that of [C₄MIm]Cl and [C₆MIm]Cl, which is consistent with the cationic sizes and hence the ionic hydration ability. Therefore, distillation separation of the azeotrope of {water + ethanol} can be sufficiently facilitated by the addition of [MIm]Cl at a specified content.     

Cloud-point measurements of the {H2O + poly(ethylene glycol) + NaNO3} system

The cloud-point (CP) temperatures and phase separation of {H₂O + poly(ethylene glycol) + NaNO₃} ternary system is studied by the turbidimetry method using a reaction calorimeter. The phase separation was also observed by visual inspection. Differences between the CP measured using the turbidimetry method and visual inspection, was up ±0.5 K. The Flory–Huggins model with a temperature and concentration-dependent interaction parameter was employed to correlate the phase diagram of the system. As a result of the correlation an average absolute deviation of 0.002 is obtained.     

Excess properties and vapour pressure of {3-diethylaminopropylamine + cyclohexane}

The vapour pressures of liquid {3-diethylaminopropylamine (3-DEPA) + cyclohexane} were measured by a static method between T = (273.15 and 363.15) K at 10 K intervals. The excess molar volumes V^E at 298.15 K and excess molar enthalpies H^E at 303.15 K were also measured. The molar excess Gibbs free energies G^E were obtained with Barker’s method and fitted to the Redlich–Kister equation. The Wilson equation was also used. Deviations between experimental and predicted G^E and H^E, by using DISQUAC model, were evaluated     

Measurement and prediction of (solid + liquid) equilibria of (alkanediamine + biphenyl) mixtures

Diamines represent, besides many technically important classes of substance, a particularly interesting family of molecules for the purpose of testing group-contribution models.A differential scanning calorimetry (DSC) was used to determine binary (solid + liquid) phase equilibria for {diamines NH₂–(CH₂)_n–NH₂ (n = 6, 8, 9, and 12) + biphenyl} mixtures. Results obtained with this technique are compared with those predicted by modified UNIFAC (Larsen and Gmehling) and DISQUAC models. It was found out that all the systems are eutectic and deviations were observed between experimental and predicted SLE.     

High-pressure (vapour + liquid) equilibria for ternary systems composed by {(E)-2-hexenal or hexanal + carbon dioxide + water}: Partition coefficient measurement

A new apparatus based on a static–analytic method assembled in this work was utilised to perform high-pressure (vapour + liquid) equilibria measurements of aqueous ternary systems. This work includes values of isothermal partition coefficients between CO₂ and water of two apple aroma constituents, (E)-2-hexenal and hexanal. Additionally, this work reports new experimental (vapour + liquid) equilibria measurements for the ternary systems (CO₂ + (E)-2-hexenal + water) and (CO₂ + hexanal + water), at fixed liquid phase composition (600 mg · kg⁻¹), at temperatures of (313, 323 and 333) K and at pressures from (8 to 19) MPa. Vapour liquid interphase was checked and monitored visually for all the systems studied in this work. No liquid immiscibility was observed at the composition, temperatures and pressures studied. In order to suggest reasonable operation conditions for fractionation of aromas with dense carbon dioxide, partition coefficients of the aroma compounds between CO₂ and water along with their separation factors from water were calculated. Partition coefficients of (E)-2-hexenal between CO₂ and water were in the range of (6 to 91) and where found to be near six times higher than those of hexanal (9 to 17). Very high separation factors from water were observed (∼10⁴) especially for (E)-2-hexenal. The highest separation factor, for both compounds, was found at a temperature of 313 K and pressures from (12 to 14) MPa.     

Excess enthalpies and excess heat capacities of binary mixtures of (cyclohexanone,or 2-butanone,or 1,4-dioxane + 1,2-dimethoxyethane) and (1,4-dioxane + 1,2-dimethoxyethane) atT = 298.15 K

Excess enthalpies and excess heat capacities of { x 2-butanone  +  (1  − x)1,4-dioxane}, and { x cyclohexanone, or 2-butanone, or 1,4-dioxane  +  (1  − x)1,2-dimethoxyethane} were measured atT =  298.15 K. Excess enthalpies were negative for { x 2-butanone  +  (1  − x)1,2-dimethoxyethane}, and negative with a small positive part in the region ofx >  0.8 for { x cyclohexanone  +  (1  − x)1,2-dimethoxyethane}, whereas excess enthalpies of { x 2-butanone  +  (1  − x)1,4-dioxane} were positive as for { x cyclohexanone  +  (1  − x)1,4-dioxane} previously reported. Excess enthalpies of {x 1,4-dioxane  +  (1  − x)1,2-dimethoxyethane} were positive. The results were compared with the systems reported earlier. Excess heat capacities are positive for { x 2-butanone  +  (1  − x)1,2-dimethoxyethane} and { x cyclohexanone  +  (1  − x)1,2-dimethoxyethane}, and negative for { x 2-butanone  +  (1  − x)1,4-dioxane} and { x 1,4-dioxane  +  (1  − x)1,2-dimethoxyethane}. The last mixture shows a W-shaped curve of excess heat capacity.     

High-pressure phase equilibria of {carbon dioxide (CO2) + n-alkyl-imidazolium bis(trifluoromethylsulfonyl)amide} ionic liquids

Ionic liquids (ILs) and carbon dioxide (CO₂) systems have unique phase behavior that has been applied to applications in reactions, extractions, materials, etc. Detailed phase equilibria and modeling are highly desired for their further development. In this work, the (vapor + liquid) equilibrium, (vapor + liquid + liquid) equilibrium, and (liquid + liquid) equilibrium of n-alkyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide ionic liquids with CO₂ were measured at temperatures of (298.15, 323.15, 343.15) K and pressure up to 25 MPa. With a constant anion of bis(trifluoromethylsulfonyl)amide, the n-alkyl chain length on the cation was varied from 1-ethyl-3-methyl-imidazolium ([EMIm][Tf₂N]), 1-hexyl-3-methyl-imidazolium ([HMIm][Tf₂N]), to 1-decyl-3-methyl-imidazolium ([DMIm][Tf₂N]). The effects of the cation on the phase behavior and CO₂ solubility were investigated. The longer alkyl chain lengths increase the CO₂ solubility. The Peng–Robinson equation of state with van der Waals 2-parameter mixing rule with estimated IL critical properties were used to model and correlate the experimental data. The models correlate the (vapor + liquid) equilibrium and (liquid + liquid) equilibrium very well. However, extrapolation of the model to much higher pressures (>30 MPa) can results in the prediction of a mixture critical point which, as of yet, has not been found in the literature.     

(Solid + solute) phase equilibria in aqueous solution. XIII. Thermodynamic properties of hydrozincite and predominance diagrams for (Zn2 + + H2O + CO2)

The thermodynamic properties ofZn₅(OH)₆(CO₃)₂ , hydrozincite, have been determined by performing solubility and d.s.c. measurements. The solubility constant in aqueous NaClO₄media has been measured at temperatures ranging from 288.15 K to 338.15 K at constant ionic strength (I =  1.00 mol · kg ^− 1). Additionally, the dependence of the solubility constant on the ionic strength has been investigated up to I =  3.00 mol · kg ^− 1NaClO₄at T =  298.15 K. The standard molar heat capacity C_{p, m}^ofunction fromT =  318.15 K to T =  418.15 K, as well as the heat of decomposition of hydrozincite, have been obtained from d.s.c. measurements. All experimental results have been simultaneously evaluated by means of the optimization routine of ChemSage yielding an internally consistent set of thermodynamic data (T =  298.15 K): solubility constant log ^* K_{ps 0}⁰ =  (9.0  ±  0.1), standard molar Gibbs energy of formationΔ_fG_m^o {Zn₅(OH)₆(CO₃)₂ }  =  ( − 3164.6  ±  3.0)kJ · mol ^− 1, standard molar enthalpy of formation Δ_fH_m^o{Zn₅(OH)₆(CO₃)₂ }  =  ( − 3584  ±  15)kJ · mol ^− 1, standard molar entropy S_m^o{Zn₅(OH)₆(CO₃)₂ }  =  (436  ±  50)J · mol ^− 1· K ^− 1and C_p,m^o / (J · mol ^− 1· K ^− 1)  =  (119  ±  11)  +  (0.834  ±  0.033)T / K. A three-dimensional predominance diagram is introduced which allows a comprehensive thermodynamic interpretation of phase relations in(Zn^2 +  +  H₂O  +  CO₂) . The axes of this phase diagram correspond to the potential quantities: temperature, partial pressure of carbon dioxide and pH of the aqueous solution. Moreover, it is shown how the stoichiometric composition{n(CO₃) / n(Zn)} of the solid compoundsZnCO₃ and Zn₅(OH)₆(CO₃)₂can be checked by thermodynamically analysing the measured solubility data.     

Thermodynamics of ion pairs in mixed solvents. I. The standard association constant of the ion pair [ MgSO4]oin { 0.03226 CO(NH2)2 + 0.96774 H2O}

The standard potential of the (Ag, AgCl) electrode E^o, the standard second ionization constant of sulfuric acid K₂, and the standard association constant of the ion pair [MgSO₄]^o, K in {0.03226CO(NH₂)₂ +  0.96774 H₂O } at five temperatures from 278.15 K to 318.15 K were determined from precise e.m.f. measurements of different cells without liquid junction. The dependence of p K on temperature T is expressed by the empirical equation pK =  6.617  −  777.9 · (K / T)  −  0.02001 · (T / K). The other thermodynamic functions of the association process were also calculated and show that the driving force for the process is the entropy of association.