Thermodynamic properties of multicomponent electrolyte solutions in mixed solvents {HCl + NaCl-tert-C4H9OH + H2O} at (278.15 to 318.15) K

The thermodynamic properties of (HCl (m_A) + NaCl (m_B)-tert-C₄H₉OH + H₂O) system were studied by means of e.m.f. measurements in the cell without liquid junction at constant total ionic strength I=1.00 mol · kg⁻¹ from 278.15 K to 318.15 K. The standard electrode potential of Ag–AgCl and activity coefficient of HCl in the mixed solvents have been determined. The results show that the activity coefficient of HCl in HCl–NaCl solution still obeys Harned’s Rule and the logarithm of HCl activity coefficient, lgγ_A, is a linear function reciprocal of temperature at constant composition of the mixture. The standard transfer Gibbs free energy of HCl was calculated.     

Activity coefficients of glycine in aqueous electrolyte solutions: experimental data for (H2O + KCl + glycine) atT = 298.15 K and (H2O + NaCl + glycine) atT = 308.15 K

Electrochemical cells with two ion-selective electrodes against a single-junction reference electrode were used to obtain the activity coefficients of glycine in aqueous electrolyte solutions. Activity coefficient data were presented for {H₂O  +  KCl (m_S)  +  glycine (m_A)}, and {H₂O  +  NaCl (m_S)  +  glycine (m_A)} atT =  298.15 K and T =  308.15 K, respectively. The results show that the presence of an electrolyte and the nature of its cation have a significant effect on the activity coefficient of glycine in aqueous electrolyte solutions and, in turn, on the method of separation from its culture media. The results of the mean ionic activity coefficients of KCl were compared with those values reported in the literature, which were obtained by the isopiestic method. It was found that the method applied in this study provides accurate activity coefficient data. The effect of temperature on the mean ionic activity coefficient of NaCl in presence of glycine was also investigated.     

Thermodynamic study of the system (LiCl + CaCl2 + H2O)

Solubility isotherms of the ternary system (LiCl + CaCl₂ + H₂O) were elaborately determined at T = (283.15 and 323.15) K. Several thermodynamic models were applied to represent the thermodynamic properties of this system. By comparing the predicted and experimental water activities in the ternary system, an empirical modified BET model was selected to represent the thermodynamic properties of this system. The solubility data determined in this work at T = (283.15 and 323.15) K, as well as those from the literature at other temperatures, were used for the model parameterization. A complete phase diagram of the ternary system was predicted over the temperature range from (273.15 to 323.15) K. Subsequently, the Gibbs free energy of formation of the solid phases CaCl₂ · 4 H₂O_(s), CaCl₂ · 2 H₂O_(s), LiCl · 2H₂O_(s), and LiCl · CaCl₂ · 5H₂O_(s) was estimated and compared with the literature data.     

Isopiestic measurement and solubility evaluation of the ternary system (CaCl2 + SrCl2 + H2O) at T = 298.15 K

Water activities in the ternary system (CaCl₂ + SrCl₂ + H₂O) and its sub-binary system (CaCl₂ + H₂O) at T = 298.15 K have been elaborately measured by an isopiestic method. The data of the measured water activity were used to justify the reliability of solubility isotherms reported in the literature by correlating them with a thermodynamic Pitzer–Simonson–Clegg (PSC) model. The model parameters for representing the thermodynamic properties of the (CaCl₂ + H₂O) system from (0 to 11) mol ⋅ kg⁻¹ at T = 298.15 K were determined, and the experimental water activity data in the ternary system were compared with those predicted by the parameters determined in the binary systems. Their agreement indicates that the PSC model parameters can reliably represent the properties of the ternary system. Under the assumption that the equilibrium solid phases are the pure solid phases (SrCl₂ ⋅ 6H₂O and CaCl₂ ⋅ 6H₂O)_(s) or the ideal solid solution consisting of CaCl₂ ⋅ 6H₂O_(s) and SrCl₂ ⋅ 6H₂O_(s), the solubility isotherms were predicted and compared with experimental data from the literature. It was found that the predicted solubility isotherm agrees with experimental data over the entire concentration range at T = 298.15 K under the second assumption described above; however, it does not under the first assumption. The modeling results reveal that the solid phase in equilibrium with the aqueous solution in the ternary system is an ideal solid solution consisting of SrCl₂ ⋅ 6H₂O_(s) and CaCl₂ ⋅ 6H₂O_(s). Based on the theoretical calculation, the possibility of the co-saturated points between SrCl₂ ⋅ 6H₂O_(s) and the solid solution (CaCl₂ ⋅ 6H₂O + SrCl₂ ⋅ 6H₂O)_(s) and between CaCl₂ ⋅ 6H₂O_(s) and the solid solution (CaCl₂ ⋅ 6H₂O + SrCl₂ ⋅ 6H₂O)_(s), which were reported by experimental researchers, has been discussed, and the Lippann diagram of this system has been presented.     

Volumetric study of (2-methoxyethanol + tetrahydrofuran + cyclohexane) at T=298.15 K

The excess molar volumes V_m^E at T=298.15 have been determined in the whole composition domain for (2-methoxyethanol + tetrahydrofuran + cyclohexane) and for the parent binary mixtures. Data on V_m^E are also reported for (2-ethoxyethanol + cyclohexane). All binaries showed positive V_m^E values, small for (methoxyethanol + tetrahydrofuran) and large for the other ones. The ternary V_m^E surface is always positive and exhibits a smooth trend with a maximum corresponding to the binary (2-methoxyethanol + cyclohexane). The capabilities of various models of either predicting or reproducing the ternary data have been compared. The behaviour of V_m^E and of the excess apparent molar volume of the components is discussed in both binary and ternary mixtures. The results suggest that hydrogen bonding decreases with alcohol dilution and increases with the tetrahydrofuran content in the ternary solutions.     

Modeling of the quaternary NaCl + KCl + CH3OH + H2O mixed electrolyte system: Binary and ternary mixing (ion + ion) and (ion + nonelectrolyte) interaction parameters

The purpose of this work is modeling of the quaternary system of mixed NaCl + KCl electrolyte in mixed CH₃OH + H₂O solvent, with different alcohol mass fractions by using particularly, the Pitzer (P) and Pitzer–Esteso (PE) equations and based on potentiometric measurement technique. The experimental data are obtained by different molal salt ratio r (r = m_NaCl/m_KCl = 100, 150, 200 and 250) in mixed solvent with different alcohol mass fractions x (x = 0.10, 0.20, 0.30, 0.40, and 0.50) in water. A galvanic cell is employed for collecting the potentiometric data by combining a Na⁺ glass membrane and Ag/AgCl electrodes and using different series of electrolyte solutions, at defined constant ionic strengths, with the molality ranging from 0.0005 up to 3.5 mol · kg⁻¹, at T = 298.15 ± 0.05 K of experiments. Comparison of the models shows that the modified Pitzer equation by Esteso (PE) present a better fit of the experimental data.     

Thermodynamic evaluation and optimization of the (NaCl + KCl + MgCl2 + CaCl2 + ZnCl2) system

A complete critical evaluation of all available phase diagram and thermodynamic data has been performed for all condensed phases and relevant gaseous species of the (NaCl + KCl + MgCl₂ + CaCl₂ + ZnCl₂) system, and optimized model parameters have been found. The (NaCl + KCl + MgCl₂ + CaCl₂) subsystem has been critically evaluated in a previous article. The model parameters obtained for the binary and ternary subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent system. The Modified Quasichemical Model for short-range ordering was used for the molten salt phase.     

Activity coefficients of CaCl2 in (serine or proline + water) mixtures at T = 298.15 K

Activity coefficients for the (CaCl₂ + amino acid + water) system were determined at a temperature of 298.15 K using ion-selective electrodes. The range of molalities of CaCl₂ is (0.01 to 0.20) mol · kg^?1, and that of amino acids is (0.10 to 0.40) mol · kg^?1. The activity coefficients obtained from the Debye–Hückel extended equation and the Pitzer equation are in good agreement with each other. Results show that the interactions between CaCl₂ and amino acid are controlled mainly by the electrostatic interactions (attraction). Gibbs free energy interaction parameters (g_EA) and salting constants (k_S) are positive, indicating that these amino acids are salted out by CaCl₂. These results are discussed based on group additivity model.     

Measurement of activity coefficients of amino acids in aqueous electrolyte solutions: experimental data for the systems (H2O + NaBr + glycine) and (H2O + NaBr + l-valine) at T=298.15 K

Electrochemical cells with two ion-selective electrodes, a cation ion-selective electrode against an anion ion-selective electrode, were used to measure the activity coefficient of amino acids in aqueous electrolyte solutions. Activity coefficient data were measured for (H₂O + NaBr + glycine) and (H₂O + NaBr + l-valine) at T=298.15 K. The maximum concentrations of sodium bromide, glycine, and l-valine were (1.0, 2.4, and 0.4) mol · kg⁻¹, respectively. The results show that the presence of an electrolyte and the nature of both the cation and the anion of the electrolyte have significant effects on the activity coefficients of amino acid in aqueous electrolyte solutions.     

Thermodynamic properties of (NaCl + KCl + LiCl + H2O) at T = 298.15 K: Water activities,osmotic and activity coefficients

The water activities of aqueous electrolyte mixture (NaCl + KCl + LiCl + H₂O) were experimentally determined at T = 298.15 K by the hygrometric method at total ionic-strength from 0.4 mol · kg⁻¹ to 6 mol · kg⁻¹ for different ionic-strength fractions y of NaCl with y = 1/3, 1/2, and 2/3. The data allow the deduction of new osmotic coefficients. The results obtained were correlated by Pitzer’s model and Dinane’s mixing rules ECA I and ECA II for calculations of the water activity in mixed aqueous electrolytes. A new Dinane–Pitzer model is proposed for the calculation of osmotic coefficients in quaternary aqueous mixtures using the newly ternary and quaternary ionic mixing parameters of this studied system. The solute activity coefficients of component in the mixture are also determined for different ionic-strength fractions y of NaCl.     

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.     

Thermodynamic evaluation and optimization of the (NaCl + KCl + MgCl2 + CaCl2 + MnCl2 + FeCl2 + CoCl2 + NiCl2) system

A complete critical evaluation of all available phase diagram and thermodynamic data has been performed for all condensed phases of the (NaCl + KCl + MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) system, and optimized model parameters have been found. The (MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) subsystem has been critically evaluated in a previous article. The model parameters obtained for the binary subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent system. The Modified Quasichemical Model was used for the molten salt phase, and the (MgCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) solid solution was modeled using a cationic substitutional model with an ideal entropy and an excess Gibbs free energy expressed as a polynomial in the component mole fractions. Finally, the (Na,K)(Mg,Ca,Mn,Fe,Co,Ni)Cl₃ and the (Na,K)₂(Mg,Mn,Fe,Co,Ni)Cl₄ solid solutions were modeled using the Compound Energy Formalism.     

Thermodynamic evaluation and optimization of the (MgCl2 + CaCl2 + MnCl2 + FeCl2 + CoCl2 + NiCl2) system

A complete critical evaluation of all available phase diagram and thermodynamic data has been performed for all condensed phases of the (MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) system, and optimized model parameters have been found. The model parameters obtained for the binary subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent system. The Modified Quasichemical Model was used for the molten salt phase, and the (MgCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) solid solution was modeled using a cationic substitutional model with an ideal entropy and an excess Gibbs free energy expressed as a polynomial in the component mole fractions. This is the first of two articles on the optimization of the (NaCl + KCl + MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) system.     

(Liquid + solid) metastable equilibria in quinary system Li2CO3 + Na2CO3 + K2CO3 + Li2B4O7 + Na2B4O7 + K2B4O7 + H2O at T=288 K for Zhabuye salt lake

An experimental study on metastable equilibria at T=288 K in the quinary system Li₂CO₃ + Na₂CO₃ + K₂CO₃ + Li₂B₄O₇ + Na₂B₄O₇ + K₂B₄O₇ + H₂O was done by isothermal evaporation method. Metastable equilibrium solubilities and densities of the solution were determined experimentally. According to the experimental data, the metastable equilibrium phase diagram under the condition saturated with Li₂CO₃ was plotted, in which there are four invariant points; nine univariant curves; six fields of crystallization: K₂CO₃ · 3/2H₂O, K₂B₄O₇ · 5H₂O, Li₂B₂O₄ · 16H₂O, Na₂B₂O₄ · 8H₂O, Na₂CO₃ · 10H₂O, NaKCO₃ · 6H₂O. Some differences were found between the stable phase diagram at T=298 K and the metastable one at T=288 K.     

Thermodynamic evaluation and optimization of the (NaNO3 + KNO3 + Na2SO4 + K2SO4) system

A complete critical evaluation of all available phase diagram and thermodynamic data has been performed for all condensed phases of the (NaNO₃ + KNO₃ + Na₂SO₄ + K₂SO₄) ternary reciprocal system, and optimised model parameters have been found. The model parameters obtained for the four binary common-ion subsystems (i.e. (NaNO₃ + Na₂SO₄), (KNO₃ + K₂SO₄), (NaNO₃ + KNO₃) and (Na₂SO₄ + K₂SO₄)) are used to predict thermodynamic properties and phase equilibria for the entire system. The Modified Quasichemical Model in the Quadruplet Approximation for short-range ordering was used for the molten salt phase, and the Compound Energy Formalism was used for the various solid solutions.     

Mean activity coefficient measurement and thermodynamic modelling of the ternary mixed electrolyte (MgCl2 + glucose + water) system at T = 298.15 K

In this work, the mean activity coefficients of MgCl₂ in pure water and (glucose + water) mixture solvent were determined using a galvanic cell without liquid junction potential of type: (Mg²⁺ + ISE)|MgCl₂ (m), glucose (wt.%), H₂O (100 wt.%)|AgCl|Ag. The measurements were performed at T = 298.15 K. Total ionic strengths were from (0.0010 to 6.0000) mol · kg⁻¹. The various (glucose + water) mixed solvents contained (0, 10, 20, 30 and 40)% mass fractions percentage of glucose respectively. The mean activity coefficients measured were correlated with Pitzer ion interaction model and the Pitzer adjustable parameters were determined. Then these parameters were used to calculate the thermodynamics properties for under investigated system. The results showed that Pitzer ion interaction model can satisfactory describe the investigated system. The modified three-characteristic-parameter correlation (TCPC) model was applied to correlate the experimental activity coefficient data for under investigation electrolyte system, too.     

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.     

Thermodynamic investigation of the (LiF + NaF + CaF2 + LaF3) system

In this work a thermodynamic assessment of the (LiF + NaF + CaF₂ + LaF₃) system is reported. For the thermodynamic modeling of the liquid phase, the classical polynomial model, and the modified quasi-chemical model were used in parallel and compared. The extrapolation to higher order systems was done according to the Toop mathematical formalism. Furthermore, differential-scanning calorimetry data of the ternary (LiF + CaF₂ + LaF₃), (NaF + CaF₂ + LaF₃), and the quaternary (LiF + NaF + CaF₂ + LaF₃) mixtures are presented. Good agreement between the experimental data and the thermodynamic assessment was obtained.     

(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.     

Volumetric properties of ternary (IL + 2-propanol or 1-butanol or 2-butanol + ethyl acetate) systems and binary (IL + 2-propanol or 1-butanol or 2-butanol) and (1-butanol or 2-butanol + ethyl acetate) systems

The experimental densities for the binary or ternary systems were determined at T = (298.15, 303.15, and 313.15) K. The ionic liquid methyl trioctylammonium bis(trifluoromethylsulfonyl)imide ([MOA]⁺[Tf₂N]⁻) was used for three of the five binary systems studied. The binary systems were ([MOA]⁺[Tf₂N]⁻ + 2-propanol or 1-butanol or 2-butanol) and (1-butanol or 2-butanol + ethyl acetate). The ternary systems were {methyl trioctylammonium bis(trifluoromethylsulfonyl)imide + 2-propanol or 1-butanol or 2-butanol + ethyl acetate}. The binary and ternary excess molar volumes for the above systems were calculated from the experimental density values for each temperature. The Redlich–Kister smoothing polynomial was fitted to the binary excess molar volume data. Virial-Based Mixing Rules were used to correlate the binary excess molar volume data. The binary excess molar volume results showed both negative and positive values over the entire composition range for all the temperatures.The ternary excess molar volume data were successfully correlated with the Cibulka equation using the Redlich–Kister binary parameters.