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.     

Activity coefficients of electrolyte and amino acid in the systems (water + potassium chloride + dl -valine) at T = 298.15 K and (water + sodium chloride + l -valine) at T = 308.15 K

The activity coefficient data were reported for (water  +  potassium chloride  + dl -valine) at T =  298.15 K and (water  +  sodium chloride  + l -valine) at T =  308.15 K. The measurements were performed in an electrochemical cell using ion-selective electrodes. The maximum concentrations of the electrolytes and the amino acids studied were 1.0 molality and 0.4 molality, respectively. The results of the activity coefficients of dl -valine are compared with the activity coefficients of dl -valine in (water  +  sodium chloride  + dl -valine) system obtained from the previous study. The results show that the presence of an electrolyte and the nature of its cation have a significant effect on the activity coefficient of dl -valine in aqueous electrolyte solutions.     

Thermodynamic study of the mixed system (CsCl + CaCl2 + H2O) by EMF Measurements at T = 298.15 K

This work reports the results of a thermodynamic investigation of the ternary mixed-electrolyte system (CsCl + CaCl₂ + H₂O). The activity coefficients of this mixed aqueous electrolyte system have been studied with the electromotive force measurement (EMF) of the cell: Cs ion-selective electrode (ISE)|CsCl(m_A), CaCl₂(m_B), H₂O|Ag/AgCl at T = 298.15 K and over total ionic strengths from (0.01 to 1.50) mol · kg^?1 for different ionic strength fractions y_B of CaCl₂ with y_B = (0, 0.2, 0.4, 0.6, and 0.8). The cesium ion-selective electrode (Cs-ISE) and the Ag/AgCl electrode used in this work were made in our laboratory and had a good Nernst response. The experimental results obey the Harned rule, and the Pitzer model can be used to describe this ternary system satisfactorily. The osmotic coefficients, excess Gibbs free energies and activities of water of the mixtures were also calculated.     

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.     

(Liquid + liquid) equilibria of (water + linalool + limonene) ternary system at T = (298.15, 308.15, and 318.15) K

(Liquid + liquid) equilibrium (LLE) data for {water (1) + linalool (2) + limonene (3)} ternary system at T = (298.15, 308.15, and 318.15 ± 0.05) K are reported. The organic chemicals were quantified by gas chromatography using a flame ionisation detector while water was quantified using a thermal conductivity detector. The effect of the temperature on (liquid + liquid) equilibrium is determined and discussed. Experimental data for the ternary mixture are compared with values calculated by the NRTL and UNIQUAC equations, and predicted by means of the UNIFAC group contribution method. It is found that the UNIQUAC and NRTL models provide a good correlation of the solubility curve at these three temperatures, while comparing the calculated values with the experimental ones, the best fit is obtained with the NRTL model. Finally, the UNIFAC model provides poor results, since it predicts a greater heterogeneous region than experimentally observed.     

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.     

(Liquid + liquid) equilibria of (heptane,or hexane,or cyclohexane + toluene + 1,3-dimethyl-2-imidazolidinone) ternary systems at T = 298.15 K

Experimental (liquid + liquid) equilibrium data for the mixtures of (heptane, or hexane, or cyclohexane + toluene + 1,3-dimethyl-2-imidazolidinone) were determined at T = 298.15 K and P = 101.3 kPa. The solubility (binodal) curves and tie-line end compositions are reported for the related mixtures and presented as complete phase diagrams. Distribution coefficients and separation factors were evaluated for the immiscibility region. The reliability of the experimental tie-line results was verified by using the Othmer–Tobias correlation. The experimental tie-line data were correlated by UNIQUAC model, which gave satisfactory representation for the systems. It was observed that the separation of toluene from cyclohexane is easier to achieve than from heptane and hexane.     

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.     

Speeds of sound and isentropic compressibilities of (n-alkoxyethanols + toluene) at T = 298.15 K

Speeds of sound u at the temperature 298.15 K for six ( n -alkoxyethanol  +  toluene) were measured over the whole composition range. The n -alkoxyethanols were 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, and 2-(2-butoxyethoxy)ethanol. Excess molar volumes V_m^E atT =  298.15 K were also measured for the mixtures of toluene and 2-methoxyethanol, 2-ethoxyethanol, or 2-butoxyethanol over the whole composition range. The speed of sound values were combined with excess molar volumes to obtain values for the product K_{S, m} of the molar volume and the isentropic compressibilityκ_S , and the corresponding excess quantities K_S,m^E were also calculated. The K_S,m^E curves are sigmoid for all mixtures. The deviations of the speeds of soundu^D from their values u^id in an ideal mixture were obtained for all measured mole fractions. These values are compared with the mixing function δu calculated in the paper. The behaviour ofu , u^D, δu, and K_S,m^E as a function of composition and number of carbon atoms in the aliphatic chain of the alkoxyethanol is discussed. Also, theoretical values of the molar isentropic compressibility K_S,m and speed of sound u were calculated using the Prigogine-Flory-Patterson theory with a van der Waals potential energy model and the results compared with experimental data.     

(Liquid + liquid) equilibrium for ternary mixtures of {heptane + aromatic compounds + [EMpy][ESO4]} at T = 298.15 K

(Liquid + liquid) equilibrium (LLE) data for the ternary systems (heptane + toluene + 1-ethyl-3-methylpyridinium ethylsulfate) and (heptane  + benzene + 1-ethyl-3-methylpyridinium ethylsulfate) were measured at T = 298.15 K and atmospheric pressure. The selectivity and aromatic distribution coefficients, calculated from the equilibrium data, were used to determine if this ionic liquid can be used as a potential extracting solvent for the separation of aromatic compounds from heptane. The consistency of tie-line data was ascertained by applying the Othmer–Tobias and Hand equations.     

(Liquid + liquid) equilibrium data for the ternary systems (cycloalkane + ethylbenzene + 1-ethyl-3-methylimidazolim ethylsulfate) at T = 298.15 K and atmospheric pressure

In this paper, (liquid + liquid) equilibrium (LLE) data for the ternary systems (cyclohexane, or cyclooctane, or methylcyclohexane + ethylbenzene + 1-ethyl-3-methylimidazolium ethylsulfate) have been determined experimentally at T = 298.15 K and atmospheric pressure. The solubility curves and the tie-line compositions of the conjugate phases were obtained by means of density. The degree of consistency of the tie-lines was tested using the Othmer–Tobias equation, and the Non-Random Two-Liquid (NRTL) and the Universal Quasi-Chemical (UNIQUAC) models were used to correlate the phase equilibrium in the systems. Selectivity and solute distribution ratio were evaluated for the immiscible region.     

Hygrometric determination of water activities,osmotic and activity coefficients of (NaCl + KCl)(aq) at T = 298.15 K

The purpose of this study is to present a model for the prediction of water activity in multicomponent aqueous solutions containing a common ion from available binary data. The hygrometric method has been used to measure relative humidities for the aqueous electrolyte mixture (NaCl  +  KCl)(aq) at total molalities ranging from 0.2 mol · kg ^− 1to saturation for different molal ratiosr of NaCl(aq) to KCl(aq) with r =  (0.2, 0.5, 1, 2, 3, and 4) at T =  298.15 K. The data obtained have been used to determine water activities and osmotic coefficients. The results show that the values of water activities and osmotic coefficients calculated with the proposed model are close to the experimental ones. This model is also compared with four other models (RS, Pitzer, RWR, and LS II) over the range of the studied total molalities. From the measurements, the activity coefficients of NaCl(aq) and KCl(aq) in the mixture have also been determined.     

(Liquid + liquid) equilibria of the (water + propionic acid + Aliquat 336 + organic solvents) at T = 298.15 K

In this work, trioctyl methyl ammonium chloride (Aliquat 336) was studied for its ability to extract propionic acid at various amine concentrations. The extraction of propionic acid with Aliquat 336 dissolved in five single solvents (cyclohexane, hexane, toluene, methyl isobutyl ketone, and ethyl acetate ) and binary solvents (hexane + MIBK, hexane + toluene, and MIBK + toluene) was investigated under various experimental conditions. The loading factors Z, extraction efficiency E and overall particular distribution coefficients were determined. All measurements were carried out at T = 298.15 K. The obtained results and the observed phenomena were discussed by taking into consideration the mechanism of extraction and the concentration of the interaction product in the aqueous phase.