(Liquid + liquid) equilibria for ternary mixtures of (water + propionic acid + organic solvent) at T = 303.2 K

Experimental tie-line results and phase diagrams were obtained for the ternary systems of {water + propionic acid + organic solvent (cyclohexane, toluene, and methylcyclohexane)} at T = 303.2 K and atmospheric pressure. The organic solvents were two cycloaliphatic hydrocarbons (i.e., cyclohexane and methylcyclohexane) and an aromatic hydrocarbon (toluene). The experimental tie-lines values were also compared with those calculated by the UNIQUAC and NRTL models. The consistency of the values of the experimental tie-lines was determined through the Othmer–Tobias and Hands plots. Distribution coefficients and separation factors were evaluated over the immiscibility regions and a comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients and separation factors. The Kamlet LSER model was applied to correlate distribution coefficients and separation factors in these ternary systems. The LSER model values showed a good regression to the experimental results.     

Thermodynamics of isomeric hexynes + MTBE binary mixtures

The vapor pressures of liquid hex-1-yne or hex-2-yne + methyl 1,1-dimethylethyl ether (MTBE) binary mixtures and of the three pure components were measured by a static method at several temperatures between 263 and 343 K. These data were correlated with the Antoine equation. Excess molar Gibbs energies G^E were calculated for several constant temperatures, taking into account the vapor-phase imperfection in terms of the second molar virial coefficients, and were fitted to the Redlich–Kister equation. Calorimetric excess enthalpy H^E measurements, for these binary mixtures, are also reported at 298.15 K. The experimental VLE and H^E data were used, examining the binary mixtures hex-1-yne or hex-2-yne + MTBE in the framework of the DISQUAC and modified UNIFAC (Do) models. The DISQUAC calculations, reporting a new set of interaction parameters for the contact carbon–carbon triple bond/oxygen ether, is regarded as a preliminary approach.     

Vapor pressures,osmotic and activity coefficients for (LiBr + acetonitrile) between the temperatures (298.15 and 343.15) K

Precise vapor pressure data for pure acetonitrile and (LiBr + acetonitrile) are given for temperatures ranging from T=(298.15 to 343.15) K. The molality range is from m=(0.0579 to 0.8298) mol · kg⁻¹. The osmotic coefficients are calculated by taking into account the second virial coefficient of acetonitrile. The parameters of the extended Pitzer ion interaction model of Archer and the mole fraction-based thermodynamic model of Clegg–Pitzer are evaluated. These models accurately reproduce the available osmotic coefficients. The parameters of the extended Pitzer ion interaction model of Archer are used to calculate the mean molal activity coefficients.     

Heat capacities and thermodynamic functions of hexagonal ice from T = 0.5 K to T = 38 K

The heat capacity of water in the form of hexagonal ice was measured between T = 0.5 K and T = 38 K using a semi-adiabatic calorimetric method. Since heat capacity data below T = 2 K have never been measured for water, this study presents the lowest measured values of the specific heat of water to date. Fits of the data were used to generate thermodynamic functions of water at smoothed temperatures between 0.5 K and 38 K. Both our experimental heat capacities and calculated enthalpy increments agree well with previously published values and thus supplement other studies well.     

Influence of temperature on the (liquid + liquid) equilibria of {3-methyl pentane + cyclopentane + methanol} ternary system at T = (293.15, 297.15, and 299.15) K

In order to show the influence of temperature on the (liquid + liquid) equilibria (LLE) of the {3-methyl pentane (1) + cyclopentane (2) + methanol (3)} ternary system, equilibrium results at T = (293.15, 297.15, and 299.15) K are reported. The effect of the temperature on the (liquid + liquid) equilibrium is determined and discussed. Experimental results show that this ternary system is completely homogeneous beyond T = 300 K. All chemicals were quantified by gas chromatography using a thermal conductivity detector. The tie line results were satisfactorily correlated by the Othmer and Tobias method, and the plait point coordinates for the three temperatures were estimated. Experimental values for the ternary system 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 similar good correlations of the solubility curve at these three temperatures. Finally, the UNIFAC model predicts binodal band type curves in the range of temperatures studied here, similar to those observed for systems classified by Treybal as type 2, instead of type 1 as experimentally observed. Distribution coefficients were also analysed through distribution curves.     

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.     

Isobaric (vapour + liquid) equilibria for the binary system of glycidyl butyrate (1) and epichlorohydrin (2) at (100, 88.66, and 56) kPa

The (vapour + liquid) equilibria (VLE) data for the binary system of glycidyl butyrate (1) and epichlorohydrin (2) was studied at (100, 88.66, and 56) kPa. Azeotropic behaviour has not been found in this work. The activity coefficients were obtained by the non-linear least squares method based on minimization from the equilibrium data. Average relative deviations between calculated values and the experimental data of temperature are all lower than 0.99% for the three models at the three different pressures investigated. The root mean square deviations (RMSD) of gas phase compositions y₁ and temperatures are all lower than 0.0099 and 1.1 K for 100 kPa, 0.0094 and 4.5 K for 88.66 kPa and 0.0095 and 3.7 K for 56 kPa. The thermodynamic consistency of the calculated data is checked by the Herrington method. The experimental VLE data are compared with the correlated values obtained by means of the NRTL, UNIQUAC, and Wilson models.     

(Vapour + liquid) equilibria and excess Gibbs free energies of (cyclohexanone + 1-chlorobutane and + 1,1,1-trichloroethane) binary mixtures at temperatures from (298.15 to 318.15) K

The vapour pressures of binary (cyclohexanone + 1-chlorobutane, + 1,1,1-trichloroethane) mixtures were measured at the temperatures of (298.15, 308.15, and 318.15) K. The vapour pressures vs. liquid phase composition data have been used to calculate the excess molar Gibbs free energies G^E of the investigated systems, using Barker’s method. Redlich–Kister, Wilson, UNIQUAC, and NRTL equations, taking into account the vapour phase imperfection in terms of the 2-nd virial coefficient, have represented the G^E values. No significant difference between G^E values obtained with these equations has been observed.     

Application of the PFV EoS correlation to excess molar volumes of (1-ethyl-3-methylimidazolium ethylsulfate + alkanols) at different temperatures

The experimental densities for the binary systems of an ionic liquid and an alkanol {1-ethyl-3-methylimidazolium ethylsulfate [EMIM]⁺ [EtSO₄]^? + methanol or 1-propanol or 2-propanol} were determined at T = (298.15, 303.15, and 313.15) K. The excess molar volumes for the above systems were then calculated from the experimental density values for each temperature. The Redlich–Kister smoothing polynomial was used to fit the experimental results and the partial molar volumes were determined from the Redlich–Kister coefficients. For all the systems studied, the excess molar volume results were negative over the entire composition range for all the temperatures. The excess molar volumes were correlated with the pentic four parameter virial (PFV) equation of state (EoS) model.     

New (p, ρ, T) data for carbon dioxide – Nitrogen mixtures from (250 to 400) K at pressures up to 20 MPa

Comprehensive (p, ρ, T) measurements on two binary mixtures (0.10 CO₂ + 0.90 N₂ and 0.15 CO₂ + 0.85 N₂) were carried out in the gas phase at seven isotherms between (250 and 400) K and pressures up to 20 MPa using a single sinker densimeter with magnetic suspension coupling. A total of 69 (p, ρ, T) data for the first mixture and 69 (p, ρ, T) data for the second are presented in this article. The uncertainty in density was estimated to be (0.02 to 0.15)%, while the uncertainty in temperature was 3.9 mK and the uncertainty in pressure was less than 0.015% (coverage factor k = 2). Experimental results were compared with densities calculated from the GERG equation of state and with data reported by other authors for similar mixtures. Results yielded that, while deviations between experimental data and values calculated from the GERG equation were lower than 0.05% in density for low pressures, the relative error at high pressures and low temperatures increased to about (0.2 to 0.3)%. The main aim of this work was to contribute to an accurate density data base for CO₂/N₂ mixtures and to check or improve equations of state existing for these binary mixtures.     

Quaternary liquid–liquid equilibria for systems of {(water + methanol or ethanol) + m-xylene + n-dodecane}

Liquid–liquid equilibrium (LLE) data were determined for the quaternary systems of {(water + methanol or ethanol) + m-xylene + n-dodecane} at three temperatures 298.15, 303.15 and 313.15 K and atmospheric pressure. The composition of liquid phases at equilibrium was determined by gas–liquid chromatography and the results were correlated with the UNIQUAC and NRTL activity coefficient models. The partition coefficients and the selectivity factor of the solvent are calculated and compared. The phase diagrams for the quaternary systems including both the experimental and correlated tie lines are presented.     

Isothermal PρT measurements on Qatar’s North Field type synthetic natural gas mixtures using a vibrating-tube densimeter

Pressure–density–temperature (PρT) measurements of five natural gas mixtures that represent Qatar’s North Field natural gas reservoirs were carried out at temperatures from (250 to 450) K and at pressures up to 65 MPa by using a Anton Paar® (Graz, Austria) vibrating tube densimeter DMA 512P high-pressure cell. Total 20 isotherms from 250 K by 10 K intervals up to 450 K were measured. Experimental density data were compared with two main industry standard equations of state (EOS) namely AGA8-DC92 EOS and GERG2008 EOS. Comparisons of the experimental data with respect to AGA8-DC92 EOS and GERG2008 EOS resulted in prediction deviation ranges of (0.05 to −0.5)% and (0.25 to −0.5)% respectively.     

Isothermal (vapour + liquid) equilibria and excess Gibbs free energies in some binary (cyclopentanone + chloroalkane) mixtures at temperatures from 298.15 K to 318.15 K

The vapour pressures of binary (cyclopentanone + 1-chlorobutane, +1,3-dichloropropane, and +1,4-dichlorobutane) mixtures, were measured at the temperatures of (298.15, 308.15, and 318.15) K. The vapour pressures vs. liquid phase composition data have been used to calculate the excess molar Gibbs free energies G^E of the investigated systems, using Barker’s method. Redlich–Kister, Wilson and NRTL equations, taking into account the vapor phase imperfection in terms of the second virial coefficient, have represented the G^E values. No significant difference between G^E values obtained with these equations has been observed.     

(Liquid + liquid) equilibria of (sulfolane + benzene + n-hexane), (N-formylmorpholine + benzene + n-hexane), and (sulfolane + N-formylmorpholine + benzene + n-hexane) at temperatures ranging from (298.15 to 318.15) K: Experimental results and correlation

The experimental (liquid + liquid) equilibrium (LLE) properties for two ternary systems containing (N-formylmorpholine + benzene + n-hexane), (sulfolane + benzene + n-hexane) and a quaternary mixed solvent system (sulfolane + N-formylmorpholine + benzene + n-hexane) were measured at temperature ranging from (298.15 to 318.15) K and at an atmospheric pressure. The experimental distribution coefficients and selectivity factors are presented to evaluate the efficiency of the solvents for extraction of benzene from n-hexane. The LLE results obtained indicate that increasing temperature decreases selectivity for all solvents. The LLE results for the systems studied were used to obtain binary interaction parameters in the UNIQUAC model by minimizing the root mean square deviations (RMSD) between the experimental and calculated results. Using the interaction parameters obtained, the phase equilibria in the systems were calculated and plotted. The calculated compositions based on the UNIQUAC model were found to be in good agreement with the experimental values. The result of the RMSD obtained by comparing the calculated and experimental two-phase compositions is 0.0163 for (N-formylmorpholine + benzene + n-hexane) system and is 0.0120 for (sulfolane + benzene + n-hexane) system.     

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.     

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.     

Isopiestic study of (calcium chloride + water) and (calcium chloride + magnesium chloride + water) atT = 313.15 K

The osmotic coefficients of aqueous calcium chloride solutions were experimentally determined atT =  313.15 K by the isopiestic method. Magnesium chloride served as the isopiestic standard for the calculation of osmotic coefficients. The molality range covered in this study correspond to about 0.1mol · kg ^− 1to 3.0mol · kg ^− 1. In addition, the osmotic coefficients of aqueous mixtures of calcium chloride and magnesium chloride were determined over the range of ionic strength levels of about 0.1mol · kg ^− 1to 9mol · kg ^− 1and at various mole fractions. The results obtained were correlated by the Pitzer equation.     

(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.     

Compressed liquid densities of 1-butanol and 2-butanol at temperatures from 313 K to 363 K and pressures up to 25 MPa

(p, ρ, T) properties were determined in liquid phase for 1-butanol and 2-butanol at temperatures from 313 K to 363 K and pressures up to 25 MPa using a vibrating tube densimeter. The uncertainty is estimated to be lower than ±0.2 kg · m⁻³ for the experimental densities. Nitrogen and water were used as reference fluids for the calibration of the vibrating tube densimeter. Experimental densities of 1-butanol and 2-butanol were correlated with a short empirical equation and the 11-parameter Benedict–Webb–Rubin–Starling equation of state (BWRS EoS) using a least square optimization. Statistical values to evaluate the different correlations were reported. Published densities of 1-butanol and 2-butanol are compared with values calculated with the BWRS EoS using the parameters obtained in this work. The experimental data determined here are also compared with available correlations for 1-butanol and 2-butanol.     

(Liquid + liquid) equilibria of (water + propionic acid + dipropyl ether or diisopropyl ether) at T = 298.2 K

(Liquid + liquid) equilibrium (LLE) data for (water + propionic acid + dipropyl ether) and (water + propionic acid + diisopropyl ether) were measured at T = 298.2 K and atmospheric pressure. The tie-line data were correlated by means of the UNIQUAC equation, and compared with results predicted by the UNIFAC method. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients, separation factors, and solvent free selectivity bases.