H2O Ternary System Research Articles

Determination of the operating parameters of an evaporator crystallizer

This work involves the study of the solid/liquid equilibrium in the NaCl–NaOH–H2O ternary system. The aim is to optimize the operating conditions of an evaporator–crystallizer used in a hydrazine extraction process. The latter is conducted at industrial scale using the Raschig method, a general method for preparing hydrazines for aerospace and pharmaceutical applications. The extraction process includes the use of a Kestner type evaporator–crystallizer to first isolate hydrazine and water by evaporation and then separate two salts: sodium hydroxide, recovered as an aqueous solution, and sodium chloride which crystallizes. However, problems related to the co-precipitation of NaCl–NaOH may be encountered in industry, leading to the clogging of installations. Therefore, it is necessary to ensure that only NaCl crystallizes while maintaining NaOH in liquid state. Knowledge of the equilibrium phases of the NaCl–NaOH–H2O ternary system is thus required, particularly the liquid/solid phase. Phase equilibrium experiments were performed by isoplethic thermal analysis (ITA) and chemical titrations over the temperature range of 313 to 353 K at atmospheric pressure. ITA is an isobaric and isothermal method developed in our laboratory and based on the measurement of the thermal effects associated with transformations in a system (appearance or disappearance of a phase) when its composition is changed. The NaCl crystallization domain was fully determined and the operating parameters of the device were defined precisely as a function of temperature and composition of the Kestner loop.

Accurate and precise quantification of major and trace element compositions of calcic–sodic fluid inclusions by combined microthermometry and LA-ICPMS analysis

Determination of absolute trace-element concentrations in fluid inclusions using laser-ablation (LA) ICPMS requires an internal standard, i.e., the concentration of one element must be independently known from independent observation. Microthermometric determination of the last melting temperature of ice, hydrohalite or halite is routinely used to calculate apparent salinities in wt.% NaCl equivalent, using phase relations in the binary H2O–NaCl system to estimate Na concentration. Calculating the concentrations of all other elements requires an empirical correction, if additional salt concentrations are of similar magnitude as that of NaCl. If CaCl2 is the main additional salt component, as in many low-temperature basin and basement brines, absolute Na concentrations (wt.% NaCl abs.) can be obtained by observing two melting temperatures (hydrohalite and either ice or halite), uniquely defining the major element composition of the fluid in the ternary model system H2O–NaCl–CaCl2 and allowing Na to be used as internal standard for quantifying all minor and trace elements. Test results for a range of compositions show that calcium concentration can be determined more precisely by microthermometry than by LA-ICPMS analysis, but that both methods agree within error. The combined approach of microthermometry and LA-ICPMS analysis described here permits reliable quantification of major (Ca, Na) as well as trace element concentrations in sodic–calcic brine inclusions, even in Ca-rich host minerals such as fluorite or Ca-bearing carbonates.

Mean Activity Coefficients of KBr in the KBr–K2SO4–H2O Ternary System at 298.15 K by an Electromotive Force Method

The mean activity coefficients of KBr in the KBr–K2SO4–H2O ternary system were determined at the total ionic strength ranging from (0.0100 to 3.0000) mol·kg–1 at 298.15 K by the electromotive force (EMF) method from the battery cell without a liquid junction: K-ISE|KBr(m1), K2SO4(m2)|Br-ISE. The mean activity coefficients of KBr were compared with those different ionic strength fractions yB of K2SO4 with yB = (0.8, 0.6, 0.4, 0.2, and 0). The experimental results showed that K-ISE and Br-ISE in this work had a good Nernst response, and the mean activity coefficients of KBr were fitted to the Pitzer models. Pitzer ion interaction parameters of θBr–·SO42– and φK+·Br–·SO42– which had not been reported were evaluated from present measurements of the mean activity coefficients of KBr.

Phase Equilibria of CO2 + N2 + H2O and N2 + CO2 + H2O + NaCl + KCl + CaCl2 Systems at Different Temperatures and Pressures

The phase equilibria of the N2 + CO2 + H2O ternary system were determined at 308.15 K and 318.15 K under 8.0 MPa, 12.0 MPa, and 16.0 MPa. It was demonstrated that the solubility of N2 in the liquid phase increased with the increase of its mole fraction in the vapor phase at fixed temperature and total pressure, and the solubility increased with reducing temperature or increasing pressure at a fixed mole fraction of N2 in the vapor phase. The dependences of the solubility of CO2 in the liquid phase on the mole fraction of CO2 in the vapor phase, temperature, and pressure are similar, but its solubility was much larger than that of N2. The effect of NaCl + KCl + CaCl2 on the solubility of the gas mixture of N2 and CO2 in water was also determined at 308.15 K and 8.0 MPa, and it was shown that the addition of the salt mixture reduced the solubility of the gases in water considerably due to the salting-out effect.

Correlation of the solubilities of alkali chlorides in mixed solvents: Polyethylene glycol+H2O and Ethanol+H2O

Solubility data for the LiCl+PEG 4000+H2O system at 25°C were obtained. These data, along with other data published in the literature for the NaCl+PEG 4000+H2O, KCl+PEG 4000+H2O, LiCl+C2H5OH+H2O, NaCl+C2H5OH+H2O, and KCl+C2H5OH+H2O ternary systems at 25°C, were correlated using a modified Pitzer model. The values of the solubilities calculated using the model are in good agreement with the experimental observations. Using the model parameterization established in this study, the yield of precipitated salt was calculated as a function of kg PEG 4000 or C2H5OH/100kg of saturated solution.

Activity Coefficients of Electrolytes in the NaCl + Na2SO4 + H2O Ternary System from Potential Difference Measurements at (298.15, 303.15, and 308.15) K

Potential difference measurements have been used to obtain the mean ionic activity and osmotic coefficients of NaCl and Na2SO4 in their aqueous solutions. Also, the mean ionic activity coefficients of NaCl in NaCl–Na2SO4–H2O ternary system with sodium as a common ion have been determined from cell potential measurements using: Na-ISE/NaCl (mNaCl); Na2SO4 (mNa2SO4)/Ag/AgCl combined with the reference cell: Na-ISE/NaCl (I = mNaCl + 3mNa2SO4), AgCl(s)/Ag. The measurements were made at ionic strength ratios for Na2SO4, yNa2SO4, of (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0), at constant total ionic strengths, I, of (0.1, 0.5, 1.0, 2.0, 3.0, and 4.0) mol·kg–1 and at temperatures of (298.15, 303.15, and 308.15) K. The experimental mean ionic activity coefficients of NaCl were correlated and analyzed with the Harned rule and Scatchard and Pitzer models. The excess free Gibbs energies of mixing were calculated from the trace activity coefficient data of NaCl and analyzed versus system composition at different temperatures...

Time-resolved fluorescence anisotropy studies of the cononsolvency of poly(N-isopropyl acrylamide) in mixtures of methanol and water

Time-resolved anisotropy measurements (TRAMS) have provided invaluable information concerning the molecular interactions responsible for cononsolvency in the poly(N-isopropylacrylamide), PNIPAM, H2O, and methanol ternary system. TRAMS have successfully monitored the intramolecular segmental dynamics of an acenaphthylene labelled sample, ACE–PNIPAM, revealing details about the conformation adopted by the polymer constituent as a function of both alcohol composition and temperature of the system. In pure aqueous solution, ACE–PNIPAM undergoes a conformational transition from an expanded solvent swollen structure to a compact globule at the lower critical solution temperature (LCST). With increasing alcohol content up to 55% v/v of methanol there is both a reduction in the magnitude and an onset temperature of the LCST of ACE–PNIPAM. From 57.5–65% v/v methanol, ACE–PNIPAM forms an extended solvent swollen structure: observation of an LCST at higher polymer concentrations (e.g., 0.1 wt%) is a consequence of intermolecular aggregation between expanded chains.

Extraction optimization of organic compounds by demixing observed in the H2O–NaOH–piperidine ternary diagram

Three isothermal sections of the isobaric ternary system H2O–NaOH–C5H10NH were determined by Isoplethic Thermal Analysis at 293, 313, and 323 K. Miscibility gaps were completely delimited and each critical point was calculated. This system is then characterized by a prevalent miscibility gap, three crystallization domains and two triphasic invariant domains. The relevant exploitation of this diagram so permits us to deduce the demixing temperature leading to the optimal transfer of the organic compounds in the light phase and also the composition of the organic phase recovered after this second step of extraction. Moreover, the addition of calculated quantities of sodium hydroxide aqueous solution allows to be in optimized conditions for the next distillation operations.

Study of the polythermal diagram water–sodium sulphate–piperidine

Two isothermal sections of the isobaric ternary system H2O–Na2SO4–C5H10NH were determined by isoplethic thermal analysis at 293 and 323 K. The compositions of the aqueous and organic invariant liquids, respectively L1 and L2, as well as that of the critical point, were characterized for each isotherm. The temperature of the invariant reaction was obtained by controlled flow thermal analysis and the temperature of the demixing ending, by interpolation of the monovariant lines. All these informations allowed us to establish the isobaric polythermal diagram of the H2O–Na2SO4–C5H10NH system, for the temperature range 293–323 K, as well as a qualitative representation of the monovariant curves. This system is then characterized by a wide miscibility gap, three crystallization domains, and four-three-phase invariant domains. The relevant exploitation of this diagram so permits us to deduce the demixing temperature leading to the optimal transfer of the organic compounds in the light phase and also the composition of the organic phase recovered after this first step of extraction.

Thermodynamic study of the ternary aqueous mixed electrolyte system [(1 − y)MgCl2 + yKCl] by electromotive force measurements

The activity coefficients for magnesium chloride in the MgCl2 + KCl + H2O ternary system were determined from electromotive force measurements as a function of total ionic strength and composition of the mixture. In this work, emf measurements were performed on the galvanic cell without liquid junction of the type: Ag|AgCl|MgCl2 (m 1), KCl (m 2), H2O|Mg-ISE, at the temperature 298 K and over total ionic-strengths from 0.015 to 6 mol kg−1 for different series of salt molal ratios. The sol–gel-based magnesium ion selective electrode (SG-ISE) and Ag/AgCl electrode used in this work were prepared in our laboratory. The Pitzer model was used for the experimental results correlation of activity coefficients. The unknown Pitzer mixing interaction parameters were evaluated (θ MgK = 0.1249, ψ MgKCl = −0.0572). Then, these parameters were used to predict the thermodynamic properties for the systems under investigation as a function of total ionic strength.

Controlled preparation of In2O3, InOOH and In(OH)3via a one-pot aqueous solvothermal route

Pure cubic In2O3, orthorhombic InOOH and cubic In(OH)3 nanocrystals were separately synthesized via a one-pot aqueous solvothermal route at low temperature by simply regulating the amount of water in the ternary system H2O–DMF–In(NO3)3·4.5H2O.

Activity Coefficients of Cesium Chloride and Cesium Sulfate in Aqueous Mixtures Using an Electromotive Force Method at 298.15 K

Activity coefficients for the CsCl + Cs2SO4 + H2O ternary system were determined at 298.15 K by electromotive force (EMF) measurements of the cell: Cs ion-selective electrode (ISE)|CsCl(mA), Cs2SO4(mB), H2O|Ag|AgCl. The cesium ion-selective electrode (Cs-ISE) and the Ag|AgCl electrode used in this work were made in this laboratory and had a good Nernst response. The experimental data were interpreted using Harned's rule and the Pitzer model. The corresponding parameters required in the Pitzer model have been evaluated for this system. Osmotic coefficients of this system and activity coefficients of the second salt Cs2SO4 were also calculated in the same molality range.

Solubility of NaF in NaF + NaX + H2O (X = ClO4 and NO3) Ternary Systems and Density and Refractive Index of the Saturated Solutions at 298.15 K

Data on the solubilities of NaF were determined in NaF + NaClO4 + H2O and NaF + NaNO3 + H2O ternary systems, and the density and refractive index of the saturated solutions were measured at 298.15 K. The solubility data and physical properties were determined for different molalities of the second electrolyte present in the ternary systems, within a range of 0 to 1.0 mol·kg-1. Experimental data on the density and refractive index were fit to polynomials as a function of NaClO4 or NaNO3 concentration. Finally, a thermodynamic description was made of the solid−liquid equilibrium for the two ternary systems, based on the Reilly, Wood, and Robinson (R−W−R) model for calculation of the mean ionic activity coefficient of NaF in the ternary saturated solution. The Bromley model was used for the calculation of the activity and osmotic coefficients of the binary systems because these are required for making calculations with the R−W−R model.

Liquid–liquid phase diagrams of H2O + 2-butanol + potassium phosphate and H2O + 2-butanol + Na2CO3 systems at 298.15 K

The phase diagrams for the ternary systems H2O + 2-butanol + K2HPO4/KH2PO4 (pH = 7) and H2O + 2-butanol + Na2CO3 at 298.15 K were determined. Experimental binodals and tie lines for these systems are presented. The experimental results were correlated using an improved regular solution theory. The agreement between the correlation and experimental data is good.

Thermodynamic Study on Mixed Electrolyte KCl and K2SO4 Aqueous Systems from EMF Measurements at 298.15 K

Activity coefficients for potassium chloride in the KCl + K2SO4 + H2O ternary system were determined from electromotive force (emf) measurements of the cell: K ion selective electrode (ISE)|KCl (mA), K2SO4 (mB), H2O|Ag|AgCl at 298.15 K and over total ionic strengths from 0.01 mol·kg-1 up to the saturated concentration 2.3 mol·kg-1. The K+ ion selective electrode (K-ISE) and Ag|AgCl electrode used in this work were prepared in our laboratory and had reasonably good Nernst responses, which demonstrate that the emf method can be applied to measure the above system with high precision in comparison with other methods. The experimental data were analyzed using the Harned rule and the Pitzer model. The Harned coefficients and the Pitzer binary and ternary ionic interaction parameters for the system have been evaluated. The experimental results obey the Harned rule, and the Pitzer model can be used to describe this aqueous system satisfactorily. The activity coefficients of K2SO4, the osmotic coefficients of the mixtures, and the excess free energy of mixing were also calculated. Finally, the mutual solubility of the mixed salts was predicted by way of the obtained Pitzer parameters.

An experimental study of phase equilibria in the systems H2O?CO2?CaCl2 and H2O?CO2?NaCl at high pressures and temperatures (500?800��C, 0.5?0.9�GPa): geological and geophysical applications

Phase equilibria in the ternary systems H2O–CO2–NaCl and H2O–CO2–CaCl2 have been determined from the study of synthetic fluid inclusions in quartz at 500 and 800 °C, 0.5 and 0.9 GPa. The crystallographic control on rates of quartz overgrowth on synthetic quartz crystals was exploited to prevent trapping of fluid inclusions prior to attainment of run conditions. Two types of fluid inclusion were found with different density or CO2 homogenisation temperature (Th(CO2)): a CO2-rich phase with low Th(CO2), and a brine with relatively high Th(CO2). The density of CO2 was calibrated using inclusions in the binary system H2O–CO2. Mass balance calculations constrain tie lines and the miscibility gap between brines and CO2-rich fluids in the H2O–CO2–NaCl and H2O–CO2–CaCl2 systems at 500 and 800 °C, and 0.5 and 0.9 GPa. The miscibility gap in the CaCl2 system is larger than in the NaCl system, and solubilities of CO2 are smaller. CaCl2 demonstrates a larger salting-out effect than NaCl at the same P–T conditions. In ternary systems, homogeneous fluids are H2O-rich and of extremely low salinity, but at medium to high concentrations of salts and non-polar gases fluids are unlikely to be homogeneous. The two-phase state of crustal fluids should be common. For low fluid-rock ratios the cation compositions of crustal fluids are buffered by major crustal minerals: feldspars and micas in pelites and granitic rocks, calcite (dolomite) in carbonates, and pyroxenes and amphiboles in metabasites. Fluids in pelitic and granitic rocks are Na-K rich, while for carbonate and metabasic rocks fluids are Ca-Mg-Fe rich. On lithological boundaries between silicate and carbonate rocks, or between pelites and metabasites, diffusive cation exchange of the salt components of the fluid will cause the surfaces of immiscibility to intersect, leading to unmixing in the fluid phase. Dispersion of acoustic energy at critical conditions of the fluid may amplify seismic reflections that result from different fluid densities on lithological boundaries.

Diagramme polythermique du systeme ternaire H2O—Al(NO3)3—Mg(NO3)2

The solid—liquid equilibria of the ternary system H2O—Al(NO3)3—Mg(NO3)2 were studied at −30, −20, −10 and 0°C by using a synthetic method which allows to detemine all the characteristic points of isothermal sections. The stable solid phases which appear are respectively: ice, Al(NO3)3·9H2O, Mg(NO3)2·9H2O and Mg(NO3)2·6H2O. Neither double salts nor mixed crystals are observed in the temperature and composition field studied. Polytherm diagram layout show two invariant transformations correspond with an eutectic point and a peritectic point.

An Investigation of the Polythermal Diagram of the Ternary System H2O–(NH4)2HPO4–(NH4)2SO4 between 0 and 25°C

Isotherms at 0, 10, and 25°C of the H2O–(NH4)2HPO4–(NH4)2SO4 ternary system have been established by conductivity measurements in the considered temperature range (0–25°C). Tracing the polythermal diagram has allowed to determine the existence domains of the solid phases: (NH4)2HPO4·2H2O, (NH4)2HPO4, and (NH4)2SO4.

Electrical Conductivity of Concentrated Aqueous Mixtures of HCl and KCl in a Wide Range of Compositions and Temperatures

The electrical conductivity of the HCl + KCl + H2O ternary system has been measured in a wide range of compositions (0 mol·dm-3 < cHCl < 6 mol·dm-3 and 0 mol·dm-3 < cKCl < 1.2 mol·dm-3) and temperatures (15 °C < t < 45 °C) making use of an automated station for conductometric titration based on the “electrodeless conductivity” technique. The experimental data obtained have been fitted to a polynomial in the HCl molar concentration, the KCl molar concentration, and the temperature. As a result, an empirical model enabling the interpolation of the conductivity of the chemical system under study within the limits of the variables investigated has been proposed.

Thermodynamic Study of the NaCI + CaCI2 + H2O Mixed System by EMF Measurements at Different Temperatures

Activity coefficients for NaCI in the NaCI + CaCI2 + H2O ternary system are determined from emf measurements of galvanic cells at 15, 25, 35 and 45 °C. The experimental data were analysed using the Harned, Scatchard and Pitzer treatments.