H2O Ternary System Research Articles

SAFT2 equation of state for the CH4–CO2–H2O–NaCl quaternary system with applications to CO2 storage in depleted gas reservoirs

Understanding the phase equilibria and physical-chemical characteristics of the CH4–CO2–H2O–NaCl quaternary system is important for evaluating costs and risks for the storage of CO2 in depleted natural gas reservoirs as well as fluid inclusion studies. In this study, phase equilibria and thermodynamic properties of this system were investigated through the utilization of a statistical association fluid theory-based (SAFT) equation of state (EOS) at temperatures from 298 to 513 K (25–240 °C), pressures up to 600 bar (60 MPa) and concentration of NaCl up to 6 mol/kgH2O. The model parameters were obtained from the fitting of available experimental data of subsystems (i.e., CH4–H2O, CH4–CO2, and CH4–H2O–NaCl) that were judged to be reliable and incorporation of available parameters for the subsystems (i.e., pure component, CO2–H2O, and CO2–H2O–NaCl). Using the SAFT EOS developed in this study, we predicted the solubility of (CH4 + CO2) gas mixtures in pure H2O and compared it with the available experimental data and the predicted values from four popular numerical simulators. The results indicate that our model can provide reliable predictions for the CH4–CO2–H2O ternary system. Subsequently, we further predicted the phase equilibria and density of the CH4–CO2–H2O–NaCl system with NaCl varying from 0 to 6 mol/kgH2O. We also employed the SAFT EOS to predict the solubility of CO2 and CH4 in the water-alternating-gas process for CO2-enhanced oil recovery, demonstrating good agreement with the simulation results obtained through the Peng-Robinson EOS for predicting the CO2 and CH4 solubility. These predicted thermodynamic properties and phase behaviors in the CH4–CO2–H2O–NaCl system provide quantitative insights into the implications of CO2 storage in depleted oil and gas reservoirs.

Development of a consistent geochemical model of the Mg(OH)2–MgCl2–H2O system from 25°C to 120°C

The formation of magnesium chloride-hydroxide salts (magnesium hydroxychlorides) has implications for many geochemical processes and technical applications. For this reason, a thermodynamic database for evaluating the Mg(OH)2–MgCl2–H2O ternary system from 0 °C–120 °C has been developed based on extensive experimental solubility data. Internally consistent sets of standard thermodynamic parameters (ΔGf°, ΔHf°, S°, and CP) were derived for several solid phases: 3 Mg(OH)2:MgCl2:8H2O, 9 Mg(OH)2:MgCl2:4H2O, 2 Mg(OH)2:MgCl2:4H2O, 2 Mg(OH)2:MgCl2: 2H2O(s), brucite (Mg(OH)2), bischofite (MgCl2:6H2O), and MgCl2:4H2O. First, estimated values for the thermodynamic parameters were derived using a component addition method. These parameters were combined with standard thermodynamic data for Mg2+(aq) consistent with CODATA (Cox et al., 1989) to generate temperature-dependent Gibbs energies for the dissolution reactions of the solid phases. These data, in combination with values for MgOH+(aq) updated to be consistent with Mg2+-CODATA, were used to compute equilibrium constants and incorporated into a Pitzer thermodynamic database for concentrated electrolyte solutions. Phase solubility diagrams were constructed as a function of temperature and magnesium chloride concentration for comparisons with available experimental data. To improve the fits to the experimental data, reaction equilibrium constants for the Mg-bearing mineral phases, the binary Pitzer parameters for the MgOH+ — Cl− interaction, and the temperature-dependent coefficients for those Pitzer parameters were constrained by experimental phase boundaries and to match phase solubilities. These parameter adjustments resulted in an updated set of standard thermodynamic data and associated temperature-dependent functions. The resulting database has direct applications to investigations of magnesia cement formation and leaching, chemical barrier interactions related to disposition of heat-generating nuclear waste, and evaluation of magnesium-rich salt and brine stabilities at elevated temperatures.

Phase Behavior and Rheological Properties of AES/CAPB/H2O Ternary System

Cleaning products are often formulated as mixtures of surfactants because the properties of surfactant mixtures are easier to adjust than those of a single surfactant. Therefore, it is of great significance to study the phase diagram of surfactant mixtures. In this paper, the phase behavior of the alkyl ethoxysulfate (AES)/cocamidopropyl betaine (CAPB)/H2O ternary system was investigated at room temperature using polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS), and the identified phases of the samples with various compositions were used to construct the ternary phase diagram of the AES/CAPB/H2O system which contains normal micellar phase (L1), normal hexagonal phase (H1), lamella phase (Lα), and one transition region (L1 → H1). The viscosity distribution of the AES/CAPB/H2O system was determined by a Brookfield DV2T touch screen viscometer. In addition, the effects of the weight percentage of CAPB and salts on the viscosity and rheological properties of the AES/CAPB/H2O system were also investigated. This work not only enriches the phase diagram of surfactant systems, but also has important guiding significance for the design and development of cleaning products.

Thermodynamic Model of the Fluid System H2O–CO2–NaCl–CaCl2 at P-T Parameters of the Middle and Lower Crust

Based on the earlier obtained equations of state for the ternary systems H2O–CO2–CaCl2 and H2O–CO2–NaCl, an equation of state for the four-component fluid system H2O–CO2–NaCl–CaCl2 is derived in terms of the Gibbs excess free energy. A corresponding numerical thermodynamic model is built. The main part of the numerical parameters of the model coincides with the corresponding parameters of the ternary systems. The NaCl–CaCl2 interaction parameter was obtained from the experimental liquidus of the salt mixture. Similar to the thermodynamic models for H2O–CO2–CaCl2 and H2O–CO2–NaCl, the range of applicability of the model is pressure 1–20 kbar and temperature from 500 to 1400°C. The model makes it possible to predict the physicochemical properties of the fluid involved in most processes of deep petrogenesis: the phase state of the system (homogeneous or multiphase fluid, presence or absence of solid salts), chemical activities of the components, densities of the fluid phases, and concentrations of the components in the coexisting phases. The model was used for a detailed study of the phase state and activity of water on the H2O–CO2–salt sections when changing the ratio {{{{x}_{{{text{NaCl}}}}}} mathord{left/ {vphantom {{{{x}_{{{text{NaCl}}}}}} {({{x}_{{{text{NaCl}}}}} + {{x}_{{{text{CaC}}{{{text{l}}}_{{text{2}}}}}}})}}} right. kern-0em} {({{x}_{{{text{NaCl}}}}} + {{x}_{{{text{CaC}}{{{text{l}}}_{{text{2}}}}}}})}} from 1 to 0. Changes in the composition and density of coexisting fluid phases at a constant activity of water and changes in the total composition of the system are studied. A set of phase diagrams on sections H2O–NaCl–CaCl2 for different mole fractions of CO2 is obtained. Pressure dependencies of the maximal activity of water in the field of coexisting unmixable fluid phases are obtained for several salt compositions of the system. Due to removal of restrictions resulting from a smaller number of components in ternary systems, the thermodynamic behavior of systems with a mixed composition of the salt significantly differs from the behavior of those with a single salt component.

Solubility, density, conductivity, and phase equilibrium of NaBr - Ba(H2PO2)2 - H2O ternary system at 298 K

Solubility, density, conductivity, and phase equilibrium of NaBr - Ba(H2PO2)2 - H2O ternary system at 298 K

Thermodynamic Model of the Fluid System H<sub>2</sub>O–CO<sub>2</sub>–NaCl–CaCl<sub>2</sub> at <i>P-T</i> Parameters of the Middle and Lower Crust

Based on the earlier obtained equations of state for the ternary systems H2O–CO2–CaCl2 and H2O–CO2–NaCl, an equation of state for the four-component fluid system H2O–CO2–NaCl–CaCl2 is derived in terms of the Gibbs excess free energy. A corresponding numerical thermodynamic model is build. The main part of the numerical parameters of the model coincides with the corresponding parameters of the ternary systems. The NaCl–CaCl2 interaction parameter was obtained from the experimental liquidus of the salt mixture. Similar to the thermodynamic models for H2O–CO2–CaCl2 and H2O–CO2–NaCl, the range of applicability of the model is pressure 1–20 kbar and temperature from 500°C to 1400°C. The model makes it possible to predict the physicochemical properties of the fluid involved in most processes of deep petrogenesis: the phase state of the system (homogeneous or multiphase fluid, presence or absence of solid salts), chemical activities of the components, densities of the fluid phases, and concentrations of the components in the coexisting phases. The model was used for a detailed study of the phase state and activity of water on the H2O–CO2–salt sections when changing the ratio \( {{{{x}_{{{\text{NaCl}}}}}} \mathord{\left/ {\vphantom {{{{x}_{{{\text{NaCl}}}}}} {\left( {{{x}_{{{\text{NaCl}}}}} + {{x}_{{{\text{CaC}}{{{\text{l}}}_{{\text{2}}}}}}}} \right)}}} \right.} {\left( {{{x}_{{{\text{NaCl}}}}} + {{x}_{{{\text{CaC}}{{{\text{l}}}_{{\text{2}}}}}}}} \right)}} \) from 1 to 0. Changes in the composition and density of coexisting fluid phases at a constant activity of water and changes in the total composition of the system are studied. A set of phase diagrams on sections H2O–NaCl–CaCl2 for different mole fractions of CO2 is obtained. Pressure dependencies of the maximal activity of water in the field of coexisting unmixable fluid phases are obtained for several salt compositions of the system. Due to removal of restrictions resulting from a smaller number of components in ternary systems, the thermodynamic behavior of systems with a mixed composition of the salt is significantly differ from the behavior of those with a single salt component.

CaF2(s) Solubility Isotherm in the CaF2–CaSO4–MSO4–H2O (M = Zn, Mn, Mg) Quaternary Systems and Their Subsystems at Various Temperatures

A ZnSO4 electrolyte solution with impurity salts such as MnSO4 and MgSO4 is often used in zinc hydrometallurgical processes over a wide temperature range. CaSO4·2H2O(s) scaling and fluorine corrosion are two encountered problems in the process. Understanding the CaF2(s) solubility behavior in MSO4 (M = Zn, Mn, Mg) aqueous solutions at various temperatures helps remove Ca2+ and F– ions from the solution. However, CaF2(s) solubility data, especially at temperatures >298 K, have not been published yet. In this work, CaF2(s) solubilities in the CaF2–CaSO4–MSO4–H2O (M = Zn, Mn, Mg) quaternary systems and its subsystems of the CaF2–MSO4–H2O (M = Zn, Mn, Mg) at 348.15 K and the CaF2–CaSO4–MSO4–H2O (M = Zn, Mg) quaternary systems and the CaF2–MgSO4–H2O ternary system at 298.15 K are systematically measured. The results show that the CaF2(s) solubility in the MSO4 (M = Zn, Mn, Mg) aqueous solution of a certain concentration at 348.15 K is considerably higher than that at 298.15 K. At 298.15 and 348.15 K, the salting-in effect of MSO4 (M = Zn, Mn, Mg) on CaF2(s) solubility is enhanced with the order ZnSO4 < MnSO4 < MgSO4. At both temperatures, CaF2(s) solubilities in CaSO4·2H2O(s)- or CaSO4(s)-saturated MSO4 (M = Zn, Mn, Mg) aqueous solutions are generally lower than those in pure MSO4 (M = Zn, Mn, Mg) aqueous solutions. Particularly, the salting-in effect of MgSO4 on CaF2 is so strong that CaF2(s) dissolves completely and is converted to CaSO4·2H2O(s) and MgF2(s) in a concentrated MgSO4 aqueous solution. Hence, this study indicates that high temperatures and high salt concentrations increase the CaF2(s) solubility, making the removal of Ca2+ and F– ions from the system challenging. Further, the existence of impurity salts MnSO4 and MgSO4 makes it more difficult.

Solid-liquid phase equilibrium for the hexamethylenetetramine–NH4Cl–H2O system: Solubility determination, model correlation and molecular simulation

The phase equilibrium of the hexamethylenetetramine (HMTA)–NH4Cl–H2O ternary system was investigated to optimize the crystallization separation process for HMTA in industrial wastewater treatment. The solubility of HMTA and NH4Cl in water was measured by the dynamic dissolution equilibrium method. Four isothermal ternary system phase diagrams were generated at 293.15, 303.15, 313.15, and 323.15 K. The solubility data were correlated by the Extended UNIQUAC model, which showed that the model predictions fit well with experimental values. Intermolecular interactions were analyzed by molecular simulations to describe the solubility behavior of the solute in the solvent from a microscopic perspective.

Solid–Liquid Phase Diagram of the Ternary System NaF–Na3PO4–H2O at 308.15, 323.15, and 348.15 K

The solid–liquid phase behavior of the NaF–Na3PO4–H2O ternary system and its binary subsystems NaF–H2O and Na3PO4–H2O at 308.15, 323.15, and 348.15 K has been measured by the isothermal dissolution equilibrium (IDE) method. Compared with the measured solid–liquid phase behavior data, the previously reported results have been evaluated and the unreasonability has been discussed. The phase diagrams at the investigated temperatures for this ternary system are drawn according to the measured solid–liquid phase behavior and the corresponding wet solid and liquid-wet solid–solid lines. From the phase diagrams, it is found that at a given temperature, there are three types of equilibrium solid phases, NaF(s), double salt 2Na3PO4·NaF·19H2O(s), and Na3PO4·12H2O(s) in the ternary system. Accordingly, there are two cosaturated points for NaF(s) and double salt 2Na3PO4·NaF·19H2O(s), double salt 2Na3PO4·NaF·19H2O(s) and Na3PO4·12H2O(s), respectively. The comparison of phase diagrams at different temperatures suggests that, with the rise of temperature, the double salt crystal region became a little bit larger, and correspondingly, the crystal regions of pure salt (NaF(s) and Na3PO4·12H2O(s)) became smaller, which is not beneficial to the separation of fluoride and phosphate. This indicates that the fluoride and phosphate separation process should be at lower temperatures.

A High-pressure Filled Ice in the H2O–CO2–CH4 System, with Possible Consequences for the CO2–CH4 Biosignature Pair

Here we constrain the speciation of carbon that may outgas in ocean exoplanets. Ocean exoplanets likely have at least a few percent by mass of water, which is sufficient to build a high-pressure ice layer between a rocky interior and the outer hydrosphere. We study the possible formation of a filled ice in the ternary system H2O–CO2–CH4. The incorporation of CH4 and CO2 in filled ice would be an important mechanism for transporting carbon across a high-pressure ice mantle into the atmosphere. The CH4–CO2 pair is also important as a potential biosignature. We find that a filled ice in the system H2O–CO2–CH4 is possible though enriched in CH4. CO2 cannot account for more than 15% by mole of the carbon content of the filled ice. Such a filled ice is less dense than an overlying ocean and would therefore discharge into the ocean, depressurize, and outgas its carbon content into the atmosphere. A high-pressure, water-rich mantle in ocean worlds may therefore support the transport of carbon from the interior into the atmosphere. More than 75% by mole of this carbon would be reduced. As long as CH4 exists/is produced in the interior and the ice mantle convects, thus transporting chemical species outward, a flux of carbon enriched in CH4 would outgas. If this persists over geological time it would negate atmospheric sinks for CH4, and explain low concentrations of atmospheric CO2. If the contrary is correct than the interior of the planet may be oxidizing.

Biaxial Hard Compression, Anisotropic Elastic Property, and Pressure-Induced Isosymmetric Phase Transition in Ammonium Bicarbonate

The elastic property, exceptional anisotropic compression, and pressure-induced isosymmetric phase transition in ammonium bicarbonate (AB) are studied by in situ synchrotron X-ray diffraction, Raman spectroscopy, and computational methods. The exceptional anisotropic compression as a result of biaxial hard compression is induced by stiff hydrogen-bonding “double-wine-rack” geometric motifs. The large values of elastic anisotropy such as Young’s moduli, Shear moduli, and Poisson’s ratio verify the anisotropic nature in AB. The biaxial hard compression further induces an isosymmetric phase transition at 2 GPa through the generation of new N–H···O hydrogen bonds. Our work first demonstrates the stiff mechanical study of “double-wine-rack” geometric hydrogen-bonding networks and its influence on the phase transition, which can be used as a model to investigate the robust nature of hydrogen bonds and the structural origin of isosymmetric phase transition. Moreover, the hydrogen-bonding “double-wine-rack” geometric mechanism also provides an inspiration to construct a covalent-bonding “double-wine-rack” geometric model favoring anomalous biaxial mechanical/thermal responses. The determination of the high-pressure phase of AB provides new information to understand the composition of the ternary system H2O–CO2–NH3.

Isopiestic Determination and Simulation of Water Activity in the LiCl−KCl−H2O Ternary System at 323.15 K

Isopiestic Determination and Simulation of Water Activity in the LiCl−KCl−H2O Ternary System at 323.15 K

Solubility, density and refractive index of formamide/N-methylformamide/N, N-dimethylformamide + Rb2SO4 + H2O ternary systems at 283.2, 298.2 and 313.2 K

In this work, the solid–liquid equilibrium (SLE) of the ternary systems formamide (FA)/N-methylformamide (NMF)/N, N-dimethylformamide (DMF) + Rb2SO4 + H2O was measured at temperatures of 283.2, 298.2, and 313.2 K. The isothermal solubility of Rb2SO4 in mixed solvents, the density and refractive index of the saturated solutions were determined. At a given temperature, with the increase of the amide content in the mixed solvent, the saturated solubility of Rb2SO4 decreased significantly. The density trend was consistent with the solubility. However, the refractive index increased with increasing the content of amide. The solubility increased with increasing the temperature, whereas, the density curves and refractive index curves at the three temperatures showed a point of intersection. In addition, the influence of the polarity and structure of amide on the solubility of the ternary system was also discussed. Finally, the experimental data were fitted with empirical equations.

Solubility isotherms determination of the H3BO3 + CsCl + H2O system at T = (273.15, 298.15, 323.15, 348.15 and 363.15) K and thermodynamic modeling

The construction of a comprehensive thermodynamic model for boron-containing salt brine is important. However, the general lack of the solubility of H3BO3 + salt + H2O ternary systems makes it difficult to determine model parameters involving boron species. Here, we systematically determined the solubility isotherms of the H3BO3 + CsCl + H2O system at T = (273.15, 298.15, 323.15, 348.15 and 363.15) K. There are three solubility branches corresponding to H3BO3(cr), CsCl(cr) and a novel adduct in the system. The determined composition of the adduct is 2H3BO3·3CsCl. Moreover, the single crystal structure of 2H3BO3·3CsCl is solved, suggesting that H3BO3 molecules keep it native plane-triangle structure, but the O atoms coordinate to the Cs ion. We modeled these ternary solubility isotherms using the Pitzer-Simonson-Clegg (PSC) model implemented in the ISLEC program. With the help of the model, a complete polythermal phase diagram of the system was constructed for the temperature range from 250 K to 373.15 K. The determined standard thermodynamic quantities of 2H3BO3·3CsCl(cr) from the model are ΔfGmΘ = − 3182.26 kJ∙mol−1, ΔfHmΘ = − 3496.19 kJ∙mol−1, SmΘ = 485.85 J∙K−1∙mol−1, Cp,mΘ = 320 J∙K−1∙mol−1, respectively.

Effects of ethylenediamine tetra-acetic acid (EDTA) and its disodium salt derivative (EDTA-Na) on the characteristics of magnesium oxysulfate (MOS) cement

Ethylenediamine tetra-acetic acid (EDTA) and its disodium salt derivative (EDTA-Na) (0.5% weight of MgO powder) were incorporated into MgO–MgSO4–H2O ternary system to prepare magnesium oxysulfate (MOS) cement. The single effect of EDTA/EDTA-Na as well as the synergistic effect of EDTA/EDTA-Na and citric acid (CA) on the hydration mechanism, phase composition, microstructure and mechanical properties of MOS cement were investigated. The results showed that EDTA and EDTA-Na addition induced no new phase, but the magnesium-EDTA complexes formed by EDTA4− and Mg2+ ions acted as nuclei for the hydration products, including brucite, 3 Mg(OH)2·MgSO4·8H2O (318 phase) and 5 Mg(OH)2·MgSO4·7H2O (517 phase). This helped to form a more homogeneous and compact microstructure, thereby improving the durability and volume stability of MOS cement in air curing condition. Moreover, the synergistic effect of EDTA/EDTA-Na and CA preferred the formation of 517 phase to that of brucite. It further improved the water resistance of MOS cement. In this study, EDTA and EDTA-Na were found to be effective additives in improving the characteristics of MOS cement.

Solid-liquid phase equilibria in the ternary systems H2O+ZnCl2+NaCl at temperatures of 298, 313 and 333 K

In this study, an economic separation method is suggested with the use of phase equilibria in order to ensure the recycling of ZnCl2, the industrial waste amount of which is very high, and to prevent it from an environmental pollutant. Sodium chloride?zinc chloride?water systems were examined by the isothermal method at temperatures of 298, 313 and 333 K. The analyses of the liquid and solid phases were used to determine the composition of the solid phase using the Schreinemaker?s graphic method. The solid?liquid phase equilibrium and viscosity data belonging to all the ternary systems were identified and the solubility and viscosity changes with temperature were compared. The viscosity values were inversely proportional to the temperature as the amount of ZnCl2 in the solution increased. NaCl, 2NaCl ZnCl2 nH2O (n: 2, 0), ZnCl2 salts were observed at 298, 313 and 333 K in the solid phases that are in equilibrium with the liquid phase at the invariant point.

Measurements and Calculations mean activity coefficients of KI in the KI–KCl–H2O ternary system at 298.15 K

Compared to the current popular methods for measuring the mean activity coefficient of the ternary aqueous solution, electromotive force method has certain advantages of rapidity and sensitivity. Herein, The electromotive force measurements were performed on the cell of the type: K–ISE|KI (m1), KCl (m2)|I–ISE, which consists of a potassium-ion combination ion selective electrode (ISE) and iodide-ion combination ion selective electrode (ISE) without a liquid junction. We chose the total ionic strength I range from 0.0100 to 1.0000 mol·kg−1 for different ionic strength fractions yb of KCl with yb = (0.0, 0.2, 0.4, 0.6, 0.8). The experimental results show that the mean activity coefficients of KI can be calculated well by using the Pitzer models and Nernstian equation. Moreover, the Pitzer ion interaction parameters of θCl,I and ψK,I,Cl were fitted using Pitzer’s equations, and the two parameters were used to calculated the mean activity coefficients of KCl in the KI–KCl–H2O ternary system. Accordingly, the osmotic coefficients, water activities, and excess Gibbs free energies in the mixtures were studied in the KI–KCl–H2O ternary system.

Solubility Isotherm Determinations at T = (273.15, 298.15, 323.15, 348.15 and 363.15) K and Thermodynamic Modeling of the H3BO3 + SrCl2 + H2O System

Boron abundantly exists in salt lake brine system as various boron-containing aqueous species or minerals. The phase behavior of boron and other substances (Li, Na, K, Rb, Cs, Mg, Ca, Sr, Cl, S etc.) in the complicated salt brine system during the solar pool process needs to be simulated and predicted by models. Basic experimental data (e.g. solubility, etc.) of simple binary and ternary system are necessary for the model parameterizations. At present, the unavailability of solubility data in the H3BO3 + SrCl2 + H2O ternary system makes the model parameterization difficult. In this paper, we determined the solubility isotherms in the H3BO3 + SrCl2 + H2O ternary system at 273.15 K, 298.15 K, 323.15 K, 348.15 K and 363.15 K. The result show that the isotherms all consisted of the solubility branches H3BO3(cr) and SrCl2⋅nH2O(cr) (n = 6 and 2), and no new phase has been found. Then, a Pitzer–Simonson–Clegg (PSC) model in the ISLEC software package was used to simulate the thermodynamic properties of the H3BO3 + H2O, SrCl2 + H2O, and H3BO3 + SrCl2 + H2O systems, including solubility, water activity, activity coefficients, heat capacity and enthalpy of dilution. With the obtained model parameters, a complete polythermal phase diagram of the H3BO3 + SrCl2 + H2O system was predicted at temperatures from 255 to 373 K. The present work lays the foundation for the future simulations of complicated salt lake brine systems containing H3BO3 and SrCl2.

Phase Behavior of N-Methylpyrrolidone + MCl (M = Na, K, Rb, Cs) + H2O Systems at 288.2, 298.2, and 308.2 K

In this paper, the solid–liquid equilibrium of N-methylpyrrolidone (NMP) + MCl (M = Na, K, Rb, and Cs) + H2O ternary systems was investigated at three temperatures (T = 288.2, 298.2, and 308.2 K). ...

Constructing the Pourbaix diagram of Fe-Cl−-H2O ternary system under supercritical water conditions

Supercritical water oxidation (SCWO) technology, which has outstanding performance, is impeded commercial development due to serious corrosion problems. In this work, the first Pourbaix diagrams of the Fe-Cl−-H2O ternary system under supercritical water conditions was established to predict the evolution process of metals in thermodynamics equilibrium. The fifteen species were rationally screened by the ion distribution coefficient, and thermodynamics parameters under supercritical conditions were calculated by the extrapolation method of the revised Helgeson-Kirkham Flowers (R-HKF) model. The results show that hematite and magnetite passivation film and ferrous iron are continuously eroded by FeCl3 (aq) corrosion zone with the increase of chloride concentration, which greatly expands the area. Interestingly, the range of the immunization zone is almost unchanged. On the other hand, most of the Fe(OH)- 3 corrosion zone, passivation zone, and immunization zone to be converted to ferrous iron caused by temperature rise when FeCl3 (aq) reaches a certain concentration. Metals often form a hematite and magnetite passivation film to reduce the dissolution rate of the substrate under alkaline conditions with relatively high potentials, so the pre-neutralization method can be used as an anti-corrosion measure.