Vapor-liquid Equilibrium Measurements Research Articles

UNIFAC PREDICTION OF VAPOR LIQUID EQUILIBRIA INVOLVING GAMMA-VALEROLACTONE DERIVATIVE SYSTEMS

Researchers have studied the hydrogenation of Gamma-Valerolactone (GVL) over Ru/C to produce 2-methyltetrahydrofuran (2-MTHF), a biomass-based platform chemical with potential as a biofuel and green solvent. Other byproducts of this reaction include 2-butanol (2-BuOH), 2-pentanol (2-PeOH), and 1,4-pentanediol (1,4-PDO). In this study, UNIFAC activity coefficient models were used to predict the vapor-liquid equilibrium of several systems included in the process to explain the phase behavior which is important in purification process. The accuracy of the UNIFAC model is tested by comparing the experimental boiling points for the binary system of 2-propanol + 1-butanol and the vapor-liquid equi-librium of the GVL + 2-MTHF system. From this comparison, the Root Mean Square Deviation (RMSD) values for the boiling point measurements are obtained to be 3.153%, and for the liquid and vapor phases in the vapor-liquid equilibrium measurements, the RMSD values are 1.934% and 0.298% respectively. These RMSD values indicate the level of accuracy of the UNIFAC model in representing the experimental data for both boiling point measurements and vapor-liquid equilibrium phase behavior. The prediction results of vapor-liquid equilibrium data for GVL derivative systems showed that the 2-BuOH + 2-MTHF system does form an azeotrope when the mol fraction of 2-BuOH is 0.0031 at 79.780C. The calculation was performed using ChemCAD commercial software for chemical process modeling and simulation

Vapor-Liquid Equilibrium Measurement of Systems Containing Glycerol for Separation Process of Glycerol as a By-Product of Biodiesel

The most popular technique to produce biodiesel were uses alcohol as a catalyst to transesterify triglycerides. The biodiesel transesterification process has a by-product in the form of glycerol which has a high selling value. Equilibrium data of glycerol and alcohol mixtures is limited in equilibrium conditions and systems which causes the glycerol purification process may not be designed and operated optimally. This research aims to obtain experimentally isobaric vapor-liquid equilibrium of methanol + glycerol binary system at 31.3, 61.3, and 100.8 kPa. A modified Glass Othmer-Still was utilised to carry out the experiment. Refractometer index type Bausch and Lomb ABBE was used to examine the equilibrium composition of the liquid and vapor phases. Using the L-W thermodynamic consistency test method, the experimental data used in this work were shown to be thermodynamically consistent. The experimental data were correlated well with the Wilson, Non-Random Two Liquid (NRTL), and Universal Quasi-Chemical (UNIQUAC) models with absolute average deviation in temperatures (AADT) and that in vapor compositions (AADy) smaller than 0.3% and 0.2%, respectively. The Universal Chemical Functional Group Activity Coefficient (UNIFAC) in predicting VLE the system studied showed good performance giving AADT and AADy smaller than 7.4% and 0.04%, respectively.

Vapor-liquid equilibrium measurements of ionic liquid [DEME][TFSI] with different hydrofluorocarbon refrigerants R152a, R32, and R143a

To overcome the shortages of traditional working pairs (LiBr/H2O and NH3/H2O) for absorption-refrigeration systems (ARSs), novel working pairs consisting of low global warming potential (GWP) hydrofluorocarbons difluoroethane (R152a) and difluoromethane (R32) plus low-viscosity ionic liquid N,N‑diethyl-2‑methoxy-N-methylethan-1-aminium bis((trifluoromethyl)sulfonyl)amide ([DEME][TFSI]) are studied. Firstly, solubilities of R152a and R32 in [DEME][TFSI] are measured by the isochoric saturation method in the temperature range of 293 K ∼ 343 K and pressure range of 0.14 MPa ∼ 1.664 MPa with the relative expanded uncertainty of 0.03. A high-GWP hydrofluorocarbon 1,1,1-trifluoroethane (R143a) is involved in the experiment for further comparison. The non-random two-liquid model is used to correlate the vapor-liquid equilibrium data with average absolute relative errors of 0.55 % (R152a), 0.58 % (R32), and 0.94 % (R143a), respectively. [DEME][TFSI] shows its low viscosity and good solubility of hydrofluorocarbons by contrast with conventional ionic liquids. A refrigerant solubility rank order in [DEME][TFSI]: R152a > trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) > R32 > 2,3,3,3-tetrafluoro-1-propene (R1234yf) > R143a is obtained from the comparison. This work provides the possibility to apply low-GWP working pairs R152a/[DEME][TFSI] and R32/[DEME][TFSI] in ARSs.

Vapor-liquid equilibrium measurement for carbon dioxide (CO2)+propylene (R1270) binary mixture at temperatures from subcritical to supercritical

CO2-based binary mixtures have good performance and environmental friendliness, which are considered a good choice for working fluid in cooling and power cycles. Analyzing the properties of the vapor-liquid equilibrium is used to calculate the enthalpy and entropy of the dew and bubble point, which are fundamental parameters of thermodynamics. In this study, we measure the vapor-liquid equilibrium experimental data of CO2-propylene mixture by static thermostatic analysis experimental system. The working fluids in this state are repeatedly collected from the equilibrium cell to the gas chromatograph by the two electromagnetic capillary samplers to analyze the molar fractions. The maximum pressure deviation and maximum relative pressure deviation of the saturation vapor pressure of propylene are -0.004 MPa and -0.38%, respectively. We measure 5 sets of isotherms from 283.73 to 323.72 K, two of which are supercritical temperatures (313.73 K and 323.72 K). The pressure is up to about 6.4 MPa. The standard experimental uncertainties of mole fractions, pressure, and temperature are within 0.004, 0.002 MPa, and 0.06 K, respectively. The association model (the Peng-Robinso equation incorporating the Wong-Sandler mixing rule and the Non-Random Two-Liquid model) is used to fit the obtained vapor-liquid equilibrium data. The value of the average absolute relative deviation of pressure (AARDp) and the average absolute deviation of vapor phase molar fractions of component 1 (AADy1) is 0.29 % and 0.0062, respectively. The relative volatility under the five isotherms is also calculated, and most of the experimental data were within ± 5 % deviation.

High-pressure vapor-liquid equilibrium measurements of methane + water mixtures by nuclear magnetic resonance spectroscopy

The vapor-liquid equilibrium (VLE) of methane + water mixtures has been studied with nuclear magnetic resonance (NMR) spectroscopy. This work had two primary goals. The first goal was to develop methods that broaden the utility of NMR spectroscopy for VLE measurements. In this regard, we report a method by which the liquid-phase and vapor-phase compositions are measured in separate experiments by adjusting the height of the liquid phase in the sample tube. We also report a method for hastening phase equilibration by adding glass beads to the sample and repeatedly inverting the sample tube. The second goal of this work was to collect VLE data on a challenging mixture with real-world importance. Mixtures of methane + water are a useful test case because of their challenging characteristics, including the widely differing vapor pressures of the two components. One use for accurate VLE data on methane + water mixtures is to better predict the formation of harmful liquid phases in natural gas pipelines. Herein we utilize 1H NMR spectroscopy to measure the VLE of methane + water mixtures at temperatures of 299.73, 307.98, and 323.25 K, and pressures ranging from 0.69 MPa to 13.89 MPa. Experiments were carried out with a 600 MHz spectrometer. Mixtures were prepared and equilibrated in a high-pressure zirconia sample tube with an integrated needle valve. NMR-based VLE measurements on the liquid phase are in good agreement with available literature data and with Henry's Law predictions at low pressures. However, the commonly used GERG-2008 model for natural gas systems deviates dramatically from the experimental data for the liquid phase. NMR-based VLE measurements on the vapor-phase resulted in measured water concentrations that are systematically lower than available literature data and models. This systematic offset is likely caused by peak overlap in the NMR spectra.

VLE measurement of binary systems 1-butyl-3-methylimidazolium-based ionic liquids and ethanol or water

Experimental vapor–liquid equilibrium (VLE) data for binary systems of ethanol or water with four ionic liquids (ILs) comprising 1-butyl-3-methylimidazolium cation and different anions were measured at atmospheric pressure within a broad region of IL concentrations, IL mole fraction ranging between 0 and 0.7 or even 0.87. Siwoloboff procedure of vapor–liquid phase transition temperature measurement was applied to estimate VLE of the binary mixtures. Obtained t–x data were fitted assuming ideal vapor and non-ideal liquid phase behavior, using the original NRTL equation to calculate component activity coefficients. VLE description results are presented in form of equilibrium diagrams and as the variation of activity coefficients with mixture composition. Quality of the VLE data fitting was assessed based on root mean square deviations and mean deviations in temperature. Some experimental binary t–x data sets were compared to those available in literature (measured in much narrower concentration range) or predicted from ternary VLE data. The selection of ILs in this study was related to the separation of ethanol−water mixture by extractive distillation. Principal IL selection criterium was its ability to affect the ethanol–water relative volatility. Thermodynamic description of the VLE data of IL-containing systems within a wide concentration range is an essential building block of the mathematical model of separation devices, especially in case of regeneration equipment where concentrated IL is present.

Vapor-liquid equilibrium measurement and heating performance modeling on eco-friendly zeotropic blends of CO2/R1234ze(Z) and CO2/R1336mzz(E)

In the context of sustainable development, CO2 and hydrofluoroolefins (HFOs) are regarded as promising refrigerant candidates. Despite recognition of application potential, the knowledge of their blends is insufficient. In this paper, vapor–liquid equilibrium (VLE) properties of two eco-friendly zeotropic CO2/HFO blends, namely CO2/R1234ze(Z) and CO2/R1336mzz(E), were measured at temperature from 253.15 K to 333.15 K at CO2 concentration from 0 to 1. Peng-Robinson (PR) model and Soave-Redlich-Kwong (SRK) model are identified as suitable models for describing VLE of CO2/HFO with deviation less than 4.5%, whereas Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) model is shown to have larger deviation. Furthermore, a heat pump water heater is modelled to demonstrate the working potential of CO2/HFO in terms of thermodynamics and safety, while the newly fitted binary interaction parameter kij being used. Both CO2/R1234ze(Z) and CO2/R1336mzz(E) show more than 150% advantage in volumetric heating capacity and comparable heating efficiency compared to R134a. The optimal concentration of CO2 is higher than 0.6, eliminating the flammability of mixture. Additionally, the operating pressures of CO2/HFO are reduced to lower than 3.2 MPa at typical working condition due to HFO addition. The results contribute to the accurate VLE description of CO2/HFO and further investigation on the applications of eco-friendly refrigerants.

Density, Excess Molar Volume and Vapor–Liquid Equilibrium Measurements at 101.3 kPa for Binary Mixtures Containing Ethyl Acetate and a Branched Alkane: Experimental Data and Modeling

Vapor–liquid equilibrium (VLE) and density data for binary systems of branched alkanes + ethyl acetate are scarce in the literature. In this study, the binary mixtures 3-methylpentane + ethyl acetate and 2,3-dimethylbutane + ethyl acetate were investigated. Density measurements at atmospheric pressure were performed using a vibrating tube density meter at 293.15, 298.15 and 303.15 K. Large and positive excess molar volumes were calculated and correlated using a Redlich–Kister-type equation. Isobaric VLE data at 101.3 kPa were obtained using a Gillespie-type recirculation ebulliometer. Equilibrium compositions were determined indirectly from density measurements. The experimental data were checked for consistency by means of the Fredenslund test and the Wisniak (L-W) test and were then successfully correlated using the NRTL model. The newly studied binary systems display high deviations from ideality and minimum boiling azeotropes, the coordinates of which are reported in this work.

Separation of Azeotropic Mixtures of Ethyl Acetate + Methylcyclohexane: Vapor–Liquid Equilibrium Measurements

It is a challenge to separate ethyl acetate from methylcyclohexane because of the azeotropic phenomenon. To provide a basis for the design of the separation process, the isobaric vapor–liquid equilibria for an ethyl acetate + methylcyclohexane binary system were measured at 101.3 and 20.0 kPa using a modified Othmer-type still. The results show that ethyl acetate and methylcyclohexane form a miscible azeotropic mixture with minimum boiling temperature (349.99 K at 101.3 kPa), of which the composition varies slightly with decreasing pressure (≤101.3 kPa). It implies that ethyl acetate cannot be separated from methylcyclohexane by pressure-swing distillation. The azeotropy of ethyl acetate and methylcyclohexane disappears in the presence of decane (∼0.5 mole fraction), which means that ethyl acetate can be separated from methylcyclohexane by extractive distillation with decane as an entrainer.

Theoretical calculation and experimental investigation on vacuum gasification separation of Ag-Cu-Au ternary alloy

In this study, an innovative method for vacuum gasification separation of Ag-Cu-Au alloy was proposed. The saturated vapor pressure of each component is calculated theoretically, and the activities of Au-Cu and Ag-Cu-Au alloys are calculated by molecular interaction volume model (MIVM). The results show that the activities of Au-Cu alloy calculated by MIVM is accurate and reliable. Based on activity prediction, the separation coefficients of Au-Cu alloy were calculated. The results show that the separation coefficients of Au-Cu alloy are between 0.0037 ∼ 0.6626 in the temperature range of 1337–1773 K. Subsequently, the vapor-liquid equilibrium composition and vapor-liquid equilibrium phase diagram of Au-Cu and Ag-Cu-Au alloys were calculated, and the vapor-liquid equilibrium measurement experiments of Ag-Cu-Au alloy were carried out. The results show that vacuum gasification is challenging to realize the separation of Au-Cu alloy. During the vacuum gasification separation process of Ag-Cu-Au alloy, silver volatilizes into the vapor phase. When the pressure is 10 Pa and the mole fractions of silver, copper and gold in the liquid phase are 0.2, 0.1 and 0.7, respectively, the equilibrium temperature is 1545.5 K, and the mole fractions of silver, copper and gold in the vapor phase are 0.994, 0.002 and 0.004 respectively. The corresponding experimentally determined mole fractions of silver, copper, and gold in the vapor phase were 0.9666, 0.0333, and 5.89 × 10−5, respectively. In addition, the distribution and occurrence state of each element in the vacuum separation process of Ag-Cu-Au alloy were determined by EPMA.

Multicomponent vapor-liquid equilibrium measurements and modeling of triethylene glycol, water, and natural gas mixtures at 6.0, 9.0 and 12.5 MPa

Triethylene glycol (TEG) is commonly used for natural gas dehydration, and with subsea processing facilities on the rise, an increasing interest is being shown in complex phase equilibria involving petroleum fluids and polar compounds. In this study, examples of such phase equilibria have been studied. New measurements for multicomponent vapor-liquid equilibrium (VLE) of TEG/Water/Natural Gas systems have been performed at pressures ranging from 6.0 MPa to 12.5 MPa and temperatures in the range 15 °C to 40 °C. Two types of natural gas, a Synthetic Gas (xCH4=0.62) and a Real Gas (xCH4=0.92), were mixed with an aqueous TEG solution, with TEG weight percentages ranging from 95 wt.% to 99 wt.%. Glycol in gas (y1), water in gas (y2), and gas solubility in liquid (xNG) were measured with relative experimental uncertainties below 32%. Since the systems are highly associating, the Cubic-Plus-Association (CPA) equation of state (EoS) was selected to model their phase behavior . Different association schemes (4C, 4F, 5F, 6F and 5C) were tested for TEG, and the classical 4C scheme is shown to perform best. The CPA EoS performed in general terms well, considering the number of components in the systems, the associated complexities, and high measurement uncertainty for such low concentrations (<1 ppm) in the gas phase. Furthermore, the content of N2, CO2, CH4 and ethane were modelled in the liquid phase at various conditions.

Vapor–Liquid Equilibrium Measurements for Aqueous Mixtures of NH3+ MDEA + CO2and KOH + MDEA

Isothermal vapor–liquid equilibrium measurements were performed for aqueous solutions containing N-methyl diethanolamine (MDEA), MDEA + ammonia (NH3), MDEA + potassium hydroxide (KOH), MDEA + carbon dioxide (CO2), NH3 + CO2, and MDEA + NH3 + CO2. The experiments were carried out between 310 and 390 K and 0.07 and 34 bar using a static synthetic apparatus. Overall, 202 data points are reported in terms of total volume, total number of moles, temperature, and pressure. The experimental results for MDEA(aq), NH3(aq) + CO2(aq), and MDEA(aq) + CO2(aq) are in good agreement with the calculations done using the Extended UNIQUAC model within the studied range. The data presented in this work are also comparable to previously published measurements. This work reports for the first time VLE measurements for aqueous mixtures of MDEA + NH3 and MDEA + KOH. These data suggest that the interactions between MDEA(aq) and NH3(aq) or K+(aq) ions have a minor effect on the equilibrium pressures. Consequently, other physical properties are needed to describe the thermodynamic state of these systems, such as heat capacity, heat of dilution, and other phase equilibrium measurements. The isothermal VLE measurements for solutions containing NH3(aq) showed a pressure minimum that was confirmed by model estimates and by other works done in similar conditions. As a consequence, it is not possible to estimate the partial pressure of CO2 based on the difference between the pressure at equilibrium conditions and the partial pressure of the lean solvent. This paper demonstrates that this common approach to determining the partial pressure of gases may introduce a bias in these values. The dissolution of CO2 into MDEA(aq) + NH3(aq) mixtures changes the speciation of the system, leading to an increase in the concentration of their protonated species (MDEAH+(aq) and NH4+(aq), respectively). For this reason, the interaction between these charged species must be determined in order to perform reliable phase equilibrium calculations. Ultimately, the measurements reported in this work can be used for thermodynamic modeling of CO2 capture solvents to ensure accurate results in process simulation.

Modeling and measurement of vapor-liquid equilibrium of In–Pb and In–Pb–Sn alloy systems in vacuum distillation

This study reports the measurement and modeling of vapor-liquid equilibrium (VLE) in In–Pb and In–Pb–Sn alloys subjected to vacuum distillation at a system pressure of 5–10 Pa in the temperature range of 1100–1280 K. Pb and In was satisfactorily separated by a single-stage distillation at 1180 K. Pb was thoroughly removed from In–Pb–Sn alloy by a single-stage distillation at 1220 K. Molecular interaction volume model (MIVM) was used to calculate the activities of components of In–Pb alloy. The deviations were small. The activities of components of In–Pb–Sn alloy were also predicted by MIVM. The VLE of In–Pb and In–Pb–Sn alloy systems were predicted by MIVM and VLE theory. The calculated results agree well with VLE data determined from experiments, which indicates that the calculated VLE is reliable. The VLE can be used to guide the separation of indium-based alloys by vacuum distillation. In this study, the model prediction was combined with vacuum distillation experiments, which not only verified the reliability of MIVM for indium-based alloys, but also optimized the process parameters of vacuum distillation of indium-based alloys, providing theoretical guidance for the separation and purification of indium-based alloys by vacuum distillation or the treatment of indium-containing complex materials.

Entrainers Selection and Vapor–Liquid Equilibrium Measurements for Separation of p-Xylene from Ethylbenzene at 101.3 kPa

Entrainers Selection and Vapor–Liquid Equilibrium Measurements for Separation of p-Xylene from Ethylbenzene at 101.3 kPa

Vapor-liquid equilibrium measurements of 3, 3, 3‑trifluoropropene with pentaerythritol tetraheptanoate and pentaerythritol tetranonanoate

Vapor-liquid equilibrium measurements for 3, 3, 3‑trifluoropropene (R1243zf) with pentaerythritol tetraheptanoate (PEC7) and pentaerythritol tetranonanoate (PEC9) were performed using isochoric saturation method over temperatures from 278.15 K to 343.15 K and pressures up to 1.0 MPa. The experimental data were regressed by non-random two liquid (NRTL) activity coefficients model. In addition, the dissolving abilities of different refrigerants (R1243zf, R600a, RE170, R1234ze(E), R152a, R134a, R1234yf) in PEC7 and PEC9 were compared and analyzed.

Experimental characterisation of CO2 + C6F6 mixture: Thermal stability and vapour liquid equilibrium test for its application in transcritical power cycle

• Analysis of CO 2 blend as working fluid in transcritical cycle for CSP application. • Experimental vapour liquid equilibrium measurements. • Equation of state calibration with VLE data. • Maximum operating temperature identified through thermal stability test. • Preliminary thermodynamic assessment of the power cycle. Nowadays supercritical CO 2 cycles are considered as a promising alternative to the traditional steam cycle for the power block in CSP plants with the aim of enhancing the system efficiency and reducing costs. This work deals with the experimental characterisation of a CO 2 blend as working fluid in transcritical cycle: the addition of C 6 F 6 as a dopant increases the fluid critical temperature allowing for a condensing cycle in hot environment with ambient temperature higher than 40 °C. The potential benefits on adopting this mixture passes through thermal stability test for identifying its maximum operating temperature and Vapour Liquid Equilibrium measurements for tuning the Equations of State, thus having a good prediction of the thermodynamic properties. The static method with thermal stress test at different operating temperatures shows that the mixture can withstand to about 600 °C in an Inconel 625 vessel. Furthermore, the standard Peng-Robinson with the optimised binary interaction parameter is selected for a preliminary thermodynamic assessment of the power cycle. An efficiency of 41.9% is found for an optimum mixture composition with a CO 2 molar content of 84% considering a turbine inlet pressure of 250 bar and a maximum and minimum cycle temperature of 550 °C and 51 °C respectively.

Isothermal P, x, y data for the nitrogen + carbon monoxide system at five temperatures from 100 to 130 K and pressures up to 3.4 MPa

Isothermal vapor-liquid equilibrium (VLE) data have been measured for the nitrogen + carbon monoxide binary system at 5 temperatures from 100.01 to 130.07 K, and at pressures from 0.37 to 3.35 MPa. This system had already been studied by different authors. Nevertheless, the existing literature data generally indicate high vapor pressure for pure CO and for the highest CO composition in the N2-CO binary VLE measurements. Our new VLE data have been measured using the “static-analytic” method, taking advantage of two pneumatic capillary samplers (Rolsi®, Armines' patent) coupled to an adapted apparatus able to work at cryogenic temperatures. The new data were compared with the predictions of the GERG equation of state and their consistency was checked by a Van Ness type test. We have observed that the isothermal P, x, y data were well represented with the Peng-Robinson equation of state, especially in the CO rich region.

Vapor-liquid equilibrium (VLE) measurements of ethanol – heptane at isothermal (363.15, 393.15 and 423.15 K) and isobaric (101.33 kPa) conditions and correlation of liquid viscosity data

Vapor-liquid equilibria (VLE) were measured for ethanol – heptane by a modified Rose-Williams equilibrium still combined with ebulliometer at three isotherms (363.15, 393.15 and 423.15 K) and an isobar (101.33 kPa). The azeotropes were observed in VLE, and the experimental data were correlated with the Peng-Robinson-Stryjek-Vera (PRSV) equation of state. The conventional mixing rule, with kij equal to zero calculates the azeotropic pressure close to the vapor pressure of ethanol. The Adachi-Sugie (AS) mixing rule provides 0.282% average absolute relative deviation (AARD) in temperature for isobaric VLE and 1.711% AARD for isothermal VLE. Eyring theory combined with the PRSV equation enabled an average of 2.810% AARD in correlation of literature liquid viscosity data, which is sufficient for considering biofuel injector. The method will be applied to flow analysis in general process design using mixtures because viscosity can be evaluated from equation of states.

Isobaric Vapor–Liquid Equilibria Measurements and Thermodynamic Modeling for the Systems Containing 2-Butanone, C3 Alcohols, and C4 Esters: Part I─Binary Mixtures

Isobaric Vapor–Liquid Equilibria Measurements and Thermodynamic Modeling for the Systems Containing 2-Butanone, C₃ Alcohols, and C₄ Esters: Part I─Binary Mixtures

Extension of the AIOMFAC model by iodine and carbonate species: applications for aerosol acidity and cloud droplet activation

Abstract. Iodine and carbonate species are important components in marine and dust aerosols, respectively. The non-ideal interactions between these species and other inorganic and organic compounds within aqueous particle phases affect hygroscopicity, acidity, and gas–particle partitioning of semivolatile components. In this work, we present an extended version of the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model by incorporating the ions I−, IO3-, HCO3-, CO32-, OH−, and CO2(aq) as new species. First, AIOMFAC ion interaction parameters for aqueous solutions were determined based on available thermodynamic data, such as water activity, mean molal activity coefficients, solubility, and vapor–liquid equilibrium measurements. Second, the interaction parameters for the new ions and various organic functional groups were optimized based on experimental data or, where data are scarce, alternative estimation methods such as multiple linear regression or a simple substitution by analogy approach. Additional bulk water activity and electrodynamic balance measurements were carried out to augment the database for the AIOMFAC parameter fit. While not optimal, we show that the use of alternative parameter estimation methods enables physically sound predictions and offers the benefit of a more broadly applicable model. Our implementation of the aqueous carbonate–bicarbonate–CO2(aq) system accounts for the associated temperature-dependent dissociation equilibria explicitly and enables closed- or open-system computations with respect to carbon dioxide equilibration with the gas phase. We discuss different numerical approaches for solving the coupled equilibrium conditions and highlight critical considerations when extremely acidic or basic mixtures are encountered. The fitted AIOMFAC model performance for inorganic aqueous systems is considered excellent over the whole range of mixture compositions where reference data are available. Moreover, the model provides physically meaningful predictions of water activity under highly concentrated conditions. For organic–inorganic mixtures involving new species, the model–measurement agreement is found to be good in most cases, especially at equilibrium relative humidities above ∼ 70 %; reasons for deviations are discussed. Several applications of the extended model are shown and discussed, including the effects of ignoring the auto-dissociation of water in carbonate systems, the effects of mixing bisulfate and bicarbonate compounds in closed- or open-system scenarios on pH and solution speciation, and the prediction of critical cloud condensation nucleus activation of NaI or Na2CO3 particles mixed with suberic acid.