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The synthetic method is used for the determination of the liquid phase solubility of methane in 1-octanol at three temperatures (273.25, 283.15, and 293.2) K and of methane in n-dodecane at 273.1 K at pressures up to about 10 MPa. The new gas solubility data is applied to evaluate the molality scale based Henry's constant of methane in those solvents: (4.31, 4.67, and 4.81 ± 0.05) MPa in 1-octanol and (2.75 ± 0.04) MPa in n-dodecane at the given temperatures, respectively. The experimental technique provides as well the density of the gas-saturated liquid phase and thus allows for evaluation of the partial molar volume of methane at infinite dilution in the solvent: (47, 49, and 49 ± 5) cm 3 /mol in 1-octanol and (45 ± 5) cm 3 /mol in n-dodecane, respectively. The experimental results are compared with the limited data from the open literature. At the investigated temperatures, the vapour phase can be treated as pure methane, and the extended Henry's law suffices to accurately correlate the new gas solubility data. However, that vapour-liquid equilibrium model is here expanded allowing to accurately predict the small vapour phase solubility of the solvent in compressed methane which is demonstrated by comparison with experimental data from the literature.

New experimental results are presented for the solubility of methane in two single solvents (hexane and a petroleum benzine) at temperatures of about (273, 283, and 293) K and pressures up to about 10 MPa. The solubility of methane (in terms of moles of methane per kilogram of solvent at given temperature and pressure) is rather similar in both solvents. The experimental results are evaluated to determine Henry’s constant and the partial molar volume of methane in those solvents. A thermodynamic model, based on the extended Henry’s law, which accounts for interactions in both liquid and gaseous phases, is applied to correlate the experimental results.

New experimental results are presented for the solubility of methane in water at constant temperatures of 283 K and 298 K and pressures up to 10 MPa, and for the pressure–temperature coordinates of the three-phase (vapour + liquid + hydrate) equilibrium (when the liquid mainly consists of water) at temperatures between 274 K and 285 K. The new experimental results are compared with literature data. The gas solubility data are used to determine Henry’s constant and the partial molar volume of methane in water. Two thermodynamic models are used to describe the gas solubility. One model neglects the amount of water in the vapour whereas the other model describes the vapour as a binary mixture of (methane + water) and allows to predict the small fraction of water in the vapour phase. The prediction results are also compared with literature data.

New experimental results are presented for the solubility and the partial molar volume of carbon dioxide in an aqueous solution of phenol and sodium sulfate at temperatures of about (314, 354, and 395) K and pressures up to about 10 MPa. The composition of the solvent expressed as molality in water is about 0.5 mol · (kg H 2 O) −1 for phenol as well as for sodium sulfate. The experimental work is a continuation of investigations on the influence of organic components and strong electrolytes on the solubility of carbon dioxide in water. It extends a data base for developing and testing thermodynamic models to describe the solubility of gases in salt-free and salt-containing aqueous solutions of organic compounds. The experimental results are compared to prediction and correlation results from a thermodynamic model. That model is a combination of a model for the solubility of CO 2 in aqueous solutions of sodium sulfate on one side and a model for the solubility of CO 2 in aqueous solutions of phenol on the other side. When ternary interactions between CO 2 , phenol, and sodium sulfate are neglected, the model allows prediction of the pressure that is required to dissolve a given amount of CO 2 in the mixed aqueous solution. The prediction results reveal a reasonable agreement. However (and as in previous investigations with N,N-dimethylformamide instead of phenol as the organic solvent component or with sodium chloride instead of sodium sulfate as the dissolved electrolyte) adjusting a ternary parameter for interactions between the three solutes ( i.e. , CO 2 , phenol, and sodium sulfate) results in a correlation that allows description of the new experimental results almost within experimental uncertainty.

Experimental results are presented for the solubility of CO2 in an aqueous solution of phenol and NaOH (molalties in water: phenol: 0.5; NaOH: 1.0) at (314, 354, and 395) K and pressures up to 10 MPa. The experimental work extends recent investigations on the influence of phenol as well as of (phenol + NaCl) on the solubility of CO2 in water. In contrast to those previous investigations, the strong electrolyte reacts with carbon dioxide and also with phenol. The experimental results are compared with predictions from a thermodynamic model. That model combines a model for the “chemical” solubility of CO2 in aqueous solutions of NaOH with a model for the “physical” solubility of CO2 in aqueous solutions of phenol. An extension is introduced to account for the chemical reaction between the weak acid phenol and the strong base sodium hydroxide. The prediction results nicely agree with the new experimental data. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2832–2840, 2015

New experimental results are presented for the solubility and the partial molar volume of carbon dioxide in an aqueous solution of phenol and sodium chloride at temperatures of about (314, 354 and 395) K and pressures up to about 10 MPa. The composition of the solvent – expressed as molality in water – is about 0.5 mol/(kg H2O) for phenol and 1 mol/(kg H2O) for sodium chloride. The experimental work is a continuation of investigations on the influence of organic components and strong electrolytes on the solubility of carbon dioxide in water. It extends a data base for developing and testing thermodynamic models to describe the solubility of gases in salt-free and salt-containing aqueous solvents mixed with organic compounds. The experimental results are compared to predictions and correlations from a thermodynamic model which combines a model for the solubility of CO2 in aqueous solutions of NaCl with a model for the solubility of CO2 in aqueous solutions of phenol. The prediction results reveal a reasonable agreement. As in a previous investigation – with N,N-dimethylformamide instead of phenol as the organic solvent component – adjusting a ternary parameter for interactions between the three solutes (i.e. CO2, NaCl, and phenol) results in a correlation that allows to describe the new experimental data within experimental uncertainty.

New experimental results are reported for the solubility of carbon dioxide in aqueous solutions of phenol and for the density of the corresponding liquid solvent mixtures at about (314, 354, and 395) K at pressures between about 0.2 MPa and 9.7 MPa. The experimental results are evaluated to determine Henry's constants for carbon dioxide (on the molality scale) and the partial molar volume of carbon dioxide at infinite dilution in such solutions at the same temperatures. Furthermore, correlations are presented that describe the new gas solubility data almost within experimental uncertainty.

New experimental results are reported for the solubility of carbon dioxide in phenol at 354 K and 395 K at pressures between about 0.15 MPa and 9 MPa and for the partial molar volume of carbon dioxide at infinite dilution in phenol at the same temperatures. Henry's constant for carbon dioxide in phenol is determined from the new solubility data and a correlation is presented that describes the new gas solubility data within experimental uncertainty.

The influence of sodium sulphate on the solubility of carbon dioxide in aqueous solutions of N,N-dimethylmethanamide {= N,N-dimethylformamide, (CH3)2N-C(H)O, DMF} was investigated experimentally at three temperatures (314 K, 354 K, and 395 K). The solvent was an aqueous solution of DMF (mole fraction of DMF in the salt-free solution ≈ 0.05) and sodium sulphate (molality ≈ 0.6 mol·(kgH2O)−1). The maximum pressure of the new experimental gas solubility data reaches nearly 10 MPa. A thermodynamic model that combines two models for the solubility of CO2 (in aqueous solutions of Na2SO4 on one side and in aqueous solutions of DMF on the other side) is used to predict the influence of Na2SO4 on the solubility of CO2 in aqueous solutions of DMF. The new experimental data are compared with such predictions and with calculations from an extension of that model where a single ternary parameter for interactions between the three solutes (i.e., CO2, Na2SO4, and DMF) is adjusted to improve the representation of the experimental data.

New experimental results are presented for the solubility of carbon dioxide in aqueous solutions of N,N-dimethylmethanamide {=N,N-dimethylformamide, (CH 3 ) 2 N C(H)O, DMF} and sodium chloride at temperatures of (314, 354, and 395) K, gas-free and salt-free solvent mixture DMF mole fractions of about (0.05, 0.1, and 0.25, respectively), and two salt molalities (about 2.2 and about 4.5 mol/kg water). The maximum pressure of the new experimental gas solubility data reaches nearly 10 MPa. The experimental work is to provide a data base for developing and testing thermodynamic models to describe the solubility of gases in salt-free and salt-containing mixed aqueous solvents, as well as to test screening methods based, for example, on molecular simulation. A particular thermodynamic model that combines a model for the solubility of CO 2 in aqueous solutions of NaCl with a model for the solubility of CO 2 in aqueous solutions of DMF is used to predict the influence of NaCl on the solubility of CO 2 in aqueous solutions of DMF. The new experimental data are compared with such predictions and with calculations from an extension of that model (where a single ternary parameter for interactions between the three solutes (i.e., CO 2 , NaCl and DMF) is introduced and fit to the new experimental data.

The “hot-potash” process is one of the most commonly used processes to remove carbon dioxide from gases in the chemical industry. The solvent of that absorption process is an aqueous solution of potassium carbonate. Dissolving carbon dioxide in an aqueous solution of K2CO3 results in the conversion of carbonate and CO2 to bicarbonate; that is, carbon dioxide is predominantly dissolved chemically. In industrial applications a single substance or a mixture of several substances are added to the solvent to improve the performance of the process. The specific role of such additives is often unknown, but it is well-established that some additives improve the performance of the “hot-potash” process. One of those additives is vanadium pentoxide. The influence of a small amount of vanadium pentoxide on the equilibrium solubility of carbon dioxide in aqueous solutions of potassium hydroxide was investigated at conditions that are typical for a “hot-ash” process. The experimental results reveal that vanadium pentox...

New experimental results are presented for the solubility of carbon dioxide in pure liquid N,N-dimethylmethanamide {= N,N-dimethylformamide, (CH3)2NC(H)O, DMF} and in solvent mixtures of (water + DMF) at gas-free solvent mixture DMF mole fractions of about (0.05, 0.1, 0.25, 0.5, 0.75, and 0.9), temperatures of (314, 354, and 395) K, and total pressures up to about 10 MPa. Numerical values are reported for the (molality scale based) Henry's constant of CO2 in DMF and in (water + DMF) liquid mixtures resulting from the new experimental data by applying a common extrapolation procedure. The experimental work is to provide a database for developing and testing thermodynamic models to describe the gas solubility in salt-free and salt-containing mixed aqueous solvents, as well as to test screening methods based, for example, on molecular simulation.

Experimental results are reported for the solubility of carbon dioxide in liquid mixtures of water and the ionic liquid 1-n-butyl-3-methylimidazolium methylsulfate ([bmim][CH3SO4]). Three (gas-free...

A high-pressure-cell technique based on the analytical method was used to investigate the simultaneous solubility of the chemically reacting gases ammonia and carbon dioxide in solvent mixtures of (water + methanol). Seven (gas-free) solvent compositions were considered (methanol mole fractions of about 0, 0.05, 0.25, 0.5, 0.75, 0.95, and 1). The temperatures were approximately (313, 353, and 393) K. In the isothermal experimental series, carbon dioxide was added stepwise to a cell containing a mixture of (water + methanol + ammonia). The stoichiometric molality of ammonia in the solvent mixture of (water + methanol) was approximately (6 and 12) mol·(kg of solvent mixture)−1. The carbon dioxide loading (i.e., the ratio of the stoichiometric molalities of carbon dioxide and ammonia) ranged up to 1.07. The total pressure ranged up to 5.5 MPa. Vapor−liquid equilibrium data, including partial pressures of all components, are reported.

Experimental results (and a correlation) are presented for the liquid−liquid equilibrium of an example for the Biphasic Acid Scavenging utilizing Ionic Liquids (BASIL) process: for the binary system (butylacetate + 1-methyl imidazolium chloride) and for the partitioning of 1-butanol and 1-methyl imidazole to the coexisting liquid phases at temperatures from (363 to 373) K.

The influence of the amino acid d,l-methionine on the solubility of carbon dioxide in pure water and in aqueous solutions of potassium carbonate was investigated. The solubility was measured with a high-pressure view-cell technique operating on the synthetic method. Temperature and total pressure ranged from about 353 to 393 K and 1 to 10 MPa, respectively. The molality of methionine was between about 0.42 mol·(kg H2O)−1 and 0.83 mol·(kg H2O)−1. The molality of potassium carbonate was about 1.25 and 2.5 mol·(kg H2O)−1. The solubility of carbon dioxide in aqueous solutions of potassium carbonate and methionine is influenced by chemical reactions: On one side, dissolving carbon dioxide in an aqueous solution of potassium carbonate shifts the chemical reaction equilibrium from carbonate to bicarbonate and, on the other side, methionine is a zwitterionic substance. The new experimental results are correlated using an extension of a previously published thermodynamic model for the solubility of carbon dioxide ...

Experimental data for the solubility of the two single gases carbon dioxide and hydrogen in the ionic liquid 1-n-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([bmpy][Tf 2 N]) are reported for temperatures between (293.1 and 413.2) K. The maximum pressure (the maximum gas molality in the solvent) was 10.8 MPa (4.43 mol·kg -1 ) for carbon dioxide and 8.9 MPa (0.14 mol·kg -1 ) for hydrogen. The experiments were performed using a high-pressure view-cell technique operating on the synthetic method. The solubility of carbon dioxide in [bmpy][Tf 2 N] is more than 1 order of magnitude higher than the solubility of hydrogen. Carbon dioxide becomes less soluble in [bmpy][Tf 2 N] with increasing temperature, whereas hydrogen shows the opposite effect. An extension of Henry's law is employed to correlate the solubility pressures. The final results for the Henry's constant (at zero pressure) of carbon dioxide and hydrogen in [bmpy][Tf 2 N] (on the molality scale) are represented within the experimental uncertainty (about 0.8 % for carbon dioxide and 1.3 % for hydrogen) by In(k (0) H,CO2 /MPa) = 8.5128 - 2057/(T/K) - 0.004274·(T/K) and In(k (0) H, H2 /MPa) = 3.5746 + 343/(T/K) - 0.0008·(T/K), respectively.

The correlation and prediction of the solubility of gases in (nonelectrolyte as well as in electrolyte) aqueous/organic solvent mixtures is an important topic in many areas of chemical engineering. Despite the importance of that field, comparatively little attention has been given to that area in both classical thermodynamics (i.e., correlation methods that are based on semiempirical expressions for the excess Gibbs energy) and molecular simulation (where gas solubility can be predicted from intermolecular pair potentials). In the work presented here, recently published experimental data for the solubility of carbon dioxide in aqueous solutions of acetone (covering temperatures from 313 to 395 K at pressures ranging up to about 9 MPa) are used for testing a semiempirical, classical method (for the correlation of such gas solubility phenomena) as well as the Gibbs ensemble Monte Carlo method (GEMC) (for predicting the solubility of carbon dioxide in aqueous solutions of acetone from published intermolecula...

Experimental data for the solubility of the two single gases carbon monoxide and oxygen in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]) are reported for temperatures between (293.25 and 413.2) K. The maximum pressure (the maximum gas molality) was 9.8 MPa (0.27 mol·kg−1) for carbon monoxide and 9.1 MPa (0.31 mol·kg−1) for oxygen. The experiments were performed using a high-pressure view-cell technique operating on the synthetic method. Oxygen shows a slightly higher solubility than carbon monoxide under all conditions investigated, but the solubility generally remains very low. Both gases become less soluble in [hmim][Tf2N] with increasing temperature; however, the effect is not very pronounced and becomes ambiguous for carbon monoxide above 373 K. An extension of Henry’s law is employed in correlating the solubility pressures. The final results for the Henry’s constant (at zero pressure) of carbon monoxide and oxygen in [hmim][Tf2N] (on the molality scale)...

New experimental results are reported for the influence of two single salts (sodium chloride and sodium sulfate) on the solubility of ammonia in liquid mixtures of water and methanol at 353 and 393 K. The mole fractions of methanol in the (gas-free and salt-free) solvent mixture of water and methanol were about 0.25, 0.5, and 0.75 in the experiments with sodium chloride and about 0.05 and 0.25 in the experiments with sodium sulfate. The molality of the salt varied between about 0.25 and 2 (0.15 and 1) mol/kg of the solvent mixture in the systems with sodium chloride (sodium sulfate). The maximum molality of ammonia was about 6.7 mol/kg of (water + methanol) for both temperatures and for both salts. The maximum total pressure above the liquid solutions was about 0.3 MPa (1 MPa) in the system containing sodium chloride at 353 K (393 K) and about 0.2 MPa (0.7 MPa) in the system with sodium sulfate at 353 K (393 K). The experimental results are used to test a thermodynamic framework which allows the influence...

New experimental results are reported for the solubility of ammonia in liquid mixtures of (water + methanol). Five (gas-free) solvent compositions are considered (mole fraction of methanol of about 0.05, 0.25, 0.5, 0.75, and 0.95). The temperature amounts to about 313 K, 353 K, and 393 K. The solubility pressure ranges up to about 0.1 MPa, 0.6 MPa, and 1.6 MPa, respectively. The molality of ammonia in the solvent mixture of (water + methanol) (the mole fraction of ammonia in the liquid) ranges up to 13 mol kg−1 (about 0.3). The experimental results are used to determine Henry's constant of ammonia in the liquid mixtures of (water + methanol). An extension of Pitzer's molality scale-based model for the Gibbs excess energy (to solvent mixtures) is applied in a thermodynamic model to describe the phase equilibrium.

This work reports new experimental results for the solubility of two single gases (methane and xenon) in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]). The solubility was measured with a high-pressure view-cell technique operating on the synthetic method. The temperature ranged from 293.3 to 413.3 K, and the maximum pressure (the maximum gas molality) was 9.3 MPa (0.51 mol·kg-1) for methane and 9.6 MPa (2.08 mol·kg-1) for xenon. Xenon shows a significantly higher solubility than methane at all conditions investigated. Both gases become less soluble in [hmim][Tf2N] with rising temperature. An extension of Henry's law is employed to correlate the solubility pressures. The final results for the Henry's constants (at zero pressure) of methane and xenon in [hmim][Tf2N] (on the molality scale) are represented within the experimental uncertainty (about 1.2% for methane and 1% for xenon) by ln( /MPa) = 6.4929 − 835.9/(T/K) − 0.003471(T/K) and ln( /MPa) = 6.3357 − 13...

The solubility of the single gases hydrogen and carbon monoxide in the ionic liquid 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][CH3SO4]) was measured with a high-pressure view-cell technique based on the synthetic method. The temperature ranged from ∼293 to ∼413 K, and the pressure reached up to ∼9.3 MPa. The gas molality amounted up to ∼0.1 mol per kilogram of [bmim][CH3SO4]. Carbon monoxide showed a slightly better solubility than hydrogen. The (extended) Henry's law was successfully applied to correlate the solubility pressures. The final results for the Henry's constant (at zero pressure) of hydrogen and carbon monoxide in [bmim][CH3SO4] (on the molality scale) are correlated within the estimated uncertainty (±1%) by ln ( k H , H 2 ( 0 ) / MPa ) = 3.074 + 602 / ( T / K ) and ln ( k H , CO ( 0 ) / MPa ) = 5.3377 − 66.85 / ( T / K ) − 0.0019517 ( T / K ) , respectively.

Solubility measurements of methane and of xenon in the ionic liquid 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][CH3SO4]) were performed with a high-pressure view-cell technique based on the synthetic method. The temperature ranged from 293.1 K to 413.2 K, and the maximum pressure (the maximum gas molality) was 8.9 MPa (0.19 mol·kg-1) for methane and 11.3 MPa (0.65 mol·kg-1) for xenon. Both gases become less soluble in [bmim][CH3SO4] with rising temperature, but xenon shows a significantly higher solubility at all conditions investigated. An extension of Henry's law is employed to correlate the solubility pressures in both cases. The final results for the Henry's constant (at zero pressure) of methane and xenon in [bmim][CH3SO4] (on the molality scale) are correlated within the experimental uncertainty (about ± 1.3 %) by ln( /MPa) = 6.216 − 564.5/(T/K) − 0.002566(T/K) and ln( /MPa) = 5.5906 − 928/(T/K) − 0.00141(T/K), respectively.

A high-pressure view-cell technique based on the synthetic method was used to determine the solubility of ammonia in liquid methanol (total pressure at a preset temperature and liquid-phase composition). The solubility pressure ranges up to about 4.2 MPa. The temperature amounts to (313.75, 354.35, and 395.0) K. The molality of ammonia in methanol (the mole fraction of ammonia in the liquid) ranges up to about 66.4 mol·kg-1 (about 0.68). Furthermore, a high-pressure cell technique based on the analytical method was used to investigate the vapor−liquid equilibrium of that same system (equilibrium pressure as well as liquid- and gas-phase compositions at a preset temperature). The solubility pressure ranges up to about 1.6 MPa. The temperature amounts to (353.1 and 393.1) K. The molality of ammonia in methanol (the mole fraction of ammonia in the liquid) ranges up to 13 mol·kg-1 (about 0.3). The experimental results are used to determine Henry's constant of ammonia in methanol. Furthermore, the experimental...

New experimental results are presented for the solubility of carbon dioxide in pure liquid acetone {= 2-propanone, (CH3)2CO} and in solvent mixtures of (acetone + water) at gas-free solvent mixture acetone mole fractions of about (0.05, 0.1, 0.25, 0.5, 0.75, 0.9, and 0.95), temperatures of (313.75, 354.35, and 395.0) K, and total pressures up to about 10 MPa. Numerical values are reported for the (molality scale based) Henry's constant of CO2 in acetone and in (acetone + water) at vanishing amount of the gas in the liquid mixture resulting from the new experimental data by applying the well-known extrapolation procedure. The experimental work is to provide a database for developing and testing thermodynamic models to describe the gas solubility in salt-free and salt-containing mixed solvents as well as to test screening methods based, for example, on molecular simulation.

A high-pressure view-cell technique based on the synthetic method was used to determine the total pressure above aqueous solutions of two single salts (potassium chloride and potassium carbonate) and carbon dioxide. In the series of measurements with potassium chloride, the molality of the salt amounted to about (2 and 4) mol·(kg of water)-1, the temperature ranged from about (313 to 433) K, and the molality of carbon dioxide ranged up to about 1 mol·(kg of water)-1, corresponding to a maximum pressure of about 9.4 MPa. In the series of measurements with potassium carbonate, the stoichiometric molality of that salt amounted to about (0.43 and 1.7) mol·(kg of water)-1 (stoichiometric mass fraction of the salt of about 0.056 and 0.19, respectively), the temperature ranged from about (313 to 393) K, and the ratio of the stoichiometric molalities of carbon dioxide to potassium carbonate ranged from about 0.7 to 3.6, corresponding to pressures from about (0.27 to 9.2) MPa. The vapor−liquid equilibrium of the s...

New experimental results are presented for the total pressure above liquid mixtures of carbon dioxide and the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]). The series of experiments were performed at preset temperature and liquid phase composition by means of a very precise high-pressure view-cell technique based on the synthetic method. A temperature range from (293.15 to 413.2) K was investigated where the maximum pressure reached approximately 10 MPa. Gas molalities in [hmim][Tf2N] ranged up to about 4.7 mol · kg−1. The (extended) Henry’s law is successfully applied to correlate the solubility pressures.

A high-pressure view-cell technique based on the synthetic method was used to determine the solubility of carbon dioxide in the ionic liquid 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][CH3...

A headspace gas chromatography technique was applied to determine the solubility of carbon dioxide in aqueous solutions of 2,2‘-methyliminodiethanol (N-methyldiethanolamine, MDEA) at low gas loadings (at stoichiometric molar ratios of carbon dioxide to MDEA between about 0.003 and 0.8). A temperature range T ≈ 313−393 K was covered. The stoichiometric molality of MDEA in water amounted to about 2, 4, and 8 mol/(kg of water) (mass fraction of MDEA ≈ 0.192, 0.323, and 0.488). The partial pressure of carbon dioxide was between about 0.1 and 70 kPa. A thermodynamic model for describing the vapor−liquid equilibrium (which applies Pitzer's molality-scale-based equation for describing the Gibbs excess energy of the aqueous phase) is revised and extended using the new data.

The liquid−liquid phase equilibrium of mixtures of the room temperature ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6], and three single alkanols (ethanol, 1-propanol, and 1-butanol) was investigated over the entire composition range at ambient pressure. The experiments were conducted from 262 K to the vicinity of the critical solution temperature of the binary mixture (at maximum 362 K) by two different methods, namely, synthetic cloud-point measurements and analytical UV spectroscopy. The cloud-point method was mainly applied for the [bmim][PF6]-rich liquid, whereas UV spectroscopy was used to determine the very small concentrations of [bmim][PF6] in the alkanols, since under these conditions the cloud-point method is no longer applicable. All three systems show an upper critical solution temperature. With increasing chain length of the alcohol, that temperature rises and simultaneously the biphasic region becomes larger. Inspired by recent publications, the liquid−liquid eq...

New experimental results are presented for the solubility of hydrogen in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf 2 N]) for temperatures from (293 to 413) K and pressures up to about 10 MPa. The extended Henry's law is applied to correlate the solubility pressures. The solubility of H 2 in [hmim][Tf 2 N] is low and increases toward higher temperatures. For example, at T ≈ 293 K (413 K) and p ≈ 9 MPa, only about 0.106 mol (0.170 mol) of the gas is dissolved in 1 kg of the ionic liquid.

The simultaneous solubility of sulfur dioxide and ammonia in aqueous solutions of (ammonium sulfate or sodium sulfate) was measured by a synthetic method in the temperature range from 313.6 to 373.2 K and at pressures up to 2.5 MPa. Furthermore, the enthalpy change upon diluting aqueous solutions of sulfur dioxide, ammonia and (ammonium sulfate or sodium sulfate) in aqueous solutions of the same salt was measured in a batch calorimeter at about 313 and 352 K. The experimental results are used for comparison with predictions from a thermodynamic model for the vapor–liquid equilibrium and the enthalpy of dilution of those chemical reacting systems. In that model, activity coefficients are calculated from Pitzer's molality-scale-based Gibbs excess energy model, where all interaction parameters are either adopted from previous investigations on the properties of the binary and ternary sub-systems (if available) or they are neglected (if they are not available).

New experimental results are presented for the influence of sodium sulfate on the total pressure above liquid mixtures of (H2O + CH3OH + CO2) at temperatures of about 313.7, 354.4, and 395 K, total pressures up to about 10 MPa, mole fractions of methanol in the binary solvent mixture (water + methanol) of about 0.055 and 0.25, and salt molalities of about 0.92 and 0.15 mol/kilogram of water + methanol, respectively, always below the solubility limit of the salt in the gas-free solvent mixture. An extension of Pitzer's molality scale based model for the Gibbs excess energy of aqueous electrolyte solutions to mixed-solvent electrolyte solutions is successfully applied to predict/correlate the new gas solubility data.

New experimental results are presented for the solubility of oxygen in the ionic liquid 1-N-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) for temperatures from (293.2 to 373.1) K and pressures up to 9.1 MPa. The ionic liquid [bmim][PF6] is a poor solvent for oxygen; for example, at 9 MPa only about 0.16 mol of the gas are dissolved in 1 kg of the ionic liquid. Nearly no influence of temperature on the solubility of oxygen in [bmim][PF6] was observed. The (extended) Henry’s law is applied to correlate the solubility pressures. Furthermore, prediction results from Gibbs ensemble Monte Carlo simulations (at constant pressure and temperature, i.e., NpT-GEMC) are reported. The intermolecular forces are approximated by an effective pair potential for oxygen (the two-center Lennard-Jones model proposed by Coon et al.) and by a quantum-chemistry based pair potential for [bmim][PF6] (the UA1 model by Shah et al.). The interactions between unlike groups are calculated by applying common mixing rules (without any adjustable binary parameters).

New experimental results are presented for the enthalpy change upon diluting aqueous solutions of sulfur dioxide containing a salt (either ammonium sulfate or sodium sulfate) in aqueous solutions of that salt at about 313 and 352 K. A previously developed thermodynamic model for the vapor–liquid equilibrium of the chemical reacting systems {SO 2 + (NH 4 ) 2 SO 4 + H 2 O} and (SO 2 + Na 2 SO 4 + H 2 O) is extended allowing for the formation of pyrosulfite and for the description of the new experimental results for the enthalpy change upon dilution.

New experimental results for the enthalpy change upon diluting aqueous solutions of sulfur dioxide as well as aqueous solutions of sulfur dioxide and ammonia in pure water at about 313 and 352 K are presented. The experimental results are used to modify a previously developed thermodynamic model for the vapor–liquid equilibrium of the chemical reacting system (SO2 + NH3 + H2O). That model is extended allowing on the one side for the formation of pyrosulfite, and on the other side for the description of experimental results for the enthalpy change upon dilution (in pure water) of (NH3 + H2O) (taken from the literature), as well as (SO2 + H2O) and (SO2 + NH3 + H2O) (from the present work).

New experimental results are presented for the solubility of carbon monoxide in the ionic liquid 1- N -butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]) for temperatures from 293 to 373 K and pressures up to about 10 MPa. The experimental results reveal nearly no influence of temperature on the solubility of CO in [bmim][PF 6 ]. The ionic liquid [bmim][PF 6 ] is a poor solvent for carbon monoxide; for example, at 9 MPa only about 0.15 mole of the gas are dissolved in 1 kg of the ionic liquid. The (extended) Henry's law is applied to correlate the solubility pressures.

The chemical reaction equilibrium constant for the formation of pyrosulfite from bisulfite in aqueous solutions { 2 HSO 3 - ( aq ) ⇌ S 2 O 5 2 - ( aq ) + H 2 O ( l ) } was determined for temperatures from (313 to 353) K from ATR-IR-spectroscopic and calorimetric investigations of the system (Na2S2O5 + H2O), resulting in ln K = −10.226 + 2123.6/(T/K), Δ r G m ∘ = ( 7.69 ± 0.33 ) kJ · mol - 1 , Δ r H m ∘ = ( - 17.7 ± 0.5 ) kJ · mol - 1 (on the molality scale). Furthermore, some ATR-IR-spectroscopic results on liquid mixtures of (NH3 + SO2 + H2O) at T = 313 K are presented, revealing considerable amounts of pyrosulfite.

New experimental results for the vapor−liquid equilibrium of the system sodium chloride + methanol + water are presented at (salt-free) solvent mixture methanol mole fractions from about 0.03 to 0.54, at sodium chloride molalities up to about 5.4 mol·kg-1 of the solvent mixture (but always below the solubility limit of the salt), at temperatures from about (313 to 397) K, and at total pressures from about (10 to 500) kPa.

A model for the Gibbs excess energy of mixed-solvent (chemical-reacting) electrolyte systems is presented. The activities of solvent and solute species are calculated by applying a new extension of Pitzer's equation for the excess Gibbs energy of aqueous electrolyte solutions, which allows for solvent mixtures. The capability of the new model to simultaneously describe such properties as, e.g., the mean ionic activity coefficient and the solubility of a salt (for example, sodium chloride) in a binary solvent mixture (for example, methanol + water), as well as the influence of that salt on the vapor−liquid equilibrium of that binary solvent mixture, is tested. The new model gives an explanation for the “salting-out” and “salting-in” effects resulting, e.g., from the addition of a salt to a liquid mixture of volatile solvents. The new model can also be applied to describe the gas solubility in mixed solvents in the presence of electrolytes. The capability of the new model to describe the solubility of a sin...

New experimental results for the solubility of carbon dioxide in solvent mixtures of methanol and water are presented (at solvent mixture methanol mole fractions of (5, 10, 25, 50, 75, 90, 95, and 100) %, at (313.75, 354.35, and 395.0) K, and total pressures up to about 10 MPa). The experimental work is to provide a database for the development of a thermodynamic model to describe the gas solubility in salt-free and salt-containing mixed solvents.

A thermodynamic model for describing the phase equilibrium for the system CO 2 + methyldiethanolamine + water has been extended, allowing for the presence of piperazine. Model parameters are estimated from new experimental results for the solubility of carbon dioxide in aqueous solutions of piperazine (for piperazine molalities up to 4 mol per kilogram of water, temperatures between 313 and 393 K, and pressures up to about 9.6 MPa). The model is tested by comparing predicted and experimental carbon dioxide solubilities in aqueous mixtures of both amines (2 molal MDEA + 2 molal piperazine, at 353 K, and pressures up to about 6.4 MPa).

1 H -NMR spectroscopic investigations were performed on aqueous solutions of carbon dioxide and piperazine at temperatures ranging from (283 to 333) K to determine quantitatively the speciation. The experimental results were used to determine the chemical equilibrium constants for the formation of piperazine carbamate, piperazine dicarbamate and protonated piperazine carbamate.

New experimental results for the solubility of hydrogen sulfide in aqueous solutions of piperazine are presented for piperazine molalities up to 4 mol/kg of water, temperatures between 313 and 393 K, and pressures up to about 9 MPa. Furthermore, the solubility of hydrogen sulfide was measured in about 2 m MDEA + 2 m piperazine aqueous solutions at 353 K up to about 6 MPa. Considering the new experimental data, a thermodynamic model for describing phase equilibria for the system H 2 S–methyldiethanolamine–water has been extended allowing for the presence of piperazine.

New experimental results are presented for the solubility of carbon dioxide in the ionic liquid 1-N-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) for temperatures from (293 to 393) K and pressures up to about 9.7 MPa. Solubility pressures are correlated by means of the extended Henry's law.

The solubility of hydrogen sulfide in aqueous solutions of N-methyldiethanolamine (MDEA) and MDEA sulfate (2 and 1 m, respectively) and in aqueous solutions of MDEA and sodium sulfate (2 and 1 m, respectively) was measured at temperatures from 313 to 393 K and total pressures up to about 3.9 MPa. The experimental results are used to extend and test a model for the thermodynamic equilibrium encountered in the solubility of hydrogen sulfide in such aqueous solutions.