Showing papers on "Activity coefficient published in 2012"
Book•
26 Mar 2012
TL;DR: In this paper, the authors describe the use of gE-models to calculate the properties of a mixture of real and ideal gases in a process simulation program and apply them to real-world applications.
Abstract: INTRODUCTION PVT BEHAVIOR OF PURE COMPONENTS General Description Caloric Properties Ideal Gases Real Fluids Equations of State CORRELATION AND ESTIMATION OF PURE COMPONENT PROPERTIES Characteristic Physical Property Constants Temperature-Dependent Properties Correlation and Estimation of Transport Properties PROPERTIES OF MIXTURES Property Changes of Mixing Partial Molar Properties Gibbs-Duhem Equation Ideal Mixture of Ideal Gases Ideal Mixture of Real Fluids Excess Properties Fugacity in Mixtures Activity and Activity Coefficient Application of Equations of State to Mixtures PHASE EQUILIBRIA IN FLUID SYSTEMS Thermodynamic Fundamentals Application of Activity Coefficient Models Calculation of Vapor-Liquid Equilibria Using gE-Models Fitting of gE-Model Parameters Calculation of Vapor-Liquid Equilibria Using Equations of State Conditions for the Occurrence of Azeotropic Behavior Solubility of Gases in Liquids Liquid-Liquid Equilibria Predictive Models CALORIC PROPERTIES Caloric Equations of State Enthalpy Description in Process Simulation Programs Caloric Properties in Chemical Reactions The G-Minimization Technique ELECTROLYTE SOLUTIONS Introduction Thermodynamics of Electrolyte Solutions Activity Coefficient Models for Electrolyte Solutions Dissociation Equilibria Influence of Salts on the Vapor-Liquid Equilibrium Behavior Complex Electrolyte Systems SOLID-LIQUID EQUILIBRIA Thermodynamic Relations for the Calculation of Solid-Liquid Equilibria Salt Solubility Solubility of Solids in Supercritical Fluids MEMBRANE PROCESSES Osmosis Pervaporation POLYMER THERMODYNAMICS Introduction gE-models Equations of State Influence of Polydispersity APPLICATIONS OF THERMODYNAMICS IN SEPARATION TECHNOLOGY Verification of Model Parameters Prior to Process Simulation Investigation of Azeotropic Points in Multicomponent Systems Residue Curves, Distillation Boundaries, and Distillation Regions Selection of Entrainers for Azeotropic and Extractive Distillation Selection of Solvents for Other Separation Processes Examination of the Applicability of Extractive Distillation for the Separation of Aliphatics from Aromatics ENTHALPY OF REACTION AND CHEMICAL EQUILIBRIA Enthalpy of Reaction Chemical Equilibrium Multiple Chemical Reaction Equilibria SPECIAL APPLICATIONS Formaldehyde Solutions Vapor Phase Association PRACTICAL APPLICATIONS Flash Joule-Thomson Effect Adiabatic Compression and Expansion Pressure Relief Limitations of Equilibrium Thermodynamics INTRODUCTION TO THE COLLECTION OF EXAMPLE PROBLEMS Mathcad Examples Examples Using the Dortmund Data Bank (DDB) and the Integrated Software Package DDBSP Examples Using Microsoft Excel and Microsoft Office VBA APPENDIX A Pure Component Parameters APPENDIX B Coefficients for High Precision Equations of State APPENDIX C Useful Derivations APPENDIX D Standard Thermodynamic Properties for Selected Electrolyte Compounds APPENDIX E Regression Technique for Pure Component Data APPENDIX F Regression Techniques for Binary Parameters Appendix G Ideal Gas Heat Capacity Polynomial Coefficients for Selected Compounds APPENDIX H UNIFAC Parameters APPENDIX I Modified UNIFAC Parameters APPENDIX J PSRK Parameters APPENDIX K VTPR Parameters Index
380 citations
TL;DR: The equilibrium solubilities of the analgesic drug indomethacin (IMC) in propylene glycol+water binary mixtures were determined at several temperatures from 293.15 to 313.15 K.
134 citations
TL;DR: In this paper, the thermophysical properties of the H2O+1,3-dimethylimidazolium dimethylphosphate (DMP) system were studied.
132 citations
TL;DR: The goal of this work was to check the ability of the PC-SAFT equation to represent the solubility of carbon dioxide (CO(2)) in ionic liquids and found that a correlation is able to predict the density with high accuracy.
Abstract: The goal of this work was to check the ability of the PC-SAFT equation to represent the solubility of carbon dioxide (CO2) in ionic liquids. Parameters of pure imidazolium-based ionic liquids were estimated using experimental densities over a large range of temperatures and then correlated with respect to the molecular weight and structure of the solvents. It was found that such a correlation is able to predict the density with high accuracy. The solubility of carbon dioxide in such ionic liquids was then studied. The binary interaction parameter kij needed for the representation of such binary systems was first fitted to experimental liquid–vapor equilibria data. In a second step, a correlation based on the group contribution concept was developed to determine this temperature-dependent parameter. The ability of the model to describe accurately carbon dioxide solubility in imidazolium-based ionic liquids is demonstrated.
129 citations
TL;DR: In this paper, the melting temperature and fusion enthalpy of capsaicin were measured using differential scanning calorimetry, and the measured solubility data were well correlated by the van-t Hoff, modified Apelblat, λh (Buchowski), Wilson, and NRTL models, with the Wilson model showing the best agreement.
Abstract: Using a static analytical model, experimental solubility data were obtained for capsaicin in n-hexane, cyclohexane, carbon disulfide, butyl ether, and isopropyl ether at temperatures ranging from 278.15 to 323.15 K. The melting temperature and fusion enthalpy of capsaicin were measured using differential scanning calorimetry. The measured solubility data were well correlated by the van’t Hoff, modified Apelblat, λh (Buchowski), Wilson, and NRTL models, with the Wilson model showing the best agreement. The activity coefficients of capsaicin and the mixing Gibbs free energies, enthalpies, and entropies of the resulting solutions were predicted on the basis of the Wilson model parameters at measured solubility points. In addition, the infinite-dilution activity coefficients and excess enthalpies of capsaicin were estimated. Finally, the effects of solute–solvent intermolecular repulsive interactions on the solubility behavior and the values of mixing Gibbs free energy were discussed.
95 citations
TL;DR: In this article, the ternary system ethanol + water + ethylene glycol and its three constituent binary mixtures were measured at 101.3 kPa using a modified Rogalski-Malanoski equilibrium still.
Abstract: Isobaric vapor–liquid equilibria were measured for the ternary system ethanol + water + ethylene glycol and its three constituent binary mixtures at 101.3 kPa using a modified Rogalski–Malanoski equilibrium still. The thermodynamic consistency of experimental binary data was checked using the point and area tests. The experimental binary data were then correlated by the Wilson, nonrandom two-liquid (NRTL), and universal quasichemical activity coefficient (UNIQUAC) equations. The ternary vapor–liquid equilibria data were predicted using the binary parameters for the three equations with good accuracy. The selectivity of ethylene glycol as entrainer for the separation of the azeotropic system ethanol + water by extractive distillation was discussed using the NRTL parameters.
90 citations
TL;DR: In this paper, a thermodynamic model is proposed for representation/prediction of phase equilibria of semi-clathrate hydrates of the CO2, CH4, or N2+tetra-nbutylammonium bromide (TBAB) aqueous solution.
87 citations
TL;DR: In this article, the activity coefficients at infinite dilution, γ 13 ∞ and (gas+ liquid) partition coefficients, KL for 61 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, butanal, nitrogen compounds and water in the ionic liquid 4-(3-hydroxy)-4-methylmorpholinium bis(trifluoromethylsulfonyl)-amide were determined by (gas + liquid
86 citations
Journal Article•
TL;DR: An extensive study on a novel approach of modeling ionic liquids (ILs) and their mixtures with molecular compounds, incorporating perturbed-chain statistical associating fluid theory (PC-SAFT) concluded that the latter method allows accurate and reliable calculations of bulk-phase properties in a totally predictive manner.
Abstract: We present the results of an extensive study on a novel approach of modeling ionic liquids (ILs) and their mixtures with molecular compounds, incorporating perturbed-chain statistical associating fluid theory (PC-SAFT). PC-SAFT was used to calculate the thermodynamic properties of different homologous series of ILs based on the bis(trifluormethylsulfonyl)imide anion ([NTf₂]). First, pure fluid parameters were obtained for each IL by means of fitting the model predictions to experimental liquid densities over a broad range of temperature and pressure. The reliability and physical significance of the parameters as well as the employed molecular scheme were tested by calculation of density, vapor pressure, and other properties of pure ILs (e.g., critical properties, normal boiling point). Additionally, the surface tension of pure ILs was calculated by coupling the PC-SAFT equation of state with density gradient theory (DGT). All correlated/predicted results were compared with literature experimental or simulation data. Afterward, we attempted to model various thermodynamic properties of some binary systems composed of IL and organic solvent or water. The properties under study were the binary vapor–liquid, liquid–liquid, and solid–liquid equilibria and the excess enthalpies of mixing. To calculate cross-interaction energies we used the standard combining rules of Lorentz–Berthelot, Kleiner–Sadowski, and Wolbach–Sandler. It was shown that incorporation of temperature-dependent binary corrections was required to obtain much more accurate results than in the case of conventional predictions. Binary corrections were adjusted to infinite dilution activity coefficients of a particular solute in a given IL determined experimentally or predicted by means of the modified UNIFAC (Dortmund) group contribution method. We concluded that the latter method allows accurate and reliable calculations of bulk-phase properties in a totally predictive manner.
80 citations
TL;DR: In this paper, the activity coefficients at infinite dilution (γ 1,2∞) for 40 diverse probe solutes, including various (cyclo)alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, ethers, nitroalkanes and ketones, were measured by inverse gas chromatography at temperatures from 323 to 343 K in three homologous 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic
Abstract: Activity coefficients at infinite dilution (γ1,2∞) for 40 diverse probe solutes, including various (cyclo)alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, ethers, nitroalkanes, and ketones, were measured by inverse gas chromatography at temperatures from 323 to 343 K in three homologous 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids (ILs), bearing hexyl, octyl, and decyl side chains. The retention data were further converted to gas-to-IL and water-to-IL partition coefficients using the corresponding gas-to-water partition coefficients. Both sets of partition coefficients were analyzed using the modified Abraham solvation parameter model, with the derived equations tightly correlating the experimental gas-to-IL and water-to-IL partition coefficient data to within average standard deviations of 0.088 and 0.111 log units, respectively.
73 citations
TL;DR: In this article, the activity coefficients at infinite dilution for 59 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, acetic acid, thiophene, ethers, ketones, esters, butanal 4, and acetonitrile, were determined by gas-liquid chromatography at six temperatures over the range (318.15 to 368.15)
TL;DR: In this paper, liquid densities, osmotic coefficients, and mean ionic activity coefficients (MIAC) of single-salt alcohol (methanol and ethanol) solutions containing univalent ions were measured and modeled with the ePC-SAFT equation of state.
TL;DR: A strategy for evaluating the water activity in molecular dynamics simulations of proteins in water/organic solvent mixtures relies on determining the water content of the bulk phase and uses a combination of Kirkwood-Buff theory and free energy calculations to determine corresponding activity coefficients.
Abstract: In nonaqueous enzymology, control of enzyme hydration is commonly approached by fixing the thermodynamic water activity of the medium. In this work, we present a strategy for evaluating the water activity in molecular dynamics simulations of proteins in water/organic solvent mixtures. The method relies on determining the water content of the bulk phase and uses a combination of Kirkwood–Buff theory and free energy calculations to determine corresponding activity coefficients. We apply the method in a molecular dynamics study of Candida antarctica lipase B in pure water and the organic solvents methanol, tert-butyl alcohol, methyl tert-butyl ether, and hexane, each mixture at five different water activities. It is shown that similar water activity yields similar enzyme hydration in the different solvents. However, both solvent and water activity are shown to have profound effects on enzyme structure and flexibility.
TL;DR: In this article, the experimental solubility data in pure solvents were correlated by the van-t Hoff plot, the modified Apelblat equation, the λh (Buchowski) equation, and the NRTL model, with the Wilson model giving the best correlation results.
Abstract: The solubilities of ginsenoside compound K in pure solvents and binary mixture solvents were determined at several temperatures from 278.15 K to 318.15 K by a static analytical method. The experimental solubility data in pure solvents were correlated by the van’t Hoff plot, the modified Apelblat equation, the λh (Buchowski) equation, the Wilson model, and the NRTL model, with the Wilson model giving the best correlation results. Based on the Wilson model and experimental data, the mixing Gibbs free energies, enthalpies, and entropies of solutions and activity coefficients in pure solvents were predicted, and other thermodynamic properties (infinite-dilution activity coefficients and excess enthalpies) were calculated as well. In addition, the solubility was maximal at a certain water mole fraction in acetone + water mixture and acetonitrile + water mixture, whereas in a methanol + water system, the solubility decreases as the water concentration increases monotonically. The solubilities in mixture solvent...
TL;DR: In this article, the thermodynamic properties of Ca-Sb alloys were determined by emf measurements in a cell configured as Ca(s)|CaF2|CaSb over the temperature range 550 −830 °C Activity coefficients of Ca and Sb, enthalpy, Gibbs free energy, and entropy of mixing of Ca −Sb was calculated for xCa.
TL;DR: In this paper, a new Real Adsorbed Solution Theory (RAST) model for competitive multicomponent adsorption equilibrium correlation in liquid systems has been developed, which explicitly takes into account the non-ideal behavior shown by most of the adorption systems.
TL;DR: In this article, the activity coefficients at infinite dilution for 60 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, acetic acid, thiophene, ethers, ketones, esters, butyraldehyde and acetonitrile, were determined by gas-liquid chromatography at six temperatures in range of 318.15-368.15
TL;DR: In this paper, a ternary system for the ionic liquid mixture was obtained at 100 kPa using a recirculating still, where the addition of [emim][DCA] to the solvent mixture produced a salting-out effect greater than that produced by other ionic liquids.
Abstract: Isobaric vapor–liquid equilibria (VLE) for the ternary system acetone + methanol +1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) as well as the two solvent + IL binary systems have been obtained at 100 kPa using a recirculating still. The addition of [emim][DCA] to the solvent mixture produced a salting-out effect greater than that produced by other ionic liquids, showing that this ionic liquid is, until now, the best IL tested as an entrainer for the extractive distillation of the acetone + methanol mixtures, causing the azeotrope to disappear for an ionic liquid mole fraction as low as 0.031, at 100 kPa. This behavior can be explained on the basis of the influence of the IL concentration on the activity coefficient of each solvent in the binary mixtures. The electrolyte nonrandom two-liquid (NRTL) model was used for fitting successfully the experimental data.
TL;DR: In this article, the authors extended the current knowledge of Barite (BaSO4) solubility to the condition of high temperature, pressure, and ionic strength, and proposed an approach to assess the temperature and pressure dependence of virial coefficients in the Pitzer's equations of ion activity coefficients.
Abstract: The ultrahigh temperature (150–200 °C), pressure (1000–1500 bar), and TDS (over 300 000 mg/L) encountered in oil and gas production from deepwater pose significant challenges to scaling prediction and control. An apparatus has been built to test scale formation at temperature up to 250 °C and pressure to 1700 bar (24 000 psi). The study expands the current knowledge of Barite (BaSO4) solubility to the condition of high temperature, pressure, and ionic strength. By fitting Pitzer’s model to experimental solubility data, this study also provides a feasible approach to assess the temperature and pressure dependence of virial coefficients in the Pitzer’s equations of ion activity coefficients through measurement of mineral solubility. The prediction of Barite solubility made by the Brine Chemistry Consortium software ScaleSoftPitzer (SSP) that has incorporated the newly developed coefficients is consistent with experimental measurement.
TL;DR: In this article, the authors investigated liquid-liquid equilibrium phase behavior of 12-ILs comprising sulfate-based anions, using three local composition models, namely non-random two liquid (NRTL), non- random two liquid nonrandom factor and universal quasi chemical (UNIQUAC) activity coefficient models.
TL;DR: In this paper, a thermodynamic model was developed to represent the solubility of CO2 and H2S in single and blend of aqueous solutions of DEA and MDEA.
TL;DR: In this paper, an equation of state is used for thermodynamic modeling of aqueous ionic liquid (IL) solutions, which is a combination of perturbed chain statistical associating fluid theory (PC-SAFT) and mean spherical approximation (MSA) term.
Abstract: In this work, an equation of state has been utilized for thermodynamic modeling of aqueous ionic liquid (IL) solutions. The proposed equation of state is a combination of perturbed chain statistical associating fluid theory (PC-SAFT) equation of state and mean spherical approximation (MSA) term. In this model, the ion-based approach has been used to adjust the model parameters. The ion parameters have been estimated through simultaneous fitting to experimental mean ionic activity coefficient and liquid density data of strong electrolytes. Using adjusted ion parameters, osmotic coefficients, mean ionic activity coefficients, liquid densities, apparent molar volume, and water activity of several ILs, assumed as chainlike electrolytes, have been calculated. Results show that PC-SAFT, in combination with the MSA term has acceptable accuracy for prediction of density, apparent molar volume, and activity coefficient of ILs. The average deviations of predicted mean ionic activity coefficients, liquid densities, water activity, and apparent molar volume are 6.43, 0.86, 0.033, and 8.20%, respectively.
TL;DR: In this article, an extension of COSMO-RS for monoatomic electrolytes is presented, which accounts for long-range ion-ion interactions and cation hydration as well as an element specific hydrogen bonding contribution for anions.
TL;DR: This kind of systematic studies, where a series of ionic media is taken into account in the determination of various thermodynamic parameters, is useful for the definition of some trends in the thermodynamic behavior of glutathione in aqueous solution.
Abstract: The acid–base properties of γ-l-glutamyl-l-cysteinyl-glycine (glutathione, GSH) were determined by potentiometry (ISE-H+, glass electrode) in pure NaI(aq) and in NaCl(aq)/MgCl2(aq), and NaCl(aq)/CaCl2(aq) mixtures, at T = 298.15 K and different ionic strengths (up to I
c
~ 5.0 mol L−1). In addition, the activity coefficients of glutathione were also determined by the distribution method at the same temperature in various ionic media (LiCl(aq), NaCl(aq), KCl(aq), CsCl(aq), MgCl2(aq), CaCl2(aq), NaI(aq)). The results obtained were also used to calculate the Specific ion Interaction Theory (SIT) and Pitzer coefficients for the dependence on medium and ionic strength of glutathione species, as well as the formation constants of weak Mg
j
H
i
(GSH)(i+2j−3) and Ca
j
H
i
(GSH)(i+2j−3) complexes. Direct calorimetric titrations were also carried out in pure NaCl(aq) and in NaCl(aq)/CaCl2(aq) mixtures at different ionic strengths (0.25 ≤ I
c
/mol L−1 ≤ 5.0) in order to determine the enthalpy changes for the protonation and complex formation equilibria in these media at T = 298.15 K. Results obtained are useful for the definition of glutathione speciation in any aqueous media containing the main cations of natural waters and biological fluids, such as Na+, K+, Mg2+, and Ca2+. Finally, this kind of systematic studies, where a series of ionic media (e.g., all alkali metal chlorides) is taken into account in the determination of various thermodynamic parameters, is useful for the definition of some trends in the thermodynamic behavior of glutathione in aqueous solution.
TL;DR: In this paper, the activity coefficients at infinite dilution, γ 13 ∞, for 43 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, ethers, ketones, acetonitrile, pyridine, and 1-nitropropane, were determined by gas-liquid chromatography at six temperatures within the range (308.15 to 358.15) K.
TL;DR: In this article, the authors measured the densities and speeds of sound for five binary systems (alcohol+1-butyl-3-methylimidazolium dicyanamide) from T = (293.15 to 323.15) K and atmospheric pressure.
TL;DR: In this paper, the authors presented a predictive method for the change in the three-phase equilibrium condition of gas hydrates upon the introduction of organic inhibitors and electrolytes, using the Peng-Robinson-Stryjek-Vera (PRSV) equation of state, combined with the COSMO-SAC activity coefficient liquid model through the modified Huron-Vidal (MHV1) mixing rule.
Abstract: Here we present a predictive method for the change in the three-phase (vapor–liquid–hydrate) equilibrium condition of gas hydrates upon the introduction of organic inhibitors and electrolytes. The Peng–Robinson–Stryjek–Vera (PRSV) equation of state, combined with the COSMO-SAC activity coefficient liquid model through the modified Huron–Vidal (MHV1) mixing rule, is used to describe the fluid phase, and the van der Waals and Platteeuw (vdW–P) model is used to describe the hydrate crystalline phase. The temperature-dependent Langmuir absorption constants for the vdW–P model are determined by fitting to the equilibrium condition of pure gas hydrates. Once determined, the method contains no adjustable binary interaction parameters and can be used for prediction of the phase behaviors of gas hydrates with additives that do not enter the cages of the clathrate hydrates (e.g., most inhibitors and electrolytes). We examined the accuracy of this method using five pure gas hydrates, five organic inhibitors, and nin...
TL;DR: The knowledge of the pH of solubilization and of the protonation constants determined in the same experimental conditions, allowed us to calculate, by means of the mass balance equations, the solubility of the neutral species at different ionic strength values, to model its dependence on the salt concentration and to determine the corresponding values at infinite dilution.
TL;DR: In this paper, the authors measured a binary system of trifluoroiodomethane (R13I1) + trans-trans-1, 3, 3 and 3-tetrafluoropropene (R1234ze (E)) within a static-analytic method within the temperature range of (258.150 to 298.150)
TL;DR: In this paper, a surface component activity (SCA) model was proposed, which suggests that surface component (adsorption site or adsorbed solute) activity coefficient is a function of Cs because of the existence of adsorbent particle-particle interactions.