Electrolyte Nonrandom Two-liquid Model Research Articles

Isothermal Vapor−Liquid Equilibrium Data for the System Methanol + Benzene + Sodium Tetraphenylborate

Isothermal vapor−liquid equilibrium data for the system methanol + benzene + sodium tetraphenylborate at five salt molalities [(0.05, 0.10, 0.15, 0.20, and 0.25) mol·kg-1] have been measured with the help of headspace gas chromatography at (298 and 308) K. The experimental data were correlated using the electrolyte nonrandom two-liquid model.

Modeling of Activity Coefficients of Aqueous Solutions of Quaternary Ammonium Salts with the Electrolyte-NRTL Equation

Ionic liquids (ILs) have been studied recently as potential “green” solvents because of their negligible vapor pressure. Modeling the phase behavior of such liquids with water and organic solvents and their partitioning between aqueous and organic phases is vital for an evaluation of their many potential uses. Unfortunately, phase behavior data for the popular imidazolium and pyridinium salts are still somewhat limited. However, a wealth of data exists for aqueous solutions of quaternary ammonium salts, a class of compounds that includes potentially interesting ILs. Therefore, as a first step toward modeling the phase behavior of IL solutions, we show how a conventional electrolyte model, the electrolyte nonrandom two-liquid (NRTL) model proposed by Chen et al. (AIChE J. 1982, 28, 588), can be applied to model activity coefficients of quaternary ammonium salts in water. This model requires two parameters per salt that must be fit to the experimental data. Particular attention is paid to computing these bi...

Isothermal Vapor−Liquid Equilibrium Data for the Systems 1,4-Dioxane + Water + Tetrabutylammonium Nitrate and Acetonitrile + Water + Tetrabutylammonium Bromide

Isothermal vapor−liquid equilibrium data for the system 1,4-dioxane + water + tetrabutylammonium nitrate at 11 constant salt molalities ((0.1, 0.25, 0.50, 0.75, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, and 4.00) mol·kg-1) have been measured with the help of gas chromatography at (288, 298, and 308) K. Isothermal vapor−liquid equilibrium data for the system acetonitrile + water + tetrabutylammonium bromide at 5 constant salt molalities ((0.20, 0.40, 0.60, 0.80, and 1.00) mol·kg-1) have also been measured with the help of gas chromatography at (298 and 323) K. The experimental data for these systems were correlated using the electrolyte nonrandom two-liquid model.

Two- and three-liquid phase equilibria in the system water+2-heptanone+caprolactam+ammonium sulfate: experiments and modeling

Liquid–liquid equilibria (LLE) were determined experimentally for the system water+2-heptanone+caprolactam+ammonium sulfate at 20, 40 and 60 °C. The equilibrium data show the salt and temperature effect on the distribution of caprolactam: at higher salt concentrations and at higher temperatures more caprolactam is transferred to the organic phase. A three-liquid phase region was found in the system and measurements were carried out to determine the three-phase region. The location of the three-phase triangles is largely dependent on the salt concentration and follows the pattern found in literature for surfactant systems. The three-liquid phase equilibrium data presented here, in combination with equilibrium data from literature, were modeled with the modified extended electrolyte non-random two-liquid (NRTL) model. The model was found able to give a satisfactory description of three-liquid phase equilibria. For the two-liquid phase equilibria, a good representation of the experimental data could be obtained as well, using the same binary parameters as for the liquid–liquid–liquid equilibria (LLLE) data.

Segment‐based excess Gibbs energy model for aqueous organic electrolytes

AbstractThe aqueous electrolyte nonrandom two‐liquid (NRTL) model of Chen et al. is extended to represent the excess Gibbs energy of aqueous organic electrolytes. These organic electrolytes exhibit very different solution nonideality from typical aqueous electrolytes with elemental ions. The proposed extension is an integration of the electrolyte NRTL model for aqueous electrolytes and the polymer NRTL model (Chen, 1993) for oligomers and polymers. Organic ions are treated as oligomers that consist of hydrocarbon segments and ionic segments that each exhibit distinctive physical interactions with neighboring species. This integrated NRTL model captures the nonideal phase behavior of aqueous organic electrolytes, including micelle formation. The model further provides a versatile thermodynamic framework to correlate solution nonideality of electrolyte systems, organic or inorganic, and complex systems containing both electrolytes and polymers.

Bubble points of hydrogen chloride–water–isopropanol and hydrogen chloride–water–isopropanol–benzene systems and liquid–liquid equilibria of hydrogen chloride–water–benzene and hydrogen chloride–water–isopropanol–benzene systems

Bubble points of the HCl–water–isopropanol and the HCl–water–isopropanol–benzene systems and liquid–liquid equilibria (LLE) of the HCl–water–benzene and the HCl–water– isopropanol–benzene systems were measured at 25–85°C and 30–70°C, respectively. The electrolyte nonrandom two-liquid model proposed by Chen et al. [C.-C. Chen, H.I. Britt, J.F. Boston, L.B. Evans, AIChE J. 28 (1982) 588–596] can satisfactorily correlate bubble points and liquid–liquid equilibria of the present mixed-solvent electrolyte systems over the entire range of temperature and concentrations using only binary adjustable parameters.

Representing Vapor−Liquid Equilibrium for an Aqueous MEA−CO2 System Using the Electrolyte Nonrandom-Two-Liquid Model

Following the work of Austgen et al., the electrolyte nonrandom-two-liquid (NRTL) model was applied in a thermodynamically consistent manner to represent the vapor−liquid equilibrium (VLE) of the aqueous monoethanolamine (MEA)−CO2 system with rigorous chemical equilibrium consideration. Special attention was given to the accurate VLE description of the system at both absorbing and stripping conditions relevant to most aqueous MEA absorption/stripping processes for CO2 removal. The influence from chemical equilibrium constants, Henry's constant, experimental data, and data regression on the representation of the VLE of the system was discussed in detail. The equilibrium constant of the carbamate reversion reaction as well as important interaction parameters of the electrolyte NRTL model were carefully fitted to experimental data. A good agreement between the calculated values and the experimental data was achieved. Moreover, the model with newly fitted parameters was successfully applied to simulate three industrial cases for CO2 removal using a rate-based approach. The results from this work were compared with those using the model by Austgen et al.