NRTL Equation Research Articles

Measurement and Correlation of Solubility of Hydrochlorothiazide in Monosolvents and Binary Solvent Mixtures from 283.15 to 323.15 K

In this paper, the solubility of hydrochlorothiazide (HCT) was determined by using a laser method in pure solvents (methanol, ethanol, n-propanol, isopropanol, acetonitrile, ethyl acetate, water, 2-butyl alcohol, 1-pentanol, and isobutyl alcohol) and binary solvent mixtures of methanol + water and acetonitrile + n-propanol at the temperatures ranging from 283.15 to 323.15 K in approximately 5 K intervals at atmospheric pressure. The solubility increases with increasing temperature in all pure solvents we chose. However, the solubility of HCT increases with increasing methanol content, and it increases first and then decreases with increasing acetonitrile content at constant temperature. The dissolving capacity of HCT ranks as methanol > acetonitrile > ethanol > ethyl acetate > n-propanol (isopropanol) > 2-butyl alcohol (isobutyl alcohol) > 1-pentanol > water. The experiment data were well correlated with the modified Apelblat equation, λh equation, NRTL equation, and modified Jouyban–Acree model.

Isobaric Vapor–Liquid Equilibria for the Quaternary System Water + Ethanol + Ethylene Glycol + Choline Chloride and the Ternary System Water + Ethanol + Choline Chloride at 101.3 kPa

An organic salt choline chloride (ChCl) was introduced in ethylene glycol (EG) for improving the entrainer performance for ethanol dehydration by extractive distillation. The mixed solvent EG + ChCl with molar ratios of 8:1, 4:1, 2:1, and 4:3 were tested through vapor–liquid equilibrium (VLE) measurement for the quaternary system water + ethanol + EG + ChCl at 101.3 kPa. Data were also measured for the ternary system water + ethanol + ChCl. VLE behavior of the quaternary system was modeled successfully using the NRTL equation. The mean absolute deviations for the quaternary data were 0.24 K for equilibrium temperature and 0.0041 for vapor mole fraction of ethanol, while deviations for the ternary data were 0.15 K and 0.0032. As compared with EG alone, the existence of ChCl in the mixed solvent decreases the activity coefficient of water and increases the activity coefficient of ethanol, both leading to the enhancement of the relative volatility of ethanol to water. The azeotrope of water + ethanol can be removed with the addition of EG + ChCl 4:3 at a solvent mass fraction of 0.062, showing favorable entrainer performance for ethanol dehydration by extractive distillation.

A new activity coefficient model for the solution of molecular solute + ionic liquid

Based on electrolyte non-random two-liquid (e-NRTL) equation, a new activity coefficient model is proposed for the solution of ionic liquid + molecular solute. In the new model, the sizes of particles have been taken into consideration by introducing volume elements into the new model. For easier application, the Pitzer-Debye-Hückel expression is cancelled in the new model, because ionic liquids work as solvents more frequently. To simplify the model, the assumptions (local electroneutrality and like-ion repulsion) have been made, which were adopted in Chen's e-NRTL model. As a result, the new model only needs 5 parameters like NRTL equation. Moreover, the new model can predict accurate results with fewer experiment data in comparison with NRTL for both totally miscible and partially miscible solutions, which has been proven with 19 kinds of solution.

Modeling of solid-liquid equilibrium using a modified group contribution based NRTL model

Solid-liquid phase equilibria data for various systems were predicted using the modified group contribution NRTL equation (GC-NRTL). A priori a previous NRTL group interaction parameters matrix was completed by introducing new groups involved in oxygenated (HCO), nitroginated (HCN, HCNO) and chlorinated (HCCl) systems, by minimizing a well defined objective function defined in terms of the sum of the squared differences between the calculated solubility values and the corresponding experimental ones reported in the literature.A sequential approach was adopted consisting of using the already determined group interaction parameters in the determination of those between new involved groups.Solid-liquid phase equilibria for systems not involved in the interaction parameters calculation were predicted by means of the modified GC-NRTL model, including the determination of the eutectic points. A quite good agreement was obtained between the predicted results and the corresponding reported experimental values.

The thermodynamics and separation process design for the ternary system 1,3-propanediol + 1,3-butanediol + 2,3-butanediol

ABSTRACT The isobaric vapor–liquid equilibrium (VLE) data at 101.3kPa for (1,3-propanediol(PG) + 1,3-butanediol(BD)), (1,3-PG+2,3-BD) and (1,3-BD+2,3-BD) and for the ternary system of (1,3-PG+1,3-BD+2,3-BD) have been measured. The thermodynamic properties of the non-ideal vapor phase have been considered with the EOS equation. The liquid activity coefficients have been calculated with Wilson, NRTL and UNIQUAC equations, and the binary interaction parameters were regressed by these models. The vapor composition of VLE data were calculated by the optimum parameter group and generated a good consistency to experimental values. Based on all the preceding results, a two-column distillation process was designed.

Separation of the mixture (isopropyl alcohol + diisopropyl ether + n-propanol): Entrainer selection, interaction exploration and vapour-liquid equilibrium measurements

For separation of the mixture {isopropyl alcohol (IPA) + diisopropyl ether (DIPE) + n-propanol (NPA)} by extractive distillation, propylene glycol ethyl ether (PGEE) was used as an entrainer based on selectivity since isopropyl alcohol + diisopropyl ether can an azeotrope. To explore the interaction mechanism between the entrainer PGEE and the components in the mixture, the charge density surface (σ-profiles) and the interaction energies were calculated based on the COSMO-SAC model and Dmol3, which could provide theoretical insight into interactions at the molecular level. Then, the data of isobaric vapour-liquid equilibrium (VLE) for (IPA + PGEE), (DIPE + PGEE) and (NPA + PGEE) systems were measured at 101.3 kPa. The NRTL, UNIQUAC and Wilson equations were applied to correlate the measured VLE data, and the thermodynamic model parameters for the binary systems were obtained by fitting the VLE data, which is helpful for the simulation and optimization of the separation process.

Reconsideration of the alpha coefficient in NRTL model on the vapor liquid phase equilibrium description of refrigerant mixtures

The NRTL equation provides a good representation of vapor-liquid equilibrium of mixed-refrigerants, but it needs three parameters for each pair of components, including a non-randomness parameter alpha. In order to reduce the number of adjustable parameters from three to two, this work aims to establish an adequate expression for alpha in terms of readily available molecular parameters. The regressed alpha coefficients vary from -1 to 10, while 74% of them are between 0 and 1. Alpha has a great effect on the AARDp, although there is a region with a small AARDp difference. The relationship between alpha and molecular weight, dipole moment is established. As expected, positive correlation between alpha and molecular weight, while negative correlation between alpha and dipole is found. Better AARDp (0.59%) is achieved by a proposed equation, comparing to alpha = (0.2, 0.3, 0.4 and 0.47), although it is slightly worse than the regressed alpha.

Methyl acetate–methanol mixture separation by extractive distillation: Economic aspects

Methyl acetate is considered low toxicity volatile solvent produced either as a by-product during methanol carbonylation or via acetic acid esterification with methanol. In both cases, pure methyl acetate has to be isolated from the reaction mixture. Simulation of methyl acetate separation from its mixture with methanol by extraction distillation was carried out in ASPEN + software. In total three case studies were assumed using two different extraction solvents and two solvent regeneration strategies. In case A, novel extraction solvent 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid, was considered. Raw material separation was achieved in an extraction distillation column while the solvent regeneration was accomplished in a second distillation column in this case. In case study B, the same extraction solvent was used; however, its regeneration was carried out in a single-effect evaporator. Dimethyl sulfoxide was the second extraction solvent selected. Its use in methyl acetate-methanol separation is presented in case study C. As high purity of dimethyl sulfoxide was required for the methyl acetate-methanol azeotrope breaking, its regeneration was carried out in the second distillation column only. To simulate the ternary methyl acetate–methanol–extraction solvent mixtures separation, vapor–liquid equilibrium was predicted based on the NRTL equation. Further, unknown properties of the considered ionic liquid and variation of these properties with temperature were predicted and introduced into the ASPEN + components properties database. Based on these data, optimum operation parameters of the respective separation equipment were established. In all case studies, the same condition had to be fulfilled, namely minimum methyl acetate content in the distillate from the extraction distillation column of 99.5mol-%. Results of simulations using the respective optimum operation parameters were employed in the economic evaluation of the three separation unit designs studied. It was found that the least energy-demanding design corresponds to the case study B in terms of both capital as well as operation expenses.

Physicochemical and thermodynamic properties of the {1-alkyl-1-methylpiperidinium bromide [C1Cn=2,4PIP][Br], or 1-butylpyridinium bromide, [C4Py][Br], or tri(ethyl)butylammonium bromide [N2,2,2,4] [Br] + water} binary systems

This work is a continuation of our comprehensive study of ionic liquids, ILs (including organic salts with melting temperature above 100 °C) and their aqueous solutions as a novel alternative working pair for the absorption heat pump. A series of organic salts: 1-ethyl-1-methyl-piperidinium bromide, [C1C2PIP][Br], 1-butyl-1-methyl-piperidinium bromide, [C1C4PIP][Br], 1-butylpyridinium bromide, [C4Py][Br] and tri(ethyl)butylammonium bromide, [N2,2,2,4][Br] have been synthesized. The structures of compounds have been confirmed using NMR spectra. The basic thermal characterization of pure organic salts, including temperature and enthalpy of phase transition (Ttr, ΔtrH), temperature and enthalpy of melting (Tfus, ΔfusH) have been measured using a differential scanning microcalorimetry technique (DSC). The physico-chemical properties that are: density (ρ) and dynamic viscosity (η) of the tested binary systems have been determined at wide temperature and composition range. From experimental densities data, the apparent molar volumes (Vϕ,1) were calculated. In order to obtain limiting apparent molar volumes (Vϕ,10), the concentration dependence of apparent molar volumes was correlated with Redlich–Mayer type equation. Additionally, the limiting molar expansibilities (Eϕ0) and isobaric thermal expansion coefficients (αP) have been calculated. Temperature dependence of the dynamic viscosity has been correlated using VFT equation. The solid−liquid phase equilibria (SLE) have been determined using a dynamic method and correlated using NRTL equation. The influence of the alkyl chain length in the piperidinium cation substituent, as well as the cation structure, on investigated properties are presented and discussed.

An artificial neural network-based NRTL model for simulating liquid-liquid equilibria of systems present in biofuels production

A new hybrid local composition model was developed for simulating the liquid-liquid equilibria of systems involved in biofuels production. This model was based on the hybridization of the NRTL equation and an artificial neural network. Numerical performance of this hybrid model was tested with experimental phase equilibria data of biofuels-based ternary systems. Results showed that this hybrid thermodynamic model has improved data fitting properties than those obtained for the original NRTL equation. This model can be utilized to improve the estimation of liquid-liquid equilibria in biofuel process simulations.

Optimization-Based Design of a Reactive Distillation Column for the Purification Process of Cyclohexanone Using Rigorous Simulation Model and Validated Using an Experimental Packed Column

This paper presents a model for a reactive distillation column where 2-cyclohexen-1-one is eliminated from a mixture of cyclohexanone and cyclohexanol. In the purification of cyclohexanone, 2-cyclohexen-1-one must be removed to produce high quality caprolactam. A common practice in industry is to promote the condensation of 2-cyclohexen-1-one with cyclohexanone using NaOH as catalyst. However, it promotes the cyclohexanone self-condensation with the drawback of incurring raw material losses. The column model was developed using gPROMS and validated using a packed distillation column on laboratory scale at steady state. The kinetic model of involved reactions and the binary interaction parameters of NRTL equation were implemented. The model can predict adequately the concentration profile for the involved compounds. The model was used to optimize the operating industrial conditions to minimize the unitary total cost to produce high purity cyclohexanone. gPROMS algorithms were used to solve the resulting mixed-integer nonlinear problem.

Separation of thiophene, or benzothiophene from model fuel using glycols. Liquid–liquid phase equilibria and oxidative desulfurization study

In this work the possibility of use glycols in extractive desulfurization will be discussed based on liquid–liquid phase equilibria (LLE) measurements for {glycol (1) + aromatic sulfur compound (2) + heptane (3)} ternary systems at T = 308.15 K and at pressure p = 0.1 MPa. Based on the experimental data, the performance of three glycols: diethylene glycol, triethylene glycol and polyethylene glycol (PEG 200) in the extraction of thiophene, or benzothiophene from heptane were determined. The selectivity, S, and solute distribution ratio, β derived from the experimental equilibrium data, were calculated and used to determine the efficiency of the tested glycols as a solvent for the extraction of sulfur compounds from model fuels. The NRTL equation was successfully used to correlate the experimental tie-lines and calculate the phase composition error in mole fraction in the ternary systems. The average root mean square deviation (RMSD) of the phase composition was less than 0.017. Additionally, the extractive desulfurization (EDS) of model fuels has been studied using diethylene glycol, triethylene glycol, polyethylene glycols (PEG 200), [BMIM][BF4] and eutectic mixtures of ([BMMOR][Br with diethylene glycol, or triethylene glycol). The oxidative extractions (ODS) were performed using different oxidative agents: the mixture of hydrogen peroxide with acetic acid, or formic acid, or benzoic acid, or iron (III) chloride and vanadium (V) oxide as well as the mixture of oxygen with N-hydroxyphthalimide (NHPI). Many parameters including the type of extractant and oxidizing agents, extraction time and temperature, as well as the ratio of the volume of model fuel to the volume of the extractant and number of extraction cycles on the extraction efficiency, were considered and discussed.

Liquid–liquid extraction of sulfur compounds from heptane with tricyanomethanide based ionic liquids

Liquid–liquid phase equilibrium (LLE) data for the {tricyanomethanide-based ionic liquid (1) + tiophene, or benzothiophene (2) + heptane (3)} ternary systems were experimentally determined at T = 308.15 K and at pressure p = 0.1 MPa. In this work three ILs, that is: 1-butyl-1-methylmorpholinium tricyanomethanide, [BMMOR][TCM], 1-butyl-1-methylpyrrolidinium tricyanomethanide, [BMPYR][TCM] and 1-hexyl-1-methylmorpholinium tricyanomethanide, [HMMOR][TCM] have been investigated. The high solubility of sulfur compounds and practically complete immiscibility of heptane with the tested ionic liquids have been observed. The selectivity, S12 and solute distribution ratio, k12 derived from the experimental equilibrium data, were calculated and used to determine the efficiency of these ionic liquids as solvents for the extraction of sulfur compounds from model fuels. The experimental results have been compared to literature data for other tricyanomethanide-based ILs and were discussed in terms of the selectivity and solute distribution ratio of separation of related systems. The NRTL equation was successfully used to correlate the experimental tie-lines. The average root mean square (RMSD) of the phase composition was less than 0.8%. Additionally, the oxidative-extractive desulfurization of model fuels has been studied using tricyanomethanide-based ionic liquid (IL): [BMMOR][TCM] and [BMPYR][TCM] and deep eutectic solvent (DES): ([BMMOR] [Br] + diethylene glycol). Model liquid fuel was prepared by dissolving benzothiophene in octane, 500 ppm of sulfur. Oxidation was achieved by adding hydrogen peroxide and acetic acid to the mixture. Different parameters such as a type of extractant, extraction time, and oxidant to sulfur molar ratio and temperature were optimized. The addition of oxidizing agent improves the efficiency of sulfur extraction and the highest extraction efficiency, equal to 69.1%, was obtained for [BMMOR][TCM] at T = 318.15 K.

Solid–Liquid Phase Equilibria, Molecular Interaction and Microstructural Studies on (N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline) Binary Mixtures

Differential scanning calorimetry (DSC) is used to investigate the thermal properties of N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline, and their binary systems. The experimental results demonstrate that the studied binary system presents a simple eutectic behavior and the corresponding mole fraction (xeu) of N-(2-ethanol)-p-nitroaniline at the eutectic point is 0.5486, whereas the temperature (Teu) is found to be equal to 363.6 K. The quality of the solid–liquid equilibria (SLE) data has been checked by thermodynamic consistency tests, presenting good quality factor. The SLE data have been correlated by means of Wilson, NRTL, and UNIQUAC equations. The three models describe satisfactorily the phase diagram as the root-mean-square deviations for the equilibrium temperatures vary from 1.25 K to 2.07 K. Nevertheless, the Wilson model provides the best correlation results. The three equations have also been used to compute excess thermodynamic functions viz. excess Gibbs energy, enthalpy and entropy. The obtained results revealed a sensitive positive deviation to ideality thus demonstrating the nature of the interactions between the compounds forming the mixture. Microstructural studies have been carried out by FTIR, XRD and optical microscopy showing weak molecular interactions for the eutectic mixture.

Study of the physicochemical properties of protein kinase CK2 inhibitors -TBBt, TBBi and 2-Me-TBBi

The examination of physicochemical properties of selected protein kinase CK2 inhibitors: 4,5,6,7-tetrabromo-1H-benzotriazole (TBBt), 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi) and 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole (2-Me-TBBi) was performed. The study includes modification of synthesis method and determination of compounds' thermal properties, the solid-liquid phase equilibria and pKa. Thermal properties (melting temperature, enthalpy of fusion, temperature and enthalpy of phase transitions) were determined by means of differential scanning calorimetry (DSC). For solid-liquid phase equilibria study, as a solvent, three liquids were used independently: water, ethanol and 1-octanol. In order to elicit the inhibitors’ solubility with alcohols (ethanol and 1-octanol), the dynamic method was applied. In the case of poorly soluble inhibitors in water, equilibria were determined by spectrophotometric method. Based on a phase diagram obtained results were interpreted and correlated using three equations: Wilson equation, NRTL equation and UNIQUAC equation.pKa values of studied polybrominated benzoazoles were estimated by the spectrophotometric Bates–Schwarzenbach method at two constant temperatures: 298.15 K as a room temperature and 310.15 K as a human body temperature.Obtained results are very important for further design of CK2 inhibitors, because they provide information about the solubility of pharmacophore in binary systems: active compound (1) + solvent (2), that may be used in differentiating the way how to apply potential drug. Moreover, all values of dissociation constants bring valuable guidelines to establish the therapeutic dose of pharmaceutics.

Influence of Temperature on Liquid–Liquid Equilibrium of Methanol + Toluene + Hexane Ternary Systems at Atmospheric Pressure

Phase equilibria of methanol + toluene + hexane ternary systems at (278.15, 283.15, 288.15 and 293.15) K at atmospheric pressure were investigated. The influence of temperature on the liquid–liquid equilibrium is discussed. All chemicals were quantified using gas chromatograph with a thermal conductivity detector coupled to a ChemStation and nitrogen as gas carrier, their mass fractions were higher than 0.999. From literature are found two articles from the same system at different temperatures studied here. Experimental data are compared with literature values. Values calculated using the NRTL and UNIQUAC equations are compared with the experimental data and it is found that the UNIQUAC equation fitted the experimental data better than the NRTL model for this ternary system.

Solubility Modeling and Solvent Effects of Allopurinol in 15 Neat Solvents

Experimental allopurinol solubility in water and 14 organic solvents, namely, N,N-dimethylformamide (DMF), isopropanol, ethanol, methanol, acetone, acetonitrile, n-propanol, n-heptanol, 1-hexanol, n-butanol, 2-butanone, N-methyl-2-pyrrolidone (NMP), 1,4-dioxane, and cyclohexane, has been studied by using the shake-flask method. The experiments were carried out over the temperature range from 278.15 to 333.15 K under p = 101.2 kPa. The solubility of allopurinol in selected solvents rose with the rise in temperature. The solubility values of allopurinol were recorded as the maximum in NMP and the minimum in cyclohexane. The obtained solubility data were mathematically described with the λh equation, Apelblat equation, and NRTL equation. The maximum percentage of the average relative deviation was 1.73 × 10–2, and the maximum value of the root-mean-square deviation was 2.416 × 10–4. Furthermore, the solvent effect was analyzed through the method of SERL (linear solvation energy relationship). The extent and types of solvent–solute and solvent–solvent interactions were recognized.

Extractive Distillation of Acetone – Methanol Mixture using 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate

Acetone and methanol are organic solvents widely used in industry. Acetone with methanol forms a homogeneous minimum-boiling azeotrope which is not separable by conventional distillation processes. A common method for its separation is the extractive distillation in the presence of a selective solvent (such as water). In this paper, the use of an ionic liquid (1-ethyl-3-methylimidazolium trifluoro methanesulfonate [Emim][triflate]) for acetone–methanol separation by extractive distillation was designed. The aim of the design calculation was to obtain acetone with the purity of 99.5 mol % and methanol with the purity of above 99.0 mol %. Calculations were carried out in a proprietary program constructed in Matlab® by solving a set of material balances at individual theoretical stages of the distillation column combined with the vapor–liquid equilibrium (VLE) of the ternary system acetone–methanol–[Emim][triflate]. For the description of VLE of the above mentioned system, the NRTL equation was used. Several optimization cycles were done resulting in optimal parameters of the extractive distillation column (number of theoretical stages, solvent consumption, reflux ratio and position of the feed stage) in regard to the required purity of products (acetone and methanol). Regeneration of ionic liquid was provided by evaporation at the low pressure of 20 kPa. The heat and cooling consumption duties of the designed separation process were analyzed. Regeneration of the ionic liquid is energy-demanding compared to the separation of acetone–methanol in an extractive distillation column. The heat consumption is only 11 % of the heat used up by the whole separation process.

Solubility data of zwitterions in water

In this work a series of ammonium- and phosphonium-based zwitterions (ZIs) namely: 3-(triethylammonio)propane-1-sulfonate, N222C3S, 4-(triethylammonio)butane-1-sulfonate, N222C4S, 3-(tributylammonio)propane-1-sulfonate, N444C3S, 4-(tributylammonio)butane-1-sulfonate, N444C4S, 3-(trihexylammonio)propane-1-sulfonate, N666C3S, 4-(trihexyl-ammonio)butane-1-sulfonate, N666C4S, 3-(tributylphosphonio)propane-1-sulfonate, P444C3S and 4-(tributyl-phosphonio)butane-1-sulfonate, P444C4S have been synthesized. The structure and purity of these compounds were confirmed by 1H NMR. The thermal properties such as temperature and enthalpy of (solid + solid) phase transition as well as the melting temperature of pure ZIs were evaluated by DSC technique. The (solid + liquid) and (liquid + liquid) phase equilibria measurements have been performed for eight binary systems of synthesized ZIs and one purchased 3-(1-pyridinio)-1-propanesulfonate [PyC3S] using the dynamic method and the experimental results were correlated using NRTL equation. Additionally, ternary system of {N666C3S (1) + N444C3S (2) + water (3)} with three different N666C3S to N444C3S initial molar fractions was determined.

Propane/propylene separation and CO2 capture in magnetic ionic liquid [bmim][FeCl4

Magnetic ionic liquids (MILs), combines the general properties of ionic liquid with magnetic properties, are starting to attract interest in the field of propane/propylene separation and CO2 capture. Solubility data of propane, propylene, cyclopropane and CO2 in magnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate [bmim][FeCl4] at temperatures of (303, 313, 323, 333, 343) K and pressures up to 3300kPa were determined in the present work. The relative expanded uncertainty of solubility measurement is estimated to be less than 4% with a level of confidence of 95%. The Henry’s constants for the four gases in [bmim][FeCl4] and selectivity of C3H6/C3H8 in [bmim][FeCl4] were calculated. And the thermodynamic properties of solvation concerned about the Gibbs energy (ΔsolG∞), the enthalpy (ΔsolH∞) and the entropy (ΔsolS∞) of solvation were also obtained to offer knowledge for understanding the progress of gases dissolved in [bmim][FeCl4]. The experimental results were correlated with a modified KK equation and NRTL equation.