UNIQUAC Models Research Articles

Phase behavior for 1-butyl-3-methylimidazolium tetrafluoroborate with sodium oxalate/succinate/formate aqueous two-phase systems at 298.15 and 308.15 K

The liquid––liquid equilibrium (LLE) data and phase composition of the aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) + sodium oxalate (Na2C2O4), [Bmim]BF4 + sodium succinate (Na2C4H4O4) and [Bmim]BF4 + sodium formate (NaHCOO) mixtures have been measured at 298.15 and 308.15 K. The effect of salts and temperature on binodal curves were studied in this work and a significant relationship has been observed between the salting-out ability and the Gibbs energy of hydration of the ions. The binodal data obtained were correlated by the Pirdashti and Merchuk equations and the tie-line compositions were well-fitted by the Othmer-Tobias and Bancroft equations and the experimental tie-line data were well correlated with extended UNIQUAC model. Additionally, the effective excluded volume values were also determined to analyze the salting-out abilities of the three salts which follow the order of Na2C2O4 > Na2C4H4O4 > NaHCOO.

Measurement and modeling correlation of capecitabine solubility in n-hexane + ethyl acetate and n-heptane + ethyl acetate at various temperatures

In this work, by using laser dynamic isothermal method, the solubilization behavior and thermodynamics of capecitabine solubility in the binary mixtures of n-hexane + ethyl acetate and n-heptane + ethyl acetate from (278.15 to 323.15) K were measured under atmospheric pressure. The measured results showed that the experimental solubility of capecitabine increased non-linearly with increasing temperature and ethyl acetate content (w1) in the studied mixture solvents. Six cosolvency mathematical models including the modified Apelblat equation, combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation, Wilson model, non-random two liquid (NRTL) model, UNIQUAC model, and the modified Jouyban-Acree-van't Hoff model were fitted to the experimental results. The maximum relative average deviation (ARD) was 0.27, the maximum root-mean-square deviation (RMSD) was 0.0007. The order of the relative average deviation (ARD) of the six cosolvency mathematical models is CNIBS/R-K > modified Jouyban-Acree-van't Hoff > NRTL > Wilson > modified Apelblat > UNIQUAC. Basically speaking, the measured solubility data in this study can be well correlated with the six thermodynamic models, while the modified Jouyban-Acree-van't Hoff model allowed the calculation of solubility of capecitabine at an arbitrary mixture composition and temperature in the studied binary solvent mixtures composition and temperature. Moreover, apparent thermodynamic properties of capecitabine dissolution process in the investigated mixed solvents including entropy, enthalpy and Gibbs free energy were computed using van't Hoff and Gibbs equations. Besides, the logarithm of activity coefficient of capecitabine (lnγ1) in the studied saturated solutions were also calculated with the NRTL model, UNIQUAC model, and Wilson model, respectively. The positive values of lnγ1 means that the repulsive interactions exist between capecitabine and the corresponding mixture solvents, and the solutions system positively deviate from Raoult's law. This work can give fundamental data for the crystallization and purification of capecitabine from ethyl acetate.

Isobaric Vapor–Liquid Equilibrium for the Binary System of Dimethyl Adipate and 1,6-Hexanediol at 10, 20, and 99 kPa

Saturated vapor pressures of pure dimethyl adipate and isobaric vapor–liquid equilibrium (VLE) data for the binary system of dimethyl adipate + 1,6-hexanediol at 10, 20, and 99 kPa were determined by a modified Othmer still. All of the VLE data passed the thermodynamic consistency test by Wisniak and Van Ness methods. The experimental data were correlated with the NRTL, Wilson, and UNIQUAC models. The results showed that the UNIQUAC model is slightly better among the three models.

Thermodynamic Investigation of 1,3,5-Trioxane, Methyl Acrylate, Methyl Acetate, and Water Mixtures, in Terms of NRTL and UNIQUAC Models

The thermodynamics of 1,3,5-trioxane, methyl acrylate, methyl acetate, and water were systematically investigated, in terms of NRTL and UNIQUAC models. Solubility data of 1,3,5-trioxane in methyl a...

Separation of olefins from FCC naphtha by propylene carbonate: Influence of critical component structure and correlation of ternary LLE thermodynamic models

The separation of olefin from aromatics and sulfides by using propylene carbonate (PC) solvent was studied by the ternary liquid–liquid equilibrium (LLE) of PC + aromatics/sulfide +olefin. The effects of aromatic, sulfide, and olefin structures were investigated by a combination of experiments and quantum chemical calculations. The aromatics and sulfides without side chains were easier to dissolve in PC. Efficient olefin separation was observed because the side chain did not change the positive charge enrichment region of the molecule, and instead increased the steric space when combined with solvent molecules. The olefin separation factor S in the separation of 1-hexene and thiophene is 12.96, which is 1.64 times higher than that in the separation of 1-hexene and 3-methylthiophene. In addition, the binary parameters between the PC and fluid catalytic cracking (FCC) naphtha components for NRTL and UNIQUAC thermodynamic models were obtained using the ternary LLE data to make up for the blank in Aspen simulation for the separation of FCC naphtha by PC solvent. Then, the correlation of NRTL and UNIQUAC models was compared, which the root-mean square deviation (RMSD) of these two models is lower than 0.0043. The NRTL model shows a better correlation with experimental data.

Calculation of Equilibrium for Multicomponent Mixtures Using the Parameters of Models for Binary Pairs of Pure Components

An algorithm and an application software package have been developed for calculating the vapor–liquid equilibrium of multicomponent mixtures using the optimal parameters of equilibrium models (namely, the Wilson, NRTL, and UNIQUAC models) for binary pairs of the pure components of a mixture. The parameters of the models have been optimized by extremum localization, simple iteration, and certain other methods at the minimum of the optimization criterion, i.e., the sum of the squared deviations between experimental and calculated values for the equilibrium compositions of the vapor phases (at checkpoints) for each of the binary pairs of pure components.

Solubility modeling, mixing properties and solvent effect of 5-norbornene-2,3-dicarboximide in eleven pure solvents at various temperatures

Mole-fraction solubility of 5-norbornene-2,3-dicarboximide (NODI) in eleven solvents including methanol (MtOH), ethanol (EtOH), 2-ethoxyethanol, methyl acetate (MAC), ethyl acetate (EAC), n-propyl acetate (NPAC), isopropyl acetate (IPAC), n-butyl acetate (NBAC), acetone (DMK), N,N-dimethylformamide (DMF) at (278.15–323.15) K and 1,4-dioxane at (288.15–323.15) K was experimentally measured by laser monitoring technique under 0.1 MPa. Solubility of NODI increased with the increasing temperature. Hansen Solubility Parameter was employed to explain the solubility behavior. The Kamlet-Taft parameters were calculated to investigate the solvent effect based on linear solvation energy relationships concept. Thermodynamic modeling including the Two-Suffix Margules model, Wilson model, NRTL model, NRTL-SAC model and UNIQUAC model were employed to correlate the experimental solubility. Wilson model and NRTL-SAC model were more suitable in correlation with solubility data. Furthermore, thermodynamic properties of mixing process (ΔmixG, ΔmixH, ΔmixS, lnγ1∞, H1E,∞, ζTS and ζH) were discussed based on Wilson equation.

Experimental measurement, correlation and COSMO-SAC prediction of liquid-liquid equilibrium for MIPK + dimethylphenols + water mixtures

Liquid-liquid equilibrium (LLE) data for ternary systems of methyl isopropyl ketone (MIPK) + 2,3-/3,4-/3,5-dimethylphenol + water was determined from 298.15 K to 338.15 K under 101.3 kPa in this work. Distribution coefficient and selectivity were calculated to investigate solvent extraction efficiency of dimethylphenol from water and their high values indicated that MIPK could extract dimethylphenols well. The NRTL and UNIQUAC models were applied to correlate experimental LLE data and related root-mean square deviations (RMSDs) were less than 0.5%. Additionally, the experimental data was predicted by COSMO-SAC model, and the corresponding RMSD values demonstrated that COSMO-SAC model can be applied as a predictive tool to calculate LLE data of the investigated ternary systems.

The study on the solubility of main group organometallics in selected solvents and the thermodynamic model of solubility correlation under inert atmosphere

The solubility of the main group organometallics under inert atmosphere is of great importance for homogeneous process, while there's still no research reported on it. The solubilities of β-diketimine (1) (LH, L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) in five selected pure organic solvents and aluminum hydrides (2) (LALH2) in three pure selected organic solvents were measured by the equilibrium method at temperature from 268.15 K to 313.15 K under a purified nitrogen atmosphere using Schlenk techniques or inside a glovebox. The results show that the solubility of compound 1 in pure solvents decrease according to the following order: tetrahydrofuran > toluene >n-hexane > ethanol > methanol, and the order of solubility of compound 2 is: tetrahydrofuran > toluene >n-hexane. The solubilities of those increase with the increase of temperature. The λh equation, Apelblat equation, Wilson model equation, NRTL model equation, and UNIQUAC model equation were applied to describe the measured system. The Wilson model equation, the Apelblat model were the best one for fitting the solubilities of compound 1 and 2, respectively. Furthermore, some thermodynamic parameters such as enthalpy, Gibb's energy, and entropy have also been evaluated for the dissolution process.

Isobaric Vapor-Liquid Equilibria for Binary System of Ethanol (1) + Eugenol (2) at 400 and 760 mmHg

Eugenol is the main component of clove oil, while the main impuritis of it is β-caryophyllene. Eugenol with a purity higher than 98% has a higher price than low purity eugenol. Thus, further eugenol purification process is needed. Common purification processes are extraction and distillation. In the design and simulation of the distillation process it requires a knowledge of Vapor-Liquid Equilibrium (VLE) data from a mixture of components to be separated (eugenol and ethanol) as the result of extraction process. In this work, the experimental VLE data were measured for binary mixtures of ethanol(1) + eugenol(2) at 400 and 760 mmHg. The apparatus used for this experiment is an othmer still equipped with a vacuum pump and a manometer. The experiments were performed to obtain equilibrium data (T), component concentrations in liquid phase (x), and in vapor phase (y). The binary VLE data were correlated with the Wilson, NRTL and UNIQUAC models to obtain the binary parameters. The reliability of these models were tested by comparing with experimental results using Root Mean Square Deviation (RMSD). For the system and the operation condition studied, the Wilson, NRTL and UNIQUAC models suited well and give satisfactory results based on the RMSD values .

Isobaric Vapor-Liquid Equilibria for Binary System of Ethanol (1) + Eugenol (2) at 400 and 760 mmHg

Eugenol is the main component of clove oil, while the main impuritis of it is β-caryophyllene. Eugenol with a purity higher than 98% has a higher price than low purity eugenol. Thus, further eugenol purification process is needed. Common purification processes are extraction and distillation. In the design and simulation of the distillation process it requires a knowledge of Vapor-Liquid Equilibrium (VLE) data from a mixture of components to be separated (eugenol and ethanol) as the result of extraction process. In this work, the experimental VLE data were measured for binary mixtures of ethanol(1) + eugenol(2) at 400 and 760 mmHg. The apparatus used for this experiment is an othmer still equipped with a vacuum pump and a manometer. The experiments were performed to obtain equilibrium data (T), component concentrations in liquid phase (x), and in vapor phase (y). The binary VLE data were correlated with the Wilson, NRTL and UNIQUAC models to obtain the binary parameters. The reliability of these models were tested by comparing with experimental results using Root Mean Square Deviation (RMSD). For the system and the operation condition studied, the Wilson, NRTL and UNIQUAC models suited well and give satisfactory results based on the RMSD values .

Experimental Measurements and Thermodynamic Modeling of Melting Temperature of the Binary Systems n-C11H24–n-C14H30, n-C12H26–n-C13H28, n-C12H26–n-C14H30, and n-C13H28–n-C15H32 for Cryogenic Thermal Energy Storage

In this study, the phase diagrams for the binary systems of n-C11H24–n-C14H30, n-C12H26–n-C13H28, n-C12H26–n-C14H30, and n-C13H28–n-C15H32 were experimentally investigated to employ potential phase change materials (PCMs) for cryogenic applications. Besides, the phase diagrams were theoretically obtained on the basis of the ideal solubility and UNIFAC models, and the UNIQUAC, Wilson, and NRTL models were applied to build correlations between experimental and predicting values. The results show that the compositions of the eutectic points appear at 10 wt % C14 for the C11–C14 system, 17.8 wt % C13 for the C12–C13 system, 18 wt % C14 for the C12–C14 system, and 10 wt % C15 for the C13–C15 system with eutectic temperatures of 246.85, 257.75, 260.45, and 265.55 K, respectively. Moreover, the melting temperatures calculated using the theoretical models are in good agreement with the experimental results. The average relative deviations for the C11–C14 system and C13–C15 systems are merely 0.3814% and 0.3220%, respectively, by using the NRTL model. Simultaneously, the minimum relative deviations for the C12–C13 and C12–C14 binary systems are 0.3649% for the ideal solubility model and 0.4856% for the UNIFAC model. Finally, upon comparing the predicted results of the studied binary systems using the results of the five models, we find that the UNIFAC model provides the most accurate results for the melting temperatures.

Olefin separation from FCC naphtha by dimethyl sulfoxide: Effect of structure on the separation and correlation of thermodynamic models

The performance of dimethyl sulfoxide (DMSO) solvent in separating olefins from aromatics and thiophene sulfides was evaluated through a series of ternary liquid-liquid equilibrium (LLE) experiments at 101.325 kPa and 303.15 K. The influences of the structures of olefins, aromatics, and thiophene sulfides on the separation efficiency were analyzed. Normal 1-hexene and isomer 2,4,4-trimethyl-1-pentene were easily separated from aromatics or thiophene sulfides, which only contain aromatic ring structures, such as benzene and thiophene. The reason is that the induced dipole on the aromatic ring structure introduced by the DMSO solvent significantly improved the polarity of aromatics and thiophene sulfide molecules, thereby enhancing the interaction with the ring structure. In addition, olefins were easier to separate from thiophene sulfides than from aromatics. The olefin separation factor of separating 2,4,4-trimethyl-1-pentene from thiophene was three times greater than that of separating the same olefin from benzene. The binary parameters between DMSO and olefins, aromatics, and thiophene sulfides for NRTL and UNIQUAC models were obtained through ternary LLE experiments. The maximum value of the root-mean-square deviation of the simulated compositions of phases compared with experimental data was 0.0052 in the two adopted models. Hence, the regressed binary parameters could efficiently describe the experimental LLE process. On the basis of the obtained binary parameters, the NRTL and UNIQUAC models are suitable for predicting the performance of olefin separation from fluid catalytic cracking naphtha. However, the NRTL model is more precise than the UNIQUAC model.

Estimation of Structural Parameters of Protic Ionic Liquids for Activity Coefficient Models and Calculations of LLE Phase Diagrams

Modeling liquid–liquid equilibrium (LLE) is essential for optimizing the operation and safety of chemical engineering processes. Therefore, some researchers have investigated the modelling of ternary systems containing protic ionic liquids. In most cases, thermodynamic modeling was performed using the non-random two-liquid model (NRTL) for its simplicity and the absence of structural parameters. UNIQUAC model has also been used, but the structural parameters of protic ionic liquids are still scarce. In this work, the area and volume parameters were calculated by Connolly’s method. The parameters obtained were used to correlate LLE data for thirteen ternary systems, among these we can high light (m-2HEAA, m-2HEABor, m-2HEAH) + DBT+ dodecane. Therefore, the estimated structural parameters allowed to generate seventy-eight interaction parameters between the solvent and the ionic liquid. New structural parameters protic ionic liquids were estimated. The results are shown with standard deviations between the calculated and experimental compositions with satisfactory results.

REACTIVE DIVIDING WALL COLUMN (RDWC) PADA PRODUKSI DIETIL KARBONAT

In this era, the needs for chemicals are increasing. One of them is an additive called diethyl carbonate that is produced by the transesterification reaction of dimethyl carbonate and ethanol. To produce diethyl carbonate by conventional distillation with high purity is expensive and requires a lot of energy, so that new breakthroughs and innovations are needed to overcome this problem. The new breakthrough and innovation proposed in this study is Reactive Dividing Wall Column (RDWC). The purpose of this study is to design an RDWC model and optimize the Reactive Dividing Wall Column. In this study, Aspen Plus software was used. The operating unit model used was RadFrac. The thermodynamic model used was the UNIQUAC model. Then using the literature on reactive distillation, the data were validated. After it was valid, the data will be used to design and optimize RDWC. Variables for optimization are: number of reactive trays, number of trays with a wall, total tray number, and DMC feed location. The results showed that RDWC for the production of diethyl carbonate produced a lower value of TAC than conventional methods. The TAC value obtained was $1,310,706,938 / year. The Reactive Dividing Wall Column design for optimum diethyl carbonate production has a total number of 24 reactive stages, a total number of 26 wall stages, 77 total stages and dimethyl carbonate feed locations on the 71 st stage.

Separation of azeotropic mixture (2, 2, 3, 3-Tetrafluoro-1-propanol + water) by extractive distillation: Entrainers selection and vapour-liquid equilibrium measurements

For separating the azeotrope of 2, 2, 3, 3-tetrafluoro-1-propanol (TFP) and water by extractive distillation, N-methyl pyrrolidone (NMP), N-methyl formamide (NMF) and N, N-dimethyl formamide (DMF) were selected as entrainers using the COSMO-SAC model based on solvent capacity. And the charge density surface of entrainers and each component in the azeotrope system were calculated. The vapour-liquid equilibrium (VLE) data for the mixtures (TFP + NMP), (TFP + NMF) and (TFP + DMF) were measured by a modified Rose-type recirculating still at the pressure 101.3 kPa. The thermodynamic consistency for the VLE data was validated using the Herington and van Ness methods. The VLE data were correlated with NRTL, Wilson and UNIQUAC models, and the interaction parameters of thermodynamic models were fitted. Meanwhile, the effect of the entrainers on the VLE for TFP and water was explored. Compared with NMF and DMF, NMP was adopted as the suitable entrainer for separation of the azeotropic mixture TFP and water by extractive distillation.

Liquid-liquid equilibrium for (water + 5-hydroxymethylfurfural + 1-pentanol/1-hexanol/1-heptanol) systems at 298.15 K

Liquid-liquid equilibrium (LLE) data for {water + 5-hydroxymethylfurfural (HMF) + 1-pentanol/1-hexanol/1-heptanol} ternary systems was measured at 298.15 K and 0.1 MPa. The solute selectivity and the capacity of alcohols were evaluated and the results showed that 1-pentanol has better performance than 1-hexanol and 1-heptanol for HMF recovery from aqueous solutions. The NRTL and UNIQUAC models were used to correlate the liquid-liquid experimental values and the binary interaction parameters obtained were thermodynamically consistent. The root-mean-square deviations (RMSD) between the experimental data measured and the calculated by the NRTL and UNIQUAC models were less than 0.69% for all systems.

Measurement and thermodynamic modeling of carbon dioxide hydrate formation conditions using dry water through hydrophobic nano silica

Dry water is accounted for as an effective medium for gas storage in a clathrate hydrated form. We used the van der Waals-Platteeuw framework for correlation of the experimental CO2 hydrate formation conditions in the presence of dry water through a reversed micellar approach. Activity of water in a reversed micelle presented an effect on the thermodynamic characteristics of a dry water system. The binary interaction parameters of the UNIQUAC model was adjusted using the CO2 – H2O hydrate equilibrium formation conditions data. Due to the hydrophobic nature of the nanoparticles, the hydration forces contributed the predominant term at the water chemical potential function using a dry water medium. The results showed that dry water presented a thermodynamic promoter effect. Therefore, applying a water-in-air microemulsion model, a good agreement of the calculated values with the experimental data was demonstrated using the two adjustable parameters of the hydration force term.

Ternary liquid-liquid equilibria for β-caryophyllene(1) + 1-propanol(2) + water(3) system at temperatures 303.15, 313.15, and 323.15 K

The experimental liquid–liquid equilibrium data of the system β–caryophyllene(1) + 1-propanol(2) + water(3) at temperatures 303.15, 313.15, and 323.15 K are presented. The mixtures of β–caryophyllene + 1-propanol + water were stirred for 4 hours and settled for at least 20 hours at constant temperature. The samples taken from both phases were analyzed by a gas chromatography (GC). The experimental equilibrium data were correlated by NRTL and UNIQUAC models. The compatibility of the models is based on the value of root mean square deviation (RMSD). The liquid-liquid phase diagram of the system shows type I phase behavior, where two binary subsystems are miscible and only one binary subsystem is partially miscible. The temperature effect of this system on immiscible zone is very small. Based on the experiment and the calculation results, the ternary equilibrium data have been successfully represented using both the NRTL and the UNIQUAC models.

Measurement and Correlation of LLE Data for the Ternary System Water + Phosphoric Acid + 1-Undecanol at 303.2 K

Experimental solubility curve and tie-line data were obtained for the ternary system (water + phosphoric acid + 1-undecanol) at T = 303.2 K and ambient pressure. The cloud point method was employed to determine the binodal curve data. The mass fraction compositions of each layer were explored by acid-base and the Karl Fisher titration methods accompanied by mass balance calculations. For above mentioned ternary system, a type-1 LLE behavior was observed. The reliability of the experimental compositions was proved by using the Othmer–Tobias and Hand plots. The UNIQUAC and NRTL thermodynamic models were applied to correlate the equilibrium tie-line points. The experimental points were adequately regressed using the thermodynamic models. Distribution coefficients and separation factors were computed over the non-miscible region. For the separation process, separation factor should be greater than one and for the investigated system, this factor was suitable to apply separation treatment in all concentrations of phosphoric acid at the studied temperature. The Katritzky parameters were utilized for LSER modeling of distribution coefficients of the studied mixtures. The ternary system showed good fittings with the LSER model.