UNIQUAC Models Research Articles

Measurement and Thermodynamic Models for Ternary Liquid–Liquid Equilibrium Systems {Water + Polyoxymethylene Dimethyl Ethers +4-Methyl-2-pentanol} at Different Temperatures

Polyoxymethylene dimethyl ethers (DMMn) have attracted particular attention in industry as excellent oxygenated fuel additives. This study aims to reveal the liquid–liquid equilibrium (LLE) values regarding ternary mixtures {water + methylal (DMM1) + 4-methyl-2-pentanol (MIBC)}, {water + DMM2 + MIBC}, {water + DMM3 + MIBC}, and {water + DMM4 + MIBC} at 298.2 and 308.2 K under 101.3 kPa. Distribution factor and selectivity were utilized to assess the extracting capabilities of the selected extractant. The well known Hand equation and Othmer–Tobias equation were utilized to test the consistency of the LLE values. In addition, the experimental results were correlated by the UNIQUAC and NRTL thermodynamic models with all of the root-mean-square deviation values less than 0.0127,which indicated that both models agree well with the experimental tie-line data.

Experimental and correlational study of phase equilibria in aqueous solutions of phosphoric acid with alcohols at different temperatures

Liquid-liquid equilibrium (LLE) data were measured for the aqueous mixtures of phosphoric acid with 1-pentanol and 1-heptanol at T=(298.2, 308.2, and 318.2) K and atmospheric pressure. These ternary systems exhibit as Treybal's type-1 liquid-liquid phase behavior. The reliability of the experimental tie-lines was checked using the Othmer-Tobias and Hand correlation equations. The activity coefficient models of NRTL and UNIQUAC were applied to fit the experimental tie lines. For these models, values of the binary interaction parameters between each pair of components in the studied systems were obtained. Experimental distribution coefficients and selectivity factors for the immiscibility regions were determined.

Vapor–liquid equilibrium for binary and ternary systems of tetrahydrofuran, ethyl acetate and N-methyl pyrrolidone at pressure 101.3 kPa

Vapor−liquid equilibrium (VLE) data for the binary systems of tetrahydrofuran (THF) + ethyl acetate (EtOAc), THF + N-methyl pyrrolidone (NMP) and EtOAc + NMP, and the ternary systems of THF + EtOAc + NMP were measured at 101.3 kPa. The modified Rose vapor recirculating type equilibrium still was utilized to obtain the experimental data. The Herington method, as well as the Van Ness test, was used to verify the thermodynamic consistency of the experimental data. The NRTL model, UNIQUAC model and Wilson model were adopted to correlate the vapor-liquid equilibrium data. Accordingly, the binary interaction parameter for each model was obtained by regressing the experimental data. The results show that the three models can accurately agreement with the experimental data.

LIQUID-LIQUID EQUILIBRIUM DATA FOR THE PSEUDO-TERNARY BIODIESEL OF CHICKEN FAT + METHANOL + GLYCEROL

Liquid-liquid equilibrium (LLE) data for the system biodiesel of chicken fat + methanol + glycerol was measured at 25 and 45 °C and atmospheric pressure. The zone of miscibility was found by means of the binodal curve, using the density of turbidity in each point for its construction. Tie lines were defined through the calibration curves of the biodiesel and glycerin phases. The distribution and selectivity coefficients for the system were determined. The validation of the equilibrium data was proved using the Othmer-Tobias and Hand correlations, with coefficients close to the unity. The LLE data were correlated with the UNIQUAC model for temperatures of 25 °C and 45 °C, with global mean deviation values of 0.78% and 0.89%, respectively.

Phase Equilibrium Involving Xylitol, Water, and Ethylene Glycol or 1,2-Propylene Glycol: Experimental Data, Activity Coefficient Modeling, and Prediction with Artificial Neural Network-Molecular Descriptors

The xylitol molecule is an important building block that can be used in the production of such interesting chemicals as ethylene glycol and 1,2-propylene glycol. The development of productive processes that enable this transformation depends on various experimental and theoretical information. In order to supply part of this demand, this work sought to study the solubility of xylitol in binary liquid solutions formed by water, ethylene glycol, and 1,2-propylene glycol in the temperature range between 293.15 and 323.15 K, covering the entire molar composition range of the solution. The Jouyban–Acree, NRTL, and UNIQUAC models were used in the correlation of experimental data, and the mUNIFAC model was applied in the prediction of experimental data. In addition, an artificial neural network associated with molecular descriptors was developed to simulate the data. Xylitol showed solubility in the pure components with decreasing values in the following order: water, ethylene glycol, and 1,2-propylene glycol. T...

Liquid–Liquid Equilibrium for the Ternary Systems (Methyl Isobutyl Ketone + Quinoline or Isoquinoline + Water) at 298.15, 318.15, and 338.15 K

Liquid–liquid equilibrium (LLE) data for the ternary systems (methyl isobutyl ketone + quinoline or isoquinoline + water) were measured at T = 298.15, 318.15, and 338.15 K and atmospheric pressure. Distribution coefficients and separation factors were calculated to evaluate extraction efficiency. The Hand, Bachman, and Othmer–Tobias equations were applied to verify the reliability of the experimental tie-line data. The NRTL and UNIQUAC models were used to correlate all of the experimental values at different temperatures simultaneously. The binary interaction parameters of these two models were obtained. The root-mean-square deviation between the experimental and calculated data indicates that the NRTL model presents a better prediction than the UNIQUAC model. The effect of temperature on the extraction performance of methyl isobutyl ketone was investigated. The extraction process of quinoline or isoquinoline by methyl isobutyl ketone is exothermic. The increase of temperature is not a benefit to extract ...

Measurement and correlation of phase equilibrium data of the mixtures consisting of water, resorcinol, mesityl oxide at different temperatures

Abstract Liquid–liquid equilibrium (LLE) data were measured for the ternary system of water + resorcinol + mesityl oxide under atmospheric pressure at temperatures of (298.2, 323.2, 333.2, 343.2 and 353.2) K. The reliability of the experimental data was verified by the Hand and Bachman equations. The distribution coefficient and selectivity were calculated from the experimental LLE data, which showed high efficiency of mesityl oxide extracting resorcinol from the aqueous solution. The NRTL and UNIQUAC models were employed to fit the measured experimental LLE data and yield corresponding binary interaction parameters.

Thermodynamic properties of aqueous ternary system CuSO4 + PEG 4000 + H2O at different temperatures

The present study has the aim to investigate the thermodynamic behaviour of the aqueous ternary system composed of CuSO4 and poly(ethylene glycol) (PEG). These compounds are known to form aqueous two-phase systems for applications in metal ions and biomolecules partitioning. To have a better understanding of these systems, water activities were determined at different temperatures (T = 303.15, 313.15, 323.15 and 333.15 K), using a vapour pressure osmometer. The results indicate that CuSO4 has a significant effect on the water activity of the system composed by salt-PEG-water. Additionally, water activities of the constituent binary systems, CuSO4 + H2O and PEG 4000 + H2O, were measured at the same temperatures of the ternary system.From these experimental measurements the vapour pressure values were determined for the systems and correlated with the extended UNIQUAC model, obtaining a good agreement between the experimental and correlated data.

Vapor–Liquid Equilibria of Binary Systems with Long-Chain Organic Compounds (Fatty Alcohol, Fatty Ester, Acylglycerol, and n-Paraffin) at Subatmospheric Pressures

In the past years, the oil and fat industry has been growing on a large scale, mostly due to the need of biodiesel production. Considering this fact, the understanding of thermophysical properties and phase equilibrium of the compounds found in this industry became crucial, that is, acylglycerols, fatty esters, alcohols. Therefore, this work aims to obtain liquid–vapor equilibrium data of the following mixtures: hexadecanol + octadecanol (1.73 kPa), hexadecanol + methyl myristate (1.72 kPa), monononanin + tributyrin (1.69 kPa), and dinonanoin + octacosane (1.70 kPa) by the differential scanning calorimetry technique. As expected, the system with two long-chain alcohols (hexadecanol + octadecanol) showed an ideal behavior. In contrast, the other systems presented nonideal behavior. Experimental data were effectively regressed by the UNIQUAC model. The pure component consistency test and the variation of Van Ness consistency test were applied to all systems. Activity coefficients were modeled using the Line...

The inclusion of organic acids dissociation in the prediction of liquid-liquid equilibrium data

Advances in thermodynamic equilibrium have led to the recent development of binary, ternary and quaternary systems including electrolytes. However, a precise determination of phase equilibrium must consider the physical-chemical aspects of the components that will can to take place in a mixture. A solute is liable to dissociate hence the need to take this consideration into account. The chosen organic acids have attracted much attention in the research works but unfortunately, their dissociation into the aqueous phase has not been taken into the calculation of phase equilibrium. The present research work focuses on the development of the calculation of the phase equilibrium methods by including the dissociation of the chosen organic acids, for predicting the liquid-liquid equilibrium (LLE) data from the binary parameters for various ternary systems composed of {water-phosphoric acid-methylisobutylketone},{water-acetic acid-cumene},{water-propionic acid-cumene},{water-formic acid-isoamyl acetate} and {water-butyric acid-isoamyl acetate} at 298.15 K and normal atmospheric pressure, so as to be able to design electrolytes having specific properties. This requires a modeling framework that is based upon the fundamental laws and models of physics. Therefore, in our study, we used the Extended UNIQUAC model to predict the LLE data. We are newly investigating the effect of including the dissociation of the picked organic acids on prediction of phase equilibrium. The results have been compared with authors who consider no dissociation of organic acids, where they have been satisfactory.

Liquid-Liquid Equilibrium for the Ternary Systems of Solvent+ m/o/p-Cresol+Water: Thermodynamic Modeling

In this study, NRTL and UNIQUAC thermodynamic models were used to predict the composition of ternary mixtures of solvents+ m/o/p-cresol+ water in organic and aqueous phases. Various solvents are used for the separation of cresols from water. In this study, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, and methyl isobutyl ketone solvents were investigated. Intermolecular interaction parameters were considered to be a function of temperature. The binary interaction parameters of water and cresols (m, o, or p) in the presence of each type of solvent were considered to be the same. Also, regardless of the type of cresol (m, o, or p), the parameters of binary interaction between water and each solvents were considered to be the same. The results proved the accuracy of the presented models, though the parameters of binary interaction parameters were considered to be the same. The root mean square deviation for NRTL and UNIQUAC models was 0.0086 and 0.0089, respectively.

Liquid–Liquid Equilibria for Ternary (Methyl Propyl Ketone + Hydroquinone or Resorcinol + Water) Systems at 298.15, 318.15, and 333.15 K

Experimental liquid–liquid equilibria (LLE) data for ternary (methyl propyl ketone + hydroquinone + water) and (methyl propyl ketone + resorcinol + water) systems were determined under atmospheric pressure at T = 298.15, 318.15, and 333.15 K. Distribution coefficients and separation factors were calculated to evaluate extraction effectiveness. Hand, Bachman, and Othmer–Tobias equations were utilized to confirm consistency of experimental LLE data. Thermodynamic NRTL and UNIQUAC models were used to correlate experimental LLE data, and corresponding binary interaction parameters were obtained. The estimated data from the two models agree well with experimental LLE data. The NRTL model gives a better agreement than the UNIQUAC model for ternary (methyl propyl ketone + hydroquinone or resorcinol + water) systems.

Conceptual Design of n-Butyl Acetate Synthesis Process by Reactive Distillation Using Residue Curve Maps

Residue curve maps are a powerful tool for the preliminary design of Reactive Distillation (RD). In this study, residue curve maps of the n-butyl acetate synthesis reaction were calculated based on the Langmuir–Hinshelwood–Hougen–Watson kinetic and UNIQUAC models to calculate the physical properties of the system. The results showed that the unstable node branch emerged from the n-butyl acetate/water edge, moved toward the chemical equilibrium surface with increasing Damkohler number, and no ternary reactive azeotropic point appeared when the reaction was added. Conceptual design of n-butyl acetate synthesis by reactive distillation based on residue curve maps is presented. Based on the simulation results, both the energy consumption and the total annual cost were lower than previously reported values.

Experimental study and modeling of citric acid solubility in alcohol mixtures

Citric acid is a weak organic acid widely used in food industries. The study of this solid's behavior in different solutions is required for the development of separation processes and new applications. Studies on the solubility of citric acid in solutions are still little explored and the information regarding solubility in pure components is imprecise. The objective of this work, therefore, was to study the solubility of citric acid in binary liquid solutions formed by methyl, ethyl and isopropyl alcohol at temperatures of 293.15 K, 303.15 K, 313.15 K and 323.15 K. The solubility results were applied in the determination of the activity coefficient of the solubilized solid. The Jouyban-Acree, NRTL and UNIQUAC models were used in the correlation of the data, and the mUNIFAC model was applied in its prediction. Citric acid had a high solubility in the pure components with the values decreasing from methyl to ethyl and isopropyl alcohol. For the solubility in the binary solutions, the solubility revealed intermediate values. The results for the activity coefficient showed a linear behavior as a function of temperature, and they decreased with increasing solubility. The employed models were able to correlate or predict the experimental data.

Paraffin solubility curves of diesel fuels from thermodynamic model adjusted through experimental DSC thermograms

DSC and wax solubility curves were measured for two diesel fuel samples. Compositional profiles were also measured for the solubility curve points. The paraffin distributions of the samples were determined and the non-paraffinic components were lumped into pseudocomponents. The liquid phase was modeled using the Peng-Robinson equation of state with the classical van der Waals mixing rule. For the solid phase, the modified UNIQUAC model was employed. The models were fitted to the DSC data by tuning only four multipliers acting on the molecular weights, boiling and critical temperatures of the pseudocomponents as well as on the paraffins’ pair interaction energies from the UNIQUAC model. Then the model is used to predict wax appearance temperature, amount and composition of solid deposit as a function of temperature during cooling. Excellent results were obtained for the two samples analyzed. This way, the methodology developed is able to predict adequately the formation of solid paraffin from diesel fuels.

Measurement and correlation of aqueous two-phase systems of polyvinylpyrrolidone (PVP) and manganese sulfate: Effects of molecular weight and temperature

Aqueous two-phase systems (ATPS) are a substitute for conventional liquid-liquid extraction systems and, are usually composed of a salt solution and the polymer polyethylene glycol (PEG). Polyvinylpyrrolidone (PVP) is an alternative polymer, inexpensive, stable, and it has great potential for ATPS. This study aimed to investigate the effect of the molecular weight of the polymer (10 000 and 40 000) and the temperature (298.15, 318.15 and 338.15 K) in the system composed of PVP10 or PVP40 + manganese sulfate + water. The Merchuk equation has been used to correlate the experimental binodal data. For all systems, the higher the temperature, the higher the two-phase region and the slope of the tie-line. The increase in the molecular weight of the polymer resulted in the expansion of the two-phase region. Furthermore, the UNIQUAC model was used to fit the experimental LLE data.

Isobaric Vapor–Liquid Phase Equilibrium Measurements, Correlation, and Prediction for Separation of the Mixtures of Cyclohexanone and Alcohols

For separation of the mixtures cyclohexanone with alcohols by distillation, the isobaric vapor–liquid equilibrium data for cyclohexanone + (ethanol/n-propanol/isopropanol) were measured at 101.3 kPa. The van Ness, pure component consistency, and Herington test were used to validate the measured data consistency. The measured data were fitted by the Wilson, NRTL, and UNIQUAC models with the optimized binary parameters. For comparison, the phase equilibrium values for the investigated mixtures were predicted by the COSMO-SAC and UNIFAC models, and the standard deviations of vapor phase composition by the two models are less than 0.0043 and 0.0055.

Liquid–Liquid Equilibria for Systems of Ethanol + Hexanol + Heptanol + Decane + Undecane + Water at 298.15 K under Atmospheric Pressure: Experiment and Simulation

The experimental liquid–liquid equilibrium (LLE) data of the quaternary systems ethanol + hexanol + decane + water, ethanol + hexanol + undecane + water, ethanol + heptanol + decane + water, and ethanol + heptanol + undecane + water were collected at 298.15 K under atmospheric pressure. The UNIQUAC model was used to regress the quaternary systems and acquire the binary interaction parameter, which was used to predict the LLE data of the six-component system. The predicted LLE data were compared with the experimental data, and the results showed they were in good agreement, which indicated that the binary interaction parameters acquired from the quaternary systems could predict the LLE data of the six-component system. The distribution coefficient and the selectivity showed that 65% ethanol aqueous solution was suitable for separating hexanol and heptanol from the hexanol–heptanol–decane–undecane mixture.

Effect of water addition on extraction ability of eutectic solvent choline chloride+ 1,2-propanediol for separation of hexane/heptane+ethanol systems

The ability of binary deep eutectic solvent choline chloride+1,2-propanediol (DES1; 1 : 3 mole ratio) and ternary deep eutectic solvent choline chloride+1,2-propanediol+water (DES2; 1 : 3 : 3 mole ratio) for breaking the azeotropes hexane/heptane+ethanol by means of liquid-liquid extraction was evaluated. Liquid-liquid equilibrium experiments were performed at 298.15 K, at atmospheric pressure, and data were correlated by NRTL and UNIQUAC models. Thermodynamic properties (density, viscosity, refractive index and speed of sound) of DES1 and DES2 were determined in temperature range from 288.15 K to 333.15 K and at atmospheric pressure. Extraction ability of the investigated eutectics yielded promising results in comparison with conventional solvents. Besides a high selectivity towards ethanol, an advantage of DES2 is its lower viscosity and higher distribution ratio values, which is an important aspect for a potential industrial application. Another advantage of both investigated eutectics is their easy and high recoverability from the extract layer based on their negligible vapor pressure.

Salting-out effect on extraction of phenol from aqueous solutions by [Hmim][NTf2] ionic liquid: Experimental investigations and modeling

Abstract This study is concerned on the influence of sodium chloride, sodium sulfate and magnesium sulfate salts on the liquid–liquid equilibrium (LLE) of water + phenol + 1-hexyl-3-methylimidazolium bus(trifluoromethanesulfonyl)imide, [Hmim][NTf2], ionic liquid (IL) system under conditions of T = 298.2 K and ambient pressure of 81.5 kPa. The results showed that salting-out effect was significant and their effectiveness appeared in the order of MgSO4 > Na2SO4 > NaCl, as predicted by the Hofmeister series. Between the used 0.005 and 0.020 salt mass fractions in aqueous phase, the higher concentration was more effective especially at low phenol concentrations. In comparison with salt-free system, enhancements in the separation factor, within (20.55–96.56)% with NaCl, (51.94–154.58)% with Na2SO4 and (73.91–242.57)% with MgSO4 were achieved. The consistency of experimental data was examined with the improved version of Eisen-Joffe equation. Further, the NRTL and UNIQUAC thermodynamic models were satisfactorily used to correlate the phase equilibrium data and the appropriate interaction parameters were determined. Prediction of mass fraction tie-lines gives the maximum root-mean square deviations of only 0.0083 and 0.0367 for NRTL and UNIQUAC models, respectively.