Universal Quasichemical Activity Coefficient Research Articles

Liquid-liquid equilibria of the ternary systems water + C1 – C3 alcohols + dimethyl adipate at 298.15 K and atmospheric pressure: Experimental data and modeling

The aim of this study was to examine the possibility of using a green organic solvent, dimethyl adipate (DMA), as a separation agent in the extraction of different alcohols from aqueous solutions. For that purpose, the liquid–liquid equilibria (LLE) of four ternary systems were analytically determined at 298.15 K and atmospheric pressure using stirred and thermo-regulated cells: {water + methanol + dimethyl adipate (DMA)}, {water + ethanol + DMA}, {water + 1-propanol + DMA}, {water + 2-propanol + DMA}. Phase diagrams for these four ternary systems were obtained by determining a binodal curve and tie-lines data using a visual cloud-point method, but also gas chromatography. Distribution coefficients and separation factors were calculated for the immiscibility region. Hand and Othmer-Tobias correlations were used to examine the reliability of the tie-line data. In addition, the experimental ternary LLE data were correlated with the UNIversal QUAsiChemical (UNIQUAC) activity coefficient models. The obtained results showed that DMA is a suitable candidate for the extraction of methanol, ethanol, 1-propanol, and 2-propanol from water. With some alcohols, this potential is more noticeable than with others. The potential of DMA as a separation agent is increasing in the following sequence: methanol < ethanol < 2-propanol < 1-propanol, and that also could be noticed from the selectivity values that also increase in this sequence. The UNIQUAC model proved as successful in correlating the LLE data.

Isobaric Vapor-Liquid Equilibrium Data for Tetrahydrofuran + Acetic Acid and Tetrahydrofuran + Trichloroethylene Mixtures.

Vapor-liquid equilibrium (VLE) data for the binary systems tetrahydrofuran (THF) + acetic acid (AA) and THF + trichloroethylene (TCE) were measured under isobaric conditions using an ebulliometer. The boiling temperatures for the systems (THF + AA/THF + TCE) are reported for 13/15 compositions and five/six different pressures ranging from 50.2/60.0 to 101.1/101.3 kPa, respectively. The THF + AA system shows simple phase behavior with no azeotrope formation. The THF + TCE system does not exhibit azeotrope formation but seems to have a pinch point close to the pure end of TCE. The nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) activity coefficient models were used to accurately fit the binary (PTx) data. Both models were able to fit the binary VLE data satisfactorily. However, the NRTL model was found to be slightly better than UNIQUAC model in fitting the VLE data for both systems. The results can be used for designing liquid-liquid extraction and distillation processes involving mixtures of THF, AA, and TCE.

Vapor–Liquid Equilibrium for the Binary System of 2-Phenylethanol + 2-Ethylphenol at 50.0, 20.0, and 10.5 kPa

The vapor–liquid equilibrium (VLE) data for binary systems 2-PE and 2-EP were measured at 50.0, 20.0, and 10.5 kPa using a modified Rose equilibrium still. The Redlich–Kister area test and Fredenslund point test were applied to test the thermodynamic consistency of the VLE data, respectively. In addition, experimental data were successfully matched using nonrandom two-liquid (NRTL), Wilson, and Universal Quasi-Chemical (UNIQUAC) activity coefficient models. Binary interaction parameters (BIPs) corresponding to three models were obtained by maximum likelihood target function regression. This paper would help the distillation design of 2-phenylethanol and 2-ethylphenol in industrial applications.

Design Optimization of Deep Eutectic Solvent Composition and Separation Performance of Cyclohexane and Benzene Mixtures with Extractive Distillation

Deep eutectic solvents (DESs) have properties that make them suitable candidates to be used as entrainers for extractive distillation. In the previous work, it was proven that DES(1:2) (tetrabutylammonium bromide: levulinic acid, 1:2, molar ratio) can break the cyclohexane-benzene azeotrope. In the present work, the HBA and HBD ratio and molar concentration of DES were optimized to obtain a better constitute and condition of DES to be utilized in cyclohexane and benzene extractive distillation. The physical properties and structure of the prepared DESs were characterized. Vapor–liquid equilibrium data of the ternary system (benzene + cyclohexane + DESs) were also measured at atmospheric pressure. All experimental equilibrium data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity coefficient models, from which the coefficient of determination (R2) of the three pseudo-ternary systems fitting was calculated. From the obtained results, the best HBA and HBD ratio in the DESs is elucidated as 1:2, the best molar concentration of DES is 0.1, and the NRTL model predicts the experimental data more accurately than the Wilson and UNIQUAC models. From the derived mechanism, the formation of stronger hydrogen bond and π–π bond interactions between DES and benzene is obtained when HBA and HBD ratio in DES is 1:2. In other conditions, the azeotrope cannot be broken, or the efficiency is low. The present work provides an environmentally friendly method to separate aromatic/aliphatic mixtures and act as a guide for further study of DESs in extractive distillation.

Measurement and Correlation of Isobaric Vapor-Liquid Equilibrium Data for Water + 2-Azido-N,N-Dimethylethanamine System at 4 kPa

Isobaric vapor-liquid equilibrium (VLE) data for binary system of water + 2-azido-N,N-dimethylethanamine (DMAZ) was measured at 4 kPa. The results showed an azeotropic point at x1 = 0.985 and T = 302.17 K. The data was correlated with nonrandom two-liquid (NRTL), Wilson and universal quasi-chemical activity coefficient (UNIQUAC) models for the liquid phase. A comparison of the model performances was made using of the criterion of the average absolute deviation, standard deviation and mean standard deviation in boiling-point temperature. The results indicated that the NRTL activity coefficient model satisfactorily correlated the VLE data.

Development of Anhydrous Ethanol Purification: Reduction of Acetal Content and Vapor-Liquid Equilibrium Study of the Ethanol-Acetal Binary System.

Acetaldehyde diethyl acetal (herein called acetal) is an important pollutant of anhydrous ethanol. Isobaric vapor–liquid equilibrium (VLE) of an ethanol–acetal binary system was measured using a vapor condensate and liquid circulation VLE still. The experimental data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity coefficient models, which were found suitable for representing the VLE data. Proper agreements between experimental and calculated VLE data were obtained, which were then confirmed with consistency tests. The applicability of the novel VLE data was demonstrated during an investigation of an anhydrous ethanol purification column. Reduction of the concentration of acetal and other pollutants was examined and optimized in a flowsheet environment. The modeling results were verified in a laboratory with an experimental distillation column, confirming a correct agreement between the results. It must be highlighted that the developed method is suitable for the production of pharmacopeial quality anhydrous alcohol, based on reliable, verified VLE data. The results show the importance of accurate VLE data in critical compositions (low pollutant content); moreover, aiming at high product purity, experimental validation has paramount importance. The consistency between the three platforms (VLE and distillation experiments and flowsheet simulation) confirms the accuracy of the developed method.

Isothermal Vapour-Liquid Equilibrium Measurements for the butan-1-ol + butane-1,4-diol/butane-2,3-diol system within 353.2–388.2 K

In this study, the isothermal binary vapour-liquid equilibrium (VLE) data for the butan-1-ol + butane-1,4-diol/butane-2,3-diol system was measured and modelled, for use in the design and rating of separation processes. P-T-x-y equilibrium measurements were performed at four temperatures from approximately 353–388 K. A dynamic-analytical apparatus was utilized to perform the measurements at sub-atmospheric conditions. The measured data was modelled by employing the γ-Φ approach. The liquid-phase correction was accounted for using the Non-Random Two-Liquid and Universal Quasi-Chemical activity coefficient models while the Hayden and O'Connell correlation for the virial equation of state was used to account for the vapour-phase correction. Thermodynamic consistency tests were performed using the point and area tests for the measured experimental data and the data sets passed both tests.

Isobaric Vapor–Liquid Equilibrium Measurements and Modeling of Water + Monoethylene Glycol + NaCl Mixtures

Vapor−liquid equilibrium (VLE) data for aqueous systems in the presence of electrolytes have many industrial applications. VLE data for water + monoethylene glycol (MEG) mixtures in the presence of sodium chloride at low pressures are important to describe the effects of composition, temperature, and pressure on a MEG (gas hydrate inhibitor) regeneration unit. A modified version of the Othmer ebulliometer was applied to measure reliable VLE data for water + MEG + NaCl at 101.325, 65, and 35 kPa. Binary systems (water + MEG and MEG + NaCl) were also experimentally studied. Vapor pressures for water and MEG were determined and compared with the selected literature data via Antoine correlation. The electrolyte nonrandom two-liquid and universal quasi-chemical activity coefficient models were successfully parameterized to describe the VLE behavior for water + MEG + NaCl systems. Thermodynamic consistence of the data sets was also checked. Interaction parameter estimation followed a systematic strategy: (1) water−MEG, (2) water−NaCl, and finally (3) MEG−NaCl with the experimental data of MEG + NaCl and ternary data. MEG + NaCl solutions presented an inverted colligative property, that is, the addition of salt decreases the boiling point. VLE data indicated that water separation is less efficient due to the addition of salt. The parameterized models allow an evaluation of the MEG regeneration process as a function of temperature, pressure, and composition

Recycling of used lubricating oil by solvent extraction: experimental results, Aspen Plus simulation and feasibility study

This study investigates the recycling of used lubricating oil (ULO) by solvent extraction using a ternary solvent consisting of 2-propanol, 1-butanol and methyl ethyl ketone (MEK) followed by a vacuum distillation unit. In order to select the best combination of solvents for the liquid–liquid extraction process, many parameters were first evaluated on a laboratory scale such as the effect of the solvent composition, the solvent-to-oil ratio and the temperature. The oil recovery efficiency and the physicochemical properties of the oil obtained from the extraction process were measured, and the results showed that a ternary system consisting of 50% 1-butanol/25% isopropanol/25% MEK is the best mixture for effectively reducing the contaminants in ULO with a good sludge separation prior to the fractionation. Also, a solvent-to-oil ratio of 3:1 and a temperature of 25 °C are the optimal parameters for the extraction when the aforementioned solvent mixture is used. The whole re-refining process including the vacuum distillation unit was then simulated for a plant capacity of 2125 kg/h using Aspen Plus™. Four pseudo-components (saturate, monoaromatic, diaromatic and polyaromatic) together with the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) were used to describe the liquid–liquid equilibrium (LLE) in the system solvent/lubricating oils during the extraction phase. The calculated yields on the extraction unit performed for different solvent composition, solvent-to-oil ratio and temperature showed a good agreement with the experimental data performed at the laboratory scale which verifies the right choice of the solvent mixture. The investigation of the amount and composition of oil loss inside the sludge obtained from the simulation showed that the contaminant reduction and the oil recovery depend on the percentage of 1-butanol in the solvent mixture. Also, the results confirmed that the amount of MEK and 2-propanol in the solvent mixture should not exceed 25% and the best results were obtained when 1-butanol was used as a base solvent with an amount of 50%. Finally, to check the feasibility of the process, the investment payback time and the return on investment of the re-refining process were evaluated. Based on the economic study results, the production process was found to be highly profitable with a return on investment equal to 55% and a payout period of 1.9 years in the worst-case scenario where the price of lubricating oil is 2.5 $/L.

Vapor–liquid equilibrium at 94 kPa and surface tension at 298.15 K for hexane + ethanol + cyclopentyl methyl ether mixture

Vapor-liquid equilibrium (VLE) and surface tension (ST) for the hexane + ethanol + cyclopentyl methyl ether mixture have been measured and modeled. VLE determinations are carried out in a dynamic Guillespie type cell at the isobaric condition of 94 kPa, whereas the dependence of ST on concentration is measured in a maximum differential bubble pressure tensiometer at atmospheric pressure and 298.15 K.The thermodynamical consistent VLE data exhibit positive deviation from ideal behavior without ternary azeotropy and are well correlated by Redlich–Kister expansion and predicted by the binary nonrandom two-liquid, Wilson and universal quasichemical activity coefficient models. The ST data exhibit negative deviation from the linear behavior and are smoothed using the Myers-Scott expansion, showing no ternary aneotropic behavior.The experimental data of VLE and ST are accurately characterized by applying the square gradient theory to the Peng–Robinson Stryjek–Vera equation of state (EoS) appropriately extended to mixtures employing the modified Huron–Vidal mixing rule. This theoretical framework shows that experimental VLE and ST data can be fully predicted by only using binary contributions within a global average absolute deviation of 1.25% for VLE and 6.1% for ST. The theoretical approach also provides a route to explore the concentration distribution of species in the interfacial region, where it is possible to conclude that hexane exhibits both adsorption and desorption; ethanol displays strong positive adsorption whereas CPME does not exhibit surface activity.

Measurement and Correlational Study of Phase Equilibria in Aqueous Solutions of N,N-Dimethylacetamide with 1-Pentanol and 1-Hexanol at 298.15 and 308.15 K

Tie-line data were determined for the systems (water + N,N-dimethylacetamide + 1-pentanol) and (water + N,N-dimethylacetamide + 1-hexanol) at the temperatures of 298.15 and 308.15 K under 101.1 KPa. The phase diagrams for these systems are of type I according to the Treyball classification. The thermodynamic consistency of the measured tie-line data was verified using the Hand and Othmer–Tobias equations. The distribution ratios (D) and selectivity (S) values were computed according to the measured tie-line data to assess the extracting behaviors of the selected solvents. The experimental data were correlated using the nonrandom two liquid and the universal quasichemical activity coefficient equations and the Elephant Herding Optimization Algorithm (EHA). EHA is an emerging nature-inspired stochastic global optimization method, and it has been used for liquid–liquid equilibrium (LLE) parameter estimation of local composition models in multicomponent mixtures. The performance of this new swarm-based metaheuristic search method for LLE modeling with and without the closure equation has been analyzed.

Liquid–Liquid Equilibrium for the Ternary Systems Water + 1-Butanol + 1-Hexanol or 1-Octanol at 303.15, 313.15, and 323.15 K

Liquid–liquid equilibrium data (LLE) of ternary systems {water + 1-butanol + 1-hexanol} and {water + 1-butanol + 1-octanol} were investigated at 303.15, 313.15, and 323.15 K at 101.3 kPa. The distribution coefficient (D) and selectivity factor (S) were calculated from experimental LLE data. Meanwhile, the effect of temperature on the two-phase zone of the two systems was discussed. The nonrandom two liquid and universal quasi-chemical activity coefficient models were used to regress experimental data sets and generate the relevant binary interaction parameters. Both thermodynamic models provided similar good descriptions for the studied systems with root mean square deviations between the calculated and experimental values less than 0.3%.

Liquid-liquid equilibria data and thermodynamic modeling for quaternary system of methanol, dimethyl carbonate, toluene and water at 298 to 318 K

Liquid-liquid equilibria (LLE) data for a quaternary mixture of methanol, Dimethyl carbonate, toluene and water were measured at 298, 308, 318 K and atmospheric pressure. The distribution of methanol and dimethyl carbonate in the organic phase and aqueous phase were searched. Experimental tie-line data reliability of the quaternary mixture was validated using the Othmer-Tobias and Bachman correlation method. This experimental data were correlated with the nonrandom tow-liquid (NRTL) and the universal quasichemical activity coefficient (UNIQUAC) model. The interactive binary parameters of these two models have been reported. Both models successfully correlated experimental data.

Measurement and correlation of vapor–liquid equilibrium data for binary systems composed of camphene, (+)-3-carene, (-)-β-caryophyllene, p-cymene, and α-pinene at 101.33 kPa

Isobaric vapor-liquid equilibrium (VLE) data have been measured in a modified Ellis still for the following binary systems: camphene + p-cymene, camphene + α-pinene, (+)-3-carene + α-pinene, α-pinene + (-)-β-caryophyllene, and camphene + (-)-β-caryophyllene, at 101.33 kPa. The pressure was controlled by a U-shape mercury manometer and a WT3000 intelligent absolute pressure transmitter. The thermodynamic consistency of the VLE experimental data was checked using the Herington area test and Van Ness test. Afterwards, the VLE data were correlated by the nonrandom two-liquid (NRTL), Wilson and universal quasichemical (UNIQUAC) activity coefficient models, with the corresponding binary interaction parameters being regressed. The root mean square deviations of temperature (RMSD(T)) and vapor-phase mole fraction (RMSD(y)) are all less than 0.61 K and 0.0076, respectively. Additionally, the average absolute deviations of temperature (AAD(T)) and vapor-phase mole fraction (AAD(y)) are all less than 0.54 K and 0.0061, respectively. Hence, all of the aforementioned models are deemed to be suitable to calculate the VLE data of the binary systems. In addition, for camphene + (-)-β-caryophyllene system, NRTL shows the best fit. Across all the binary systems studied no azeotropic behavior was observed.

Liquid–Liquid Equilibrium for Ternary Systems of N-Methylformamide + Pyrrole/Indole + Alkanes at 298.15 K: Phase Equilibrium Measurement and Correlation

For the purpose of separating nitrogen compounds, pyrrole and indole, N-methylformamide (NMF) was selected as the extractive solvent. The liquid–liquid equilibrium (LLE) data for {NMF + pyrrole/indole + alkanes} systems were measured at 298.15 K under atmospheric pressure of 101.3 kPa. The triangular diagrams of the above eight systems, {NMF + pyrrole/indole + n-hexane/n-heptane/n-decane/n-dodecane}, were classified as Treybal’s type I. Meanwhile, the nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models were applied to correlate the LLE data, and the UNIQUAC model shows better agreement than the NRTL model. In addition, the distribution constant and selectivity factor were calculated on the basis of the experimental data and utilized to investigate the extraction capabilities of NMF for pyrrole and indole.

Modeling of wax and asphaltene precipitation in crude oils using four-phase equilibrium

A thermodynamic model is developed for predicting wax and asphaltene precipitation in crude oil mixtures with up to four phases, i.e. vapor, liquid, wax-rich and asphaltene-rich. The model adopts the experimentally supported hypothesis that asphaltenes precipitate before waxes with decreasing temperature and aggregate as the nucleus of wax crystals. The simplified perturbed chain statistical associating fluid theory (sPC-SAFT) equation of states (EOS) is applied in order to describe phase behavior in crude oils. In this research, a characterization method is proposed for mixtures containing asphaltenes and waxes using the sPC-SAFT EOS. And a correlation is modified for prediction of binary interaction parameter for the sPC-SAFT based on measured binary solid solubilities of twelve n-alkane mixtures. The universal quasi chemical activity coefficient (UNIQUAC) model is used to account for the non-ideality of the wax-rich phase. It is shown that the cloud point and the amount of wax and asphaltene precipitates obtained in the proposed model have an excellent agreement with the experimental data.

Liquid-liquid equilibrium measurement and thermodynamics modeling for the systems water + thioglycolic acid + isopropyl ether/methyl tert-butyl ether at 298.15 and 308.15 K

To separate thioglycolic acid (TGA) from its aqueous mixture, isopropyl ether and methyl tert-butyl ether were adopted as extractants, and the liquid-liquid equilibrium data for the ternary systems water + TGA + isopropyl ether/methyl tert-butyl ether were determined at 298.15 K and 308.15 K under pressure of 101.3 kPa. The influence of the different extractants and temperatures on the phase behavior was explored. In addition, the measured experimental data were correlated by the nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models, and the binary interaction parameters of the two models were also optimized.

Isobaric Vapor–Liquid Equilibrium for Binary and Ternary Systems of tert-Butanol + tert-Butyl Acetate + Chlorobenzene at 101.33 kPa

Isobaric vapor–liquid equilibria of tert-butanol + chlorobenzene and tert-butyl acetate + chlorobenzene binary systems and the tert-butanol + tert-butyl acetate + chlorobenzene ternary system at 101.33 kPa were measured using a circulation VLE still. The data of binary systems passed the thermodynamic consistency test of the Herington method and the Van Ness point test, and the experimental data of the ternary system also passed the Wisniak consistency test. These binary systems’ VLE data were fitted by the Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity coefficient models with minor deviations. Furthermore, the obtained binary interaction parameters from the binary systems were used to predict the VLE behavior of the tert-butanol + tert-butyl acetate + chlorobenzene ternary system. The rmsd of vapor and the temperature between the experimental and predicted values for the ternary system were smaller than 0.0304 and 0.81K, respectively. The results indicated that the re...

Measurement and modeling of isobaric vapor – Liquid equilibrium and isothermal interfacial tensions of ethanol + hexane + 2,5 – Dimethylfuran mixture

Isobaric vapor-liquid equilibrium data have been measured for the ternary system ethanol + hexane + 2,5 – dimethylfuran at 94 kPa and in the temperature range 330–344 K. Equilibrium determinations were performed in a vapor-liquid equilibrium still with circulation of both phases. The dependence of interfacial tensions of the ternary mixture on concentration was also experimentally determined at atmospheric pressure and 298.15 K, using the maximum differential bubble pressure technique.From the experimental results, it follows that the ternary mixture exhibits positive deviation from ideal behavior. Furthermore, the determined interfacial tensions exhibit negative deviations from the linear behavior, and ternary aneotropy is observed.The vapor-liquid equilibrium (VLE) data of the ternary mixture past the consistency test and were well correlated by Redlich–Kister expansion and predicted by the nonrandom two-liquid (NRTL), Wilson and universal quasichemical (UNIQUAC) activity coefficient models using binary parameters only. The interfacial tensions (IFT) were smoothed using the Myers-Scott expansion, showing an important contribution of parameters that describe three-body interactions, thus suggesting that the ternary interfacial tensions data cannot be initially predicted from the binary contributions.The experimental isobaric VLE and isothermal IFT data of the ternary mixture were accurately characterized by applying the linear square gradient theory to the Peng–Robinson Stryjek–Vera equation of state (EoS) appropriately extended to mixtures by means of the modified Huron–Vidal mixing rule. This model allows directly transferring the experimental excess Gibbs energy function to the EoS model for equilibrium and interfacial tension calculation purposes. This theoretical framework shows that both experimental VLE and IFT data can be accurately predicted by using binary contributions and provide a route to interpolate values phase equilibrium and interfacial tension.

Phase boundaries for synthetic light oils and gas condensate mixtures using predictive equations of state with a solid solution model

AbstractPhase boundaries for five synthetic paraffinic mixtures were predicted using a previously developed Gibbs energy minimization algorithm. In this method, the vapour and liquid phases were described by cubic equations of state (EoS). These EoS employed a predictive temperature‐dependent group‐contribution binary interaction parameter model. The solid phase was described using a universal quasi‐chemical activity coefficient (UNIQUAC) solid solution model. Using this algorithm, the phase boundaries were calculated from a temperature‐search strategy. The predicted phase boundaries were found to be in good agreement with experimental phase boundaries for vapour‐liquid (VL), solid‐liquid (SL), solid‐vapour (SV), and solid‐vapour‐liquid (SVL) regions. The model was also used to predict the phase boundaries at low temperatures where no experimental data were available.