Liquid Equilibrium Behavior Research Articles

Solid–Liquid Equilibrium Behavior and Thermodynamic Analysis of Dibenzoylmethane in Different Pure and Binary Solvent Systems from 278.15 to 318.15 K

Solid–Liquid Equilibrium Behavior and Thermodynamic Analysis of Dibenzoylmethane in Different Pure and Binary Solvent Systems from 278.15 to 318.15 K

Experimental measurement and thermodynamic modelling of ethenzamide solubility in three binary solvent systems

The solid–liquid phase equilibrium of ethenzamide (ETZ), a classic anti-inflammatory drug, in binary solvent systems was experimentally investigated and simulated. The equilibrium solubility of ETZ in binary solvent mixtures of methanol + acetonitrile, ethanol + acetonitrile, and isopropanol + acetonitrile was determined via a gravimetric method at temperatures ranging from 293.15 K to 323.15 K at atmospheric pressure (0.1 MPa). In all binary solvent systems, the solubility of ETZ increases with the increasing of temperature at a given solvent composition, but it initially increased and then decreased with the increase in alcohol composition (good solvent). Additionally, the Jouyban-Acree, van’t Hoff-Jouyban-Acree, Apelblat-Jouyban-Acree, and Ma models were utilized to correlate the experimental data. Results showed that the Jouyban-Acree model achieved the best correlation performance. Molecular dynamic simulation and radial distribution function analysis revealed the cooperation effect originating from solute-solvent and solvent–solvent interactions, which explained the dissolution behaviors of ETZ in various solvent mixtures. Calculations of dissolution thermodynamic properties, including enthalpy, Gibbs free energy, and entropy, revealed that the dissolution behavior of ETZ was an endothermic and entropy-driven process. This study provides insights into modulating ETZ crystallization and in understanding solid–liquid phase equilibrium behaviors in mixed solvent systems.

Hydrophobic Deep Eutectic Solvents for the Recovery of Bio-Based Chemicals: Solid–Liquid Equilibria and Liquid–Liquid Extraction

The solid–liquid equilibrium (SLE) behavior and liquid–liquid extraction (LLX) abilities of deep eutectic solvents (DESs) containing (a) thymol and L-menthol, and (b) trioctylphosphine oxide (TOPO) and L-menthol were evaluated. The distribution coefficients (KD) were determined for the solutes relevant for two biorefinery cases, including formic acid, levulinic acid, furfural, acetic acid, propionic acid, butyric acid, and L-lactic acid. Overall, for both cases, an increasing KD was observed for both DESs for acids increasing in size and thus hydrophobicity. Furfural, being the most hydrophobic, was seen to extract the highest KD (for DES (a) 14.2 ± 2.2 and (b) 4.1 ± 0.3), and the KD of lactic acid was small, independent of the DESs (DES (a) 0.5 ± 0.07 and DES (b) 0.4 ± 0.05). The KD of the acids for the TOPO and L-menthol DES were in similar ranges as for traditional TOPO-containing composite solvents, while for the thymol/L-menthol DES, in the absence of the Lewis base functionality, a smaller KD was observed. The selectivity of formic acid and levulinic acid separation was different for the two DESs investigated because of the acid–base interaction of the phosphine group. The thymol and L-menthol DES was selective towards levulinic acid (Sij = 9.3 ± 0.10, and the TOPO and L-menthol DES was selective towards FA (Sij = 2.1 ± 0.28).

Kinetic modeling and experimental investigations of dry reforming of methanol over a Cr-Mo-Mn/SiO2 catalyst

To derive a kinetic model for dry reforming of methanol, the experimental investigations were accomplished at vast working conditions (i.e., temperature: 500 °C–900 °C and CO2/CH3OH ratio (C/M) of 1–2.5) on Cr-Mo-Mn/SiO2 catalyst. The kinetic model developed based on the Langmuir–Hinshelwood (LH) approach and mechanism contained three reversible reactions on three types of active sites. The results of the statistical analysis presented that kinetic model parameters were statistically significant. The error of the suggested kinetic model was 9.87% using equation state (EoS) of Soave–Redlich–Kwong on the basis of modified Huron–Vidal mixing rule (SRK/MHV2) applied to evaluate vapor–liquid equilibrium behavior. The highest precision in predicting the experimental data by the suggested kinetic model was assigned to methanol conversion. The outcomes presented the high temperature is suitable for higher CO yield, methanol and CO2 conversions. An augmentation in carbon dioxide percentage of the inlet feed led to enhance in CO yield, methanol and CO2 conversions, while H2 yield was decreased.

Vapor–liquid behavior of phenol and cumene in ternary and quaternary mixtures

AbstractBACKGROUNDAlthough phenol is a key intermediate in the plastics and polycarbonate industry, it is also a toxic component that requires removal from dilute aqueous streams, potentially by liquid–liquid extraction (LLX). For LLX, cumene is suggested as a solvent as it is already present in processes in the polycarbonate industry. For the recovery of cumene from phenol by distillation, knowledge on vapor–liquid equilibrium (VLE) behavior is important, in combination with how this is affected by other components possibly present as an impurity or explicitly added as a solvent. This was investigated in this work.RESULTSThe binary cumene–phenol system shows a tangent pinch in the binary VLE diagram. Addition of a range of impurities and solvents showed that hydrogen bond accepting compounds strongly improve the relative volatility of the mixture, whereas dodecane, not capable of forming hydrogen bonds, has a negative effect on the relative volatility.CONCLUSIONAddition of polar components with hydrogen bonding abilities, i.e. ketones or ethers, affected the relative volatility of cumene over phenol the most positively. Combining two types of components results in similar effects, and clear synergistic effects could not be shown based on current VLE measurements. Addition of an apolar component in combination with polar components with hydrogen abilities had only a minor effect on the relative volatility. © 2021 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Isothermal measurement and modeling of VLE properties for 2,3,3,3-tetrafluoroprop-1-ene + trifluoromethane + tetrafluoromethane ternary system at temperatures from 253.15 K to 273.15 K

Abstract At present, the difficulty in the research of auto cascade refrigeration system lies in the selection of the mixed refrigerant ratio and the design of system process. Accurate thermodynamic data is the key to solve those problems. In this paper, isothermal vapor liquid equilibrium (VLE) behavior was experimentally studied for the strongly-zeotropic ternary mixture 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) + trifluoromethane (R23) + tetrafluoromethane (R14) at 253.15 K, 263.15 K, and 273.15 K. The pressures and the vapor mass fractions were found to be thermodynamically consistent and were satisfactorily correlated with the NRTL-RK model and the MUNIFAC-SRK model. The average absolute relative deviations of pressure (AARD-p), and the average absolute deviations of vapor phase mass fraction (AAD-y1, AAD-y2 and AAD-y3) are less than 0.25%, 0.0032, 0.0048 and 0.0040 for the MUNIFAC-SRK model, respectively, which are better than those of 0.4%, 0.0138, 0.0198 and 0.0049 for the NRTL-RK model. The results of the MUNIFAC-SRK model showed excellent agreement with the experimental values. The isothermal three-dimensional VLE behavior and the isothermal-isobaric ternary VLE diagrams under 1500 kPa were also established using a flash calculation method.

Investigation of carbon dioxide capture and storage by a novel LSSVM-GA method

Accurate knowledge about vapor–liquid equilibrium (VLE) and phase behavior of impure carbon dioxide has noticeable effect on designing carbon dioxide capture and storage (CCS) processes. In the current work, a novel computational method namely least square support vector machine (LSSVM) was used to predict VLE of binary system of carbon dioxide with nitrogen, hydrogen, oxygen, and argon. To this end, two models based on LSSVM were developed for vapor and liquid phases. The accuracy of predicting models was investigated by different methods. The results express that the proposed algorithms are dependable for the estimation of phase behavior of impure CO2.

Effect of Ionic liquids on vapor liquid equilibrium of Methanol + Ethyl acetate

The objective of this research work is to determine the effect of ionic liquids on the vapor liquid equilibrium behaviour of methanol and ethyl acetate binary system at atmospheric pressure. The ionic liquids used in the experiments are: 1-ethyl-3-methylimidazolium Chloride [EMIM][Cl], 1-ethyl-1-methylpyrrolidinium Bromide [EMPyrr][Br]. VLE experiments were conducted with Othmer still experimental setup and the VLE data sets were tested for thermodynamic consistency. Experimental results average deviations were within the experimental toleration limits and satisfied the Gibbs-Duhem equation. The results showed that the addition of ionic liquids (ILs) caused salting-out of methanol from the system. For the same concentrations of the ionic liquids, [EMIM][Cl] is observed to be more effective than the [EMPyrr][Br] in breaking the azeotropes and in increasing the salting effect. For the 15% concentration of [EMPyrr][Br] the azeotrope was completely disappeared.

Improved Design of Maximum-Boiling Phenol/Cyclohexanone Separation with Experimentally Verified Vapor–Liquid Equilibrium Behaviors

There are very few papers in the open literature studying the design of extractive distillation system for separating maximum-boiling mixtures. Using the knowledge of the curvature of the distillat...

Thermodynamic analysis of phase equilibrium and surface tension of ternary polymer solutions

AbstractThe liquid–liquid equilibrium (LLE) and surface behavior of polymer solutions were investigated. Systems of poly vinyl methyl ether (PVME)/water and polystyrene (PS)/cyclohexane were chosen as model systems because they show different types of LLE and surface behavior. Ternary polymer solutions of PVME/water/alcohol and PS/cyclohexane/alcohol were also studied. The cloud points of given systems were determined by thermo‐optical analysis method. For surface tension measurements at the air/polymer solution interface, the well‐known plate method was utilized. The investigated polymer solutions exhibit various types of LLE and surface behavior depending on the type of solvent and temperature. The modified double lattice model with chain length dependence is used for description of the phase equilibrium. To improve the interpretation of the surface behavior of the polymer solution, we developed a new thermodynamic frame work based on density gradient theory. Thermodynamic analysis was also conducted using the proposed model to provide understanding of the surface behavior. The surface energy difference and interchange energy had an important role in the driving force of the surface behavior. Utilizing the predetermined model parameters from the phase equilibrium calculation, the proposed model provides satisfactory agreement with measured surface tension data, with less than 5% error.

Liquid–Liquid Equilibrium for Systems Containing Epoxidized Oils, Formic Acid, and Water: Experimental and Modeling

AbstractEpoxidized oils are eco‐friendly plasticizers, which are industrially produced through the epoxidation reaction in a formic acid‐hydrogen peroxide autocatalyzed system. The fundamental knowledge to describe the phase equilibrium of systems after epoxidation reaction is lacking, which is crucial for the design of the purification facilities. This work reported experimental data for the liquid–liquid equilibrium of three systems, i.e., epoxidized fatty acid methyl esters + formic acid + water, epoxidized fatty acid 2‐ethylhexyl esters + formic acid + water, and epoxidized soybean oil + formic acid + water, in the temperature range (303.15–348.15) K under atmospheric pressure. The results indicated that the liquid–liquid equilibrium constant of formic acid in the systems followed the order of epoxidized fatty acid 2‐ethylhexyl esters > epoxidized fatty acid methyl esters > epoxidized soybean oil. Moreover, the obtained experimental data were correlated using nonrandom two liquid (NRTL) and universal quasi chemical (UNIQUAC) models. The maximum root mean square deviation (RMSD) values as low as 0.0052 and 0.0263 were estimated using the NRTL and UNIQUAC model, respectively. The NRTL model is more suitable than the UNIQUAC model to describe the liquid–liquid equilibrium behavior of these ternary systems.

CO2 Solubility in Physicochemical Absorbent: Dibutyl Ether/N-Methylethanolamine/Ethanol

In this work, a physicochemical absorbent was proposed for CO2 capture, which consists of dibutyl ether as physical solvent, N-methylethanolamine (NMEA) as chemical additive, and ethanol as dissolvent. The vapor–liquid equilibrium behavior of this CO2 + physicochemical absorbent system was measured using an isothermal synthetic apparatus. The solubility data of CO2 in ethanol at 313.15 K were measured and compared with literature data to verify the validity of this method. Then, the CO2 solubility data of above system with varying NMEA mass fractions of 15 %, 25 %, and 50 % were, respectively, measured at 298.15 K. It shows that the CO2 solubility increases when NMEA mass fraction goes up. The CO2 solubility data in the absorbent with 25 % NMEA mass fraction were measured at a temperature range from 298.15 K to 328.15 K with the interval of 10 K and at a pressure range from 0 MPa to 3 MPa. The result shows that CO2 turns out to be more soluble in the physicochemical absorbents than in dibutyl ether at the same conditions of temperature and pressure.

Hansen solubility parameters and thermodynamic modeling for LLE description during glycerol-settling in ester production from coconut oil

The liquid–liquid equilibrium behavior is important when describing the separation of components involved in alkyl ester production during the glycerol-settling step. Therefore, this study presents original data on a liquid–liquid equilibrium system composed of glycerol + ethanol + ethyl esters from coconut oil at 298 K using an untapped approach based on the Hansen solubility parameters describing the individual ethyl ester distribution between the glycerol and ester rich phases. The difference in average molar masses of the ester mixtures in both phases when compared to fatty acid alkyl ester in overall composition reaches more than 10% depending on the ethanol content in the overall composition. The individual partition of ethyl esters in the glycerol-rich phase increases as result of the decrease in molecular size of this class of components. This behavior was shown based on the smaller difference in Hansen solubility parameters among esters with less carbon and the glycerol-rich phases as compared to esters with longer carbon chain atoms. Deviations between the experimental and calculated mass fractions were 0.83%, 4.07%, and 0.87% when using NRTL, UNIFAC-LLE, and UNIFAC-OHgly.

The influence of temperature on the phase behavior of ionic liquid aqueous two-phase systems

In this article, the equilibrium behavior of solutions of 1-ethyl-3-methylimidazolium dimethyl phosphate ([Emim]DMP) and ethyl acetate or acetone in aqueous two-phase system (ATPS) was discussed to understand the liquid–liquid equilibrium (LLE) behavior of these organic solvents. Thus, we determined phase diagrams and LLE data at 303.15, 308.15, 313.15, and 323.15 K for the investigated biphasic systems. Four empirical equations were used to study the tie lines. The results showed that for the [Emim]DMP + acetone + water biphasic systems within the investigated temperature range, temperature influences the phase behavior, but for the [Emim]DMP + ethyl acetate + water biphasic systems within the investigated temperature range, there are no notable changes on the phase behavior with rising temperature. The results may have important applications for the separation of antibiotics and for the recovery of ionic liquids (ILs).

Vapour–liquid equilibrium study of binary mixtures of aniline with isopropanol, n-butanol and ethylene glycol at the local atmospheric pressure

ABSTRACTThe present work analyses the vapour–liquid equilibrium (VLE) behaviour of the binary systems of aniline with isopropanol, n-butanol and ethylene glycol. The isobaric VLE data have been generated at the local atmospheric pressure of 96.15 kPa for all the binary systems of aniline. A dynamic type vapour–liquid circulating VLE still was used for generating the data. Calibration curves were generated using mole fraction and refractive index data for all pairs for composition measurement. The VLE data, generated in T-x,y form for all pairs, were found thermodynamically consistent through the Herington area test and the mean absolute deviation test. Activity coefficient models, Wilson, NRTL and UNIQUAC, were fitted to the data to estimate binary interaction parameters using an objective function of minimising the deviation between the experimental and the calculated total pressure and vapour composition. The experimental data were compared with the model predictions with the estimated parameters and the model predictions were found appropriate. The binary system of aniline and ethylene glycol was found to exhibit azeotropic behaviour at 0.61 mole fraction aniline and 445.1 K.

Solubility of p-Aminobenzoic Acid Potassium in Organic Solvents and Binary (Water + Isopropyl Alcohol) Mixture at Temperatures from (283.15 to 318.15) K

The solid–liquid equilibrium behavior of p-aminobenzoic acid potassium (KPAB) in pure organic solvents and binary (water + isopropyl alcohol) solvents were determined over the temperature range (283.15–318.15) K using a laser dynamic method. It was found that KPAB is easily dissolved in water, polyhydroxy alcohols and amides; slightly soluble in ethyl acetate, isopropyl alcohol, and n-propanol. The solubility of KPAB in both the mono- and binary mixed solvents increases with the increasing temperature, whereas it decreases with the rise of mole fraction of isopropyl alcohol in binary (water + isopropyl alcohol) mixed solvents. The solubility in pure solvents was correlated by the modified Apelblat equation, and the solubility in binary mixed solvents was correlated with the modified Apelblat equation and Combined Nearly Ideal Binary Solvent/Redlich–Kister (CNIBS/R-K) model. All the models give satisfactory correlation results with an average relative deviation (ARD) less than 2.5%, which provide basic dat...

Effect of bis(trifluoromethylsulfonyl)imide-based ionic liquids on the isobaric vapor - liquid equilibrium behavior of ethanol + dimethyl carbonate at 101.3 kPa

Isobaric vapor - liquid equilibrium (VLE) data for the binary system of ethanol + dimethyl carbonate (DMC) and the ternary systems of ethanol + DMC + 1-hexyl-3-methylimidazolium bis[(trifluoromethyl) sulfonyl] imide ([HMIM][NTf2]) and ethanol + DMC + 1-butyl-3-methylimidazolium bis[(trifluoromethyl) sulfonyl] imide ([BMIM][NTf2]) were obtained by using a modified Othmer still at a constant pressure of 101.3 kPa. The experimental results indicated that both [HMIM][NTf2] and [BMIM][NTf2] had a notable effect on the azeotropic system of ethanol - DMC. The NRTL model was used in this work to correlate VLE data and the calculated data agreed well with the experimental value. The minimum mole fractions of [HMIM][NTf2] and [BMIM][NTf2] needed to eliminate azeotrope were 0.125 and 0.170 calculated by NRTL model, respectively. And the [HMIM][NTf2] was found to be a better candidate of entrainer for separating the ethanol - DMC azeotrope.

Screening of ionic liquids as entrainers for the separation of 1-propanol + water and 2-propanol + water mixtures using COSMO-RS model

ABSTRACTThe COSMO-RS model was used to screen potential ionic liquids for the separation of aqueous azeotropic mixtures 1-propanol + water and 2-propanol + water. A combination of 22 cations (involving imidazolium, pyridinium, pyrrolidinium, quinolinium, and ammonium) and 36 anions were investigated. The anions chloride [Cl] and dihydrogen phosphate [H2O4P] were found to strongly influence the vapor liquid equilibrium behavior, whereas the ammonium-based cations diethanol ammonium [(Et)2AMM]+ and tetra methyl ammonium [M4AMM]+ were the most promising cations. In addition, the study of mixing enthalpy and excess Gibbs free energy confirmed that the molecular interaction of ionic liquids with water was found to be much larger than that with alcohols 1-propanol and 2-propanol, indicating the presence of a strong hydrogen bonding between the ionic liquids and water. Further, the addition of ionic liquids to the alcohol–water mixture reduces the activity coefficient of water and increases the relative volatility of the mixture, facilitating easier separation. Ionic liquids [(Et)2AMM][Cl], [(Et)2AMM][H2O4P], [M4AMM][Cl], and [M4AMM][H2O4P] are expected to be effective entrainers for the separation of the industrially important 1-propanol + water and 2-propanol + water systems.

Thermodynamic modelling of scale (Calcite, Barite, Anhydrite and Gypsum) deposition from brine

Abstract Solid – liquid equilibrium (SLE) behaviour of four scales of Calcite, Barite, Anhydrite and Gypsum in water has been investigated in the ranges of 0–250 °C and 1–1500 bar. Solubility of the abovementioned scales in water is calculated considering Saturation Index (SI) model, and Pitzer's theory is applied to calculate the activity coefficients. Good agreement has been achieved between the model results and the literature data. To identify the best activity coefficient model among e-NRTL, e-UNIQUAC and Pitzer approaches, activity coefficients of the above said chemicals have been calculated at different thermodynamic conditions with respect to the available data collected from the literature and the results have been compared to the experimental data. It is shown that the most precise model is Pitzer's one and the second accurate model is e-UNIQUAC.

Vapor-liquid equilibrium (VLE) of CO2 in aqueous solutions of benzylamine: New data and modeling using ENRTL-equation

In this work, new experimental data of carbon dioxide (CO2) solubility in aqueous benzylamine (BZA) solutions were generated at 313.15K, 323.15K, 333.15K and 343.15K, with the BZA concentrations of 5, 10, 20, 30mass% and pressure up to 190kPa. A rigorous thermodynamically consistent model based on Electrolyte Non-Random Two-Liquid (ENRTL) theory has been developed to correlate and predict the vapor liquid equilibrium behavior of CO2 in aqueous BZA. The model predicted CO2 solubility is in good agreement with experimental data showing 19% average absolute deviation (AAD). The model is also utilized to estimate equilibrium liquid phase speciation; pH of the CO2 loaded aqueous BZA solutions and heat of CO2 absorption (∼80kJ/mol).