Liquid Equilibrium Behavior Research Articles

Separation of 2-ethoxyethanol from wastewater by four esters: Correlation of LLE thermodynamic modeling, influence of molecular structure, and investigation of component interactions

To prevent the wastewater containing 2-ethoxyethanol (2EE) from causing environmental pollution and economic waste, liquid–liquid extraction was used to recover 2-ethoxyethanol from wastewater in this study. The liquid–liquid equilibrium behavior of water + 2-ethoxyethanol + four solvents (propyl acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate) was investigated at 303.2 K and atmospheric pressure. The distribution coefficient (D) and separation factor (S) were used to compare and discuss the extraction efficiency of each system. The results indicated that all esters could effectively separate 2-ethoxyethanol from water. Among them, isobutyl acetate exhibited the highest values for D and S, demonstrating its superior separation capability. The experimental data were correlated with the thermodynamic model and interaction parameters were obtained. These parameters were verified using the GUI-MATLAB tool, and all four systems passed validation, confirming the reliability of the obtained binary interaction parameters. Furthermore, the root mean square deviation (RMSD) was used to assess the deviation between the experimental and regression values. The RMSD values for the NRTL and UNIQUAC models were 0.008 and 0.007, respectively. The interactions between 2-ethoxyethanol and water or esters were explored using σ-Profile, and it was found that esters with a branched chain structure provided better extraction. To explain the properties of the extractants microscopically, the interaction energies between 2-ethoxyethanol molecules and water or ester molecules, as well as the non-bonding energies of 2-ethoxyethanol in different media, were calculated.

The insight into the separation of erucic acid, palmitic acid, and nervous acid in Acer truncatum seed oil from solid–liquid phase equilibrium and eutectic behaviors

The insight into the separation of erucic acid, palmitic acid, and nervous acid in Acer truncatum seed oil from solid–liquid phase equilibrium and eutectic behaviors

Insights into solid–liquid equilibrium behavior of 2′,4′-Dichloro-5′-fluoroacetophenone

2′,4′-Dichloro-5′-fluoroacetophenone is a key intermediate in the preparation of ciprofloxacin hydrochloride, a broad-spectrum quinolone antibacterial drug. Wherein, crystallization and solid–liquid equilibrium thermodynamics play an irreplaceable role in the separation and purification of 2′,4′-Dichloro-5′-fluoroacetophenone. Therefore, in this work, the solubility of 2′,4′-Dichloro-5′-fluoroacetophenone was measured by dynamic method in eight different solvents and range from 273.15 K to 288.15 K. The results showed that the solubility of 2′,4′-Dichloro-5′-fluoroacetophenone increased with increasing temperature. Further analysis showed that the solubility of 2′,4′-Dichloro-5′-fluoroacetophenone increased with increasing carbon chain length in ester solvents. Single crystals of 2′,4′-Dichloro-5′-fluoroacetophenone were successfully prepared and the result reveals that the Cl⋯H, O⋯H, and F⋯H interactions dominated the packing and long-range order of the crystals. Then, different thermodynamic models were employed to describe the thermodynamic behavior of 2′,4′-Dichloro-5′-fluoroacetophenone. The calculated ARD% and RMSD values show that the correlation results are in good agreement with the experimental data, and the Van’t Hoff equation has the best regression performance. Finally, it is interesting to find that the contribution of entropy and enthalpy change to dissolution of 2′,4′-Dichloro-5′-fluoroacetophenone tends to be equal with increasing temperature.

Revealing Solid–Liquid Equilibrium Behavior of 4-Fluorobenzoic Acid in 12 Pure Solvents from 283.15 to 323.15 K by Experiments and Molecular Simulations

Revealing Solid–Liquid Equilibrium Behavior of 4-Fluorobenzoic Acid in 12 Pure Solvents from 283.15 to 323.15 K by Experiments and Molecular Simulations

Measurements and modeling of liquid–liquid equilibrium for epichlorohydrin, water, and different extractants at 303.2 K

In order to remove epichlorohydrin from wastewater, liquid–liquid equilibrium behaviors in the systems {water + epichlorohydrin + solvents (1-hexanol/1-heptanol/2-octanol/1-nonanol)} were determined at 303.2 K under101.3 kPa. The partition coefficients and separation factors in each system were used to compare and discuss the effects of extraction. The σ-profiles were used to discuss the interactions of substances in this work. The experimental data were correlated with the NRTL and UNIQUAC models, to obtain the binary interaction parameters required for each system. The GMcal_TieLinesLL GUI tools were applied to verify the consistency of the binary interaction parameters.

Investigation on solid–liquid equilibrium behavior of 4-cyanobenzoic acid in fourteen mono-solvents: Determination, correlation, molecular simulation and thermodynamic analysis

4-Cyanobenzoic acid (4-CyBZA) is an important pharmaceutical intermediate, and the research on solubility behavior of 4-CyBZA in organic solvents is very necessary for its crystallization and separation processes. Therefore, this study aimed at exploring dissolution behavior of 4-CyBZA in several pure solvents via experiment, calculation, and simulation process. In this study, mole-fraction solubility values of 4-CyBZA in fourteen common solvents including four low alcohols (methanol (MeOH), ethanol (EtOH), n-propanol (NPOH), n-butanol (NBOH)), four acetates (methyl acetate (MeAC), ethyl acetate (EtAC), n-propyl acetate (NPAC), n-butyl acetate (NBAC)), two alcohol ethers (2-ethoxyethanol (EGEE), 2-methoxyethanol (EGME)) as well as four common heteroatom/heterocyclic solvents (acetonitrile (MeCN), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), 1,4-dioxane (Diox)) were critically measured by using laser monitoring method from 278.15/288.15 K to 323.15 K under 100 kPa. Interestingly, experimental results indicated that an increase in temperature facilitated the dissolution of 4-CyBZA in selected 14 solvents. At the same time, the solubility curve underwent a crossover phenomenon. At 298.15 K, the common order of 4-CyBZA solubility was: DMF > EGME > EGEE > NMP > Diox > MeOH > MeAC > EtOH > EtAC > NPAC > NPOH > NBOH > NBAC > MeCN. The Hansen solubility parameter (HSP) was introduced to analyze solubility behavior via molecular similarity between 4-CyBZA and chosen solvents. Molecular modeling including Hirshfeld surface (HS) analysis and molecular electrostatic potential surface (MEPS) were employed to understand internal interactions within 4-CyBZA crystals. Moreover, solubility was fitted by Margules model, NRTL model, NRTL-SAC model, UNIQUAC model as well as a combined model (Jouyban model). Results showed that NRTL and NRTL-SAC model were more suitable for correlating 4-CyBZA solubility with absolute temperature. Furthermore, given the high accuracy of the NRTL model, dissolution thermodynamic characteristics of 4-CyBZA in chosen solvents were analyzed by NRTL model, which revealed that the dissolving process and mixing process were spontaneous and entropy-driven.

Solid-liquid equilibrium of glucosamine hydrochloride in four binary solvents: Experiments, modeling, and molecular simulation

Glucosamine hydrochloride (GAH) is a marine biological preparation derived from natural chitin and improves articular cartilage metabolism. In this study, the solubility of GAH in four binary solvents (water + methanol, water + ethanol, water + isopropanol, and water + acetone) was gravimetrically determined over the temperature range of 283.15 K to 323.15 K. The solubility of GAH were found increasing monotonically with water content and temperature. In alcohol mixtures, the solubility of GAH can be ranked as: (water + methanol) > (water + ethanol) > (water + isopropanol). Four thermodynamic models (the modified Apelblat equation, van't Hoff equation, (CNIBS)/R-K model and Jouyban-Acree model) were used to correlate the experimental solubility data, which the (CNIBS)/R-K model showed the best fitting performance. The dissolution thermodynamic properties of GAH were also calculated. The results indicate that the dissolution process is driven by both entropy and enthalpy. To explore the solid–liquid equilibrium behavior from molecular level, the Hirshfeld surface of GAH crystal was generated and molecular dynamics simulations of mixed systems were performed. Based on equilibrium configurations of different mixtures, molecular interactions between solvent–solvent and solute–solvent were calculated. Meanwhile, the simulation snapshots and radial distribution function plots were analyzed to interpret association of solvents.

Thermodynamic analysis and molecular dynamic simulation of solid–liquid equilibrium behavior of antipsychotic drug aripiprazole (Form III) in three binary solvent mixtures

Aripiprazole (APZ), an effective second-generation antipsychotic drug indicated for the treatment of schizophrenia, was chosen to investigate its solubility in three binary solvent mixtures at the temperature range of 278.15–318.15 K. Due to clinical usage Form III is metastable, and the solubility was studied via the synthetic method. It was found that in the butanone + acetone and butanone + ethyl acetate mixed solvent systems, the solubility values of APZ Form III increased with the increase of the proportion of butanone solvent, and the maximum mole fraction solubility at each selected temperature point ranges from 0.001924 to 0.009015. However, in the mixed solvent system of butanone and n-propanol, the solubility of APZ Form III reaches its maximum when the molar fraction of butanone is 0.6 with the maximum mole fraction solubility at each selected temperature point ranging from 0.003126 to 0.012721. The modified Apelblat model, λh model, Van’t Hoff model, and NRTL model were used to correlate the experimental solubility data of APZ Form III, and the results showed that these models are suitable. In addition, according to the result of mixing thermodynamic functions, the negative values of ΔmixG and ΔmixH in all binary solvent mixtures are negative, indicating that the dissolution process of APZ Form III in the binary solvent mixtures is spontaneous and entropy-driven. Furthermore, the molecular dynamic simulations were used to illustrate and understand the dissolution behavior of APZ Form III in selected solvents from a molecular perspective.

Implementation of solvation free energy framework to predict the vapor-liquid equilibrium behaviors for the water–hydrazine and ethanol–water azeotropic systems

An azeotrope is a special vapor–liquid equilibrium in which the composition of two coexisting phases is equal. Due to its strong deviation from the Raoult’s law, it poses a great challenge to the simple distillation process and the understanding of fundamental molecular mechanisms. In this study, we calculated the coupling work of solute species based on the solvation free energy framework to predict the vapor–liquid equilibrium (VLE) behavior and azeotrope point of mixtures. Two prototypical binary mixtures: the negative water-hydrazine and positive ethanol–water azeotrope were investigated using molecular dynamic simulations and the OPLS-AA force field. All the simulations were performed with the TIP3P water model, because it has a good capability to represent enthalpy properties. The molecular models of hydrazine and ethanol have been re-parameterized to reproduce the density and solvation free energy properties of pure substance. Using free energy perturbation simulation, the coupling work of each substance was studied against liquid mixture composition. The coupling work is also translated to x-y or T-x-y phase diagrams for comparison with available experimental data. The tendency of two azeotropes is that the more volatile components experience the less pronounced coupling work changes in their local environments as the azeotropes form. The coupling work is also divided into van der Waals and Coulomb contributions to investigate the interactions between particles. Lithium Chloride was investigated as an entrainer for the separation of ethanol–water system. The coupling works of binary mixtures were calculated at different salt concentrations to study the salt-out effect for the violate species and salt-in effect for the less violate species. By adding LiCl, it was found that the azeotrope point was efficiently eliminated at a salinity 0.05 mol fraction at 1 bar. All the results show that the simulation methodology of coupling work are reliable for calculating the liquid–vapor equilibrium behavior. This method is also valuable for selecting and designing new extractants for distillation process.

Liquid–Liquid Equilibrium for Ternary Systems 2,2,2-Trifluoroethanol + Water + (Ethyl Acetate/Isopropyl Acetate/Isobutyl Acetate) at 308.15 K under 101.3 kPa

2,2,2-Trifluoroethanol (C2H3F3O, TFE) is a useful fluorine-containing alcohol. During the synthesis and application of TFE, TFE, and water can form an azeotropic mixture. To recover TFE from the mixture of TFE and water by liquid–liquid extraction (LLET), in the current work, three organic solvents, isobutyl acetate (C6H12O2), isopropyl acetate (C5H10O2), and ethyl acetate (C4H8O2), were chosen as the extractants. The liquid–liquid equilibrium (LLE) behavior for the three mixtures (water + TFE + ethyl acetate/isopropyl acetate/isobutyl acetate) was investigated at 101.3 kPa and 308.15 K. Selectivity (S) and distribution constant (D) were calculated as indexes to evaluate the extraction capacity of the three extractants. The results indicated that isobutyl acetate has better extraction ability in extracting TFE from its aqueous solution of TFE compared to the esters. The NRTL model was used to regress the determined tie-line data. The coherence of the fitted parameters of the NRTL model with the experimental data was checked by topological analysis.

Unveiling the thermodynamic and molecular mechanisms for the separation of diethoxymethane and ethanol azeotrope by deep eutectic solvents

The selection of efficient and environmental extractants is essential for the sustainable development of extraction processes. Based on the conductor-like screening model for the segment activity coefficient (COSMO-SAC), three deep eutectic solvents (DESs) were screened from 1000 DESs for the separation of diethoxymethane (DEM) and ethanol (EA). Subsequently, the liquid–liquid equilibrium behavior of the DEM + EA + DES system at different temperatures was measured. The results show that benzyltrimethylammonium chloride/glycerol (BTACl/GLY) has the highest selectivity and benzyltrimethylammonium chloride/ethylene glycol (BTACl/EG) and tetraethylammonium chloride/ethylene glycol (TEACl/EG) have similar extraction performance. More importantly, the extraction performance of DESs reported in this work is stronger than that of the solvents already reported. Additionally, analysis of the separation mechanism by various quantum chemical methods revealed that the purification of DEM and EA mixtures is mainly ascribed to the difference in electrostatic forces between the solvent and DEM/EA. The result confirmed that solvents with small molecular structures and strong nucleophilic sites are more competitive in separating the mixtures.

Assessment of solid–liquid equilibrium behavior and thermodynamic analysis of natural plant extracts artemisinin (Form I) in twelve mono-solvents

Solid-liquid equilibrium solubility of artemisinin (ART) Form I in twelve mono-solvents namely N, N-dimethylformamide (DMF), oxolane (THF), n-propanol (NPA), 4-methylpentan-2-one (MIBK), ethyl formate (EF), butyl acetate (BAC), 2-ethoxyethanol (EGEE), 1,4-Dioxane, 2-methoxyethanol (EGME), 2-propoxyethanol (EGPE), propyl acetate (NPAC) and 2-butoxyethanol (EGBE) from 283.15 K to 323.15 K were determined by a laser dynamic method under 0.1 MPa. The minimum solubility of ART (Form I) was found in NPA at 283.15 K (0.004541), the maximum mole fraction solubility of ART (Form I) was observed as 0.2523 in DMF at 323.15 K. At the temperature of 298.15 K, the experimental mole fraction solubility order of ART Form I in the tested solvents was DMF (0.1559) > 1,4-Dioxane (0.09117) > THF (0.08301) > MIBK (0.05054) > EF (0.04902) > NPAC (0.03860) > BAC (0.03658) > EGME (0.02031) > EGEE (0.01859) > EGPE (0.01817) > EGBE (0.01689) > NPA (0.007185). The solubility behavior was computationally correlated by Margules model, Wilson model, NRTL model, NRTL-SAC model, Buchowski-Ksiazczak λh model and UNIQUAC model, the total RMSD was no>0.025 in the selected models. With the help of Hansen solubility parameters (HSPs) analysis, molecular similarities of ART (Form I) in twelve mono-solvents were investigated. Besides, Hirschfeld surface analysis (HSs) was considered to evaluate the intermolecular interaction of artemisinin. Moreover, thermodynamic properties including ΔmixH, ΔmixG, ΔmixS, lnγ1, lnγ1∞ of ART (Form I) in the selected solvents were estimated. All the negative ΔmixG and positive ΔmixS values indicated that the mixing process were spontaneous and entropy-increasing.

ß-Damascenone Highly Diluted in Hydroalcoholic Mixtures: Phase Equilibrium Measurements, Thermodynamic Modeling, and Simulation of a Batch Distillation

ß-Damascenone is a carotenoid-derived compound that plays a key role in the characteristic aroma of wines and distilled spirits. Despite the valuable contribution of this compound to the flavor quality of alcoholic beverages, little is known about its volatility and its vapor–liquid equilibrium behavior in hydroalcoholic mixtures of different compositions. Such information is essential to be able to choose the right thermodynamic model for ß-damascenone when using a distillation process simulation software to gain a better understanding of the behavior of ß-damascenone during spirit distillation. In this context, this work presents new experimental VLE data for ß-damascenone highly diluted in ethanol + water mixtures. The measurements were carried out in a recirculation ebulliometer operating at 101.3 kPa for ethanol mass fractions between (0.10 and 0.79) g·g–1. Activity coefficient model NRTL was used to correlate the experimental data and binary interaction parameters. The parameters obtained for the NRTL model were employed to simulate a laboratory-scale batch distillation of a model solution of ß-damascenone, ethanol, and water. The simulation results were well fitted to experimental data. This approach can be further extended to other compounds that contribute to the aroma of distilled spirits, and the results can be transferred to simulate larger scale distillations.

Effect of Sulfate, Citrate, and Tartrate Anions on the Liquid-Liquid Equilibrium Behavior of Water + Surfactant

Cloud point extraction is a versatile method aimed at separating compounds from complex mixtures and arouses great technological interest, particularly among the biochemical industries. However, one must have deep knowledge of the liquid–liquid equilibrium behavior of systems to properly use the method. Thus, we used thermodynamic parameters to evaluate the effect of citrate, sulfate, and tartrate anions on the phase separation of water + Triton X-114® mixtures at 283.2 K, 293.2 K, and 303.2 K. In these systems, increasing the temperature and the anion molar fraction expanded the biphasic region in the following order: C6H5O73-> SO42- > C4H4O62−. Unlike other studies based on the Hofmeister series, the Gibbs free energy of micellization correlated the anion effect on the biphasic region with the spontaneity of the micelle formation. The water molecules structured around these anions were evaluated according to the shell volume of the immobilized water by electrostriction, volume of water around the hydration shell, Gibbs free energy of hydration, and Gibbs free energy of electrostriction (ΔGel12). The citrate anion presented a higher ΔGel12 of −1781.49 kJ mol−1, due to the larger number of electrons around it. In addition, the partition coefficient of the surfactant in the two liquid phases revealed a linear dependence upon the anion mole fractions by following the previous anion sequence and temperature in the phase separation.

Analysis of solid-liquid equilibrium behavior of highly water-soluble beet herbicide metamitron in thirteen pure solvents using experiments and molecular simulations

Metamitron (MET), a highly water-soluble herbicide for sugar beets, has posed a significant threat to aquatic species due to its high solubility in water; therefore, understanding its solid–liquid phase equilibrium data in different solvents is essential for the future development of more environmentally friendly forms. In this study, the solubility data of MET in 12 pure solvents were determined gravimetrically and analyzed using theoretical methods (primarily Molecular electrostatic potential surface analysis, Hirshfeld surface analysis, Reduced Density Gradient analysis, radial distribution function, and solute–solvent interaction energy) to further investigate the solid–liquid equilibrium behavior. Although MET's high solubility in water contributes to environmental contamination, its value is low in comparison to that of other organic solvents. Four models, including the Apelblat equation, the λh equation, the van't Hoff equation, and the NRTL, were used to examine all solid–liquid equilibrium data, and an ARD% below 5 confirmed its good correlation. The MET solubility data is anticipated to provide solid guidance for the future development of more effective and environmentally acceptable green formulations.

Study on the Isobaric Vapor–Liquid Equilibrium Behavior of the Methanol + Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

Study on the Isobaric Vapor–Liquid Equilibrium Behavior of the Methanol + Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

Measurement and thermodynamic modelling of Liquid-liquid equilibrium for extraction of acrylonitrile from water with n-Alkyl acetates

In order to recover the acrylonitrile from wastewater solution, liquid–liquid equilibrium behaviors in the systems {water + acrylonitrile + n-alkyl acetates} were explored at 303.2 K and 101.3 kPa., respectively. The partition coefficients and separation factors in each system were used to compare and discuss the effects of extraction. The experimental data were correlated with the NRTL and UNIQUAC models, and the binary interaction parameters required for each model were obtained. The mixing surface analysis of Gibbs energy topology was used to test the parameters in models. The UNIFAC model was used to predict LLE data compared with experimental data. The deviation between the calculated and experimental values of the three thermodynamic models was evaluated by the root mean square deviation, and the values were lower than 0.0082, 0.0088, and 0.0143, respectively. The σ-profiles were used to discuss the interactions of substances in this work.

Solubility study of m-aminobenzoic acid form III in different mono-solvents by thermodynamic analysis and molecular simulation

The solid–liquid equilibrium behavior of m–aminobenzoic acid (m–ABA) form III in eleven mono–solvents (methanol, ethanol, n–propanol, isopropanol, n–butanol, methyl acetate, propyl acetate, butyl acetate, acetone, butanone and water) was investigated in the temperature from 283.15 K to 323.15 K. Solubility data were successfully described and correlated by four thermodynamic models, and all calculated ARD% values are lower than 5%. The thermodynamic functions of mixing were calculated and analyzed based on the NRTL model, and the results show that the mixing process is spontaneous and entropy–driving. The characteristics of m–ABA form III both in solution and solid phases were studied. Molecular electrostatic potential surface has been employed to present the overall charge distribution and estimate intermolecular interactions between the form III and solvents. Hirshfeld surface analysis has been applied to visualize various molecular interactions. Besides, the effect of selected solvent properties on the dissolution behavior of m–ABA form III was examined. Finally, molecular simulations have been further applied to disclose the interactions between solute and solvent molecules. This work has guiding significance for the design and optimization of the m–ABA crystallization process.

Assessment of solid–liquid equilibrium behavior of naphazoline nitrate in ten pure solvents by molecular simulation and thermodynamic analysis

A laser monitoring method was used to determine the mole-fraction solubility of naphazoline nitrate (NPZN) in ten mono-solvents namely “methanol (MeOH), ethylene glycol monomethyl ether (EGME), ethanol (EtOH), ethylene glycol monoethyl ether (EGEE), n-propanol (n-PrOH), ethylene glycol monopropyl ether (EGPE), isopropanol (i-PrOH), ethylene glycol (EG), ethylene glycol monobutyl ether (EGBE) and N,N-dimethylformamide (DMF)” at (278.15 ∼ 323.15) K and 0.1 MPa. Results suggested that NPZN solubility values exhibited an increasing trend at investigated temperature ranges. Simultaneously, experimental solubility of NPZH had a general order of “DMF > EGME > EG > MeOH > EGEE > EGPE > EtOH > EGBE > n-PrOH > i-PrOH”. Hirshfeld surface was employed to analyze and quantize the intermolecular interaction of NPZN during the crystal construction process. The impact of solute–solvent interaction on NPZN solubility was investigated by calculating the solvation free energies of solute in selected solvents through molecular dynamic (MD) simulation. It turned out that NPZN solubility was positively associated with solute–solvent interaction. Solubility values of NPZN were correlated by Wilson, NRTL, NRTL-SAC as well as UNIQUAC model, corresponding fitting accuracies of different model were in variation based on various root mean squared deviation (RMSD) and average relative deviation (ARD). The computational results indicated that UNIQUAC model performed the highest accuracy in correlation of experimental solubility. Finally, thermodynamic properties of dissolution process and mixing process were investigated by UNIQUAC model in this research work. The existences of negative Gibbs energy changes and positive entropy changes were observed, which suggested that the dissolution process and mixing process were always spontaneous and entropy-increasing.

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