Vapor-liquid Equilibrium Values Research Articles

Phase behavior of sodium and potassium salts in their aqueous solutions: Experiment and computational thermodynamics

AbstractWith the rapid development of the semiconductor industry, the demand for ultraclean and high‐purity electronic chemicals, especially ultrapure water as a general solvent for cleaning semiconductor chips, has increased dramatically. The distillation process is a good choice for large‐scale production of ultrapure water that can be used to clean semiconductor chips, but there is a lack of basic thermodynamic theory for removing ionic impurities. In this work, the temperature and vapor–liquid phase composition of sodium and potassium salts aqueous solutions at vapor–liquid equilibrium (VLE) were investigated by experiments. The microstructure of each inorganic salt aqueous solution was explored by molecular dynamics simulation and quantum chemical calculation, and the interaction between each ion and water molecule was analyzed. A volatilization mechanism of inorganic salts was proposed, and it was found that the volatilization of inorganic salts in an aqueous solution was affected by the strength of interaction between the dissociated anions and cations and water molecules. Finally, the conductor‐like screening model segment activity coefficient (COSMO‐SAC) model predicted the VLE values of inorganic salt aqueous solutions. The prediction at low concentrations (xs < 0.06) was in good agreement with the experimental data.

Clean and efficient recovery of In–Sn and In–Sn–Bi lead-free brazing materials by vacuum volatilization and thermodynamic modeling

In this study, a novel method was proposed for the clean and efficient recovery of high-value-added In–Sn and In–Sn–Bi alloys. Vacuum volatilization of the In–Sn binary alloy was conducted in a temperature range of 1373–1573 K with a system pressure of 5 Pa. The results showed that In and Sn were effectively separated. The Sn content in the residue was 99.9908%, and the In content in the volatile fraction reached 99.66%. Vacuum volatilization of the In–Sn–Bi ternary alloy was conducted out at 1073–1373 K and 5 Pa. The results showed that Bi could be separated from In and Sn, the Bi content in the residue decreased from 32.5% to 3.88%, and the Bi content in the volatile fraction reached 95.67%. The residual In–Sn alloy could be effectively separated by vacuum volatilization. The MIVM, M-MIVM, Wilson equation and NRTL were used to calculate and analyze the activity and activity coefficients of In–Sn, In–Bi, Sn–Bi and In–Sn–Bi alloy elements, respectively, and the results showed that M-MIVM had the highest prediction accuracy. The vapor-liquid equilibrium (VLE) data of the In–Sn, In–Bi, Sn–Bi, and In–Sn–Bi alloys were predicted, and the corresponding VLE phase diagrams were plotted based on the M-MIVM and VLE theory. The predicted VLE values were in good agreement with the corresponding experimental data determined in this study, indicating that the M-MIVM was reliable for indium-based alloys. The results of this work provided reliable experimental data and a thermodynamic model for the VLE study of In-based alloys, opening a new technique for the clean and efficient recycling of binary and multicomponent In-based alloys.

Simulation prediction and experimental study of phase equilibria of Bi–Sb and Bi–Sb–Cd alloys in vacuum distillation

In this study, experimental determination and model prediction of the vacuum distillation vapor-liquid equilibrium (VLE) values of Bi–Sb binary alloy and Bi–Sb–Cd ternary alloy at different temperatures were undertaken under a vacuum of 1–5Pa. The experimental result shows that Bi and Sb were separated effectively from Bi–Sb binary alloy and Cd in Bi–Sb–Cd ternary alloy preferentially volatilized and entered the vapor phase completely. Combined with the above two-step experiments, the segmented distillation can purify crude antimony. The molecular interaction volume model (MIVM) was used to predict both the activity of each alloy element of Bi–Sb, Bi–Cd and Sb–Cd and VLE values. The average relative deviation of activity was <±5.19% compared with the adopted experimental values, and the VLE values were consistent with the trend of the experimental values. The MIVM was further used to predict the activity and VLE values of Bi–Sb–Cd ternary alloy, and the result corresponds with the experimental values. This combination of experiment and model prediction not only verified the reliability of the MIVM in predicting the activity and VLE values of antimony-based alloys, but also optimized their process parameters of vacuum distillation, providing theoretical guidance for vacuum distillation purification of crude antimony and further industrial experiments.

Separation of azeotropic mixture (acetone + n-heptane) by extractive distillation with intermediate and heavy boiling entrainers: Vapour-liquid equilibrium measurements and correlation

Acetone and n-heptane are widely applied in pharmaceutical industry as benign solvents and are observed in the wastewater. Because acetone and n-hexane can form an azeotropic mixture, it is impossible to recover acetone and n-heptane with high purity from the wastewater using conventional distillation. In this research, for separating the azeotrope (acetone + n-heptane) by homogeneous extractive distillation, 1-chlorobutane and butyl propanoate were chosen as the intermediate and heavy boiling entrainers. The isobaric vapour-liquid equilibrium (VLE) behaviour for the three binary systems (acetone + 1-chlorobutane), (butyl propanoate + acetone) and (n-heptane + butyl propanoate) were reported at 101.3 kPa. The values of the excess Gibbs energy (GE) were calculated to explore the nonideal of the systems. The thermodynamic consistency of the determined VLE values was checked by the van Ness and Herington tests. In addition, the determined VLE data were fitted by the UNIQUAC, Wilson, and NRTL models. The parameters of those models were regressed, which are helpful for simulating the separation process with the intermediate and heavy boiling entrainers by extractive distillation.

Measurement of VLE Data by Using an Experimental Installation with Automatic Control: Modeling of Binary Systems of Methyl Acetate or Ethyl Acetate with n-Heptane or 2,2,4-Trimethylpentane at Both 0.1 and 1.5 MPa

The excess volume of binary mixtures and the isobaric vapor–liquid equilibrium (VLE) data at high pressure have been determined. The VLE values for methyl acetate + n-heptane or 2,2,4-trimethylpent...

Isobaric Vapor–Liquid Equilibrium Data for Two Binary Systems n-Hexane + 1,2-Dimethoxyethane and Methylcyclopentane + 1,2-Dimethoxyethane at 101.3 kPa

Isobaric vapor–liquid equilibrium (VLE) data for binary systems of n-hexane + 1,2-dimethoxyethane and methylcyclopentane + 1,2-dimethoxyethane were measured at 101.3 kPa with an Ellis vapor–liquid equilibrium still, and the thermodynamic consistency of the experimental data was checked and passed by the Herington method and Wisniak test. The VLE values were correlated with the nonrandom two-liquid, universal quasichemical and Wilson activity coefficient models, and the corresponding binary interaction parameters of the three models were obtained. The results correlated with three models have good agreement with the experimental data, indicating that the three models were all fitted well.

Measurement and Correlation of Isobaric Vapor–Liquid Equilibrium of Three Binary Systems Containing Chlorobenzene at 50.00 and 101.33 kPa

Isobaric vapor–liquid equilibrium (VLE) data for three binary systems, chlorobenzene + N,N-dimethylformamide, chlorobenzene + furfural, and chlorobenzene + benzaldehyde, were measured at 50.00 and 101.33 kPa using a modified Rose–Williams still. Gas chromatography was used to analyze the compositions of the samples and no azeotropic behavior was found. All of the measured VLE values were checked by the semi-empirical method proposed by Herington and the point-to-point Van Ness test method modified by Fredenslund. The experimental data were correlated by using the Wilson, the non-random two-liquid and universal quasi-chemical activity coefficient models. The corresponding parameters for the three models were obtained.

Isobaric Vapor–Liquid Equilibrium for Three Binary Systems of Acetaldehyde + Ethanol, Ethyl Acetate, 1-Butanol at 101.3 kPa

In this article, isobaric vapor–liquid equilibrium (VLE) data for three binary systems of acetaldehyde + ethanol, acetaldehyde + ethyl acetate, and acetaldehyde +1-butanol were determined using a modified Rose–Williams equilibrium still at 101.3 kPa. The experimental data were confirmed by the area method of Herington and point-to-point method of Van Ness. Activity coefficient models, Wilson, NRTL, and UNIQUAC were employed to correlate the experimental VLE values. Both models showed a good agreement and the binary interaction parameters were estimated.

Isobaric Vapor–Liquid Equilibrium for the Binary Systems of sec-Butyl Acetate + n-Butyl Alcohol, Isobutyl Alcohol, or tert-Butyl Alcohol at 101.3 kPa

The isobaric vapor–liquid equilibrium (VLE) data of n-butyl alcohol + SBAC, isobutyl alcohol + SBAC, and tert-butyl alcohol + SBAC binary systems were determined at 101.3 kPa by using an Ellis vapor liquid equilibrium still. The experimental data passed the thermodynamic consistency test by the Herington method and showed positive deviations from ideal behavior. The VLE values were correlated by the Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity-coefficient models with satisfactory results. The results show that n-butyl alcohol + SBAC and isobutyl alcohol + SBAC systems form minimum temperature azeotropic mixtures.

Isobaric vapour–liquid equilibrium of (tert-butanol + water) system with biological buffer TRIS at 101.3 kPa

Isobaric vapour–liquid equilibrium (VLE) data were measured for the binary system of {tert-butanol (1)+water (2)} and the ternary system of {tert-butanol (1)+water (2)+tris(hydroxymethyl)aminomethane (TRIS) (3)} at 101.3kPa by using a modified recirculating type of Othmer equilibrium still. The concentration range of the biological buffer TRIS in the feed mixtures is from 0.05 to 0.20 in mass fraction. The experimental results show that the presence of TRIS induces significant shift of azeotropic composition and increases the relative volatility of tert-butanol to water. TRIS can be a promising mass separating agent for the separation of (tert-butanol+water) mixtures. The experimental VLE values were correlated with the NRTL-HOC model to determine the binary interaction parameters. Generally, the NRTL-HOC model well correlates the VLE data for the systems investigated in this study. The model parameters obtained from this study can be applied to design a new green process for separating -tert-butanol from its aqueous solution.

Estimation of variation in Vapour Liquid Equilibrium constants for modeling a multicomponent crude distillation column

In this paper, the mathematical model of a multicomponent crude distillation column is investigated which aimed at predicting the concentration (mole fraction) of any component on each tray of the column. In literature, it is observed that there is a drastic up and down variations in the steady state composition profile of various multicomponent at each tray of the column. These variations are due to the assumption that Vapor Liquid Equilibrium (VLE) ratios are kept constant throughout the tray for any component and are not true in real time petroleum industries. The proposed method shows a proper procedure for choosing equilibrium constants by using an estimation technique by reverse calculation of Thomas algorithm. Hence, a reverse calculation is performed using a Tridiagonal matrix method for estimating the VLE values from the steady state composition profile for each component mixture. Further, the composition profile for various components, mainly Whole Naphtha, Straight Run Kerosene (SRK), Light Diesel Oil (LDO), Heavy Diesel Oil (HDO) and Atmospheric Residue (AR) are estimated and compared. This modified algorithm is a simple technique for ideal and non-ideal systems with ease of implementing a composition profile for a multicomponent mixture and reduction in computational complexities.

Isobaric Vapor–Liquid Equilibrium for the Binary Systems of sec-Butyl Acetate + Methyl Ethyl Ketone, 2-Methoxyethanol, or 1,2-Dimethoxyethane at 101.3 kPa

The isobaric vapor–liquid equilibrium (VLE) data of methyl ethyl ketone (MEK) + sec-butyl acetate (SBAC), 2-methoxyethanol + SBAC, and 1, 2-dimethoxyethane (DME) + SBAC were determined at 101.3 kPa by using an Ellis vapor–liquid equilibrium still. The experimental data passed the thermodynamic consistency test by Herington method and Wisniak test. The VLE values were correlated by the nonrandom two-liquid (NRTL), universal quasichemical activity coefficience (UNIQUAC), and Wilson activity-coefficient models. The results indicated that the three models had good agreement with the experimental data. The 2-methoxyethanol + SBAC system forms a minimum temperature binary azeotrope at 101.3 kPa. The azeotropic temperature is 383.86 K, and the composition of SBAC is 85.1 mol %.

Measurements of isothermal (vapor + liquid) phase equilibrium for {trifluoroiodomethane (R13I1) + 1,1-difluoroethane (R152a)} from T = (258.150 to 283.150) K

In this paper, isothermal (vapor+liquid) equilibrium (VLE) values for {trifluoroiodomethane (R13I1)+1,1-difluoroethane (R152a)} at T=(258.150 to 283.150)K are presented. The experimental apparatus was based on a vapor-recirculation method. The VLE measurements were regressed by the Peng–Robinson equation of state with two models, the Van der Waals mixing rules and the Huron–Vidal mixing rules using the NRTL activity coefficient model. The newly measured VLE values satisfied the thermodynamic consistency test. The results have led to that the two models selected are both suitable for the description of the binary system. Azeotropic behavior can be found for the system measured.

A Parametric Study of the Choice of Binary Interaction Parameter and Equation of State for High Pressure Vapor-Liquid Equilibrium of Nitrogen – n-Dodecane Binary System

A parametric study of the effects of binary interaction parameter and real-gas equations of state on the high pressure vapor-liquid equilibrium of nitrogen-n-dodecane system was carried out. Different values of the binary interaction parameter reported in literature, including one which depends on temperature, were employed in different equations of state to predict the vapor-liquid equilibrium as a function of ambient pressure and temperature. The findings were compared against the available experimental values reported in literature. Constant values of binary interaction parameter, estimated based on temperature dependent values, are demonstrated to predict the experimentally observed vapor-liquid equilibrium values accurately. The Peng-Robinson equation of state and an average binary interaction parameter were demonstrated to predict the vapor-liquid equilibrium over a wide range of temperature and pressures for nitrogen-n-dodecane binary system.

Modification of Peng Robinson EOS for modelling (vapour+liquid) equilibria with electrolyte solutions

► Extended PR-EOS was presented for VLE of H 2 O/Salt/CO 2 systems at high pressure. ► The proposed EPR-EOS is based upon contributions to the Helmholtz energy. ► Born, Margules, and Debye–Huckel or mean spherical approximation terms were used. ► Two different mixing rules Panagiotopoulos and Reid and Kwak and Mansoori (KM) were used. ► A combination of KM mixing rule with DH term results more accurate VLE results. A modification of the extended Peng–Robinson equation of state (PR-EOS) is presented to describe the (vapour + liquid) equilibria of systems containing water and salts. The modification employs three additional terms including a Born term, a Margules term and two terms separately used for estimation of the long-range electrostatic interactions (the Debye–Huckel (DH) or the mean spherical approximation (MSA) terms). Effects of two mixing rules, first, the Panagiotopoulos and Reid mixing rule (PR) and, second, the Kwak and Mansoori mixing rule (KM), on the final values of VLE calculations are also investigated. The results show that the KM mixing rule is more appropriate than the PR mixing rule. The proposed equation of state is used to calculate the (vapour + liquid) equilibrium (VLE) of the systems containing (water + sodium sulphate + carbon dioxide) and (water + sodium chloride + carbon dioxide) at high pressure. The comparison of calculated results with the experimental data shows that a combination of KM mixing rule with the DH term results a more accurate VLE values.

Predicting the excess enthalpies and vapor–liquid equilibria of multicomponent systems containing ether and hydrocarbons

The Liebermann–Fried model was used to correlate the excess enthalpy values for selected binary ether+hydrocarbon mixtures. The binary interaction parameters so determined were then used in conjunction with an extended form of the model to predict the excess enthalpies and vapor–liquid equilibria for several multicomponent systems containing ether and hydrocarbons. The Flory–Patterson theory approach was also used to calculate the same thermodynamic properties. The predicted values were found to be in good agreement with the experimental results reported in the literature. The Liebermann–Fried model was found to be comparable to the Flory–Patterson theory approach in the prediction of excess enthalpy. However, the vapor–liquid equilibrium values predicted by means of the former were of better quality than those calculated by means of the latter.

Modification of the Furter equation and correlation of the vapor–liquid equilibrium for mixed-solvent electrolyte systems

Isobaric vapor–liquid equilibrium values at 1 atm pressure were measured for the systems 1-propanol–water–potassium acetate and 2-propanol–water–potassium acetate under fixed salt mole fractions using a modified Othmer recirculation still. A modified Furter equation, ln( α s/ α)= k 1 z+ k 2 z 2, was proposed for correlating the effect of dissolved salts on vapor–liquid equilibrium (VLE). The modified equation contains two parameters that are applicable to the entire salt/solvent composition range. Correlation of VLE for 15 mixed-solvent electrolyte systems was made by means of the proposed modified equation with better results than those obtained from the original equation.

Isothermal Vapor-Liquid Equilibrium with Computer-Aided Measurement.

Isothermal vapor-liquid equilibrium measurement system with the computer was developed in the region of less than atmospheric pressure. Vapor-liquid equilibria were measured using a still with the aid of computer for control of temperature and measurement of total pressure. A modified Rogalski-Malanowski still with a provision for both vapor and liquid re-circulation was used for the determination of vapor-liquid equilibrium values. The performance of the apparatus was shown by the results of thermodynamic consistency tests for the experimental isothermal vapor-liquid equilibria.

CALCULATION OF VAPOR-LIQUID EQUILIBRIA AND SATURATED LIQUID VOLUMES FOR WATER-AMMONIA MIXTURES

Abstract The approach of using T, at ΔZ= Zs vZs L = 0.5 for a balanced representation of saturated volumes (Vs L and Vs Vs L ( of pure components has been extended from non-polar fluids to water and ammonia. For the mixtures of these two compounds, the average absolute percentage deviation in the calculated V s L values is less than 2% without affecting the representation of vapor-liquid equilibrium values.

Vapor-liquid equilibria of five binary systems containing R-22

Xu, N., Yao, J., Wang, Y., Shi, J. and Lu, B.C.-Y., 1991. Vapor-liquid equilibria of five binary systems containing R-22. Fluid Phase Equilibria, 69: 261-270. A high pressure static apparatus was used to determine the isothermal vapor-liquid equilibrium values from 343 to 400 K for five binary systems containing R-22 (CHClF2) with ethanol, 2-propanol, 1-hexane, cyclohexane or tetrachloromethane. The experimental results were successfully correlated by means of a modified volume-translated Peng-Robinson equation.