Phase Equilibrium Research Papers - Academia.edu (original) (raw)

2025, Industrial & Engineering Chemistry Research

A new corresponding states model for predicting the viscosity of heavy crude oils and petroleum fractions is proposed in this work. The model uses decane and eicosane as reference components for petroleum fractions of average molecular weight higher than 142. The viscosity of a component or fraction may be obtained from the viscosities of these two reference fluids (decane and eicosane) a t the same reduced temperature and reduced pressure using the molecular weight as an interpolation parameter. This model showed better accuracy in predicting the viscosity than the model that uses one reference (methane) or two references (methane and decane), when the molecular weight is higher than 142. The present model, when tested on 187 data points for 29 undefined heavy petroleum fractions from 15 worldwide crudes, yielded an overall deviation of 5.3%. Testing of the model on 53 data points for seven crude oils from offshore Abu Dhabi yielded an average absolute deviation of 5.9%.

2025, Annual Review of Physical Chemistry

▪ This review provides a discussion of recent techniques for simulation of phase equilibria of complex fluids. Monte Carlo methods are emphasized over molecular dynamics methods. We describe recent developments, such as the use of expanded-ensemble, tempering, or histogram reweighting techniques. Our discussion of such developments is aimed at a general audience and is intended to provide an overview of the main advantages and limitations of each particular technique. References are provided to allow interested readers to identify and trace back most recent applications of a particular simulation technique. We conclude with general guidelines regarding selection of suitable simulation methods for particular problems and systems of interest.

2025, Proc. NIPR Symp. Antarct …

Proc. NIPR Symp. Antarct. Meteorites, 8, 153-166, 1995 REEXAMINATION OF MOCS AND TAUTI CHONDRITIC METEORITES: CLASSIFICATION WITH SHOCK DEGREE Yasunori Miura1, Gabriel O. Iancu1*, Gabriela Iancu1*, Keizo Yanai2 and Hiroshi Haramura2 1... more

2025, Energies

The first part of the current reported work presents experimental results of brewers’ spent grains gasification in a pilot-scale downdraft gasifier. The gasification procedure is assessed through various process characteristics such as gas yield, lower heating value, carbon conversion efficiency, and cold gas efficiency. Power production was varied from 3.0 to 5.0 kWh during the gasification experiments. The produced gas was supplied to an internal combustion engine coupled to a synchronous generator to produce electricity. Here, 1.0 kWh of electricity was obtained for about 1.3 kg of brewers’ spent grains pellets gasified, with an average electrical efficiency of 16.5%. The second part of the current reported work is dedicated to the development of a modified thermodynamic equilibrium model of the downdraft gasification to assess the potential applications of the main Portuguese biomasses through produced gas quality indices. The Portuguese biomasses selected are the main represent...

2025, Korean Journal of Chemical Engineering

Refractive index and speeds of sound for the binary mixture of isomer of butanol (1) + cyclohexane, benzene and toluene (2) were measured at 308.15 K. The measured data were used to calculate deviation in refractive index Δn, ultrasonic speed Δu, isentropic compressibility K s E , available volume V a , excess intermolecular free length L f and molecular association M A . All the derived properties were correlated with polynomial equation. Ultrasonic speed data were predicted using various empirical correlations like Nomoto, van Dael, impedance dependence and theoretically with Schaaff's collision factor theory (CFT). Jacobson free length theory (FLT) was used to calculate L f . The measured refractive index was also correlated with various mixing rules. The deviation in refractive index Δn and ultrasonic speed Δu was used to determine the intermolecular interactions.

2025, Korean Journal of Chemical Engineering

Refractive index and speeds of sound for the binary mixture of isomer of butanol (1) + cyclohexane, benzene and toluene (2) were measured at 308.15 K. The measured data were used to calculate deviation in refractive index Δn, ultrasonic speed Δu, isentropic compressibility KsE, available volume Va, excess intermolecular free length Lf and molecular association MA. All the derived properties were correlated with polynomial equation. Ultrasonic speed data were predicted using various empirical correlations like Nomoto, van Dael, impedance dependence and theoretically with Schaaff’s collision factor theory (CFT). Jacobson free length theory (FLT) was used to calculate Lf. The measured refractive index was also correlated with various mixing rules. The deviation in refractive index Δn and ultrasonic speed Δu was used to determine the intermolecular interactions.

2025, Journal of Molecular Liquids

2025, Asian Journal of Chemistry

The thermodynamic properties of the binary mixtures having potential oxygenates, biodiesel, aromatic and aliphatic compounds are of considerable importance to chemical engineers in formulation of motor fuel. In order to study the interactions of oxygenate with fuel components, excess molar enthalpy for 2-propanol (1) + aromatic hydrocarbon (2) mixtures were measured with flow microcalorimeter at 303.15 K. At equimole fraction, excess enthalpy values follow the order as: n-hexane > cyclohexane and 2-propanol > 1-propanol. The data have also been interpreted in terms of graph-theoretical approach and Prigogine-Flory-Patterson (PFP) theory and Flory-Treszczanowicz-Benson association (FTB) model. It has been observed that while Prigogine-Flory-Patterson theory fails to predict the excess enthalpy (Hm E ) values for these system in the composition range x1 > 0.05, agreement with experimental values is reasonably good in propanol lean region. Flory-Treszczanowicz-Benson (FTB) association model and graphtheoretical approach predict the measured Hm E quite well.

2025, The Journal of Chemical Thermodynamics

In this work, the thermodynamic properties of the ternary mixed electrolyte system (NaCl + Na 2 HPO 4 +water), using the potentiometric method, are reported. The potentiometric measurements were performed on the galvanic cells without liquid junction of the type: Ag-AgCl|NaCl (m 1 ), Na 2 HPO 4 (m 2 ), H 2 O|Na-ISE, over total ionic strengths from (0.0130 to 4.000) mol Á kg À1 for different series of salt molal ratios r (r = m NaCl /m Na 2 HPO 4 = 2.5, 5.0, 7.5, and 10.0) and pure NaCl in aqueous system at T = 298.2. The PVC based sodium ion selective electrode (Na-ISE) and Ag-AgCl electrode used in this work were prepared in our laboratory and had a reasonably Nernst response. The activity coefficient results were interpreted based on the Harned rule and Pitzer model. The unknown Pitzer mixing interaction parameters (h ClHPO 4 , w NaClHPO 4 ) were evaluated for the ternary system studied according to Pitzer graphical method .Then, the parameters obtained with the Pitzer model were used to calculate the values of the mean activity coefficients of Na 2 HPO 4 , the osmotic coefficients, the solvent activity and the excess Gibbs free energy for the whole series of the studied mixed electrolyte system.

2025

One of the most important design considerations that should not be ignored during industrial purpose equipment designing is vapour-liquid equilibrium (VLE). Thus, in chemical engineering, the first step is the computation of VLE properties of materials by employing equations of state (EOS). In this study, we have used a thermodynamic model established for a binary system of carbon dioxide (1)-aqueous ethanol (2), which was employed to estimate the gas-liquid equilibrium at moderate pressures (up to 6 bar) and varying temperatures (288-323 K). The Peng-Robinson EOS was employed to determine the VLE properties. Mixing rules such as van der Waals and quadratic mixing rules were also used for the determination of ethanol-water mixture critical parameters, which entails the pseudo-critical method as one component, and the results obtained from this study were similar to the ones reported in recent literature for empirical phase equilibrium studies.

2025, Draft

Here we report 19 publications about the principles and applications of continuous and pseudoization thermodynamics for multi-component mixtures property and phase behavior predictions.

2025, Fluid Phase Equilibria

We present Gibbs ensemble Monte Carlo (GEMC) simulations of SCPDP polarizable model for water. Our results seem to be more consistent and accurate than the literature data. Our simulations suggest that GEMC of polarizable models with exact treatment of the polarizable interactions is feasible, though its efficiency is rather low. The application of a newly proposed approximate method to treat the polarizable interactions in Monte Carlo is expected to remedy this deficiency.

2025, Contributions to Mineralogy and Petrology

We have measured the thermal expansivity of talc, Mg Si O (OH) , and phase A, Mg Si O (OH) , and the compressibility of talc, phase A and 10-A s phase, Mg Si O (OH) • xH O, using powder X-ray diffraction. The thermal expansivity of talc and phase A were measured at temperatures up to 810°C and 600°C, respectively. Volumes of both phases increase linearly with temperature, and can be described as follows: Talc: »/» "1#2.15 ($0.05);10\ (¹! 298), » "136.52 ($0.03) cm mol\; Phase A: »/ » "1#4.86 ($0.18);10\ (¹ -298), » "154.42 ($0.09) cm mol\. Compressibility measurements of talc, 10-A s phase and phase A were made at pressures up to 6.05, 8.52 and 9.85 GPa, respectively. Values of the isothermal bulk modulus K and its pressure derivative K, obtained by fitting the compressibility data to the Murnaghan equation, are as follows: Talc: K "41.

2025

In this work, the 450°C Mg-Mn-{Ce, Nd} and 300°C Ce-Mg-Zn isothermal sections were established using diffusion couples and key alloys. The phase relationships were determined using XDR, EDS/WDS and metallography. Diffusion couples were also used to measure the interdiffusion coefficients of the Mg-{Ce, Nd, Zn} and Zn-{Ce, Nd} binary systems based on the experimental composition profiles and Boltzmann-Matano method. No ternary compounds were found in the Mg-Mn-{Ce, Nd} isothermal sections at 450°C. Microstructures of the ternary diffusion couples showed stationary Mn grain morphology in most of the diffusion zones. This was attributed to the affinity of Ce and Nd to Mg atoms, which forming several Mg-{Ce, Nd} binary compounds during the diffusion process. However, some of these binary compounds dissolved Mn. The ternary solubility of (γ-Ce) Mg,Mn , (CeMg), (CeMg 3 ), (CeMg 12 ), (α-Nd) Mg,Mn , (MgNd) and (Mg 3 Nd) was measured at 450°C to be 3.0, 5.1, 3.2, 1.8, 3.0, 13.0 and 3.7 at.% Mn, respectively. In both systems, the phase boundary lines were pointing towards the Mnrich corner, except for the (α-Nd) Mg,Mn +Mn 17 Nd 2 +(MgNd) phase field. Eight ternary compounds were observed in the Ce-Mg-Zn isothermal section at 300°C. These are: τ

2025

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2025, Journal of Supercritical Fluids

To evaluate the selectivity of supercritical carbon dioxide (scCO2) as a solvent to deacidify vegetable oils, the solubility of oleic acid and of a mixture of oleic acid and refined sunflower oil in scCO2 was measured. Sunflower oil was adopted as a pseudo-pure component and the phase equilibrium of ternary and binary systems were thermodynamically modeled by the Peng-Robinson equation of state with classical mixing rule. The values of the estimated and/or adopted critical properties in modeling thermodynamics were shown to be of great influence on the quality of data correlation. Although correlating data from binary systems is possible, the modeling was incapable of satisfactorily predicting the behavior of the phase equilibrium of the ternary system. The large deviations observed may derive from the presence of specific intermolecular interactions between the components of these systems that were not considered in this type of modeling.

2025, The Journal of Supercritical Fluids

2025

What is the shape of the Atomic Nucleus? Can it be a cone? Can we modify a nucleus in such way that it gets possible to do nuclear fusion reactions at low energies?

2025, Molecular Physics

our methodology for the development of accurate coarse-grained (CG) SAFT-force fields for the computer simulation of molecular fluids was introduced with carbon dioxide as a particular case study. The procedure involves the use of a molecular-based equation of state to obtain effective intermolecular parameters (from experimental fluid phase equilibrium data) appropriate for molecular simulation over a wide range of fluid conditions. We now extend the methodology to develop coarse-grained models for benzene (C 6 H 6 ) that can be used in fluid phase simulations. Our SAFT-CG force fields for benzene consist of a simple single-segment spherical model, and a rigid three-segment ring structure of tangent spherical groups interacting via Mie (generalized Lennard-Jones) segment-segment interactions. The description of the fluid phase behaviour of benzene with our simplified CG force fields is found to be comparable to that obtained with the more sophisticated models commonly used in the field; a marked improvement is seen with our SAFTmodels for the vapour pressure, particularly at lower temperatures. These models of benzene together with the previously developed SAFT-three-segment chain model of n-decane are used to develop hetero-group force fields for n-decylbenzene, in the spirit of a group contribution methodology. In our approach, the parameters of the phenyl and n-decyl groups are obtained transferably from the individual models of benzene and n-decane, respectively, and the unlike energetic parameters between the phenyl and decyl segments can be obtained from vapour-liquid equilibria data for n-decylbenzene using the SAFT-equation of state. The resulting CG heterogroup models are found to describe the fluid properties of n-decylbenzene over a wide range of conditions, exemplifying how our approach can be used as a group contribution methodology. This is the first example of the development of hetero-group SAFT-force fields for molecules formed from Mie segments of different size, energy, softness/hardness, and range.

2025

The primary oxide components of the bottom ash and the vitrified bottom ash slag from municipal solid waste incineration (MSWI) are CaO, Al2O3, SiO2, Fe2O3, Na2O and MgO. As a main subsystem, CaO-Na2O-SiO2 is found to be important for the phase transformation during thermal processing of the bottom ash. In the present work, thermodynamic modeling was carried out on this ternary oxide system based on literature data and authors’ own the experimental results. The modified associate species model was chosen to perform the assessment and calculations, which allows a more accurate representation of the thermodynamic properties over a wide concentration range of the complex oxide system, especially for high silica composition region. The Na2O-SiO2 phase diagram calculated with the newly generated database is in a good agreement with the experimental results. The pseudobinary systems CaO·SiO2-Na2O·SiO2 and Na2O·2SiO2-Na2O·2CaO·3SiO2 were evaluated. The phase diagram in the more than 50 wt%...

2025

Typical methods for calculation of binary liquid-liquid equilibrium compositions such as surfactant systems need proper initial guesses and/or checking the sign of the second derivative of molar Gibbs energy change of mixing, ∆G. Eubank and Hall have shown the equal area rule (EAR) applies to the composition derivative of the Gibbs energy of a binary system at fixed pressure and temperature. Methods based on EAR do not need to check the sign of the second derivative of ∆G because EAR is a necessary and sufficient condition for phase equilibrium. However, the algorithm proposed by Eubank and Hall needs a reasonable initial guess. Furthermore, it is not easy to apply the algorithm to activity coefficient models such as Non-Random Two Liquid (NRTL) because the first and second derivatives of ∆G as a function of composition have various shapes for some sets of NRTL parameters. In this work, we have developed an improved algorithm for calculation of binary liquid-liquid equilibrium compositions based on EAR considering the various shapes of NRTL model. This algorithm needs neither any initial guess nor checking the sign of the second derivative of ∆G.

2025, Cement and Concrete Research

A model is described for predicting the equilibrium phase assemblage in hydrated Portland cement and for calculating the relative contents and composition of phases present in the assemblage, from the chemical composition of the cement and the water/cement ratio. The method is also used to calculate the content of capillary pores using the best available data for the densities for each of the phases. These calculations were carried out on three different Portland cements (two white Portland cements and one grey) at water/cement ratios of 0.70. Energy dispersive spectroscopy (EDS) analysis on the SEM was used to verify the presence of all phases predicted by the model. A density for the C-S-H phase of approximately 2.10 g/cm 3 and an evaporable water content in the C-S-H of approximately 19% provided the best agreement between the predicted values of chemical shrinkage, loss of ignition and content of evaporable water, and experimental data. Other results

2025, The Journal of Chemical Physics

2025, The Journal of Chemical Thermodynamics

The densities and refractive indices of the pure ionic liquid (IL) HMIMPF 6 were determined at temperature range from T =(278.15 to 318.15) K for density and from T = (288.15 to 318.15) K for refractive index. The coefficient of thermal expansion of HMIMPF 6 was calculated from the experimental values of density. The densities and refractive indices of binary mixtures involving dimethyl carbonate (DMC), diethyl carbonate (DEC), acetone, 2-butanone, 2-pentanone, methylacetate, ethylacetate, and butylacetate + HMIMPF 6 (1-hexyl-3-methylimidazolium hexafluorophosphate) have been measured at T = 298.15 K and atmospheric pressure. Excess molar volumes and changes of refractive index on mixing for the binary systems were calculated. The miscibility of IL with different organic solvents and (liquid + liquid) equilibrium (LLE) data of binary mixture HMIMPF 6 + DEC have been determined experimentally.

2025, The Journal of Chemical Thermodynamics

2025, Revista Facultad De Ingenieria

Se hace una revisión de las principales ecuaciones de estado, su aplicación a la ingeniería química de procesos y, fundamentalmente, de las ecuaciones basadas en la teoría química y las que hacen conjunción con los métodos de contribuciones de grupos. Otras ecuaciones de estado, desde su surgimiento hasta la fecha, con especial énfasis en las ecuaciones de estado cúbicas, las del virial y las basadas en simulación molecular se tratan en la primera parte de esta revisión.

2025, Journal of Supercritical Fluids

• Literature experimental data on phase behavior and density for water, ethanol and CO 2 . • Literature data bank on phase equi- librium and density for CO 2 +water and CO 2 +ethanol. • Data selected for wide ranges of T, P and composition and kij estimation for CPA EoS. • Application of CPA EoS with CR-1 for phase equilibrium and volumetric description. • Validation of CPA EoS for calcula- tion of thermodynamic properties and process design.

2025, Journal of Chemical & Engineering Data

Vapor-liquid equilibria (VLE) for binary and ternary aqueous solutions of water, monoethanolamine (MEA), N-methyldiethanolamine (MDEA), and 3-(methylamino)propylamine (MAPA) were measured in a modified Swietoslawski ebulliometer at (40, 60, 80, and 100) °C. Experimental temperature (T) and total pressure (P) were measured, and the compositions of both the liquid (x) and vapor (y) phases were analyzed. Boiling temperatures (T b ) of pure water and amines were measured over the pressure range of P ) (2.5 to 101.3) kPa. Experimental activity coefficients (γ) were calculated from the experimental P, T, x, and y data and were fit to the Wilson and NRTL equations.

2025, Chemical Engineering Journal

Isobaric vapor-liquid equilibrium data at 705 ± 1 mm Hg for the systems water-pyridine and water-pyridine-CaCl 2 were obtained using the modified Othmer circulation still. The experimental data for the water-pyridine system exhibited an azeotropic point at a water composition of 75.0 mol% and a temperature of 92.60 • C. The isobaric salt-free binary data were compared with predicted vapor-liquid equilibrium (VLE) data using the UNIFAC model. Good agreement between the experimental and the predicted results was obtained, with a root-mean-square-deviation (RMSD) in predicted bubble-point temperature and predicted vapor-phase composition of 0.28 K and 0.007, respectively. In addition to that, the experimental data were correlated with the Wilson, the NRTL and the UNIQUAC models. The calculated VLE data using the parameters found by these models were in good agreement with the experimental results. The VLE of water-pyridine mixtures in the presence of calcium chloride at different concentrations was found to be dramatically different from that of the salt-free mixtures. Calcium chloride had showed a salting-out effect on water and could eliminate the azeotropic point of the system when used under saturated conditions. In addition, analysis of the data showed that the salt resulted in "splitting" the liquid mixtures into two different liquid phases.

2025, mose.units.it

In this paper, we present a hierarchical procedure for bridging the gap between atomistic and macroscopic (FEM) modelling passing through mesoscopic simulations. In particular, we will discuss the concept of multiscale (or many scale) modelling, and present an example of applications of multiscale procedures for ABS -organoclay nanocomposites of industrial interest.

2025, Journal of Petroleum Science and Engineering

A simple thermodynamic model with only two adjustable parameters has been developed which can accurately correlate hydrate-liquid water-vapor (H-L W -V) phase equilibrium for single-guest gas hydrates at temperatures below 300 K. The approach combines the van der Waals-Platteeuw theory and the Peng-Robinson equation of state, and provides a unified treatment of the two fluid phases (liquid water and hydrocarbon). The present model compares favorably with other methods in the literature in terms of average absolute percent deviation (AAPD) from available experimental data. We further find that the accuracy of the calculations is insensitive to the solubility of guest molecules in liquid water.

2025, Lithos

In-situ electron microprobe (EMP) U-Th-Pb monazite-, sensitive high-resolution ion microprobe (SHRIMP) zircon analyses, metamorphic phase equilibrium (Domino/Theriak)-and geothermobarometric calculations are performed on kyanite/sillimanite-bearing garnet biotite gneisses forming part of the dominant rock association in the Xitieshan ultra-high pressure metamorphic belt, north Qaidam, western China. Results are consistent with the following complex polyphase tectono-metamorphic evolution. The kyanite/sillimanite bearing garnet biotite gneisses contain monazite ages of 938 ± 23 Ma and zircon SHRIMP ages of 945 ± 7 Ma, referring to a Neoproterozoic metamorphism, i.e. similar to the age of the Jinning orogeny in the Yangtze block of southern China. This correlation suggests that the paragneiss has affinities with the Yangtze block (South China block). The Neoproterozoic monazites were found inside coarse grained porphyroblastic garnets containing amphibolite facies mineral inclusion assemblages. The kyanite/sillimanite-bearing garnet biotite gneisses also contain early Paleozoic monazite ages of 422-425 Ma and 455-460 Ma, detected in amphibolite facies mineral assemblages associated with matrix minerals. Using phase equilibrium-and geothermobarometric calculations, PT conditions of 560-610 °C/5.8-7.0 kbar and 610-675 °C/4.6-6.5 kbar were calculated respectively for both amphibolite facies assemblages. The early Paleozoic ages of 422-425 Ma and 455-460 Ma were detected in 8 monazite grains from the investigated paragneiss samples. Based on the Y and Eu contents variation of the early Paleozoic monazite domains (measured by EMP), the 422-425 Ma monazite ages are interpreted to have formed during an amphibolite facies tectono-metamorphic overprint that post-dates (U)HP metamorphism and can thus be related to exhumation of previously deeply subducted rocks. Alternatively, the 455-460 Ma monazite ages are interpreted to represent the age of the prograde subduction zone metamorphism. We conclude therefore that the mineral assemblage of the kyanite/sillimanite-bearing garnet-biotite gneiss (and associated retro-eclogite) was formed during an early Paleozoic subduction/collision event, which involved late Proterozoic (938-945 Ma) crystalline basement inliers of minimal mid amphibolite facies grade. Early Paleozoic deep subduction towards (U)HP depths occurred around 455-460 Ma followed by retrograde amphibolite facies metamorphism at 422-425 Ma during exhumation.

2025, Fluid Phase Equilibria

Methanol/CO 2 phase behavior was investigated previously by a number of researchers. However, the entire composition range at moderate temperatures was not mapped in a single study. Extensive acetonitrile/CO 2 vapor-liquid phase information has not been reported. The goals of this research were twofold: (1) to demonstrate the accuracy and precision of visual observation for vapor-liquid phase boundary determination using a high-pressure, variable-volume view cell with the methanol/CO 2 system relative to the data available, and (2) to examine phase behavior of methanol/CO 2 and acetonitrile/CO 2, commonly used binary fluids for supercritical fluid chromatography and extraction, from 0-1.00 mole fraction CO 2 and over a 25-100°C temperature range. Results for methanol/CO 2 were found to be very comparable to the literature values.

2025, Korean Journal of Chemical Engineering

A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems and its consistent method for phase equilibrium calculation were presented in the previous paper. In this work, the model was extended to mixtures by using consistent method for phase equilibrium calculation with fugacity coefficients derived from the present equation of state and it was applied to vapor-liquid equilibrium. We consistently tested the present model on 17 phase equilibrium data sets of vapor-liquid equilibria and compared it with the MF-NLF model and the SAFT model. The present model (3 pure parameters for pure component and one binary interaction parameter) showed better results for most systems than the MF-NLF model (6 adjustable pure parameters and one binary interaction parameter) and the SAFT model (3 pure parameters and one binary interaction parameter).

2025, Solar Energy

A methodology is developed for the application of thermodynamic equations of state of fluids and fluid mixtures in evaluating working fluid combinations of absorption cooling cycles. Thermodynamic phase equilibrium formulation of this methodology is presented. In the application of this approach for the comparative study and choice of working fluids, the Redlich-Kwong equation of state is used for a number of possible working fluid combinations for solar absorption cooling cycles. It is demonstrated that when limited experimental data are at hand this approach could be a useful screening technique for potential working fluid combinations.

2025, Iranian Journal of Chemistry & Chemical Engineering-international English Edition

) is used to model the vapor-liquid equilibrium (VLE) in systems containing (water + NaCl + CO 2 ), (water + methanol + NaCl + CO 2 ), (water + Na 2 SO 4 + CO 2 ) and (water + NH 4 Cl + CO 2 ). The binary and ternary interaction parameters between salt and solvent are adjusted to experimental mean solvent activity of salts (NaCl and Na 2 SO 4 ). For the system containing (water + Na 2 SO 4 + CO 2 ), the EPR-EOS is used to predict the P-T diagram when the moles of Na 2 SO 4 in 1 kg water are 0.25, 0.5 and 1. The calculated results for the (water + Na 2 SO 4 + CO 2 ) system by the extended PR-EOS are compared with the correlation results by Anderko-Pitzer EOS. The average absolute deviation of (ΔP/P exp ) % between the correlation results by Anderko-Pitzer EOS and experimental data is 8.4 % while this value for extended PR-EOS is 6 %. The P-x diagram for (water + NH 4 Cl + supercritical-CO 2 ) system at temperatures (333 and 353 K) are also obtained and compared with the calculation results by VTPRLIFAC model. The average absolute deviation between calculation results by VTPRLIFAC model and experimental data is 7.8 % but this value for our calculations is 6.2 %.

2025

Reactive separation (RS) is the combination of a chemical (catalytic) reaction and a separation technique. For reactive distillation (RD), the reaction is combined with distillation. Rapid development of RS is the result of growing environmental demands and increasing energy costs. Several processes are performed using RD, such as esterification, etherification (fuel antiknocks), and hydrodesulphurisation. Other RS techniques also develop rapidly. However, the success has not come without some serious problems. The heterogeneous proton catalysts still do not meet the requirements of many processes. The column internals with a built-in catalyst are rather sparse and expensive and their characteristics are not studied well enough. Therefore intensive studies are still being performed. This study presents a brief summary of the processes realisable with the usage of reactive distillation, catalysts, and column internals. Some interesting research results and application examples are also quoted.

2025

2025, The Journal of Supercritical Fluids

A dynamic simulation model of a countercurrent packed column operating at supercritical fluid (SCF) conditions is presented. The model was developed and applied to a case study involving the fractionation of a binary mixture of squalene and methyl oleate using supercritical carbon dioxide. The purpose of the separation process is to remove the methyl oleate from the solution and concentrate squalene in the raffinate phase. The final model comprises the differential material balances in the packed column and algebraic equations describing the thermodynamic phase equilibrium, mass transfer and the hydrodynamics of the two countercurrent phases. The model was validated by carrying out a series of experiments in a lab-scale continuous SCF extraction unit. A good agreement was obtained between measured and predicted composition profile of the outlet streams over time.

2025, Journal of Chemical & Engineering Data

Vapor-liquid equilibrium data are reported for the ternary system oleic acid + squalene + carbon dioxide in the temperature range of (313 to 333) K and in the pressure range of (14 to 22) MPa. Experiments were performed in a continuous-type equilibrium apparatus where a static mixer promotes the equilibrium between the gas and liquid phases. A low selectivity of carbon dioxide toward squalene was obtained, indicating that the separation is poor. Oleic acid was of technical grade containing other fatty acids in minor quantities. Distribution coefficients of major fatty acids were evaluated in the range described. Equilibrium data were correlated using the Peng-Robinson equation of state with a reasonably good agreement. The interaction parameters of the equation were optimized by minimizing the deviations between the calculated and experimentally determined vapor and liquidphase compositions and distribution coefficients of each component.

2025, Fluid Phase Equilibria

Incipient hydrate, aqueous liquid, vapor equilibrium conditions of hydrates formed from mixtures containing carbon dioxide and hydrogen or carbon dioxide, hydrogen and propane were determined. The gas phase concentrations at equilibrium were also measured. The presence of carbon dioxide lowers the hydrate formation pressure substantially compared to that for pure hydrogen. Addition of propane as a third substance reduces the pressure even further. An analysis of the pressure-temperature conditions based on the Clapeyron equation was also carried out to infer the structures formed. In both cases it is believed that hydrogen participates in the hydrate phase.

2025, Continuum Mechanics and Thermodynamics

We give a numerical treatment of phase mixtures in pseudoelasticity from a purely mathematical point of view. It is based on a surprising result that the approximate solution may consist of persistent oscillations in strain which resemble the experimentally observed interface patterns. Such a solution is obtained from a sequence of solutions for a rate-type viscoelastic problem with a non-monotone equilibrium stress-strain relation, for which in the limit as the viscosity tends to infinity the viscoelastic problem reduces to the rateindependent elastic problem describing phase transitions. In this manner, it seems to give yet another perspective for the phase mixture from dynamic point of view as the evolution of an unstable state, in contrast to the traditional treatment from stability analysis for phase equilibrium.

2025, Macromolecules

Experimental and modeling/simulation studies of phase equilibrium and growth morphologies of novel polymer-dispersed liquid crystal (PDLC) mixtures of PS (polystyrene) and liquid crystals that exhibit a direct isotropic/smectic-A (lamellar) mesophase transition were performed for PS/10CB (decylcyanobiphenyl) and PS/12CB (dodecyl-cyanobiphenyl). Partial phase diagrams were determined using polarized optical microscopy (POM) and differential scanning calorimetry (DSC) for different compositions of both materials, determining both phase separation (liquid/liquid demixing) and phase ordering (isotropic/smectic-A transition) temperatures. The Flory-Huggins theory of isotropic mixing and Maier-Saupe-McMillan theory for smectic-A liquid crystalline ordering were used to computationally determine phase diagrams for both systems, showing good agreement with the experimental results. In addition to thermodynamic observations, growth morphology relations were found depending on phase transition sequence, quench rate, and material composition. Three stages of liquid crystal-rich domain growth morphology were observed: spherical macroscale domain growth ("stage I"), highly anisotropic domain growth ("stage II"), and sub-micron spheroid domain growth ("stage III"). Nano-scale structure of spheroidal and spherocylindrical morphologies were then determined via two-dimensional simulation of a high-order Landau-de Gennes model. Morphologies observed during stage II growth are typical of direct isotropic/smectic-A phase transitions, such as highly anisotropic "batonnets" and filaments. These morphologies, which are found to be persistent in direct isotropic/smectic-A PDLCs, could provide new functionality and applications for these functional materials.

2025, Industrial & Engineering Chemistry Research

Specific requirements are presented for the measurement of multiple-component, multiple-phase equilibria. Details of an apparatus capable of operation in the ranges of 310-425 K and 60-345 bar are given. The apparatus features a moveable... more

2025, Journal of Chemical & Engineering Data

Activity coefficient values for NaCl and glycine are determined by studying their aqueous mixtures at different electrolyte and glycine concentrations. The mean ionic activity coefficient of NaCl was calculated from cell potential measurements: Na-ISE/NaCl (m NaCl ); glycine (m Gly )/Ag/AgCl. Measurements were made over the concentration range of (0.005 to 2) mol • kg -1 glycine and of (0.05 to 2) mol • kg -1 NaCl at temperatures (298.2, 308.2, and 318.2) K. The experimental data were correlated with the Roberts-Kirkwood and Scatchard-Prentiss virial expansion series. The activity coefficient of glycine is related to the mean ionic activity coefficient of the electrolyte through the cross-differential relation and evaluated by the standard deviation, σ. The mean ionic activity coefficient of NaCl decreases as the molality of glycine in the solution increases. The presence of NaCl decreases the activity coefficient of glycine and consequently represents a salt-in effect for amino acid.

2025, Mathematics and Computers in Simulation

We present a new method to solve general systems of equations containing complementarity conditions, with a special focus on those arising in the thermodynamics of multicomponent multiphase mixtures at equilibrium. Indeed, the unified formulation introduced by Lauser et al. [Adv. Water Res. 34 (2011), 957-966] has recently emerged as a promising way to automatically handle the appearance and disappearance of phases in porous media compositional multiphase flows. From a mathematical viewpoint and after discretization in space and time, this leads to a system consisting of algebraic equations and nonlinear complementarity equations. Such a system exhibit serious convergence difficulties for the existing semismooth and smoothing methods. This observation led us to design a new strategy called NPIPM (Non-Parametric Interior-Point Method ). Inspired from interior-point methods in optimization, the technique we propose avoids any parameter management while ensuring good theoretical convergence results. These are validated by extensive numerical tests, in which we compare NPIPM to the Newton-min method.

2025, Russian Journal of Physical Chemistry A

Liquid-solid phase equilibria are studied in the eutectic benzoic acid-naphthalene system by means of thermic analysis (DTA, CTA), on the basis of which the liquidus line and eutectic point (x e ≈ 50 mol %, T e ± 340 K) are determined and the phase diagram is constructed. Average precrystallization supercooling tem peratures ΔT of the liquid phase relative to liquidus temperature T L are determined, allowing us to locate the region of solution metastability on the phase diagram. Excessive functions of the components in the liquid phase are found via thermodynamic modeling using the Margules equation and experimental data. The boundaries of the region of liquid solution metastability are estimated from the thermodynamic conditions of solution stability.

2025

The process of recovery by liquid-liquid extraction of ethanol manufactured in a fermentation process could be improved by using solvents such as 1-decanol which have a good separation factor. In this work, liquid-liquid equilibrium data... more

2025, Fluid Phase Equilibria

Heterogeneous azeotropic distillation is a widely used technique to separate binary azeotropic mixtures into their components. One of its most important applications is the dehydration of ethanol, which is blended with gasoline to obtain automobile fuel. Among all the compounds that could be used as an entrainer, heptane was chosen because it is one of the common components of gasoline. The advantage of this entrainer is that the remaining quantity of heptane in the ethanol will not be a problem for its subsequent use as a fuel. Obviously, to carry out that research, knowledge of the vapor-liquid (VLE) and the isobaric vapor-liquid-liquid equilibrium (VLLE) data is required. In this study, VLE and VLLE were measured for the ternary system water + ethanol + n-heptane at 101.3 kPa. The experimental data were correlated using NRTL and UNIQUAC and predicted with UNIFAC.