Miscibility Curve Research Articles

Equations of State, Thermodynamics, and Miscibility Curves for Jovian Planet and Giant Exoplanet Evolutionary Models

The equation of state of hydrogen–helium (H–He) mixtures plays a vital role in the evolution and structure of gas giant planets and exoplanets. Recent equations of state that account for H–He interactions, coupled with H–He immiscibility curves, can now produce more physical evolutionary models, such as accounting for helium rain with greater fidelity than in the past. In this work, we present a set of tools for planetary evolution that provides a Python interface for existing tables of useful thermodynamic quantities, state-of-the-art H–He equations of state, and pressure-dependent H–He immiscibility curves. In particular, for a collection of independent variable choices, we provide scripts to calculate the variety of thermodynamic derivatives used to model convection and energy transport. These include the chemical potential derived from the internal energy, which is a modeling necessity in the presence of composition gradients when entropy is the other primary variable. Finally, an entropy-based convection formalism is presented and fully described that highlights the physical differences between adiabatic and isentropic interior models. This centralized resource is meant to facilitate both giant planet structural and evolutionary modeling and the entry of new research groups into the field of giant planet modeling. All tables of thermodynamic quantities and derivatives are available at https://github.com/Rob685/hhe_eos_misc, along with a unified Python interface. Tutorials demonstrating the interface are also available in the repository.

Removing aromatic organic pollutants by cloud point extraction using biodegradable nonionic surfactants: equilibrium constants and diffusion kinetics

ABSTRACT The impacts of inadequate disposal of industrial wastewater cause environmental, economic, social and human health damage. The search for innovative and viable methodologies from a technical and economic standpoint aims to promote suitable management of effluents produced by different industrial activities. The objective of this paper was to study phenol, aromatic alcohol and aromatic amine removal using cloud point extraction based on analysis of extraction capacity, miscibility curves, equilibrium lines, distribution coefficients and mass transfer solubilisation diffusion. The oxo-C10E3P4E2 surfactant produced the best results, exhibiting smaller coacervate volume fractions, low concentration in the diluted phase and efficient extraction (E%) of phenol (81.79%), 1-phenylethanol (67.88%), 2-phenylethanol (65.41%), benzyl alcohol (57.01%), aniline (56.91%), p-toluidine (73.96%) and 2,4-dimethylaniline (84.87%). The ternary phase diagrams revealed a large miscibility area favourable to extraction, with equilibrium lines showing a pronounced slope in favour of the coacervate, indicating high compound concentration factors. Equilibrium isotherms were used to obtain the distribution and solubilisation constants (Log KC/D KS), in the following order: aniline (1.05; 9.15) < p-toluidine (1.35; 20.40) < 2,4-dimethylaniline (1.76; 45.10) and benzyl alcohol (1.07; 8.19) < 2-phenylethanol (1.22; 14.04) < 1-phenylethanol (1.28; 15.23) < phenol (1.59; 36.72). These parameters show a linear correlation with Log KO/W, revealing that micellar solubilisation is governed by the hydrophobic nature of aromatic organic compounds. The evolution of pH demonstrated that the ionised forms of phenol and 2,4-dimethylaniline do not establish interactions (electrostatic, van der Waals, hydrogen bonds) with surfactants. Mass transfer diffusion is governed by hydrophobic compounds, slightly compromising phenol due to its high solubility in water.

Binary isobaric phase diagrams of stearyl alcohol-poloxamer 407 formulations in the molten and solid state

Multiparticulate formulations allow for the design of specialized pharmaceutical dosage forms that cater to the needs of a wide range of patient demographics, such as pediatric and geriatric populations, by affording control over the release rate and facilitating the formulation of fixed-dose combination drugs. Melt spray-congealing (MSC) is a method for preparing multiparticulate dosage forms from a suspension or solid solution of active pharamaceutical ingredients (API) and a molten carrier matrix. Stearyl alcohol and poloxamer 407 mixtures are widely used as carrier matrices in MSC microsphere formulations. In this report, the phase equilibria of stearyl alcohol-poloxamer 407 mixtures were investigated by generating binary phase diagrams of composition, i.e. weight/weight percent of poloxamer 407 in stearyl alcohol, and temperature in the molten form and the solid state. The phase equilibria of the molten state were characterized by 1H NMR measurements. The miscibility curves of stearyl alcohol-poloxamer 407 molten mixtures revealed that stearyl alcohol and poloxamer 407 are not miscible in all proportions and that miscibility substantially increases with temperature. The phase equilibria of the solid state were characterized by DSC and PXRD experiments. The phase diagrams of the solid state indicate that stearyl alcohol and poloxamer 407 crystallize and melt separately and, thus, do not form a eutectic or a single phase. The phases equilibria of the bulk mixtures were compared to the phases observed in placebo MSC microspheres and it was determined that the microspheres consist of a mixture of thermodynamically stable and metastable stearyl alcohol crystals immediately after manufacture.

On the miscibility gap of Cu-Ni system

The existence of the miscibility gap in the Cu-Ni system has been an issue in both computational and experimental discussions for half a century. Here we propose a new miscibility gap in the Cu-Ni system measured in nano-layered films by Secondary Neutral Mass Spectrometry. The maximum of the symmetrical miscibility curve is around 780K at Cu50%Ni50%. This is the first experiment determining the miscibility from the measurement of the atomic fraction of Copper and Nickel in the whole composition range.

Nonergodicity in binary alloys

For binary liquids with limited miscibility of the components, we provide the corrections to the equation of state which arise from the nonergogic diffusivity. It is shown that these corrections result in lowering of critical miscibility point. In some cases, it may result in a bifurcation of miscibility curve: the mixtures near 50% concentration which are homogeneous at the microscopic level, occur to be too stable to provide a quasi - eutectic triple point. These features provide a new look on the phase diagrams of some binary systems. In present work, we discuss Ga-Pb, Fe-Cu, and Cu-Zr alloys. Our investigation corresponds their complex behavior in liquid state to the shapes of their phase diagrams.

English

This paper describes a new experiment for undergraduate students in physical chemistry. This experiment describes a separation process of liquid-liquid extraction using mixtures with a critical point of miscibility. In this experiment, students will learn how to measure solute concentration, and a new liquid-liquid extraction technique that we called Phase Transition Extraction (PTE). In this experiment, a liquid mixture, together with the solute to be separated, is first heated above its critical temperature, where it forms a uniform solution, and then cooled to the region below the miscibility curve, where it separates. Students will understand that this separation process has the advantage that the resulting separation of the solvents is very rapid. In addition, the extraction speed of it may be 10 times higher than that of the traditional liquid-liquid extraction. The new process is thought of having significant advantages in the extraction of products from fermentation broths, plants, and other natural sources. In this paper, miscibility of binary liquid mixtures of methanol-cyclohexane and acetonitrile-water-toluene will be studied. A two-phase distribution ratio will be determined. Temperature and composition of the liquid-liquid critical point will be determined. Key words: Miscibility, liquid mixtures, methanol-cyclohexane, acetonitrile-water-toluene.

Theoretical prediction of a phase diagram for solid dispersions.

To predict the temperature-composition phase diagram of solid dispersions (SDs) through theoretical approaches using cinnarizine-Soluplus(®) SD as a model system and evaluate the predicted results. A complete phase diagram of cinnarizine-Soluplus(®) SD, including the solubility curve, miscibility curve and glass transition temperature curve, was constructed on the basis of the solid-liquid equilibrium (SLE) equation, Florry-Huggins (F-H) theory and Fox equation. Cinnarizine-Soluplus(®) SDs with different drug loadings were prepared by hot melt extrusion. The extrudates and corresponding physical mixtures were analyzed to check the predicted results. The experimental data revealed a solubility of 7.9 wt% at 110°C and a miscibility level of 65 wt% at room temperature, which were both consistent with predicted values. The predicted phase diagram agrees well with the experimental results for the non-polar components which mainly interact through dispersion forces, thus facilitating the formulation design of SDs.

Effects of Oleic Acid on Stratum Corneum Lipids in Langmuir Monolayers

The mechanism of oleic acid (OA) as a transdermal permeation enhancer has long been debated. In this study, the interaction between OA and stratum corneum (SC) lipids was investigated with an aqueous monolayer of model SC lipids. Different amount of OA was cospread with equal molar mixture of ceramide, cholesterol and palmitic acid at the air/water interface. The monolayer phase behavior was monitored through surface pressure-molecular area isotherms (π-A isotherms). With increasing OA concentration in the monolayer, the resultant films became more fluid and more compressible. OA also modified the domain structure in SC monolayers as visilized through Brewster Angle Microscope (BAM). The miscibility curve derived from π-A isotherms demonstrated the preferential interaction between OA and SC lipids. IRRAS measurements showed that OA mixed with ceramide and disordered its acyl chains. The acyl chain order of palmitic acid was also lowered by OA but to a lesser extent.

Liquid–Liquid Equilibria in Binary Solutions Formed by [Pyridinium-Derived][F4B] Ionic Liquids and Alkanols: New Experimental Data and Validation of a Multiparametric Model for Correlating LLE Data

Experimental solubility data are presented for a set of binary systems composed of ionic liquids (IL) derived from pyridium, with the tetrafluoroborate anion, and normal alcohols ranging from ethanol to decanol, in the temperature interval of 275–420 K, at atmospheric pressure. For each case, the miscibility curve and the upper critical solubility temperature (UCST) values are presented. The effects of the ILs on the behavior of solutions with alkanols are analyzed, paying special attention to the pyridine derivatives, and considering a series of structural characteristics of the compounds involved. Miscibility curves are modeled using, for the first time in a LLE study, an adimensional form of a semiempirical model proposed for the Gibbs excess function, GE = GE(p,T,x) [Ind. Eng. Chem. Res.2010, 49, 406], whose particular form in this work isgE(T,x)=z(x)[1−z(x)]∑i=0rgi(T)zi(x)The results are compared with those of an extended form of the Non-Random Two-Liquids (NRTL) equation, using temperature-dependent...

Liquid–Liquid Phase Equilibria of 1-Propanol + Water + n-Alcohol Ternary Systems at 298.15 K and Atmospheric Pressure

Liquid–liquid equilibrium (LLE) data for the ternary systems 1-propanol + water + n-alcohols (1-pentanol, 1-hexanol, 1-octanol, 1-nonanol, 1-decanol, or 1-dodecanol) were determined at 298.15 K and atmospheric pressure. The n-alcohols from 1-pentanol up to 1-dodecanol can be used as extraction solvents for the separation of 1-propanol from aqueous solutions. The miscibility curves, the conode lines, and the plait points were obtained. The phase diagrams for all of these systems are of type I in according to Trayball classification. The Othmer–Tobias and Hand equations, used to verify the quality of the experimental data, give similar and generally good results for all of the systems. The experimental ternary LLE data were correlated with the universal quasichemical activity coefficient (UNIQUAC) model which represents satisfactorily the obtained experimental data. Distribution coefficients (Di) and separation factors (S) were calculated from tie-line data to evaluate the extracting capability of the solvents, which increases with increasing alcohol chain length.

Thermodynamic Behavior of the Binaries 1-Butylpyridinium Tetrafluoroborate with Water and Alkanols: Their Interpretation Using 1H NMR Spectroscopy and Quantum-Chemistry Calculations

Here we present experimental data of different properties for a set of binary mixtures composed of water or alkanols (methanol to butanol) with an ionic liquid (IL), butylpyridinium tetrafluoroborate [bpy][BF(4)]. Solubility data (x(IL),T) are presented for each of the mixtures, including water, which is found to have a small interval of compositions in IL, x(IL), with immiscibility. In each case, the upper critical solubility temperature (UCST) is determined and a correlation was observed between the UCST and the nature of the compounds in the mixtures. Miscibility curves establish the composition and temperature intervals where thermodynamic properties of the mixtures, such as enthalpies H(m)(E) and volumes V(m)(E), can be determined. Hence, at 298.15 and 318.15 K these can only be found with the first four alkanols. All mixing properties are correlated with a suitable equation ξ (x(IL),T,Y(m)(E) = 0. An analysis on the influence of the temperature in the properties is shown, likewise a comparison between the results obtained here and those of analogous mixtures, discussing the position of the -CH(3) group in the pyridinic ring. The (1)H NMR spectra are determined to analyze the molecular interactions present, especially those due to hydrogen bonds. Additional information about the molecular interactions and their influence on the mixing properties is obtained by quantum chemistry calculations.

Miscibility Holes and Continuous Liquid−Liquid Miscibility Curves in Type III and IV Systems

Liquid−liquid miscibility in binary and ternary fluids has been studied to a great extent by Professor Schneider. One of the important results of his studies was the description of the so-called immiscibility holes or islands in type IV systems. In these holes, the liquid−liquid coexistence curve virtually disappears; i.e., it goes below the vapor pressure of the mixture where the liquid becomes metastable to the liquid−vapor phase transition. In the case of the ternary system, the critical end-points then form a closed loop which is the so-called immiscibility hole. Changing, for example, the composition in ternary systems or the molar mass in binary systems containing chain molecules, one can show that a type III-like liquid−liquid critical curve can emerge from this hole. Here we show that this type III-like critical curve already exists within the hole. As a consequence, the liquid−liquid critical curves of type III and IV systems are similar if metastable states are included. The possibility of indir...

Liquid–liquid equilibria of lactam containing binary systems

In this work, we report a study on the liquid–liquid phase equilibria for N-methyl-2-pyrrolidone (NMP) + hydrocarbon ( n-hexane, n-octane, n-decane, cyclohexane, cyclooctane, 2-methylpentane, 3-methylpentane, isooctane, 2,2-dimethylbutane and 2,3-dimethylbutane) and N-cyclohexyl-2-pyrrolidone (NCP) + water binary mixtures at ambient pressure. The studied systems, except NCP + water, present miscibility curves with upper critical solutions temperatures (UCSTs). The results for NMP + hydrocarbon mixtures are correlated using two different approaches: (i) NRTL and UNIQUAC semiempirical models and (ii) molecular-based equations of state (statistical associating fluid theory (SAFT) and perturbed-chain statistical associating fluid theory (PC-SAFT)). Accurate correlations are inferred for NRTL and UNIQUAC models whereas for SAFT and PC-SAFT EOS complex mixing rules are required to obtain accurate results.

The Use of Critical Solution Mixtures for Contaminated Sediments Remediation

AbstractUsing a critical solution mixture, into which chelating agents have been dissolved, resulted in the efficient, rapid and simultaneous removal of both heavy metals and organic pollutants from contaminated sediments. Both heating and cooling across the immiscibility curve and isothermal extraction were investigated. In addition, the extraction yields were compared to those obtained with solution mixtures that do not possess a critical point of miscibility. Extraction yields of the former were superior to those of the latter in the range of relevant pressures (1 atm.) and temperatures. Extraction via heating and cooling across the miscibility curve resulted in the removal of close to 90% of the heavy metals and practically all of the organic contaminants, compared to only about 40% when the extraction was performed isothermally at around 20oC.

The Use of Critical Solution Mixtures for Contaminated Sediments Remediation

Using a critical solution mixture, into which chelating agents have been dissolved, resulted in the efficient, rapid and simultaneous removal of both heavy metals and organic pollutants from contaminated sediments. Both heating and cooling across the immiscibility curve and isothermal extraction were investigated. In addition, the extraction yields were compared to those obtained with solution mixtures that do not possess a critical point of miscibility. Extraction yields of the former were superior to those of the latter in the range of relevant pressures (1 atm.) and temperatures. Extraction via heating and cooling across the miscibility curve resulted in the removal of close to 90% of the heavy metals and practically all of the organic contaminants, compared to only about 40% when the extraction was performed isothermally at around 20oC.

Experimental study and modeling of the salt effect on phase equilibria for binary hydroxylic liquid systems

Experimental measurements of the influence of the presence of a salt on miscibility curves have been performed for different binary systems involving water and another compound having the hydroxyl group OH. The choice of these systems has been motivated by the fact that, generally these compounds tend to have a good miscibility with water. This may be explained by the similarity of intermolecular forces characterised by the presence of hydrogen bonding. Consequently, it is interesting to examine how this affinity is influenced by the salt. The experimental results have also been used to obtain interaction parameters necessary for the modelling of these binary equilibria, using known thermodynamic models for the activity coefficients calculations. Different chemical systems have been considered, but in this work the results for water-phenol system are presented with and without the presence of NaCl, KCl and BaCl 2 as the salts.

TCE recovery mechanisms using micellar and alcohol solutions: phase diagrams and sand column experiments

Forty-one phase diagrams and fifteen sand column experiments were conducted to evaluate the efficiency of three types of washing solutions to recover trichloroethylene (TCE) at residual saturation and to identify the recovery mechanisms involved. This study demonstrates that: (1) an alcohol and a surfactant combination is more efficient than an alcohol used alone in water; (2) the prediction of the dominant recovery mechanism from the tie line slopes in phase diagram is accurate and can be reproduced in sand column experiments; and (3) TCE recovery efficiency in sand column experiments is generally well represented by the position of the miscibility curve in phase diagrams in the low concentration range. However, the miscibility curve alone is not sufficient to exactly predict the TCE recovery mechanisms involved. Tie line slopes and the critical tie line have to be taken into consideration to select the active matter as well as its concentration and to predict the dominant recovery mechanism in sand column experiments. The sand column experiments quantified the recovery efficiency of each solution and identified the proportion of the recovery mechanisms (mobilisation vs. solubilisation). Washing solutions with an active matter concentration above the critical tie line caused dominating mobilisation. Mobilisation was also dominant when the active matter of the washing solution partitioned into the organic phase and the active matter concentration was below the critical tie line. Solubilisation and emulsification were dominant for washing solutions containing active matter, which principally partitioned into the aqueous phase and an active matter concentration below the critical tie line.

Theoretical study of the Al xGa 1− xN alloys

In this work we use a first-principles method based on the density functional theory, the full-potential linear augmented plane-wave method (FPLAPW), in order to calculate the electronic structures of the Al x Ga 1− x N alloys in the cubic modification. We adopt a model which allows the simulation of the composition x=0.0, 0.25, 0.50, 0.75 and 1.0. We obtain the equilibrium lattice parameters, the bulk moduli, the formation energies, the miscibility curves and the effective masses of the conduction and valence bands in the [100], [111] and [110] directions. The results can be used in the parameterization of theories based on effective hamiltonians. To our knowledge, this is the first time such a systematic ab initio study of effective masses of these semiconductor alloys is accomplished.

Miscibility study in the bismuth-zinc system extension to the isotherms 425 and 500°C of the ternary system BiSbZn

Abstract The miscibility curve of the system ZnBi has been studied by using calorimetric analysis and isothermal solubility measurements. A thermodynamical equation of this curve has been established and the critical point co-ordinates have been calculated: T c = 595°C, W Bi = 0.363. The compositions of the invariant solutions and the temperatures of the three-phase equilibria have been stated precisely. The reaction enthalpies of the monotectic ( ΔH = 90 ± 4 J g −1 ) and the eutectic ( ΔH = 53 ± 1 J g −1 ) transformations have been determined. In the ternary system ZnBiSb, the miscibility gap has been completely delimited at two temperatures. At 425°C, the one-phase liquid field is very reduced, but at 500°C, a liquid solution can be obtained whatever the ratio bismuth/zinc in the alloy.

Liquid−Liquid Extraction Using the Composition-Induced Phase Separation Process

This paper describes a new separation process of liquid−liquid extraction. It consists of first mixing the system to be extracted with a primary solvent, which is soluble with the native solvent, and subsequently adding a modifier, which is insoluble with either the native or the primary solvent. This process is similar to the phase transition extraction, which was described in a previous paper, where the liquid mixture, together with the solute to be separated, is first heated above its critical temperature, where it forms a uniform solution, and then cooled to the region below the miscibility curve, where it separates. Both processes have the advantage that the resulting separation of the solvents is very rapid, even in the presence of emulsion-forming impurities. In addition, the extraction efficiency of the new process may be 10 times higher than that of the traditional liquid−liquid extraction. The new process is thought of having significant advantages in the extraction of products from fermentation broths, plants, and other natural sources.