Effect of Temperature on Phase Separation in Liquid Binary System Constituted by Tetradecane and Samarium(III) Nitrate Solvate with Tri-n-Butyl Phosphate and Ternary System Constituted by Tetradecane,Tri-n-Butyl Phosphate,and Samarium(III) Nitrate Solvate with Tri-n-Butyl Phosphate

The phase diagrams of a binary liquid system constituted by tetradecane and samarium(III) nitrate solvate with tri-n-butyl phosphate and a ternary system constituted by tetradecane, tri-n-butyl phosphate, and samarium(III) nitrate solvate with tri-n-butyl phosphate were studied at 298.15-355.15 K. The distribution of components between the phases was considered. The points of critical compositions of the ternary system at various temperatures and the upper critical temperature of mixing of the binary and ternary systems were estimated.     

Structure and phase equilibria of mixtures of the complex salt hexadecyltrimethylammonium polymethacrylate, water and different oils

This work reports on phase diagrams for mixtures of a complex salt formed by a cationic surfactant and an oppositely charged polyelectrolyte, hexadecyltrimethylammonium polymethacrylate, in binary mixtures with water and in ternary mixtures containing water and organic solvents of different polarity ('oils'): decanol, octanol, p-xylene and cyclohexane. The liquid crystalline structures formed were identified by small angle X-ray scattering measurements, which also provided information about changes in the size of the aggregates as a function of the system composition. These results are analysed in comparison with others previously reported [Bernardes et al., J. Phys. Chem. B 110 (2006) 10332-10340] for the analog complex formed with polyacrylate and, in general, reveal that the presence of an extra methylene group in the polymer chain does not produce significant changes in the complex phase diagrams nor in the structure of the liquid crystalline phases formed. Additionally, the obtained results confirm once more the approach used to analyze these kinds of systems formed by polymer and oppositely charged surfactant.     

Vapor–liquid equilibrium of systems containing alcohols,water, carbon dioxide and hydrocarbons using SAFT

The statistical associating fluid theory (SAFT) equation of state is employed for the correlation and prediction of vapor–liquid equilibrium (VLE) of eighteen binary mixtures. These include water with methane, ethane, propane, butane, propylene, carbon dioxide, methanol, ethanol and ethylene glycol (EG), ethanol with ethane, propane, butane and propylene, methanol with methane, ethane and carbon dioxide and finally EG with methane and ethane. Moreover, vapor–liquid equilibrium for nine ternary systems was predicted. The systems are water/ethanol/alkane (ethane, propane, butane), water/ethanol/propylene, water/methanol/carbon dioxide, water/methanol/methane, water/methanol/ethane, water/EG/methane and water/EG/ethane. The results were found to be in satisfactory agreement with the experimental data except for the water/methanol/methane system for which the root mean square deviations for pressure were 60–68% when the methanol concentration in the liquid phase was 60 wt.%.     

A Monte Carlo simulation of the aggregation, phase-separation, and gelation of model globular molecules

Monte Carlo computer simulation on a square 3-D lattice is used to model state behavior of globular copolymers. Two types of globular molecules were defined. One consisted of a single type of subunit (a homopolymer) while the second contained a core of strongly attractive subunits and an outer layer of less strongly attractive subunits (a heteropolymer). Systems of globules were simulated at varied volume fraction (V(F)) and reduced temperature (T(R)), and state diagrams were constructed. These state diagrams contained state boundaries defined by the V(F)/T(R) combinations at which the system formed a percolating network and at which the various component subunits in the globule unfolded. Simulated systems could exist in a number of states (between 4 and 7), depending on the V(F), T(R), whether the molecule was a homo- or heteroglobule and whether the globules were allowed to interact with each other or not. All systems exhibited a gelation/crossover line that resembled a lower critical solution temperature. All systems also exhibited a critical gelation concentration, above which a continuous network was formed. The critical gelation concentration varied between about 2-4% V(F) depending on the type of system. This is comparable to experimental critical gelation concentrations of in the region of 4% (w/w) for a range of associating polymers and biopolymers such as globular proteins and polysaccharides. Other states were formed which included one where elongated, fibril-like aggregated strands were formed, and a micelle-like aggregated state. The results are discussed in terms of the known state behavior of associating polymers and biopolymers (proteins and polysaccharides).     

Salting-out of isopropyl alcohol from aqueous solutions with potassium nitrate

The solubility of components and critical phenomena in a ternary system constituted by potassium nitrate, water, and isopropyl alcohol were studied by the visual-polythermic method in the temperature range 25–90°C. The formation temperature of the critical node of the monotectic equilibrium (critical solution—solid phase) and the solution compositions corresponding to the critical solubility points at different temperatures were determined. Isothermal solubility diagrams of the system were constructed, the previously suggested scheme of the topological transformation of the phase diagrams of ternary stratifying systems constituted by a salt and a binary solvent was confirmed, and the distribution coefficients of isopropyl alcohol at different temperatures were calculated.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 12, 2004, pp. 1945–1949.Original Russian Text Copyright © 2004 by Sinegubova, Ilin, Cherkasov, Kurskii, Tkachenko.     

Topological transformation of a phase diagram for the sodium nitrate-water-isopropanol ternary system

Phase equilibria and critical phenomena in the sodium nitrate-water-isopropanol ternary system, where a boundary binary liquid system shows no immiscibility over the entire temperature range of its liquid state, were studied in the range from 5 to 90°C using a visual polythermal method. The formation temperature of a monotectic critical tie-line was determined to be 6.1°C, and the solution compositions corresponding to critical solution points at various temperatures were determined. Isopropanol partition coefficients between the aqueous and organic phases of monotectic equilibrium were calculated for seven temperatures. The isopropanol salting out from aqueous solutions by sodium nitrate was shown to be enhanced by rising temperature. Isothermal phase diagrams of the title system were constructed to verify a fragment of the general scheme of topological transformations of phase diagrams for salt-binary solvent ternary systems with salting out.     

Phase equilibria and critical phenomena in the cesium nitrate–water–pyridine ternary system

The solubilities of components, phase equilibria, and critical phenomena in the cesium nitrate–water–pyridine ternary system are studied in the 5–100°C temperature range by the visual–polythermal method. Cesium nitrate is found to exhibit a salting-out effect at temperatures above 79.9°C causing phase separation in homogeneous water–pyridine solutions. The temperature of formation of the critical monotectic tie line (79.9°C) and the compositions of solutions corresponding to the liquid–liquid critical points at three temperatures are determined. The pyridine distribution coefficients between the aqueous and organic phases of the monotectic state at 85.0, 90.0, and 100.0°C are calculated. Their values demonstrate that salting-out of pyridine from aqueous solutions by cesium nitrate increases at higher temperatures. The plotted isotherms of phase diagrams confirm the fragment of the scheme of topological transformation of the phase diagrams of salt–binary solvent ternary systems with salting-in and salting-out phenomena.     

Liquid—liquid equilibria for ternary systems of water—phenol and solvents: new UNIFAC parameters for interactions between the groups ACOH/COOH and prediction

The UNIFAC group-contribution method is used to predict ternary liquid—liquid equilibrium data presented in a recent paper (Alvarez Gonzalez et al.) for the systems water/phenol/benzene, water/phenol/ethylbenzene, water/phenol/nonanoic acid, water/phenol/ethyl acetate, water/phenol/isopropyl acetate, water/phenol/n-butyl acetate, water/phenol/isoamyl acetate and water/phenol/cyclohexyl acetate at 25°C and water/phenol/n-hexyl acetate at 25, 35 and 45°C. New UNIFAC interaction parameters between the groups ACOH/COOH have been obtained.A comparison between the experimental and predicted values is presented.     

Separation of systems based on uranium hexafluoride and some of halogen fluorides

The purpose of this paper is to present the results of the comprehensive study of the phase equilibriums liquid-solid and liquid-vapour in binary and ternary systems, formed by uranium hexafluoride, bromine trifluoride and iodine pentafluoride.Investigation of the phase equilibriums in condensed systems is done by methods of differential thermoanalysis and visual polythermal analysis. All systems belong to simple eutectics; formation of the compounds is not detected. For all systems under investigation diagrams of the phase equilibrium liquid-solid are plotted.Phase equilibriums liquid-vapour in studied systems were studied by statistical method. All systems are non-aseotropic. The article presents diagrams of the phase equilibrium liquid-vapour in binary systems, pressure of the saturated vapour dependences on liquid composition, surface of the boiling liquid and lines of the constant content of uranium hexafluoride and iodine pentafluoride in vapour phase of the ternary system UF₆-BrF₃-IF₅.     

Calculation of vapour-liquid equilibrium of associated systems by an equation of state

A recently proposed equation of state of the van der Waals type is applied to calculate phase equilibria in hydrogen-bonding, non-electrolytic systems. Association is accounted for by treating alcohols, acids, etc., as mixtures of associated species formed by up to 14 monomers. The method involves essentially one weakly temperature-dependent adjustable parameter per binary system.The calculations cover vapour-liquid equilibrium both at low and elevated pressure in binary systems formed by an associating substance and a non-associating compound such as a hydrocarbon or halogenated hydrocarbon. An attempt has been made to include all experimental data available for these systems in the literature. A number of calculations for ternary systems as well as of liquid-liquid equilibria are included, and a limited number of solvated systems are also treated.Owing to its single adjustable parameter, the method may be used to test existing experimental data and to predict such data.     

Unusual S-shaped binodal curves of the systems water+lithium chloride+1-butanol or 2-butanol or 2-methyl-1-propanol

Solid–liquid–liquid equilibrium data of the ternary systems water+LiCl+2-butanol, water+LiCl+2-methyl-1-propanol (i-butanol) and water+LiCl+1-butanol have been experimentally determined at 25°C. The equilibrium diagrams determined show differences between the systems. In the system with 1-butanol, the solid phase of the liquid–liquid–solid region is monohydrated salt. However, in the systems with 2-butanol and 2-methyl-1-propanol it is anhydrous salt. With respect to the liquid+liquid zone, the three diagrams are very similar with an unusual S-shaped solubility curve in the organic branch that can be explained depending on whether the organic solvent takes part in the solvation of ions. The more salt, the more numbers of ions solvated by water and organic solvent and the solubility of water and salt in the organic phase increase notably producing the unusual S-shaped solubility curve.     

Phase diagrams of liquid-liquid equilibria for the systems water-phosphoric acid-solvent entrainer at 313.15 and 333.15 K

Liquid-liquid equilibria data have been determined for the ternary system of water + phosphoric acid + solvent entrainer (1,4-dimethylbenzene, 1,2-dichloroethane, and n-hexane) at 313.15 and 333.15 K. Experiments were carried out at atmospheric pressure using stirred and thermo-regulated cells. The ternary phase diagrams were obtained by the experimental solubility and tie-line data. The Othmer-Tobias equation was used to correlate the tie-line compositions. The measured liquid-liquid equilibrium data were compared with the non-random two liquid activity coefficient model. Root mean square deviations between experimental and calculated compositions were considered satisfactory. It was showed that the non-random two liquid model of all ternary systems presented very good satisfactory results with root mean square deviations so that this model was highly appropriate to calculate thermodynamic properties of the ternary solutions. The liquid-liquid equilibrium thermodynamic properties of water + phosphoric acid + solvent entrainer can be used in research on the nature of mixing behavior of the ternary system for molecular models and industrial applications in concentration the phosphoric acid aqueous solution.     

Cyclodextrin-surfactant coassembly depends on the cyclodextrin ability to crystallize

Full equilibrium phase diagrams are presented for two ternary systems composed of the cationic surfactant dodecyltrimethylammonium bromide (DTAB), water (D(2)O), and a cyclodextrin, either β-cyclodextrin (β-CD) or (2-hydroypropyl)-β-cyclodextrin (2HPβCD). (2)H NMR, SAXS, WAXS, and visual examination were used to determine the phase boundaries and characterize the nature of the phases formed. Additionally, diffusion (1)H NMR was used to investigate parts of the diagrams. The water solubility of 2HPβCD is 80% (w/w), whereas it is only 1.85% (w/w) for β-CD. Solubility increases for both species upon complexation with DTAB; while the increase is minute for 2HPβCD, it is dramatic for β-CD. Both systems displayed an isotropic liquid solution (L(1)) one-phase region, the extension of which differs extensively between the two systems. Additionally, the DTAB:2HPβCD:water system also comprised a normal hexagonal (H(1)) area, which was not found for the DTAB:β-CD:water system. In the DTAB:β-CD:water system, on the other hand, we found cocrystallization of DTAB and β-CD. From this work we conclude that DTAB and CD molecules form 1:1 inclusion complexes with high affinities. Moreover, we observed indications of an association of 2HPβCD to DTAB micelles in the isotropic solution phase, which was not the case for β-CD and DTAB micelles. This is, to our knowledge, the first complete phase diagrams of surfactant-CD mixtures; as a novel feature it includes the observation of cocrystallization at high concentrations.     

Vapor-liquid and vapor-liquid-liquid equilibria of carbon dioxide/n-perfluoroalkane/n-alkane ternary mixtures

Perfluoroalkanes have numerous applications (e.g., in the medical field and the chemical industry), and their high affinity for carbon dioxide makes them attractive as surfactants and cosolvents. Although research in this area has grown in the past few years, very little phase-equilibrium data is available in the open literature for these systems. In this work, we present, for the first time, predictions of vapor-liquid and vapor-liquid-liquid equilibria of binary and ternary systems of carbon dioxide/n-perfluoroalkane/n-alkane. Our results are based on the SAFT-VR EOS (statistical associating fluid theory of variable range, equation of state), and we study the influence of temperature, pressure, composition, and chain length on the phase diagram. The predicted phase diagrams are based on temperature-independent binary interaction parameters, and no ternary parameters are introduced. Comparisons to the available experimental and molecular simulation data show that the predicted diagrams should provide a good representation of the phase equilibria.     

Phase Behavior of Oleyl Oleate with Nonionic Surfactants

Oleyl oleate (OE), a liquid wax ester, has been reported as a potential raw material for cosmetic and pharmaceutical uses but little is known about its phase behavior in ternary systems. Two types of nonionic surfactants were selected, namely, Tween‐60 (T60) and Span 20 (S20). Phase diagrams of OE/T60/water and OE/S20/water systems were constructed at 25.0±0.5°C. Ternary phase diagrams of OE/T60∶S20 (20∶80 and 60∶40)/water systems were then constructed at the same temperature. The ratios of 80∶20 and 60∶40 of T60∶S20 were selected due to different solubility points of the surfactants in water. The results showed that the oleyl oleate with mixed surfactants system, OE/T60∶S20 (20∶80 and 60∶40)/water, gave better performance than the individual surfactant systems. The high percent of T60 of 80∶20 in the T60∶S20 system contributes to enlargement of the isotropic region. In contrast, by increasing the percent of S20 of 60∶40 in T60∶S20 contributes to a larger liquid crystalline region.     

NdCl3-LiCl及NdCl3-LiCl-NaCl体系相图的研究

利用DTA和X射线结构分析研究了NdCl3-LiCl二元体系相图和NdCl3-LiCl-NaCl三元体系液相限. 发现NdCl3-LiCl体系相图属于简单低共熔型, 低共熔点e3为28.5(wt%)LiCl, 452℃. 在低共熔温度以下有一固相下生成的介稳化合物, 在443℃分解, 组成为2NdCl3.LiCl. 经长时间退火, 该化合物消失. NdCl3-LiCl-NaCl体系有对应NdCl3、LiCl、NaCl、2NaCl.LiCl、NaCl.LiCl的五个液相面, 七条两次结晶线, 一个三元低共熔点E[69.0(wt%)NdCl3, 13.5(wt%)NaCl, 374℃], 两个三元转熔点P1[69.5(wt%)NdCl3, 14.5(wt%)NaCl, 380℃], P2[70.0(wt%)NdCl3,15.5(wt%)NaCl, 385℃].     

Investigations into the formation and characterization of microemulsions. I. Phase diagrams of the ternary system water—sodium alkyl benzene sulfonate—hexanol and the quaternary system water—xylene—sodium alkyl benzene sulfonate—hexanol

The phase diagrams of the ternary system water—sodium alkylbenzene sulfonate (NaDBS)-hexanol and the quaternary system water—xylene—NADBS—hexanol have been established at three different temperatures, namely 25, 37, and 50°C. The different phases formed have been qualitatively examined using optical (phase contrast and polarizing) microscopy. The textures of the various liquid crystalline phases in the ternary system have been identified, by comparison with previous studies in the literature. Some of the liquid crystalline phases have been quantitatively assessed using low angle X-ray diffraction. The latter measurements were also used to determine the unit cell dimensions in the various phases studied. With the quaternary system, particular attention was paid to the transparent region which consisted of an L₂ (inverse micellar) phase extending into another transparent region which has a blue “tinge” in some cases, namely the microemulsion (M) region. The amount of water solubilized in the L₂ (reverse micelle) or M + L₂ phase was calculated from the phase diagrams. With the ternary system the results showed a maximum in moles of water solubilized per mole total surfactant (NaDBS + hexanol) at a concentration of 0.3 mole surfactant, at an optimum molar ratio of n-hexanol to NaDBS of 4.5:1. This maximum was about twice with the quaternary system, when compared with that of the ternary system, indicating the importance of the role of xylene in solubilization of water by the surfactants. The present investigation has also shown that the extent of the microemulsion region is significantly reduced by increases of temperature when the NaDBS is lower than 15 wt%.     

An NMR self-diffusion investigation of water/xylene/alkyl amine solutions

Extensions of the solution phases have been determined and the self-diffusion behaviour investigated in ternary systems containing water/xylene/primary alkyl amine, where the chain length of the amine varied between C₆ and C₁₀. The phase diagrams at 25°C are dominated by a solution phase and a rather large water/xylene miscibility gap which increases slightly in size with increasing chain length of the amine. A lamellar liquid crystalline phase was found in all binary amine/water systems at 25°C, except for hexylamine where the lamellar phase melts below this temperature. The self-diffusion coefficients of all components decrease in a similar way when water is added to a xylene/amine solution. The self-diffusion is rapid and of similar magnitude for all components, which shows that no well-defined inverse aggregates are formed. The data are discussed in terms of hydrogen bonding between the different species in the solution.     

Hexagonal liquid crystalline phases formed in ternary systems of Brij 97-water-ionic liquids

Phase diagrams of two ionic liquids: hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate (bmim-PF(6)) and relatively hydrophilic 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF(4)) in aqueous solutions of Brij 97 were determined at 25 degrees C. Two hexagonal liquid crystalline phases formed in bmim-PF(6)- and bmim-BF(4)-containing ternary systems were investigated by means of small-angle X-ray scattering (SAXS) and rheological techniques, with comparison of composition and temperature effects. From analysis of the SAXS data, bmim-PF(6) is dominantly penetrated between the oxyethylene chains of surfactant molecules, whereas bmim-BF(4) is mainly located in the water layer of hexagonal phases. The strength of the network of hexagonal phase formed in the Brij 97/water/bmim-BF(4) system is appreciably stronger than that of the Brij 97/water/bmim-PF(6) system, indicated by the smaller area of the surfactant molecule at the interface and the higher moduli (G', G' '). Temperature has a converse effect on the lattice parameters of the two hexagonal phases.