Pseudoternary System Research Articles

Modeling the phase behavior of heavy oil and solvent mixtures

The capability of conventional oil characterization methods combined with a cubic equation of state to predict the phase behavior of heavy oil and solvent mixtures was evaluated using data for mixtures of bitumen, propane, and carbon dioxide. The bitumen was characterized based on simulated distillation (SimDist) data extrapolated using six different approaches. Each curve was divided into temperature-based pseudo-components with physical and critical properties determined from established correlations. Four sets of correlations were evaluated and modifications were proposed to extend the Twu critical property correlations to pseudo-components with normal boiling points higher than 730 °C. The phase behavior of the oil was modeled using the advanced Peng–Robinson equation of state and the interaction parameters were optimized to fit experimental saturation pressures of pseudo-binary mixtures of each solvent with the bitumen. The model was then used to predict saturation pressures and liquid–liquid phase boundaries of pseudo-ternary systems as well as asphaltene precipitation from n-heptane diluted bitumen. The best characterization of the bitumen was a Gaussian distribution of boiling points from the SimDist for the maltenes plus a Gamma distribution of the molecular weight of the asphaltene fraction. Characterizations with boiling points above 800 °C failed. Both the Lee–Kesler and Twu property correlations could be applied to heavy fractions but the Lee–Kesler correlations provided a better fit to the data. The model correctly predicted the saturation pressures and liquid–liquid boundaries for pseudo-ternary mixtures of propane–CO 2–bitumen with an AARD of less than 6%. However, the model could not correctly predict asphaltene precipitation yields from bitumen at high dilution with n-heptane.

Design of compositions of low-melting phosphate glass-enamel coatings based on composites in the R 2O-TiO2-Al2O3-B2O3-P2O5 system for aluminum

The pseudoternary system intended for synthesis of low-melting phosphate glass-enamel coatings for aluminum articles has been studied. The optimum ratio between concentrations of alkali oxides providing the maximum mixed-alkali effect has been determined and its influence on the properties of enamels (such as chemical durability, electrical resistivity, thermal expansion, and fusibility characteristics) has been investigated.

Rhombohedral-Tetragonal Phase Coexistence and Piezoelectric Properties of (NaK)(NbSb)O3-LiTaO3-BaZrO3 Lead-Free Ceramics

The phase transitional behavior and composition-dependent piezoelectric properties of (NaK)(NbSb)O3–LiTaO3–BaZrO3 (NKNS–LT–BZ) pseudo-ternary system were investigated. A composition–temperature phase diagram was generalized within a certain range of BZ content in which a rhombohedral–tetragonal (R–T ) ferroelectric phase boundary connecting orthorhombic and cubic phase zones is formed near room temperature between two trifurcate points. Piezoelectric and electromechanical properties of NKNS–LT–BZ ceramics exhibit optimum values of d33=365 pC/N and kp=45% in the vicinity of the R–T phase coexistence zone. The dielectric and ferroelectric properties and the phase transition of NKNS–LT–BZ ceramics were discussed from a crystallographic point of view.

Glass formation and third-order optical nonlinear properties within TeO 2–Bi 2O 3–BaO pseudo-ternary system

Tellurite glasses from TeO 2–Bi 2O 3–BaO pseudo-ternary system were prepared using a conventional melt-quenching method and its glass-forming region was determined. A series of glasses were selected and their third-order optical nonlinearities (TONL) were measured by employing the Z-scan method at a wavelength of 800 nm with femtosecond laser pulses. The results showed that glass former Te 4+ ions exhibited positive influences on the TONL and glass modifiers Ba 2+ ions behaved similarly; low concentrated Bi 3+ ions as glass modifiers weakened the nonlinearities, but an excess amount of Bi 3+ behaved oppositely. FTIR measurements demonstrated that chemical bonds especially Te–O eq vibrated at a high energy level remarkably promoted the TONL susceptibility χ (3), and the glass sample with the highest Bi 2O 3 content exhibited the largest χ (3) value which was due to the presence of BiO 3 polyhedra.

Effect of temperature on pseudoternary system Tween-80–butanol–hexane–water

Phase diagrams of pseudoternary systems of Tween-80, butanol, hexane and water were constructed by a visual titration method. The cloud points (CPs) at various compositions were determined and the variations in the cloud points were analyzed on the basis of changes in the composition of the different components in the microemulsions. A quantitative model was established by using multiple regression analysis considering weight percent of emulsifier (surfactant + cosurfactant) and oil as independent variables. A lowering in the CP with increase in emulsifier content and decrease in oil content was observed. Addition of sodium chloride also depressed the CP significantly. Further, with the increase in temperature the turbid phase started separating to three different transparent zones. The upper layer was recognized as the oil-rich phase, middle layer was due to microemulsion and the lower layer was found to be a micellar system. Metal ions and colored organic substrates partitioned into these different phases, which provides scope for applications in metal ion preconcentration.

High-Temperature Protonic Conduction in LaFeO3 – SrFeO3 − δ – SrZrO3 Solid Solutions

The electrical conductivity of a pseudoternary system, consisting of , , was evaluated both in oxygen and hydrogen containing environments by a two-probe ac technique. Correlations of oxygen partial pressure, water vapor pressure, and composition dependences of the electrical conductivities with possible defect concentrations are examined by a semiquantitatively derived Brouwer diagram. In oxygen for below 0.25, major carriers were identified to be oxide ions and electron holes, while for they were a mixture of oxide ions, electron holes, and protons. In a hydrogen containing environment, the oxides with compositions for and 0.5 were unstable. Thus, the electrical conductivity was analyzed in detail for . It was found that the oxide conducts protons significantly at temperatures below , which was evidenced by the isotope effect of hydrogen and deuteron on the electrical conductivity. The electrical conductivity of the oxide increased with decreasing oxygen partial pressure due to the variation of oxygen nonstoichiometry, accompanied by partial reduction of Fe ions in the oxide. The transport number of proton increased as the oxygen partial pressure decreased. The gas partial pressure and the composition dependences of the electrical conductivity and the transport number of proton could be well explained by the conceptual Brouwer diagram proposed in this work.

MPB design and crystal growth of PMN–PT–PZ relaxor ferroelectrics

Rhombohedral–tetragonal ferroelectric structural phase transition temperature (TR−T), far below the Curie temperature (Tc) in lead magnesium niobate–lead titanate (PMN–PT) relaxor ferroelectric single crystal, heavily restricts its further applications either as a sensor or transducer. To overcome this shortcoming, lead zirconate (PZ) was introduced into the PMN–PT pseudo-binary system to increase TR−T via the morphotropic phase boundary (MPB) composition design and optimization. According to the PMN–PT–PZ pseudo-ternary phase diagram, various compositions have been selected to discuss the relations between their phase structural transition and piezoelectric properties in the PMN–PT–PZ pseudo-ternary system. X-ray diffraction (XRD) investigation indicates clearly that PMN–PT–PZ ceramics with MPB compositions experience a typical structural phase transition process from rhombohedral phase to tetragonal phase. Remnant polarization (Pr=33.4μC/cm2) and piezoelectric coefficient (d33=1050pC/N) were obtained at the (001) cut PMN–PT–PZ single crystal. TR−T was increased up to 120°C by measuring its dependence of dielectric constant on temperature.

Phase equilibria in the Ag2Se-AgAsSe2-AgBiSe2 system

Phase equilibria in the pseudoternary system Ag2Se-AgAsSe2-AgBiSe2 have been studied using differential thermal analysis, X-ray diffraction, microhardness tests, and emf measurements on silver concentration cells with Ag4RbI5 as solid electrolyte. The results are used to construct the 300-, 600-, and 800-K isothermal sections, a number of partial phase diagrams, and the liquidus projection. Several in- and univariant peritectic and eutectic equilibria and a broad region of AgBiSe2-based solid solutions are identified. The homogeneity range of the high-temperature phase of AgBiSe2 reaches −50 mol % in width (650 K), and that of the low-temperature phase is 20 mol % in width (300 K) along the AgAsSe2-AgBiSe2 constituent binary. The melting points, lattice parameters, and microhardness of the solid solutions are determined.

A novel water-in-ionic liquid microemulsion and its interfacial effect on the activity of laccase

It is of great significance to develop an appropriate water-in-ionic liquid (W/IL) microemulsion suitable for the expression of the catalytic activity of a given enzyme. In this paper, the phase diagram of a new AOT/Triton X-100/H 2O/[Bmim][PF 6] pseudo ternary system is presented. With the aid of nonionic surfactant Triton X-100, AOT could be dissolved in hydrophobic ionic liquid [Bmim][PF 6], forming a large single phase microemulsion region. The water-in-[Bmim][PF 6] (W/IL) microemulsion domain was identified electrochemically by using K 3Fe(CN) 6 as a probe. The existence of W/IL microemulsions was demonstrated spectrophotometrically by using CoCl 2 as a probe. New evidences from the FTIR spectroscopic study, which was first introduced to the W/IL microemulsion by substituting D 2O for H 2O to eliminate the spectral interference, demonstrated that there existed bulk water at larger ω 0 values ( ω 0 was defined as the molar ratio of water to the total surfactant) in the W/IL microemulsion, which had remained unclear before. In addition to the inorganic salts, biomacromolecule laccase could be solubilized in the W/IL microemulsion. The laccase hosted in the microemulsion exhibited a catalytic activity and the activity could be regulated by the composition of the interfacial membrane.

First-Principles Thermochemistry and Thermodynamic Modeling of the Al2O3-Nd2O3-SiO2-Y2O3 Pseudoquaternary System

The Al2O3–Nd2O3–SiO2–Y2O3 pseudoquaternary system was thermodynamically modeled with a focus on the phase equilibria concerning the sintering of neodymium-doped yttrium aluminum garnet, Nd:YAG ((Y1−xNdx)3Al5O12). The Nd2O3–SiO2 and Nd2O3–Y2O3 systems were evaluated. Due to the lack of experimental thermochemical data, first-principles calculations were used to predict the enthalpy of formation of Nd2SiO5 and the enthalpy of mixing of Nd in YAG. Isothermal sections of the Al2O3–Nd2O3–SiO2, Al2O3–Nd2O3–Y2O3, and Nd2O3–SiO2–Y2O3 pseudoternary systems are presented.

Synthesis of biosurfactant-based silver nanoparticles with purified rhamnolipids isolated from Pseudomonas aeruginosa BS-161R

The biological synthesis of nanoparticles has gained considerable attention in view of their excellent biocompatibility and low toxicity. We isolated and purified rhamnolipids from Pseudomonas aeruginosa strain BS-161R and these purified rhamnolipids were used to synthesize silver nanoparticles. The purified rhamnolipids were further characterized and the structure was elucidated based on one- and two-dimensional (1)H and (13)C NMR, FT-IR, and HR-MS spectral data. Purified rhamnolipids in a pseudoternary system of n-heptane and water system along with n-butanol as a cosurfactant were added to the aqueous solutions of silver nitrate and sodium borohydride to form reverse micelles. When these micelles were mixed, they resulted in the rapid formation of silver nanoparticles. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The nanoparticles formed had a sharp adsorption peak at 410 nm which is characteristic of surface plasmon resonance of the silver nanoparticles. The nanoparticles were monodispersed with an average particle size of 15.1 nm (sigma = +/-5.82 nm) and spherical in shape. The EDS analysis revealed the presence of elemental silver signal in the synthesized nanoparticles. The silver nanoparticles formed exhibited good antibiotic activity against both Gram-positive and Gram-negative pathogens and Candida albicans, suggesting their broad spectrum antimicrobial activity.

Phase diagrams of the CuSbS2-MS (M = Pb, Eu, Yb) systems

The phase equilibria in the pseudoternary systems CuSbS2-MS (M = Pb, Eu, Yb) have been studied, and their phase diagrams have been mapped out. The systems contain MCuSbS3 sulfides with an orthorhombic lattice, isostructural with the mineral bournonite (sp. gr. Pmn21, Z = 4). PbCuSbS3: a = 8.162, b = 8.71, c = 7.81 A; EuCuSbS3: a = 8.156, b = 8.682, c = 7.786 A; YbCuSbS3: a = 8.150, b = 8.664, c = 7.78 A.

Preparation and evaluation of fexofenadine microemulsions for intranasal delivery

To enhance the solubility and bioavailability of poorly absorbable fexofenadine, microemulsion system composed of oil, surfactant and co-surfactant was developed for intranasal delivery. Phase behavior, particle size, viscosity and solubilization capacity of the microemulsion system were characterized. Histopathology and in vivo nasal absorption of the optimized microemulsion formulations were also investigated in rats. A single isotropic region was found in the pseudo-ternary phase diagrams developed at various ratios with Lauroglycol 90 as oil, Labrasol as surfactant and Plurol Oleique CC49 or its mixture with PEG-400 (1:1) as cosurfactant. An increase in the microemulsion region in pseudo-ternary phase systems was observed with increased surfactant concentration. The optimized microemulsion formulations showed higher solubulization of fexofenadine, i.e., F1 (22.64 mg/mL) and F2 (22.98 mg/mL), compared to its intrinsic water solubility (1.51 mg/mL). Nasal absorption of fexofenadine from these microemulsions was found to be fairly rapid. T max was observed within 5 min after intranasal administration at 1.0 mg/kg dose, and the absolute bioavailability (0–4 h) was about 68% compared to the intravenous administration in rats. Our results suggested that these microemulsion formulations could be used as an effective intranasal dosage form for the rapid-onset delivery of fexofenadine.

Extreme alkali bicarbonate- and carbonate-rich fluid inclusions in granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark

Our study of fluid and melt inclusions in quartz and feldspar from granite pegmatite from the Precambrian Ronne granite, Bornholm Island, Denmark revealed extremely alkali bicarbonate- and carbonate-rich inclusions. The solid phases (daughter crystals) are mainly nahcolite [NaHCO3], zabuyelite [Li2CO3], and in rare cases potash [K2CO3] in addition to the volatile phases CO2 and aqueous carbonate/bicarbonate solution. Rare melt inclusions contain nahcolite, dawsonite [NaAl(CO3)(OH)2], and muscovite. In addition to fluid and melt inclusions, there are primary CO2-rich vapor inclusions, which mostly contain small nahcolite crystals. The identification of potash as a naturally occurring mineral would appear to be the first recorded instance. From the appearance of high concentrations of these carbonates and bicarbonates, we suggest that the mineral-forming media were water- and alkali carbonate-rich silicate melts or highly concentrated fluids. The coexistence of silicate melt inclusions with carbonate-rich fluid and nahcolite-rich vapor inclusions indicates a melt-melt-vapor equilibrium during the crystallization of the pegmatite. These results are supported by the results of hydrothermal diamond anvil cell experiments in the pseudoternary system H2O–NaHCO3–SiO2. Additionally, we show that boundary layer effects were insignificant in the Bornholm pegmatites and are not required for the origin of primary textures in compositionally simple pegmatites at least.

Phase equilibria in pseudoternary systems of IV–VI compounds

Using literature data, experimental data obtained in this study, and a unified thermodynamic model, we have calculated the T-x-y phase diagrams of all the pseudoternary systems formed by the Group 14 chalcogenides: (Ge, Sn, Pb)Te, Pb(S, Se, Te), and Sn(S, Se, Te). The phase diagrams have been constructed using the known interaction parameters of the pseudobinary systems and the ternary interaction parameters derived from experimental data. The systems have small negative ternary interaction parameters, which decrease in the order β-(Ge, Sn, Pb)Te < β-Pb(S, Se, Te) < δ-Sn(S, Se, Te).

Supercritical fluid extraction from dried banana peel ( Musa spp., genomic group AAB): Extraction yield, mathematical modeling, economical analysis and phase equilibria

Supercritical fluid extraction from dried banana peel ( Musa spp., subgroup Prata, genomic group AAB, popularly known in Brazil as Enxerto) was studied. The aspects investigated were: overall extraction curve (OEC), mass transfer modeling of the yield curves, economical analysis of the process and phase equilibrium data for the pseudo-ternary system of banana peel extract, carbon dioxide and ethanol. The extraction operating conditions evaluated were: pressure ranging from 100 bar to 300 bar, temperature from 40 to 50 °C and constant solvent flow rate of 5.0 gCO 2/min. Experimental extraction data were correlated using three kinetic models based on mass transfer equations (logistic, diffusion and Esquível models). Phase equilibrium measurements were performed using pressure from 64.9 bar to 239.9 bar and mass fraction of supercritical extract from 0.52 to 3.55 wt%. Yield results ranged from 0.6 to 6.9% d.b. (dry basis). The lowest deviation between experimental and correlated data was obtained by the Logistic model, except for the curve at 300 bar and 40 °C which was best represented by the Esquível model. The economical analysis identified the possibility to apply the supercritical fluids to obtain extracts from banana peel in an industrial scale. Phase equilibrium for the supercritical extract from banana peel with carbon dioxide modified by ethanol exhibited liquid–liquid, vapor–liquid (bubble point) and vapor–liquid–liquid phase transitions. A crossover phenomenon for the systems evaluated was observed for pressures between 200 bar and 240 bar, for both groups of assays, i.e., supercritical extraction and phase equilibrium.

Obtaining NiHCF Nanoparticles Using a Reverse Micellar System

The synthesis of metallic nanoparticles using a reverse microemulsion medium brings controlled size and shape. In this study, reverse micelar system was employed for the synthesis of nickel hexacyanoferrate nanoparticles, NiHCF, by direct encapsulation in the water pools of reverse micelles formed in a pseudoternary system that consist of a mixture of 95 %wt. cetyltrimetyl ammonium bromide (CTAB) and 5 %wt. of a novel modified surfactant cetyltrimetyl ammonium ferrocyanate (CTA[Fe(CN6)]4-, CTAFe)/n-butanol/Hexane/Water. These NiHCF nanoparticles were produced with particle size ranging with 20 – 60 nm.

Formulation and Physicochemical Characterization of Imwitor 308 Based Self Microemulsifying Drug Delivery Systems

Self Microemulsifying Drug Delivery Systems (SMEDDS) are a novel alternative to the conventional transdermal delivery systems. SMEDDS are water-free systems, made up of oils and surfactants that can readily form a microemulsion upon dilution within an aqueous medium. Before SMEDDS can be used as a drug delivery system it is necessary to investigate the internal microstructure of the resulting microemulsion. Novel Imwitor 308 based SMEDDS were prepared and investigated. Phase behaviour of the comprising components was investigated through the construction of pseudoternary phase diagrams. The formed systems were characterized using visual inspection, measurement of electrical conductivity, viscosity and droplet size. Amongst the pseudoternary systems investigated, IPM/Cremophor EL (50% w/w)/Imwitor (50% w/w) and Myritol 318/Tween 85 (64% w/w)/ Transcutol P (20% w/w)/Imwitor (16% w/w) possessed the largest microemulsion area. Electrical conductivity and viscosity studies depict structural transitions from w/o microemulsion to bicontinuous or o/w microemulsion around 20-35% water. This was further supported by the droplet size and Fourier transform (FT)-IR measurements. The FT-IR data suggests that below the percolation threshold (ψ(C)) the water molecules are mainly bounded to the surfactant head group (bound water). Above this value, water molecule move to the outer phase of the microemulsion mainly interacting with each other though hydrogen bounding (free water). It was also found that pseudoternary systems with water content of less than 30% were stable at 32°C. Such systems may form stable microemulsion upon contact with the skin. Absorption of water may also result in a supersaturated solution with enhanced transdermal flux.

Ag3Fe(VO4)2and AgFeV2O7: Synthesis, Structure, and Electrochemical Characteristics of Two New Silver Iron(III) Vanadates

The structural features and electrochemical properties of two new silver iron(III) vanadates have been determined, and their relevance to cathode materials for primary lithium battery devices is reported. Ag3Fe(VO4)2 (SFVO-1) and AgFeV2O7 (SFVO-2) were isolated via a pseudoternary (Ag2O−Fe2O3−V2O5) system at 600 °C. The crystallographic data of the phases are the following: Ag3Fe(VO4)2 monoclinic C2/c (no. 15), a = 9.771(2) A, b = 5.153(1) A, c = 14.325(3) A, β = 93.85(3)o, V = 719.7(2) A3, Z = 4; AgFeV2O7, triclinic, P1 (no. 2), a = 5.603(1) A, b = 7.485(2) A, c = 7.644(2) A, α = 65.07(3)o, β = 89.48(3)o, γ = 78.98(3)o, V = 284.4(1) A3, Z = 2. The single crystal X-ray diffraction studies show that the Ag+ cations reside in the open space of layered (SFVO-1) and channeled (SFVO-2) Fe−O−V frameworks. The extended electrochemical capacity above 2 V (vs Li/Li+) in these phases is consistent with their higher (Ag++Fe3+)/V5+ ratios, compared to the corresponding Ag+/V5+ in Ag2V4O11 (SVO). The discharge voltag...

Structural Investigations of Glass Ceramics in the Ga2S3−GeS2−CsCl System

Transparent glass ceramics have been prepared in the Ga(2)S(3)-GeS(2)-CsCl pseudoternary system using appropriate heat treatment time and temperature. In situ X-ray diffraction at the heat treatment temperature and (133)Cs and (71)Ga solid-state nuclear magnetic resonance have been performed in function of annealing time to understand the crystallization process. Both techniques have evidenced the nucleating agent role played by gallium with the formation of Ga(2)S(3) nanocrystals. On the other hand, cesium is incorporated very much later into the crystallites during the ceramization. Moreover, the addition of CsCl, which is readily integrated into the glassy network, permits us to shift the optical band gap toward shorter wavelength. Thus, new glass ceramics transmitting in the whole visible range up to 11.5 mum have been successfully synthesized from the (Ga(2)S(3))(35)-(GeS(2))(25)-CsCl(40) base glass composition.