Showing papers on "Binary system published in 2017"

Mass transfer and disc formation in AGB binary systems

Abstract: We investigate mass transfer and the formation of disc in binary systems using a combination of numerical simulations and theory. We consider six models distinguished by binary separation, secondary mass and outflow mechanisms. Each system consists of an asymptotic-giant-branch (AGB) star and an accreting secondary. The AGB star loses its mass via a wind. In one of our six models, the AGB star incurs a short period of outburst. In all cases, the secondary accretes part of the ejected mass and also influences the mass-loss rate of the AGB star. The ejected mass may remain gravitationally bound to the binary system and form a circumbinary disk, or contribute to an accretion disk around the secondary. In other cases, the ejecta will escape the binary system. The accretion rate on to the secondary changes non-linearly with binary separation. In our closest binary simulations, our models exemplify the wind Roche lobe overflow while in our wide binary cases, the mass transfer exhibits Bondi-Hoyle accretion. The morphologies of the outflows in the binary systems are varied. The variety may provide clues to how the late AGB phase influences planetary nebulae shaping. We employ the adaptive-mesh-refinement code ASTROBEAR for our simulations and include ray-tracing, radiation transfer, cooling and dust formation. To attain the highest computational efficiency and the most stable results, all simulations are run in the corotating frame.

New insights into single-compound and binary adsorption of copper and lead ions on a treated sea mango shell: experimental and theoretical studies.

Abstract: Herein, adsorption isotherms of Pb(ii) and Cu(ii) ions on treated sea mango fruit in both single-compound and binary systems were experimentally realized at different temperatures in the range of 30-50 °C. Experimental results show that adsorption of Pb(ii) was more as compared to that of Cu(ii) ions; however, for both ions, a significant reduction in the adsorption capacity was observed in the binary system as compared to that in the single-compound systems. Moreover, under all the investigated conditions, adsorption seems to be promoted by an increase in temperature. To understand and interpret the experimental evidences, the Hill and competitive Hill models developed on the basis of the grand canonical ensemble were applied for the analysis of adsorption equilibrium data. These models contain some physicochemical parameters that allow an exhaustive analysis of the dynamics of single-compound and binary adsorptions. Based on the fitting results, in particular, through the evaluation of the number of ions bonded per site (n and ni), it was found that lead and copper ions interacted by inclined and horizontal positions on treated sea mango in single-compound and binary systems, respectively. In addition, based on the same parameters, a significant interaction between ions was retrieved. A study focused on the saturation adsorption capacity in single-compound and binary systems affirmed that the adsorbent was more selective for lead than for copper. The reduction of the adsorbed capacity ratio between the binary and single-compound systems (i.e. Qb/Qs) explained and confirmed that an inhibition effect between copper and lead ions at the same receptor site occurred. Finally, based on the energetic investigations, it was deduced that the adsorption energy represented the dominant factor promoting the greater adsorption of lead than that of copper in both systems.

Interpretation of single and competitive adsorption of cadmium and zinc on activated carbon using monolayer and exclusive extended monolayer models

Abstract: In this work, a modeling analysis based on experimental tests of cadmium/zinc adsorption, in both single-compound and binary systems, was carried out. All the experimental tests were conducted at constant pH (around neutrality) and temperature (20 °C). The experimental results showed that the zinc adsorption capacity was higher than that of cadmium and it does not depend on cadmium presence in binary system. Conversely, cadmium adsorption is affected by zinc presence. In order to provide good understanding of the adsorption process, two statistical physics models were proposed. A monolayer and exclusive extended monolayer models were applied to interpret the single-compound and binary adsorption isotherms of zinc and cadmium on activated carbon. Based on these models, the modeling analysis demonstrated that zinc is dominant in solution and more favorably adsorbed on activated carbon surface. For instance, in single-compound systems, the number of ions bound per each receptor site was n (Zn2+) = 2.12 > n (Cd2+) = 0.98. Thus, the receptor sites of activated carbon are more selective for Zn2+ than for Cd2+. Moreover, the determination of adsorption energy through the adopted models confirmed that zinc is more favored for adsorption in single-compound system (adsorption energies equal to 12.12 and 7.12 kJ/mol for Zn and Cd, respectively) and its adsorption energy does not depend on the cadmium presence in binary system. Finally, the adsorption energy values suggested that single-compound and binary adsorption of zinc and cadmium is a physisorption.

Circumbinary discs: Numerical and physical behaviour

Abstract: Aims. Discs around a central binary system play an important role in star and planet formation and in the evolution of galactic discs. These circumbinary discs are strongly disturbed by the time varying potential of the binary system and display a complex dynamical evolution that is not well understood. Our goal is to investigate the impact of disc and binary parameters on the dynamical aspects of the disc. Methods. We study the evolution of circumbinary discs under the gravitational influence of the binary using two-dimensional hydrodynamical simulations. To distinguish between physical and numerical effects we apply three hydrodynamical codes. First we analyse in detail numerical issues concerning the conditions at the boundaries and grid resolution. We then perform a series of simulations with different binary parameters (eccentricity, mass ratio) and disc parameters (viscosity, aspect ratio) starting from a reference model with Kepler-16 parameters. Results. Concerning the numerical aspects we find that the length of the inner grid radius and the binary semi-major axis must be comparable, with free outflow conditions applied such that mass can flow onto the central binary. A closed inner boundary leads to unstable evolutions. We find that the inner disc turns eccentric and precesses for all investigated physical parameters. The precession rate is slow with periods (T prec ) starting at around 500 binary orbits (T bin ) for high viscosity and a high aspect ratio H /R where the inner hole is smaller and more circular. Reducing α and H /R increases the gap size and T prec reaches 2500 T bin . For varying binary mass ratios q bin the gap size remains constant, whereas T prec decreases with increasing q bin . For varying binary eccentricities e bin we find two separate branches in the gap size and eccentricity diagram. The bifurcation occurs at around e crit ≈ 0.18 where the gap is smallest with the shortest T prec . For e bin lower and higher than e crit , the gap size and T prec increase. Circular binaries create the most eccentric discs.

An Organoselective Zirconium-Based Metal–Organic-Framework UiO-66 Membrane for Pervaporation

Abstract: A UiO-66 membrane was synthesized on an Al2O3 support using an in-situ solvothermal method with a coordination modulation technique. We first confirmed the organic selectivity of the UiO-66 membrane from organic/water mixtures such as methanol, ethanol and acetone. The membrane displayed highly stable pervaporation performance during the test and exhibited a separation factor of approximately 4.3 and flux of 1.28 kg m-2 h-1 in ethanol/water. From the water and ethanol vapor adsorption measurement, the water uptake was lower in a binary system than that in a single system, although the ethanol uptake was similar between binary and single systems. Therefore, the ethanol selectivity of UiO-66 membrane would be owing to preferential adsorption of organic compound rather than water confirmed by a binary vapor adsorption measurement.

Dependence of SAS particle morphologies on the ternary phase equilibria

Abstract: In this work, the precipitation of a model compound (cefonicid) from DMSO by Supercritical Antisolvent (SAS) was performed. Various morphologies; i.e., expanded microparticles, microparticles, and nanoparticles were obtained, varying operating conditions. In order to explain these results, high-pressure vapor–liquid phase equilibria (VLEs) of the binary system DMSO-CO2 and of the ternary system DMSO-CO2-cefonicid were investigated, using a static analytic method. At 313 K and low concentrations, the presence of the solute had a negligible effect on VLEs with respect to the binary system solvent-CO2. At concentrations up to 90 mg/mL (at 313 K) or increasing temperature at 333 K (at 30 mg/mL), a large modification of the VLEs was observed. The changes in phase behavior were successfully correlated to the powder morphologies, considering the position of the SAS operating point with respect to the ternary mixture critical point. The given explanations can be readily extended to other compounds.

Adsorption of copper ions and alizarin red S from aqueous solutions onto a polymeric nanocomposite in single and binary systems

Abstract: Adsorption of Cu(II) ions and alizarin red S (ARS) has been studied using beads of chitosan (CS) and a chitosan/ZnO nanorod composite (CS-ZnO) in single and binary systems. The beads were synthesized and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. Factors affecting adsorption of Cu(II) ions and ARS such as pH and initial concentrations as well as adsorption kinetics, isotherms, thermodynamics, reusability, and competitive adsorption in binary systems were studied. The results showed that the adsorption kinetics and isotherm data for both adsorbates followed a pseudo-second-order model and the Freundlich model, respectively. Studies of intraparticle diffusion and Dumwald--Wagner models indicated that the adsorption occurred in a complex mechanism where the intraparticle diffusion stage was not the only rate-determining step for both adsorbates. Thermodynamic studies showed that the adsorption process was favorable, endothermic, and physisorptive in nature. In both single and binary systems, CS-ZnO beads showed better adsorption efficiency than CS beads. For the binary system, Cu(II) ions did not affect the adsorption of ARS; however, ARS reduced the Cu(II) adsorption.

Measurements of isothermal vapour–liquid equilibrium for the 2,3,3,3-tetrafluoroprop-1-ene + propane system at temperatures from 253.150 to 293.150 K

Abstract: The vapour–liquid phase equilibrium was measured using an apparatus based on the recirculation method for the 2,3,3,3-tetrafluoroprop-1-ene + propane binary system. A total of 55 data points were obtained over the temperature range from 253.150 to 293.150 K. The experimental standard uncertainties were less than 5 mK for the temperature, 800 Pa for the pressure, and 0.005 for the mole fraction. The experimental data were correlated by the PR-VDW model and PR-HV-NRTL model. Both models can present the experimental data well and the PR-HV-NRTL model achieves a higher degree of precision. The relative deviations of pressure are within ±0.50% and the maximum absolute deviation of vapour mole fraction is 0.006 for the PR-HV-NRTL model. A positive azeotropic behaviour can be observed for the binary system.

Thermodynamic model for prediction of binary alloy nanoparticle phase diagram including size dependent surface tension effect

Abstract: Considering the size effect of nanoparticles on surface tension, a new CALPHAD type thermodynamic model was developed to predict phase diagram of binary alloy nanoparticle systems. In contrast to conventional model, the new model can be applied to the nanoparticles smaller than the critical size (5 NM in radius). For an example, the model applied to Ag – Au binary system and the results were compared with experimental data as well as conventional CALPHAD model and molecular dynamics simulation results.

PâN Conversion in a WaterâIonic Liquid Binary System for Nonredox Thermocapacitive Converters

Abstract: An intriguing p-n conversion of thermoelectric property was observed in a water-ionic liquid ([EMIm][Ac]) binary system with precise control over water content. The highest p-type and n-type Seebeck coefficient were optimized at water-[EMIm][Ac] molar ratio of 2:1 and 4:1, respectively. DFT calculation illustrates that a configuration of solvent separation ion pairs is preferred at the water-[EMIm][Ac] molar ratio of 4:1, leading to the p-n conversion through weakening interaction between anion clusters and gold electrodes. Furthermore, p-n thermocapacitive converters were integrated to enhance the output Seebeck voltages. This work opens up new perspectives for harvesting low grade heat with the use of fluidic materials.

Removal of reactive anionic dyes from binary solutions by adsorption onto quaternized kenaf core fiber

Abstract: The most challenging mission in wastewater treatment plants is the removal of anionic dyes, because they are water-soluble and produce very shining colours in the water. In this regard, kenaf core fiber (KCF) was chemically modified by the quaternized agent (3-chloro-2-hydroxypropyl)trimethylammonium chloride to increase surface area and change the surface properties in order to improve the removing reactive anionic dyes from binary aqueous solution. The influencing operating factors like dye concentration, pH, adsorbent dosage, and contact time were examined in a batch mode. The results indicate that the percentage of removal of Reactive Red-RB (RR-RB) and Reactive Black-5 (RB-5) dyes from binary solution was increased with increasing dyes concentrations and the maximum percentage of removal reached up to 98.4% and 99.9% for RR-RB and RB-5, respectively. Studies on effect of pH showed that the adsorption was not significantly influenced by pH. The equilibrium analyses explain that, in spite of the extended Langmuir model failure to describe the data in the binary system, it is better than the Jain and Snoeyink model in describing the adsorption behavior of binary dyes onto QKCF. Also, the pseudo-second-order model was better to represent the adsorption kinetics for RR-RB and RB-5 dyes on QKCF.

Accurate Experimental (p, ρ, T) Data for the Introduction of Hydrogen into the Natural Gas Grid: Thermodynamic Characterization of the Nitrogen–Hydrogen Binary System from 240 to 350 K and Pressures up to 20 MPa

Abstract: The experimental density data of the binary system nitrogen–hydrogen available at the time of the development of the equation of state for natural gases and related mixtures, GERG-2008, were limited to hydrogen contents higher than 0.15 (amount-of-substance fraction) and temperatures above 270 K. This work provides accurate experimental (p, ρ, T) data for three binary mixtures of nitrogen and hydrogen: (0.95 N2 + 0.05 H2), (0.90 N2 + 0.10 H2), and (0.50 N2 + 0.50 H2) at temperatures of 240, 250, 260, 275, 300, 325, and 350 K, thus extending the range of available experimental data to low hydrogen contents and low temperatures. The density measurements were performed by using a single-sinker densimeter with magnetic suspension coupling at pressures up to 20 MPa. Experimental data were compared with the corresponding densities calculated from the GERG-2008 and the AGA8-DC92 equations of state. The relative deviations of the experimental data from both equations of state were within the estimated uncertainty...

Predicting miscibility of binary liquids from small cluster QCE calculations

Abstract: The quantum cluster equilibrium method is applied to model binary systems of molecular solvents. We minimize the computational effort as well as the experimental input and present the results obtained for the completely miscible acetonitrile/acetone, benzene/acetone, and water/acetone systems, as well as for the hardly miscible water/benzene system. Only clusters of sizes up to n = 3 are applied and these are optimized employing the low-cost functional PBEh-3c. The thermodynamic functions of the pure liquids are in reasonable agreement with experiments. For both non-water containing binary systems, the Gibbs energy of mixing can be reproduced with an accuracy of ≈0.25 kJ/mol. Water containing systems are not sufficiently described by small clusters. The empirical mean-field parameter amf and exclusion volume scaling parameter bxv which depend on the experimental input are approximated by linear interpolation between their neat liquids’ reference values. This makes the approach independent from the experimental data of the binary system. Despite the roughness of the approximation as well as the small size of the cluster sets, the approach is able to correctly predict the mixing behavior of all acetone systems. The benzene/water system is correctly predicted to be non-miscible at most mole fractions. A small range at high benzene concentrations (x> 0.8) is falsely predicted to be miscible.

First principles, thermal stability and thermodynamic assessment of the binary Ni–W system

Abstract: The Ni–W binary system was assessed using critically evaluated experimental data with assistance from first principles analysis and the CALPHAD method The solution phases (liquid, fcc-A1

Dielectric and FTIR studies on the hydrogen bonded binary system of ester and alcohol

Abstract: Concentration dependent dielectric constant, relaxation time, excess dielectric constant, excess inverse relaxation time and the effective Kirkwood correlation factor of the binary mixture of methy...

Direct decomposition X-ray diffraction method for amorphous phase quantification and glassy phase determination in binary blends of siliceous fly ash and hydrated cement

Abstract: A direct decomposition method of X-ray diffraction pattern associated with amorphous phases in a binary blend containing hydrated cement and siliceous fly ash is developed. The method relies on identifying patterns associated with individual components within the overall intensity pattern produced by the total amorphous phase. The intensity pattern associated with the total amorphous phase in a binary blend of siliceous fly ash and hydrated cement is obtained using the Pawley intensity refinement method. The features of the intensity patterns associated with the amorphous reaction products in hydrated cement and the glassy content of siliceous fly ash extracted by decomposition of the overall intensity pattern produced by the combined amorphous phase are shown to match the features obtained directly from the pure phases. The direct decomposition method allows for quantification of amorphous components, which can be applied to study the evolving phases in a hydrating binary system.

Phase behavior of binary and ternary mixture for the poly(TBAEMA) and TBAEMA in supercritical solvents

Abstract: The cloud-point pressure of poly(t-butylaminoethyl methacrylate) [Poly(TBAEMA)] in various solvents such as supercritical carbon dioxide (CO2), dimethyl ether (DME) and t-butylaminoethyl methacrylate (TBAEMA) was measured to maximum pressure and temperature of 218.79MPa and 452.9 K, respectively. The phase behavior for the Poly(TBAEMA)+CO2+TBAEMA mixture was investigated according to the various contribution factors, such as pressure, temperature and concentration with TBAEMA mass fraction of 9.9 wt%, 10.4 wt%, 14.9 wt%, 24.4 wt% and 35.2 wt%. The cloud point curves for the Poly(TBAEMA)+CO2+DME (15.6-78.7 wt%) systems show the variation of the (p, T) curve from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as DME concentration increases. The experimental data for the CO2+TBAEMA system were reported at the broad temperature range of 313.2 K to 393.2 K and the pressure range of 3.70MPa to 20.62MPa. The CO2+TBAEMA binary system shows the type-I phase behavior with a continuous critical mixture curve, and is correlated by Peng-Robinson equation of state with the critical properties for TBAEMA obtained by Joback and Lyderson group contribution method.

Prediction of Binary Gas Adsorption of CO2/N2 and Thermodynamic Studies on Nitrogen Enriched Nanostructured Carbon Adsorbents

Abstract: Pure component adsorption isotherms for CO2 and N2 on the prepared nitrogen enriched carbon were evaluated using a static volumetric analyzer at four different adsorption temperatures ranging from 30–100 °C and were then correlated with three pure component adsorption isotherm models, namely, Langmuir, Sips, and dual-site Langmuir (DSL) models. Adsorption equilibria of binary CO2–N2 adsorption was then predicted by extending Sips and DSL equations empirically along with the usage of ideal adsorbed solution theory and was compared with experimental data obtained from the breakthrough curves through various phase diagrams. Breakthrough data for binary system were obtained at four different CO2 feed concentrations (5–12.5% by volume) and four adsorption temperatures (30–100 °C) using a fixed-bed reactor. Among three adsorption isotherms models used to investigate the equilibrium data of pure component system, Sips and DSL adsorption isotherm models fitted well, indicating energetically heterogeneous adsorben...