Pseudo-binary Mixture Research Articles

Understanding the surface tension reduction of the water/air interface due to the synergistic effect of the SDS-CTAB mixture: A molecular dynamics simulation study

Using molecular dynamics simulation, the surface tension is calculated and compared with experimental data to provide a microscopic interpretation of the synergistic effect on water surface tension reduction caused by a binary mixture composed of anionic and cationic surfactants. For the anionic and cationic surfactants, the sodium dodecyl sulphate (SDS) and the cetyl trimethylammonium bromide (CTAB) were used, respectively. Besides the electrostatic attraction between the anionic and cationic surfactants, resulting in a synergistic effect, other properties were analysed to study the reduction of the surface tension from a molecular level. For different SDS:CTAB composition of distinct properties of the pseudobinary mixture, such as the hydrogen bonds, order of the tails, and the arrangement of the surfactants at the interface were calculated. Those properties present different behaviours at the maximum and minimum values of the surface tension. The CTAB tails present a higher order than the SDS tails at all SDS:CTAB compositions however, the first ones show a maximum order at the minimum in the surface tension. The excess configurational energy was also calculated and shows a minimum value in the same composition as the minimum value of the surface tension.

ВЛИЯНИЕ ЭКСТРАКТИВНЫХ АГЕНТОВ НА ПЛОТНОСТЬ И ВЯЗКОСТЬ ЖИДКОЙ ФАЗЫ ПРИ РЕКТИФИКАЦИИ СМЕСИ ИЗОПРОПАНОЛ-ВОДА

In this work, the dynamic viscosity and density of three-component mixtures consisting of a binary azeotropic mixture of isopropanol-water and an extractive agent were investigated. Three points of the profile of concentrations in the liquid phase in the extractive separation column of isopropanol-water mixture in recalculation on the pseudobinary mixture were selected for research: the first point - 95/5 % wt. %; the second point - 5/95 % wt. %; the third azeotrope point - 88/12 % wt. %. For the selected points model mixtures were prepared to which 13 % wt. % of the extractive agent was added. The extractants used in this work were monoethylene glycol (EG), which is used in industrial processes, 1-ethyl-3-methyl imidazolium chloride ([Emim][Cl]) and triethylene glycol-based boronic acid amino ester (AEBA). Experimental data on concentration and temperature dependences of dynamic viscosity and density were obtained for these mixtures. The results showed that the viscosity of the system increases in the series of EG, AEBA, [Emim][Cl]. To carry out calculations of the investigated thermophysical properties in the work we used known expressions: for density - through the sum of volumes; for viscosity - the Kendall-Manroe model. For a three-component mixture with EG, the results of calculations of properties performed in the AspenPlus V12 package are presented. The studies carried out in this work have shown that the density modeling of the studied mixtures is quite accurate, the discrepancy between experimental and calculated data does not exceed 1%. Modeling of the dynamic viscosity coefficient of the system by the Kendall-Manroe model for isopropanol-water mixture in the presence of the studied extractive agents can lead to significant errors, the maximum value reaches 52%. The calculated values of the dynamic viscosity coefficient are underestimated, which in turn can lead to errors in modeling (on the basis of these properties) of heat and mass transfer processes occurring in the apparatus.

A Study of the Effect of Pressure on the Relative Volatility of the Components in the Process of Rectification of Mixtures of Different Natures

The effect of pressure on the coefficient of relative volatility of binary mixtures of different natures and ternary mixtures containing potential separating agents such as dimethylsulfoxide (DMSO) and butyl propionate is studied. A wide range of information is obtained based on the data on the vapor–liquid equilibrium, and effects of the pressure on the relative volatility of various nature and cause for a fixed composition of the initial mixture are determined. In the presence of points of intersection of the phase-equilibrium curves in the initial binary mixture and pseudobinary mixture (in the section with a constant concentration of the third high-boiling component), the concentration simplex is divided into regions in which the values of the coefficient of relative volatility decrease (increase) upon varying pressure. This fact makes it possible to improve the procedure of optimization of the process of separation at the stage of selection of the working pressure in the columns.

Dihydroxyacetone Production: From Glycerol Catalytic Oxidation with Commercial Catalysts to Chromatographic Separation

A process for catalytic production of dihydroxyacetone through glycerol oxidation and dihydroxyacetone purification by chromatographic processes is herein presented. Glycerol oxidation over commercial Pt/AC and Pt–Bi/AC catalysts was performed on a batch reactor operating under base-free conditions, using water as a solvent and oxygen as the oxidant agent. The highest dihydroxyacetone yield obtained was 36%, using the Pt5%-Bi1.5%/AC catalyst, whereas the monometallic Pt/AC catalyst was selective to glyceric acid. It is herein reported for the first time dihydroxyacetone separation from unreacted glycerol and reaction byproducts (organic acids). Two commercial polystyrene-divinylbenzene ion-exchange resins were used as a stationary phase, one in the hydrogen form and the other in the calcium form, and water was used as the mobile phase. Adsorption equilibrium data for the species present in the reaction mixture were determined in both resins through single-component adsorption breakthrough experiments. A continuous chromatographic separation process was designed based on the simulated moving bed (SMB) technology and simulated using the gPROMS model builder software. A two SMB cascade was then considered, performing the pseudobinary mixture separation on the first SMB. The extract stream from the first SMB containing dihydroxyacetone and glycerol was fed to the second SMB, obtaining dihydroxyacetone with a purity of 97%. Considering the overall unit, a dihydroxyacetone productivity of 64 kgDHA (LAds day)−1 was obtained with an eluent consumption of 1218 LDes kgDHA–1.

Insight into structural properties and molecular interactions of maline (choline chloride + malonic acid) and 1, 4- butanediol based pseudo-binary mixture: A thermophysical, spectral, and simulation portrayal

The current study elucidate the thermophysical, spectral, and simulation depiction of the prepared deep eutectic solvent (DES) named as maline comprising of an equimolar mixture of choline chloride (ChCl) as hydrogen bond acceptor (HBA) and malonic acid (MA) as hydrogen bond donor (HBD) in the presence of 1, 4-butanediol (BTD) as other HBD (cosolvent). Various thermophysical properties viz., (densities, ρ, speeds of sound, u, viscosity, η and refractive index, nD) were comprehended for the examined pseudo-binary (maline and BTD) mixtures as a function of composition and temperature. The derived thermophysical properties viz., excess molar volume, VmE, excess isentropic compressibility, κsE, excess intermolecular free length, LfE, deviation in viscosity, Δη, and deviation in molar refraction, ΔRM were found to be negative while the excess speed of sound, uE, excess acoustic impedance, ZE, and deviation in refractive index, ΔnDwere found to be positive which signified the favourable hydrogen bonding interactions between maline and BTD. The partial molar volumes, V¯m,1, V¯m,2 and excess partial molar volumes, V¯m,1o and V¯m,2o of the components at infinite dilution exhibited the negative value due to the contraction in volume over the entire concentration thereby strengthening the presence of specific interaction. The molecular interaction in the examined pseudo-binary system conferred in terms of excess parameters with composition and temperature have also been correlated using the Redlich-Kister (R-K) equation. The significant shifting in the spectral profile as observed from FT-IR (Fourier-transform infrared) spectroscopy evidently inferred the favorable inter-molecular interaction within the maline and BTD based pseudo-binary mixture. A noteworthy change in the chemical shifts as deduced from1H- and 13C- NMR (Nuclear Magnetic Resonance) spectral peaks confirmed the hydrogen bonding networks between maline and BTD. Additionally, the 2D 1H–1H COSY (correlation spectroscopy) outcomes exposed the degree of variation in the inter-molecular interactions and structural arrangement between maline and BTD system. The spectral results were further validated employing theoretical (computational simulation) analysis which accounted the extensive hydrogen bonding from the evaluated computed descriptors Also, the 3D-molecular electrostatic potential (3D-MEP) explicated the effect of charge delocalization in the proximity of hydrogen bonding networks.

Optimizing temperature-dependent molar volume fraction of biodiesel fuel in a pseudo-binary mixture through Bragg fiber waveguide sensor having defect layer

In the present communication, the temperature-dependent molar volume fraction of various kinds of renewable biodiesel fuel resources in a pseudo-binary mixture is theoretically optimized through the Bragg fiber waveguide (BFW) sensor with a geometrical defect in periodic cylindrical Bragg reflectors. BFW structure is modelled using a transfer matrix method (TMM) and Henkel formalism in a cylindrical coordinate system. The temperature dependence molar volume fraction is linked to the change in the refractive index of the pseudo-binary mixture, which is further predicted using the capacity of various models; Lorentz-Lorenz, Dale-Gladstone, Eykman, Newton, and Kay. In the presence of a geometric defect layer, a sharp transmission peak of 0.1nmfull width at half maxima (FWHM) is obtained in the considered photonic band gap (PBG), which is sensitive to the change in core refractive index. The temperature-dependent (due to different weather conditions) maximum sensitivity of the proposed sensor is found to be 1280 nm/RIU, which is further compared with the phoxonic crystal-based static temperature sensor having sensitivity 142 nm/RIU only. Along with improved sensitivity in the proposed sensor, other sensing performance parameters detection accuracy and quality parameter (which are inversely proportional to the FWHM) are also improved due to least FWHM of resonant transmission peak about 0.1 nm comparatively.

A volumetric and acoustic study of pseudo-binary mixtures of (water + 1,3-propanediol + 3-butoxypropan-1-amine) from T = (283.15 to 303.15) K

Due to the relevant role that polyols play either as solvents or additives in many industries thermodynamic properties of aqueous mixtures of these compounds have been largely studied. In this work we aim to study the effect of adding a small amount of 3-butoxypropan-1-amine on the volumetric properties of the binary (water + 1,3-propanediol) mixture. Densities and speeds of sound of the ternary (pseudo-binary) mixture, (water + 1,3-propanediol + 3-butoxypropan-1-amine), were measured at five different temperatures ranging from T = (283.15 to 303.15) K. Excess molar, volumes, isobaric expansions and isentropic compressions of the system, as well as the excess partial molar, volumes and isentropic compressions for water and 1,3-propanediol were derived. Some functions of transference of the 1,3-propanediol and water from the binary{water + 1,3-propanediol} to the ternary mixtures were estimated. The interpretation of the results was made in terms of changes in aggregation patterns and hydration.

Forms and distribution of Ce in a ferromanganese nodule

Author(s): Marcus, MA; Toner, BM; Takahashi, Y | Abstract: We studied the distribution and speciation of Ce in a previously-characterized ferromanganese nodule from the South Pacific Gyre using X-ray microspectroscopy.We find Ce in three types of environment – diffusely in all parts of the nodule except the Fe-rich, Mn-poor “matrix”, fluorapatite grains with a negative Ce anomaly suggestive of an authigenic origin, and localized spots whose composition is consistent with a pseudobinary mixture of sorbed Ce4+ and a mix of sorbed Ce3+ and CeO2. In contrast with some other elements such as Ti, there is no clear correlation of the Ce concentration in the diffuse areas with either that of Mn, Fe or any linear combination of the two.We argue that the CeO2 came from oxidation of Ce3+ in the water column, while the Ce in the Mn-rich regions may have been initially deposited as Ce4+ and then partially reduced.

Phase Behavior and Thermophysical Properties of Peace River Bitumen + Propane Mixtures from 303 K to 393 K

Propane and mixtures including propane as a principal component are among the leading potential candidates for co-injection along with steam for improving the process and environmental efficiency of oil sands bitumen production processes. Phase diagrams and thermophysical property data enable technologies for the development and optimization of such processes. In this work, phase behavior, phase composition, and phase densities of propane + Peace River bitumen mixtures are reported in the temperature range 303 to 393 K at pressures ranging from 1 to 6 MPa. The phase behavior of this pseudobinary mixture can be categorized as Type III according to the van Konynenburg–Scott nomenclature. Pressure–temperature at fixed composition, and pressure–composition at fixed temperature phase diagrams, and pressure–temperature phase projections are presented, along with saturated compositions and densities of the coexisting bitumen-saturated propane liquid (L1) and propane-saturated bitumen liquid (L2) phases. Saturated L1 and L2 phases are both significantly less dense than liquid water phases at the same temperatures and pressures, and the volumes of mixing, particularly for the L1 phase, are large and negative. This data set provides a benchmark for process development and process design calculations for ongoing bitumen production and deasphalting applications.

Purification of single-chain antibody fragments exploiting pH-gradients in simulated moving bed chromatography

This paper deals with the theoretical design and experimental validation of an affinity-based continuous multi-column chromatography process for the purification of single-chain Fragment variable (scFv) antibodies. An open-loop 3-zone pH-gradient simulated moving bed (SMB) process was investigated exploiting the highly specific affinity of metal ions toward histidine-tagged recombinant proteins. The separation problem was simplified by considering the cell culture supernatant as a pseudo-binary mixture. The influence of mobile phase pH on the adsorption isotherm parameters was estimated by the inverse method using recorded pH-gradient batch elution profiles. Suitable operating parameters for the SMB process were identified using an equilibrium stage model and subsequently validated in a lab-scale SMB unit. Finally, the performance of the pH-gradient SMB process was compared against a non-optimized batch process. Biologically active single-chain Fragment variable antibody formats were purified continuously with 9% more recovery, 11 times more productivity (576mg of purified scFv per day and liter stationary phase in SMB) and enriched by a factor of 2.5 compared to those obtained in the non-optimized batch process.

Molar mass and temperature dependence of the thermodiffusion of polyethylene oxide in water/ethanol mixtures.

In this work, we study the molar mass dependence of the thermodiffusion of polyethylene oxide at different temperatures in ethanol, water/ethanol mixture (c(water) = 0.7), and water in a molar mass range up to M(w) = 180,000 g/mol. Due to the low solubility of polyethylene oxide oligomers in ethanol the measurements are limited up to M(w) = 2200 g/mol. The specific water/ethanol concentration 0.7 has been chosen, because at this weight fraction the thermal diffusion coefficient, D(T), of water/ethanol vanishes so that the system can be treated as a pseudo binary mixture. The addition of ethanol will degrade the solvent quality, so that we expect a change of the interaction energies between polymer and solvent. The analysis of the experimental data within a theoretical model shows the need of a refined model, which takes specific interactions into account.

Study on phase diagram of fatty acids mixtures to determine eutectic temperatures and the corresponding mixing proportions

This study was focused on preparation and characterization of fatty acid eutectic mixtures as phase change materials (PCMs). The four common fatty acids: stearic acid (SA), palmitic acid (PA), myristic acid (MA) and lauric acid (LA) were selected as representative to prepare binary and ternary eutectic mixtures by heating-ultrasonic method. The melting points of LA–MA, LA–SA, SA–MA, SA–PA, MA–PA, LA–MA–SA, MA–SA–PA mixtures with varying combination proportions were determined and then analyzed by drawing the phase diagrams to determine the eutectic points and the corresponding mixing proportions. The results showed that the eutectic temperature of ternary fatty acids was lower than binary fatty acids’; ternary mixture possessed the same thermal properties with pseudo-binary mixture in both melting temperature and latent heat of phase change; the Schröeder-Van Laar equation can be taken as a basis for mixing proportion of pseudo-binary fatty acid and ternary fatty acid systems; the ternary eutectic point on the ternary phase diagram was just in the vicinity of a small triangle which was formed by the connection between the three vertices and the three eutectic points of binary fatty acid in the corresponding across flats. Moreover, ternary and pseudo-binary mixtures had advantage in energy conservation applications such as building heating/cooling and indoor temperature controlling especially when the temperature in need was low.

Structure of silver bromide doped chalcogenide glasses

High-energy X-ray diffraction, neutron diffraction and extended X-ray absorption fine structure experiments have been carried out for (AgBr)x(As2Se3)1-x glasses. The addition of a large amount of AgBr does not significantly affect short-range orderings of the host network matrix. The interatomic distance of Ag-Br pairs in the present glass is much shorter than that of crystalline AgBr. Moreover, the coordination number of Ag ions is also different from the case of crystalline AgBr, and it decreases to be nearly four at x = 0.6. These results suggest that the basic structural motif around mobile Ag ions in the (AgBr)x(As2Se3)1-x glass is tetrahedral AgBr4 units as same as in the AgI-doped chalcogenide glass system AgI-As2Se3. It would be predictable that the structure model for AgBr-As2Se3 glasses is proposed to be a pseudo-binary mixture of the As(Se1/2)3 network matrix and AgBr-related conduction pathways.

Association indépendante entre l’hypoxémie intermittente et la dyslipidémie métabolique dans le syndrome d’apnées-hypopnées obstructives du sommeil

This work describes the adsorption–desorption behavior of a histidine-tagged single-chain Fragment variable antibody (D1.3 scFv) on a commercial immobilized metal ion affinity chromatography (IMAC) column. A clarified cell culture supernatant originating from Bacillus megaterium was characterized using single column experiments in a pH-gradient elution mode. The cell culture supernatant containing the antibody fragment D1.3 scFv could be treated in the chromatographic separation process as a pseudo-binary mixture. Adsorption equilibrium constants of the antibody fragment fraction (ABF) and the non-specifically retained protein impurity fraction (IMP) were determined experimentally at constant pH by reinjecting pulses of pooled fractions collected in preliminary batch gradient elution runs. Based on the estimated adsorption equilibrium constants a possible multicolumn open-loop three-zone two-step pH-gradient simulated moving bed (SMB) process is suggested and designed, which possesses the potential to isolate continuously the antibody fragment fraction (ABF) containing the single-chain antibody fragment D1.3 scFv.

Mechanism of Flow Properties for Biodiesel Blends at Low Temperature

The chemical composition of biodiesel was analyzed by gas chromatography-mass spectrometry. The cold filter plugging point of biodiesel was measured according to GB/T 20828-2007. The cold flow properties of biodiesel were investigated on the basis of the crystallization theory, including chemical composition and molecular structure. Biodiesel might be considered a pseudobinary mixture, namely, high-melting-point saturated fatty acid methyl esters and low–melting-point unsaturated ones. Bilayer crystal structure of biodiesel was founded. Bilayer structure with headgroups aligned next to each other inside the crystal and away from nonpolar bulk liquid was large platelet lamellae. The results showed that biodiesel was mainly composed of saturated fatty acid methyl esters (C14:0～C24:0 ) and unsaturated ones(C16:1～C22:1、C18:2 and C18:3 ). The cold flow properties for biodiesel were determined mainly by the amount and molecular structure of saturated fatty acid methyl esters. The long-straight-chain saturated fatty acid methyl esters tend to have relatively poor cold flow properties. The cold flow properties worsen with increasing the amount and carbon chain length of straight-chain saturated fatty acid methyl esters. The ways of adjusting biodiesel composition and treating with depression of cold filter plugging point were given; they could improve cold flow properties.

Characterization of the Solutol® HS15/water phase diagram and the impact of the Δ9-tetrahydrocannabinol solubilization

Here, the phase behavior of the commercial non-ionic surfactant Solutol® HS15 in water was investigated. The focus was on the evolution of the system nanostructure at low water content. Particularly, it was demonstrated that spherical micelles found in dilute surfactant solutions coalesce at a surfactant volume fraction close to 0.5. As consequence, a heterogeneous pseudo-binary mixture occurs. No liquid crystalline phases were detected even at the highest HS15 concentrations in water. Alteration of the micellar morphology induced by the addition of Δ9-tetrahydrocannabinol to the surfactant/water binary system was also investigated. It was found that the cannabinoid molecules become entrapped within the surfactant hydrophobic tails, thus increasing the surfactant effective packing parameter and inducing a radical change of the micelle shape. At sufficiently low water content (18–35wt.%), such alteration of the interfacial packing results in a lamellar organization of the surfactant molecules.

Discontinuous and continuous purification of single-chain antibody fragments using immobilized metal ion affinity chromatography

This work describes the adsorption–desorption behavior of a histidine-tagged single-chain Fragment variable antibody (D1.3 scFv) on a commercial immobilized metal ion affinity chromatography (IMAC) column. A clarified cell culture supernatant originating from Bacillus megaterium was characterized using single column experiments in a pH-gradient elution mode. The cell culture supernatant containing the antibody fragment D1.3 scFv could be treated in the chromatographic separation process as a pseudo-binary mixture. Adsorption equilibrium constants of the antibody fragment fraction (ABF) and the non-specifically retained protein impurity fraction (IMP) were determined experimentally at constant pH by reinjecting pulses of pooled fractions collected in preliminary batch gradient elution runs. Based on the estimated adsorption equilibrium constants a possible multicolumn open-loop three-zone two-step pH-gradient simulated moving bed (SMB) process is suggested and designed, which possesses the potential to isolate continuously the antibody fragment fraction (ABF) containing the single-chain antibody fragment D1.3 scFv.

An alternate computational architecture for advanced process engineering

An algorithm for equation-oriented (EO) flowsheeting to which the interfacing of external modular procedures is readily allowed is presented. In the algorithm, all the process units in a flowsheet are solved simultaneously in an EO environment while taking advantage of the external software as it is. The algorithm is the basis for the process simulator MIKAN. The simulator consists of two parts, namely EO main, which is the simulator's executive, and add-on blocks to incorporate external procedures. EO main also serves to solve separation processes. The PBM (Pseudo-Binary-Mixture)-based algorithm for separation processes ( Ishii & Otto, 2008) is fully exploited in EO main. The equations of the entire system are composed of a set of equations for separation processes and sets of equations representing the input–output relation of each add-on block. The input–output relation is obtained by numerical perturbation where all the component flow rates are perturbed collectively. Although the proposed perturbation is simple and significantly less expensive, it is very reliable since the interactions among the input variables affecting the output are fully accounted for. Robustness, flexibility and efficiency of the new algorithm have been confirmed by its implementation. A serious drawback with the EO approach is the difficult accessibility to the user when incorporating new or external process models. Easy accessibility is an important attribute of the new algorithm, even though the simulator's executive is highly integrated and complex. It is significant that the derivative information at various levels of a flowsheet is easily obtained in the algorithm. The novel algorithmic capabilities of the algorithm provide a robust platform for the next stage of advanced process engineering.

Towards closing the gap between hygroscopic growth and activation for secondary organic aerosol – Part 2: Theoretical approaches

Abstract. We examine the hygroscopic properties of secondary organic aerosol particles generated through the reaction of α-pinene and ozone using a continuous flow reaction chamber. The water activity versus composition relationship is calculated from measurements of growth factors at relative humidities up to 99.6% and from measurements of cloud condensation nuclei activity. The observed relationships are complex, suggesting highly non-ideal behavior for aerosol water contents at relative humidities less than 98%. We present two models that may explain the observed water activity-composition relationship equally well. The first model assumes that the aerosol is a pseudo binary mixture of infinitely water soluble compounds and sparingly soluble compounds that gradually enter the solution as dilution increases. The second model is used to compute the Gibbs free energy of the aerosol-water mixture and shows that the aerosol behaves similarly to what can be expected for single compounds that contain a certain fraction of oxygenated and non-polar functional groups.

Complex formation study of thermodynamical, structural properties and density of states of Al–Mg binary alloy

Within the framework of complex formation model the thermodynamical, structural and surface properties of Al–Mg alloy have been studied presuming the formation of Al 3 Mg 2 complexes. The Gibb's free energy of mixing ( G M ), Heat of formation ( H M ) and entropy of mixing ( S M ) are compute for the system assuming it to be a pseudo-binary mixture. The alloy appears to be weakly interacting in nature and the thermodynamical properties are almost symmetrical about the equiatomic composition. We have also performed the first-principles calculation of the electronic band structure of Al–Mg alloy employing full-potential linearized augmented plane wave (FLAPW) as well tight-binding linear muffin-tin orbital (TBLMTO) methods. Total energy minimization enables us to estimate the equilibrium volume, bulk modulus and its pressure derivative. We have also described the total density of states (DOS) and the partial DOS (PDOS) around the Fermi energy to explain the variation of resistivity of the alloy with carrier concentration.