Binary Organic Mixtures Research Articles

Analytical study of thermodynamic quantities with surface tension and Debye temperature variations in Quinoline & p-Xylene at T = 303.15 K to 318.15 K

Abstract Thermo dynamic physical quantities viz., compressibility (β), molecular free length (Lf) and impedance (Z) are calculated in the binary organic liquid mixture having Quinoline + p-Xylene at temperatures T = 303.15 K to 318.15 K with 5 K variation using experimentally measured ultrasonic velocities, densities and viscosities with the molar concentration of Quinoline. Theoretical estimations are used to calculate Debye temperature and Surface tension in the above liquid mixture at different temperatures. A correlation of Surface Tension and Debye Temperature with the thermodynamic physical quantities are examined to bring out the inclusion of structural changes occurred due to the temperature variations in the aforesaid binary mixture. The output data is analysed the molecular association and to discuss component molecules structural behaviour with the temperature in the binary organic liquid mixture.

International Standardization of S-SIMS Quantitative Analysis of Binary Organic Mixtures with Relative Sensitivity Factor Method

International Standardization of S-SIMS Quantitative Analysis of Binary Organic Mixtures with Relative Sensitivity Factor Method

Electrical Conductivity and Viscosity in Binary Organic Liquid Mixtures: Participation of Molecular Interactions and Nanodomains

The present work aims to shed light on recent literature reports suggesting that ionic species are implicated in the electrical conductivity of 1-octanol and its mixtures with hydrocarbons. Other workers have questioned this interpretation, and herein, based on new experimentation and with reference to various literature studies, we consider that molecular interactions are more likely to be responsible. To investigate this, we have studied mixtures of 1-octanol and either silicone oil (SO) or n-dodecane as nonpolar components, using dielectric (in particular electrical conductivity) and viscometric measurements. With reference to the literature, the self-association of alcohols is known to create microheterogeneity in the neat liquids and in mixtures with nonpolar, low dielectric constant liquids, and it has previously been considered to be responsible for the particular solvent properties of alcohols. The present results suggest that the electrical conductivity of alkane/alcohol systems may have similar origins, with percolating pathways formed from octanol-rich nanodomains comprising polar regions containing hydrogen-bonded hydroxyl groups and nonpolar regions dominated by alkyl chains. The percolation threshold found for dodecane/octanol mixtures, in which interactions between the component molecules are found from viscosity measurements to be repulsive, agrees well with results from experimental and theoretical studies of disordered arrangements of packed spheres, and moreover, it is consistent with other published alkane/alcohol results. On the other hand, the situation is more complex for SO/octanol mixtures, in which interactions between the two components are attractive, based on viscosity data, and in which the phase separation of SO occurs at high octanol concentrations. Overall, we have concluded that electrical conductivity in octanol (and potentially all liquid alcohols) and its mixtures with nonpolar molecules, such as alkanes, is consistent with the presence of conducting networks comprising octanol-rich nanodomains formed by self-association, and not as a result of ionic conduction.

Molecular dynamics investigation on the composition separation of binary organic mixture in a double-walled T-shaped carbon nanotube separator

The composition separation of binary mixtures in a single-walled T-shaped carbon nanotube has aroused widespread interest. Practically, the double-walled carbon nanotube is widely utilized as well due to its advantageous thermal stability and mechanical properties. However, composition separation in a double-walled, T-shaped carbon nanotube is rarely reported in published literature, which presents a knowledge gap in the application of carbon nanotubes in designing nanodevices. Therefore, in this work, the transport and composition separation of a promising binary organic mixed working fluid in thermodynamic cycles, HFC32/HC600a, in a double-walled, T-shaped carbon nanotube are investigated through non-equilibrium molecular dynamics simulation. The transport and composition separation are driven by the temperature difference; the effects of these temperature differences and interlayer twist angles are carefully discussed. Moreover, the transport and composition separation performance in a double-walled, T-shaped carbon nanotube are compared to those in a single-walled one. The underlying mechanism is analyzed from the perspective of the interaction force and the potential of mean force point of view. The results indicate that satisfactory composition separation can be obtained in a double-walled T-shaped carbon nanotube, and the performance difference from the single-walled one contributes to a larger interaction force between the nanotube and the mixture molecules.

Molecular-scale descriptions and experimental characterizations of nitrocellulose soaked in pure liquid ethanol or diethyl ether respectively at room temperature

Studies on nitrocellulose (NC) mixtures with little solubilities were neglected in many cases previously. This investigation was performed to provide supplemental characterizations of NC and its soaked state with pure liquid ethanol or diethyl ether by simulations and practical methods. Above all, a short-chained NC model (polymerisation degree: 8) and a dried NC specimen were characterized for their substitution of nitrate and microstructure. It was confirmed that both the numerical model and practical specimen belonged to low-nitrated NC. The bonding information of a glycosyl unit and nitrate ester were summarized via first-principle calculations. Then, ReaxFF potential based Molecular Dynamic (MD) simulations and soaking tests on binary organic mixtures demonstrated that both ethanol and diethyl ether had limited solubility for our specified NC. However, potential energies and diffusion coefficients of both computational models showed that the interactions from ethanol molecules were relatively stronger than diethyl ether molecules. The viscosities of saturated NC solutions also proved this consequence, as the difference between pure ether and its filtered NC solution was only 0.02 mm2 s−1. Finally, the strong volatility of diethyl ether itself could keep the wetness of NC upper surface shortly, because this was an upward volatilization effect. Due to this effect, the penetration of NC-diethyl ether mixture was higher in the early period of penetration tests.

Surface tension of binary organic mixtures based on a new dimensionless number

Surface tension of various binary mixtures has been evaluated over the past years since the results add great contribution to many engineering applications. The binary systems {nonane + toluene, nonane + benzene, nonane + cyclooctane, hexadecane + toluene, hexadecane + benzene, hexadecane + cyclooctane} were studied since no literature data were conveyed based on our best review. Therefore, surface tension (σ) and density (ρ) of these binary systems were appraised at different temperatures of 298.2 K, 303.2 K, 308.2 K and 313.2 K at atmospheric pressure, and various mole fractions. Du Nouy Ring Device was applied experimentally to determine the surface tension of these organic mixtures. The outcomes were analyzed with the existing theoretical values attained from Brock-Bird correlation and Goldsack-Sarvas method and the average absolute relative deviations (AAD %) were obtained as 10.26% and 3.75%, respectively. In this work we have shown the success of our recent proposed model for correlating the surface tension of the studied binary organic mixtures with an overall average absolute relative deviation of 3.00%.

Organic solvent mixture separation during reverse osmosis and nanofiltration by a perfluorodioxole copolymer membrane

Highly selective separation of one organic solvent from its mixture with another organic solvent by reverse osmosis will be very useful. Using a 1.67 μm thick film of a particular variety of a glassy amorphous copolymer, perfluoro-2,2-dimethyl-1,3-dioxole copolymerized with tetrafluoroethylene, (PDD-TFE), supported on an e-PTFE support, organic solvent reverse osmosis (OSRO) separations of a number of types of binary organic solvent mixtures were studied. A few studies employed a 0.6 μm thick film of the same copolymer variety designated CMS-7. The feed pressures were varied between 1000 and 5000 kPa; most of the data involved 2500–3500 kPa. Different types of solvent mixtures were studied (similar classes mentioned together): ethanol-NMP, ethanol-dimethylsulfoxide (DMSO); methanol-DMSO, methanol-NMP; toluene-methanol, toluene-N-Methyl-2-pyrrolidone (NMP), toluene-dimethylformamide (DMF); heptane-dodecane; heptane-ethanol. In quite a few cases, a pure solvent was obtained as permeate; the permeate flux could be as much as 3.5 L/m2-hr depending on the feed composition and pressure. Since this behavior is unusual in reverse osmosis, mixture sorption studies were implemented. Mixture sorption data of various mixtures in the copolymer show exclusive sorption by the species showing up as the pure permeate under certain conditions. These and other observed OSRO permeation rate and sorption behavior in the perfluoro-copolymers explain the basis for such extraordinary selectivity for quite a few systems.To illustrate OSRO-facilitated solvent-exchange in organic solvent nanofiltration, studies were carried out also to retain the dye Oil Blue N using the following binary solvent mixtures: toluene-NMP; methanol-NMP. These and other potential applications of highly selective OSRO have been discussed.

Preparation of dextran cryogels for separation processes of binary dye and pesticide mixtures from aqueous solutions

AbstractWe present mechanically strong macroporous, squeezable dextran cryogels as a column filling material for the removal and separation of binary organic dye and pesticide mixtures from aquatic medium. Dextran cryogels were prepared from aqueous solutions of dextran of various molecular weights (MWs) in the presence of 20 to 50 mol% divinyl sulfone (DVS) as a cross‐linker at −18°C. The cryogels have interconnected irregular pores of 100 μm in sizes, and exhibit 69‐84% reversible squeezability without damaging the 3D dextran network. Their total open pore volumes (6.3‐10 mL g−1), weight swelling ratios in water (1380%‐2200%), and mechanical parameters could easily be adjusted by both DVS mol% and MW of dextran. Dextran cryogel with the highest modulus (3.8 ± 0.5 MPa), compressive stress (8 ± 2 MPa) and plateau stress (0.46 ± 0.04 MPa) was obtained at 50 mol% DVS using dextran with a MW of 15 to 25 kg·mol−1. Dextran cryogels are hydrolysable at pH = 1 and 9 but stable at 7.4 independent on both the degree of cross‐linking and MW of dextran. At below 50 mol% DVS, they are blood compatible and possess slight thrombogenic effect with blood clotting index value of 98% ± 5%. They are also capable to separate binary dye and pesticide mixtures from aqueous solutions via ionic interactions.

Separation of binary organic mixture in T-shaped carbon nanotube separator: Insights from molecular dynamics simulation

Separation performance of a binary organic mixture in a T-shaped carbon nanotube separator was firstly reported. One of the binary organic mixtures, difluoromethane/isobutane mixture, was selected as the studied mixture due to its great application potential as working fluid in thermodynamic cycles for efficient-utilization of low grade energy. Molecular dynamics simulation was utilized because of its advantages in revealing the molecular behavior and mechanism of the separation from the molecular interaction point of view. Both positive separation which driven by the external temperature difference, and passive separation resulting from the physical chemistry properties of the mixture were investigated. The potential of mean force and the interaction between the nanotube and the mixture molecules were utilized to analyze the underlying mechanism of the separation. The results indicate that a satisfactory separation performance can be obtained by the positive separation, and there's a remarkable separation. The asymmetric free energy change of each composition, and different interactions of the T-shaped carbon nanotube on the two types of molecules attribute to the separation.

A novel method for predicting the flash points of binary mixtures from molecular structures

Flash point (FP) is one of the most important parameters used to characterize the potential fire and explosion hazards for flammable liquids. A quantitative structure–property relationship (QSPR) study is conducted to develop mathematical models for predicting the flash points of binary mixtures from only their molecular structures. The modified Simplex Representation of Molecular Structure (m-SiRMS) descriptors were proposed to characterize the molecular features of a total of 288 binary organic mixtures. A set of optimal descriptor subsets that significantly contribute to the FP property were determined by combining the genetic algorithm with multiple linear regression (GA-MLR) and then develop the prediction model. The resulted model is a multiple linear equation with seven SiRMS descriptors. The average absolute error and the root mean square error of the external test set was 3.48 K and 4.73, respectively. The developed model was rigorously validated using multiple strategies, and further extensively compared to the corresponding model developed based on traditional SiRMS descriptors as well as other previously published models. The results demonstrated the robustness, validity and satisfactory predictivity of the proposed model, and the superiority of the proposed m-SiRMS descriptors as well. The proposed method could be reasonably expected to reliably predict the FP of the binary mixtures for engineering.

Study of ultrasonic wave velocity in organic binary mixture liquids of methyl propyl ketone and bezaldehyde (MPK+C6H5CHO) at 308.15K

Study of ultrasonic wave velocity in organic binary mixture liquids of methyl propyl ketone and bezaldehyde (MPK+C6H5CHO) at 308.15K

Predicting acute contact toxicity of organic binary mixtures in honey bees (A. mellifera) through innovative QSAR models

Pollinators such as honey bees are of considerable importance, because of the crucial pollination services they provide for food crops and wild plants. Since bees are exposed to a wide range of multiple chemicals “mixtures” both of anthropogenic (e.g. plant protection products) and natural origin (e.g. plant toxins), understanding their combined toxicity is critical. Although honey bees are employed worldwide as surrogate species for Apis and non-Apis bees in toxicity tests, it is practically unfeasible to perform in vivo tests for all mixtures of chemicals. Therefore, Quantitative Structure-Activity Relationships (QSAR) models can be developed using available data and can provide useful tools to predict such combined toxicity. Here, three different QSAR models within the CORAL software have been calibrated and validated for honey bees (A. mellifera) to predict the acute contact mixtures potency (LD50-mix), in two regression based-models, and the nature of combined toxicity (synergism / non-synergism) in a classification-based model. Experimental data on binary mixtures (n = 123) (LD50-mix) including dose response data (n = 97) and corresponding Toxic Unit values were retrieved from EFSA databases. The models were built using the principle of extraction of attributes from SMILES (or quasi-SMILES) while calculating so-called correlation weights for these attributes using Monte Carlo techniques. The two regression models were validated for their reliability and robustness (R2 = 0.89, CCC = 0.92, Q2 = 0.81; R2 = 0.87, CCC = 0.89, Q2 = 0.75). The classification model was validated using sensitivity (=0.86), specificity (=1), accuracy (=0.96), and Matthews correlation coefficient (MCC = 0.90) as qualitative statistical validation parameters. Results indicate that these QSAR models successfully predict acute contact toxicity of binary mixtures in honey bees and can support prioritisation of multiple chemicals of concerns. Data gaps and further development of QSAR models for honey bees are highlighted particularly for chronic and sub-lethal effects.

Solubility Measurement Study on a Metastable Polymorph of β-2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane by Raman Spectroscopy

Raman spectroscopy was used to measure the solubility of the metastable form of β-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (β-HNIW) in organic binary solvent mixtures. The distinct Raman spectra peaks of the solid, solute, solution, and solvent were investigated. Peaks that were not overlapping each other were used to develop a calibration curve. Then, linear relationships between solution concentration and Raman intensity were used to measure the solubility of β-HNIW in binary solvent mixtures during the dissolving process. The solubility of β-HNIW in binary solvent mixtures (ethyl acetate + n-hetpane, ethyl acetate + 1,1,2-trichloroethane, ethyl acetate + cyclohexane, ethyl acetate + toluene, ethyl acetate + diethyl ether, and ethyl acetate + petroleum ether) was investigated. The temperature ranged from 283.15 K to 333.15 K at atmospheric pressure. The solubility of β-HNIW in binary solvent mixtures decreases with increasing temperature. In order to correlate the solubility of β-HNIW,...

Effect of organic eutectic on nitrocellulose stability during artificial aging

ABSTRACTRecently, the eutectic composition of organic binary mixtures MENA+DPA has been found to be an efficient stabilizer of nitrocellulose. However, the behavior of such new stabilizer must be further investigated, especially after a long period of storage of the energetic composition. In this study, the stabilizing effect of the eutectic MENA+DPA on NC stability during artificial aging (at 338.65 K for 120 days), compared to its pure components, has been investigated by conventional stability tests and kinetic modeling. According to Bergmann & Junk (T = 405.15 K) results and over the entire period of aging, the eutectic MENA+DPA exhibits the best stabilizing effect on NC. The vacuum stability test (T = 353.15, 363.15, 373.15, and 383.15 K) results revealed that the amount of the evolved gas of NC containing this eutectic composition is very close to that of DPA, known as the conventional stabilizer. Furthermore, the kinetic modeling on VST data, obtained at four isothermal temperatures, was performed by two different methodologies, viz, fitting and free models to determine the kinetic triplets, which have been subsequently used to predict the storage lifetime for the studied systems. It was found that the NC stabilized by the eutectic MENA+DPA presents the highest value of the activation energy and has the longest storage lifetime during the entire heating period corroborating the stability tests results and affirming the excellent stabilizing effect of this mixture with respect to its pure component even if a long storage period is expected.

Dissolution of aluminium from metakaolin with oxalic, citric and lactic acids

AbstractThis study examines the leaching of aluminium from calcined kaolin (metakaolin) with citric, oxalic and lactic acid and binary combinations of these organic acids. The investigated parameters were the pulp density, acid concentration, pH, agitation speed, temperature and contact time. The kinetics of aluminium dissolution from metakaolin in binary organic acid mixtures were determined and scanning electron microscopy examination and energy-dispersive spectrometry mapping of Si and Al of untreated kaolin and residual solids were also carried out. Aluminium dissolution increased with temperature, time, acid concentration, pulp density and acidity. At maximum dissolution, citric–oxalic (1:4 w/w) and lactic–oxalic (1:4 w/w) mixtures dissolved 77% and 78% aluminium, respectively, from metakaolin in 11 h. The activation energy ranged from 57.8 to 74.6 kJ/mol. The most effective parameter in the dissolution of aluminium was the temperature, indicating that the reaction was not diffusion-controlled. It was concluded on the basis of the activation energy values and the sensitivity of the reaction to temperature that the dissolution was under chemical-reaction control.

Competitive and synergistic adsorption of binary volatile organic compound mixtures on activated carbon**Project supported by the National Natural Science Foundation of China (Grant No. 11574401), the Science Foundation of China University of Petroleum, Beijing (Grant Nos. 2462017YJRC029 and yjs2017019), and the Beijing Natural Science Foundation, China (Grant No. 1184016).

The adsorption of four substances and their binary mixture is investigated via the terahertz time domain spectroscopy (THz-TDS). The selected unary compound (ethanol, acetone, ethyl acetate, and n-propyl acetate) and binary mixture (solution 1 is composed of ethanol and acetone, and solution 2 is composed of ethyl acetate and n-propyl acetate) exhibit different adsorption behaviors with varied polarities. In comparison with single component, solution 1 shows shorter adsorption equilibrium time, faster adsorption rate, and stronger adsorption capacity, which conform to a synergistic adsorption mechanism, while the competitive behavior is attributed to the slower adsorption in solution 2. In addition, the pseudo-second-order equation with terahertz parameter is used to assess the rate of binary component organics. The present results indicate a further understanding of multicomponent adsorption mechanisms.

Behavior of fullerene C70 in binary organic solvent mixtures as studied using UV-Vis spectra and dynamic light scattering

In this paper, the formation of colloidal species of fullerene C70 in organic solvents was studied. The examining of the UV-visible spectra was accompanied by particle size analysis using dynamic light scattering, DLS. Stock solutions of C70 in non-polar toluene and n-hexane were diluted with polar solvents acetonitrile and methanol. The appearance of colloidal species with a size within the range of ≈50–500 nm is accompanied by alterations of the absorption spectra. In the toluene–acetonitrile and toluene–methanol binary mixed solvents at 25 oC, the absorption spectra of C70 (5×10–6 M) tend to retain the features of the spectrum in neat aromatic solvent even if the C70 molecules are gathered into colloidal aggregates. Earlier such phenomenon was observed for C60 in benzene–acetonitrile and toluene–methanol solvent systems. This gives support to the idea of rather stable primary solvate shells formed by aromatic molecules around the fullerene molecules. The behavior of C70 in toluene mixtures with methanol was compared with the earlier reported results from this laboratory for the C60 fullerene in the same solvent system. The study of n-hexane–methanol mixtures was performed at elevated temperature because of limited miscibility of these solvents at 25 oC. Accordingly, the C70–toluene–methanol system was also examined at 40 oC. A small but distinctly noticeable difference was revealed. Whereas in the case of the last-named system, the absorption spectrum typical for molecular form of C70 is still observable when colloidal species are already present in the solution, the turning-point between molecules and colloids as determined by both UV-visible spectra and DLS coincides for the n-hexane–methanol binary mixed solvent. Hence, the solvation shells formed by the aliphatic solvent around C70 are less stable as compared with those formed by toluene. Finally, the absorption spectra of C70 in the mixed solvents toluene–n-hexane were analyzed. These data give some support to the assumption of preferable solvation of the C70 molecules by the aromatic co-solvent.

A molecular contact theory for simulating polarization: application to dielectric constant prediction.

Microscopic polarization in liquids, which is challenging to account for intuitively and quantitatively, can impact the behavior of liquids in numerous ways and thus is ubiquitous in a broad range of domains and applications. To overcome this challenge, in this work, a molecular contact theory was proposed as a proxy to simulate microscopic polarization in liquids. In particular, molecular surfaces from implicit solvation models were used to predict both the dipole moment of individual molecules and mutual orientations arising from contacts between molecules. Then, the calculated dipole moments and orientations were combined in an analytical coupling, which allowed for the prediction of effective (polarized) dipole moments for all distinct species in the liquid. As a proof-of-concept, the model focused on predicting the dielectric constant and was tested on 420 pure liquids, 269 binary organic mixtures (3792 individual compositions) and 46 aqueous mixtures (704 individual compositions). The model proved to be flexible enough to reach an unprecedented satisfactory mean relative error of about 16-22% and a classification accuracy of 84-90% within four meaningful classes of weak, low average, high average and strong dielectric constants. The method also proved to be computationally very efficient, with calculation times ranging from a few seconds to about ten minutes on a personal computer with a single CPU. This success demonstrates that much of the microscopic polarization concept can be satisfactorily described based on a simple molecular contact theory. Moreover, the new model for dielectric constants provides a useful alternative to computationally expensive molecular dynamics simulations for large scale virtual screenings in chemical engineering and material sciences.

Comprehensive evaluation of supercritical power cycle system using non-azeotropic mixtures driven by medium-temperature solar heat source

Aimed at the medium-temperature solar energy heat source, the use of low-boiling binary non-azeotropic organic mixtures as the supercritical cycle working fluids to generate power was put forward. On the premises of meeting the requirements of thermal property, safety, and economic efficiency, 8 working fluids combining R245fa with R152a according to different mass ratios were used and the supercritical thermal system mathematical model was established based on the first and second laws of thermodynamics. The cycle characteristics were contrasted from the multi-angle aspects including seven indices like thermal efficiency, exergy efficiency, and so on. Considering various factors, the multi-index comprehensive evaluation model of energy efficiency was constructed by using the analytic hierarchy process method. Through simulation calculations, the results show that properly increasing the proportion of R245fa promotes effective improvement of the supercritical cycle characteristics and working fluid R245fa/R152a(0.96/0.04) can improve the indexes including net output power, economy, and environmental performance of the system. The proposed one has the optimal evaluation index value among the candidates.

Novel parameter predicting stability of magnetic fluids for possible application in nanocomposite preparation

Concentrated magnetite colloids in kerosene – magnetic fluids – have been synthesized. For stabilization of magnetite nanoparticles, a number of organic acids –lauric, myristic, palmitic, stearic, oleic, behenic and erucic– have been used. Particle size and structure were determined by transmission electron microscopy. Coagulation effect of 15 binary organic mixtures, containing a solvent and a precipitant, in relation to magnetic fluids has been studied in detail. Residual magnetite concentration in above precipitate liquid has been estimated photocolorimetrically. The sets of precipitation curves have been constructed for each stabilizer. A novel parameter for predicting of coagulation effect of precipitants has been suggested. The use of the parameter resulted in fitting of the precipitation curves into a single approximation curve. A method for quantitative determination of medium composition resulting in sedimentation or stability of magnetic fluids can be useful for manufacturing of magnetic elastomers.