Binary Liquid Mixture Research Articles

Low-Temperature Chemical Sintered TiO2 Photoanodes Based on a Binary Liquid Mixture for Flexible Dye-Sensitized Solar Cells

A chemically sintered and binder-free paste of TiO2 nanoparticles (NPs) was prepared using a binary-liquid mixture of 1-octanol and CCl4. The 1:1 (v/v) complex of CCl4 and 1-octanol easily interacted chemically with the TiO2 NPs and induced the formation of a highly viscous paste. The as-prepared binary-liquid paste (<bold>P</bold>BL)-based TiO2 film exhibited the complete removal of the binary-liquid and residuals with the subsequent low-temperature sintering (~150°C) and UV-O3 treatment. This facilitated the fabrication of TiO2 photoanodes for flexible dye-sensitized solar cells (f-DSSCs). For comparison purposes, pure 1-octanol-based TiO2 paste (<bold>P</bold>O) with moderate viscosity was prepared. The <bold>P</bold>BL-based TiO2 film exhibited strong adhesion and high mechanical stability with the conducting oxide coated glass and plastic substrates compared to the <bold>P</bold>O-based film. The corresponding low-temperature sintered <bold>P</bold>BL-based f-DSSC showed a power conversion efficiency (PCE) of 3.5%, while it was 2.0% for <bold>P</bold>O-based f-DSSC. The <bold>P</bold>BL<bold>-</bold>based low- and high-temperature (500°C) sintered glass-based rigid DSSCs exhibited the PCE of 6.0 and 6.3%, respectively, while this value was 7.1% for a 500°C sintered rigid DSSC based on a commercial (or conventional) paste.

Thermodynamic modeling of adsorption at the liquid-solid interface

Adsorptive separation techniques are significantly energy efficient in comparison to conventional thermal separation techniques such as distillation. Despite extensive research and development activities undertaken for mixed-gas adsorption, the use of adsorption techniques for the separation of multicomponent liquid mixtures is still limited. A major barrier is the lack of accurate adsorption thermodynamic models, which form the scientific foundation of process simulation of such systems, making the translation to industrial scale challenging. In this work, we have rigorously computed the surface excess of adsorption for six binary liquid mixtures on silica gel at 303 K using the frameworks of the generalized Langmuir isotherm (gL) and the adsorbed solution theory (AST). The six binary liquid mixtures were formed by the pair-wise combinations of four components: benzene, 1,2-dichloroethane, cyclohexane, and n-heptane. We have based our calculations by considering simultaneous equilibria of three phases: saturated vapor phase, bulk liquid phase, and adsorbed phase. The composition of the corresponding saturated vapor phase was estimated by the Nonrandom Two-Liquid activity coefficient model and experimental vapor-liquid equilibria data. The activity coefficients of the adsorbed phase, the central issue of multicomponent adsorption thermodynamics, were calculated using the adsorption Nonrandom Two-Liquid activity coefficient model. Devoid of simplifying assumptions, gL and AST provide rigorous thermodynamic frameworks for adsorption equilibria of multicomponent liquid mixtures.

Conformer Selection Upon Dilution with Water: The Fascinating Case of Liquid Ethylene Glycol Studied via Molecular Dynamics Simulations.

The aqueous solution of ethylene glycol (EG) is a binary liquid mixture that displays rich conformational and structural behaviour, which has not yet been adequately explored through atomistic molecular dynamics simulations. Herein, employing an accurate force field for EG, several physical properties of this solution are calculated to be in quantitative agreement with experimental data. While 79 % of molecules in neat liquid EG exist with their central OCCO dihedral in the gauche state, this fraction increases to 89 % in the dilute aqueous solution, largely in response to the increase in the static dielectric constant of the solution from that of neat liquid EG. The increase in gauche conformers increases the mean dipole moment of EG molecules in the solution which is additionally contributed by specific conformational states of the two terminal HOCC dihedral angles.

An Acoustic Add-Drop Filter in a Phononic Crystal for High-Sensitivity Detection of Methanol in Ethanol in the Liquid Phase

An add-drop filter based on linear waveguides coupled through a ring resonator in a two-dimensional phononic crystal is introduced and its operation in detecting methanol concentration in ethanol is numerically investigated. The filter, which operates at around 200 kHz, has a small footprint of approximately 71.2 mm-by-84.0 mm, corresponding to 9.6-by-12.0 wavelengths. Band analyses of the phononic crystal and waveguide, as well as frequency domain simulations of filter operation for different methanol concentrations in the ring resonator cells are carried out through finite-element method. When the ring resonator cells are filled with pure ethanol, the drop port output is maximized, whereas through and add port outputs are minimized at the resonance frequency of 212.3 kHz. The contrast ratio between the drop and through/add port outputs is close to 1.0 at this frequency. Although the speed of sound and density are close in the two materials, the sensitivity is calculated as 12.54 Hz/% in terms of molar fraction of methanol. The corresponding figure of merit, obtained by dividing the sensitivity by drop port output peak width, varies between approximately 4.0 and 5.0. Moreover, a linear shift in the drop port peak frequency as a function of methanol concentration is observed. The add-drop filter can be calibrated for concentration sensing in different binary liquid mixtures. Higher sensitivities can be expected when the contrast of acoustic parameters, i.e., speed of sound and density, are larger for the constituents of the mixture.

Comments on excess molar volumes reported in “Study of short range and long range molecular interactions in binary liquid mixtures of N,N-dimethylformamide (DMF) and 1-propanol”

• V m E values of Prajapati and coworkers compared to published literature data of ten other researchers. • Published V m E values are much smaller in absolute magnitude than values of Prajapati and coworkers. • Published V m E versus mole fraction curves show simple parabolic behavior. • V m E versus mole fraction curves of Prajapati and coworkers show several local minima and maxima. A polemic is given concerning the volumetric properties reported for binary N,N-dimethylformamide + 1-propanol mixtures in the published paper by Prajapati and coworkers. The reported excess molar volumes differ significantly from the published literature values of ten independent research groups, all of which are much smaller in absolute magnitude than the values reported by Prajapati and coworkers.

Physicochemical and excess properties of binary system mixtures of ether-functionalized ionic liquids with DMSO

In the full molar fraction range, the density, surface tension and viscosity of 1-(4-methoxybutyl)-3-methylimidazolium glycine ([COC4mim][Gly]), 1-(4-methoxybutyl)-3-methylimidazolium alanine ([COC4mim][Ala]) and 1-(4-methoxybutyl)-3-methylimidazolium threonine ([COC4mim][Thr]) with DMSO binary mixtures were determined. The variation trends of excess molar volume (VE), excess molar surface Gibbs energy (gsE), Gibbs energy of activation for viscous flow of the relative viscosity (ΔG≠r) and x1 of binary system mixture were systematically studied, and the interaction between ether-functionalized ionic liquids (ILs) and solvent molecules in binary system mixtures was studied. According to the molar surface Gibbs energy definition, excess molar surface Gibbs energy definition and Redlich-Kister empirical equation, the correlation between the predicted and experimental surface tension values of ILs + DMSO binary system mixtures was investigated. Furthermore, using the improved Eötvös empirical equation and thermodynamic formula, molar surface entropy and molar surface enthalpy of binary system mixture were calculated. The molar surface enthalpy of binary mixture was independent of temperature. This fact indicated that the process from the bulk to the surface of binary system mixture was an isocoulombic reaction.

Comparative Study of Physicochemical and Acoustic Properties of Binary Liquid Mixtures of Cyclopentyl Methyl Ether with Chlorobenzene and Cyclopentyl Methyl Ether with Methyl Acrylate at 298.15 K Temperature

Physicochemical and acoustic propertie of liquid mixtures give knowlegeble information behaviour and interactions studies of liquids. Ultrasonic studies in liquids and solutions provide some valuable information about the structure and interaction in such systems. Ultrasonic velocity and density have been proved to be important properties to test the validity of liquid state model. The ultrasonic velocity (U) and density (ρ) of the binary liquid mixtures Chlorobenzene (polar)+Cyclopentyl methyl ether (nonpolar) [system I] and Methyl acrylate (polar) +Cyclopentyl methyl ether (nonpolar) [system II] are measured at 298.15 K temp. with pure components. With the help of these measured properties are calculated excess acoustic parameters using standard relations. Excess acoustic parameters are used as a qualitative and quantitative analysis in multicomponent liquid mixtures. The sign and magnitude of excess parameters provided information of different type interactions. Structural chemistry is related to the interactions involved in the liquid systems. structural effects also define nature and bonding of both liquid mixture system I and II.

Carbon nanotube assisted highly selective separation of organic liquid mixtures

Carbon nanotubes (CNTs) are prominent candidates for the separation of various polar and non-polar liquid mixtures. Numerous studies report the application of CNTs for isolating the binary aqueous liquid mixtures, but very few demonstrate the separation of organic liquid mixtures. Here, we investigate the selective permeation of cosolvents such as ethanol, isopropanol, n-butanol, acetone, and tetrahydrofuran into the CNTs from the binary mixtures of benzene using molecular dynamics simulations. Our findings reveal that extremely small-sized (11,0) CNTs achieve almost 100% cosolvent capture selectivity in all five equimolar binary mixtures. In considerably bigger-sized CNTs such as (20,0), benzene accumulates inside along with the cosolvent, however, forms a well-distinguishable layer close to the interior wall of CNTs analogous to the second layer of a double-walled CNT. The results confirm that the liquid capture and selectivity are governed by the polarity and molecular size of the solvents as well as the CNT diameters.

Binary Mixtures of Imidazolium-Based Protic Ionic Liquids. Extended Temperature Range of the Liquid State Keeping High Ionic Conductivities.

Binary mixtures based on the two protic ionic liquids 1-ethylimidazolium triflate ([C2HIm][TfO]) and 1-ethylimidazolium bis(trifluoromethanesulfonyl)imide ([C2HIm][TFSI]) have been investigated, with focus on phase behavior, ionic conductivity, and intermolecular interactions as a function of composition (χ TFSI indicating the mole fraction of the added compound). It is found that on addition of [C2HIm][TFSI] to [C2HIm][TfO], the melting temperature is first decreased (0 0.3) and then suppressed (0.3 0.8) resulting in mixtures with no phase transitions. These mixtures display a wide temperature range of the liquid state and should be interesting for use in devices operating at extreme temperatures. The ionic conductivity does not vary significantly across the composition range analyzed, as evidenced in the comparative Arrhenius plot. The activation energy, E a , estimated by fitting with the Arrhenius relation in a limited temperature range (between 60 and 140 °C) varies marginally and keeps values between 0.17 and 0.21 eV. These marginal differences can be rationalized by the initially very similar values of the two neat protic ionic liquids. Vibrational spectroscopy, including both Raman and infrared spectroscopies, reveals weakening of the cation–anion interactions for increasing content of [C2HIm][TFSI], which is reflected by the blue shift of the average N-H stretching mode and the red shift of the S-O stretching mode in the TfO anion. These trends correlate with the higher disorder in the mixtures observed by DSC and are evidenced by the decrease and suppression of the melting temperature as the amount of [C2HIm][TFSI] is increased.

Isothermal Vapor–Liquid Equilibria and Excess Gibbs Energy for Binary Liquid Mixtures of 1,2-Dichloroethane with Some Aliphatic Polyethers

Isothermal Vapor–Liquid Equilibria and Excess Gibbs Energy for Binary Liquid Mixtures of 1,2-Dichloroethane with Some Aliphatic Polyethers

Thermodynamic modelling of perchlorate/chloride and perchlorate/chlorate deliquescence at Mars-relevant temperatures

Perchlorate (ClO4−) salts were discovered on Mars and are known to absorb water vapor from the atmosphere and deliquesce into the aqueous phase. Other species such as chlorides (Cl−) and chlorates (ClO3−) were also identified; these species can affect the deliquescence of perchlorates. Here we generate phase diagrams of perchlorate/chloride and perchlorate/chlorate binary mixtures for K, Na, Mg and Ca in the temperature range 223–273 K. Using a new approach based on thermodynamic modelling of evaporation, we determined the deliquescence relative humidity (the minimum relative humidity at which a salt converts into a liquid by absorbing atmospheric water vapor) and the eutonic relative humidity (the minimum relative humidity at which two salts are in equilibrium with liquid) for binary salt mixtures. Our modelling results show that the deliquescence relative humidity values of all salt mixtures is always lower than that of each individual end-member salt at a fixed temperature, typically a few percent lower. The closer the eutonic is to one of the end-member, the smaller the decrease in relative humidity compared to the pure pole. Thus, only eutonics which are far from both poles exhibit a significant drop in relative humidity. Moreover, the eutonic relative humidity always increases with decreasing temperature, which does not favor liquids in the dry and cold Martian environment. Finally, the increased stability of water ice at the lowest temperatures always reduces or even eliminates the stability of liquids. Therefore, the favorable temperature and relative humidity conditions under which binary salt liquid mixtures exist are generally not significantly improved compared to single salts.

Infrared spectroscopy of quasi-ideal binary liquid mixtures: The challenges of conventional chemometric regression

We have recorded ATR-IR spectra of binary mixtures in the (quasi-)ideal systems Benzene-Toluene, Benzene-Carbon tetrachloride and Benzene-Cyclohexane and performed classical least squares, inverse least squares and principal component regression on the resulting spectra. In contrast to the general expectation, the spectra of ideal mixtures follow only roughly Beer’s approximation, in particular stronger bands show shifts and increased intensities for intermediary compositions since the polarization of matter by light cannot be neglected. As a consequence, these conventional regression techniques lead to principle and unavoidable errors, even though some of the classical regression techniques are assumed to be able to cope with nonlinearities. In particular in the system Benzene-Carbon tetrachloride large errors result and the relative average error of the volume fraction determination is about 10 % for all three methods. Especially remarkable is that the multivariate regression methods do not perform better than the classical univariate calibration if for the latter a peak due to an oscillator with comparably low oscillator strength is selected, since for such bands polarization effects are weak and Beer’s approximation holds comparably well.

Ultrasonic Investigation of Thermodynamic Parameters in Binary Liquid Mixture of Acetonitrile in 2- Propanol at 301.15K

The ultrasonic velocity (u), density (ρ) and viscosity (η) and related thermo-acoustic parameters are the important tools in understanding the nature and extent of pattern of molecular interactions between components of liquid mixture. The ultrasonic velocity, density and viscosities of binary liquid mixture containing Acetonitrile in 2- Propanol over whole concentration range have been measured at 305.15K. This measured data have been used to compute derived thermo-acoustic parameters like adiabatic compressibility (βad), free length (Lf)), free volume (Vf), internal pressure (πi), and acoustic impedance (Z). The variation of these parameters with concentration and temperature are also used to correlate with the structural changes observed in binary liquid mixture. Keywords: Binary liquid mixture, ultrasonic velocity (u), density (ρ) and viscosity (η), adiabatic compressibility (βad), free length (Lf), free volume (Vf),internal pressure (πi), molar volume(Vm).

Phase field modeling in liquid binary mixtures: Isothermal and nonisothermal problems

Based on the conservative phase field model of Lowengrub and Truskinovsky for almost incompressible liquid binary mixtures, we propose an extended scheme for studying immiscible/miscible liquids. Below a critical temperature ${T}_{c}$, the liquids are immiscible with separating interfaces. Above ${T}_{c}$ interfacial effects vanish and the liquids become perfectly miscible. The free energy density of the system depends not only on the system composition through the phase field $\ensuremath{\phi}$ but also on the reduced temperature $r=({T}_{c}\ensuremath{-}T)/{T}_{c}$. The free energy transforms through ${T}_{c}$ to permit a two-phase system in the subcritical (immiscible) regime and a mono phase in the supercritical (miscible) regime.

Density, viscosity, surface tension, and spectral analysis of polyethylene glycol 300 + 1,2-Propylenediaminebinary liquid mixture

At T = 293.15 ∼ 318.15 K, the density (ρ), viscosity (η), and surface tension (γ) data of polyethylene glycol 300 (PEG300) and 1,2-propane diamine (1,2-PDA) binary liquid mixture in the entire composition range were systemically measured. Meanwhile, the influence of different temperatures on the physical properties of the binary liquid mixture was deeply discussed. The values of ρ and η of PEG300 were compared with the reported values of ρ and η of different linear alcohols under the same experimental conditions. It was found that the values of ρ and η of linear alcohols were related to the number of carbon chains. Under isothermal conditions, the values of ρ and η increased with the number of carbon chains. After that, excess molar volume (VmE), excess viscosity (ηE), surface tension deviation (Δγ), excess Gibbs energy of activation of viscous flow (ΔG∗E), and molar isobaric thermal expansion (Ep,m) of PEG (1) + 1,2-PDA (2) binary mixture were calculated. The η values were fitted with four semi-empirical formulas, and the VmE, ηE, and Δγ values were fitted with Redlich-Kister (R-K) equation. IR, UV, FLS, and Raman spectral technologies were used to further prove the interaction among different molecules of the liquid mixture.

A new robust modeling strategy for multi-component droplet heat and mass transfer in general ambient conditions

Liquid fuels used for spray combustion processes are predominantly composed of several mixed components. The atomization of a liquid jet forms multi-component liquid droplets. These droplets are subject to heat and mass transfers in a vast range of atmosphere configurations, resulting in complex interactions. This example of spray combustion summarizes the diversity of scenarios that a droplet may experience in a spray flow. Unfortunately, available models in the literature exhibit limitations for characterizing such complex interactions. This work proposes a novel modeling strategy to account for such interactions in diverse scenarios grounded in a consistent computational approach. We derive a new formulation from general transport equations of the gas phase. We validate the resulting model by comparing numerical results with available experimental data and consider binary mixtures of liquids evaporating in different ambient conditions. Compared to other reference approaches, the proposed model proves to be efficient in all tested scenarios, including severe atmosphere compositions and states. Additional differential diffusion effects among participating species are observed, not only for mass but also for heat transfer.

Investigating the effects of intermolecular interactions on nonlinear optical properties of binary mixtures with high repetition rate femtosecond laser pulses

Measurements of nonlinear optical (NLO) properties of different binary mixtures having carbon disulfide (CS2) as the common component, namely CS2-acetone, CS2-cyclopentanone, CS2-toluene, and CS2-carbon tetrachloride (CCl4), are carried out by using the z-scan technique. Open-aperture z-scan (OAZS) and close-aperture z-scan (CAZS) experiments are performed to determine the nonlinear absorption coefficient (β) and nonlinear refractive index (n2) of all binary liquid mixtures at various compositions of the components by employing a pulsed, high repetition rate (HRR) femtosecond laser. Also, we were able to use the flowing liquid to measure NLO properties in the CS2-acetone binary mixture to remove the cumulative thermal effects produced due to the pulsed HRR laser light. Nonlinear refractive index (n2) values are found to be influenced by the weak dipole-induced dipole intermolecular interactions between the nonpolar CS2 and polar acetone as well as cyclopentanone of the respective binary mixtures. On the contrary n2 values are not found to be affected by the intermolecular interactions in CS2-toluene and CS2-CCl4 binary mixtures. In comparison, the nonlinear absorption coefficient (β) values are not found to be affected by the same in all different sets of binary mixtures.

Free Volume and Internal Pressure of Binary Liquid Mixtures from Ultrasonic Velocity at 303.15 K

Ultrasonic velocity (u), density (ρ), and viscosity (η) measurements have been taken in six binary liquid mixtures ethyl acetate + methanol, ethyl acetate + ethanol, ethyl acetate + propanol, ethyl acetate + butanol, ethyl acetate + hexanol and ethyl acetate + octanol at 303.15 K over the entire mole fraction range. The experimental data has been used to calculate the free volume, internal pressure and their excess values. Excess values of free volume〖(V〗_f^E) and internal pressure (p_i^E) were plotted against the mole fraction of ethyl acetate over the whole composition range at 303.15 K. They have been analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.

Statistical Mechanic and Phenomenological Approaches to Isomeric Effects in Thermodiffusion.

We present a model that explains variance in the thermodiffusion of hydrocarbon isomers in binary liquid mixtures. The model relies on material transport equations for binary nonisothermal liquid systems that were derived through a nonequilibrium thermodynamic approach in a previous work, coupled with one of two methods: (i) use of equilibrium chemical potentials for each component under conditions of constant pressure, derived using statistical mechanics or (ii) use of the temperature derivative of chemical potential expressed phenomenologically as molecular entropy. The model is evaluated using Soret coefficients (ST) measured in binary solutions of heptane isomers in benzene. The statistical mechanic approach yields moderately acceptable agreement with experimental data. The phenomenological approach, which relies on both measured and calculated values of molecular entropy from the literature, yields values of ST centered around the experimental data, with the scatter likely due to poor precision in the measured or calculated values of entropy. For the latter case, we identify several methods for calculating entropy that yield good agreement with experimental data.

Enhanced oxidative depolymerization of lignin in cooperative imidazolium-based ionic liquid binary mixtures

The aerobic oxidation of lignin model 2-phenoxyacetophenone (2-PAP) in cooperative ionic liquid mixtures (CoILs) with 1-ethyl-3-methylimidazolium acetate ([C2C1im]OAc) and 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BZC1im]NTf2) was investigated. Complete degradation of 2-PAP was achieved with [C2C1im]OAc/[BZC1im]NTf2 molar ratio (RIL) of 1/1 and 1/2 at 100 °C for 2 h. The conversion and product yields from CoILs were higher than those in pure ILs, indicating the cooperative effects of [C2C1im]OAc/[BZC1im]NTf2 on cleaving aryl–ether bonds. [C2C1im]OAc promoted the catalytic cleavage of aryl–ether bonds and solvation, and [BZC1im]NTf2 induced the formation of alkyl radicals and enhanced the product selectivity. Accordingly, the highest conversion of alkali lignin (79.8%) was obtained with RIL of 5/1 at 100 °C for 2 h, and phenol monomers (306 mg/g) were selectively produced. The CoILs exhibited good catalytic capacities for oxidative depolymerization of lignin, which strongly depends on the changes in intermolecular interactions and structural organization with varying RIL.