Binary Liquid Mixture Research Articles

Thermo-Reversible Cellulose Micro Phase-Separation in Mixtures of Methyltributylphosphonium Acetate and γ-Valerolactone or DMSO.

We have identified cellulose solvents, comprised of binary mixtures of molecular solvents and ionic liquids that rapidly dissolve cellulose to high concentration and show upper‐critical solution temperature (UCST)‐like thermodynamic behaviour ‐ upon cooling and micro phase‐separation to roughly spherical microparticle particle‐gel mixtures. This is a result of an entropy‐dominant process, controllable by changing temperature, with an overall exothermic regeneration step. However, the initial dissolution of cellulose in this system, from the majority cellulose I allomorph upon increasing temperature, is also exothermic. The mixtures essentially act as ‘thermo‐switchable’ gels. Upon initial dissolution and cooling, micro‐scaled spherical particles are formed, the formation onset and size of which are dependent on the presence of traces of water. Wide‐angle X‐ray scattering (WAXS) and 13C cross‐polarisation magic‐angle spinning (CP‐MAS) NMR spectroscopy have identified that the cellulose micro phase‐separates with no remaining cellulose I allomorph and eventually forms a proportion of the cellulose II allomorph after water washing and drying. The rheological properties of these solutions demonstrate the possibility of a new type of cellulose processing, whereby morphology can be influenced by changing temperature.

Phase transitions affected by natural and forceful molecular interconversion.

If a binary liquid mixture, composed of two alternative species with equal amounts, is quenched from a high temperature to a low temperature, below the critical point of demixing, then the mixture will phase separate through a process known as spinodal decomposition. However, if the two alternative species are allowed to interconvert, either naturally (e.g., the equilibrium interconversion of enantiomers) or forcefully (e.g., via an external source of energy or matter), then the process of phase separation may drastically change. In this case, depending on the nature of interconversion, two phenomena could be observed: either phase amplification, the growth of one phase at the expense of another stable phase, or microphase separation, the formation of nongrowing (steady-state) microphase domains. In this work, we phenomenologically generalize the Cahn-Hilliard theory of spinodal decomposition to include the molecular interconversion of species and describe the physical properties of systems undergoing either phase amplification or microphase separation. We apply the developed phenomenology to accurately describe the simulation results of three atomistic models that demonstrate phase amplification and/or microphase separation. We also discuss the application of our approach to phase transitions in polyamorphic liquids. Finally, we describe the effects of fluctuations of the order parameter in the critical region on phase amplification and microphase separation.

DEVELOPMENT OF WRIGHT BLENDING METHOD IN VISCOSITY ESTIMATION OF LIQUID-BINARY MIXTURE OF BASE OIL AND OLEFIN COPOLYMERS (OCPs)

This study aims to develop mathematical equations used in Wright’s method to predictkinematic viscosity of liquid-binary mixture consisting of base oil and additive. The equationis developed by addition of specific constants (αi and αc), representing interaction ofeach component in the mixtures. Evaluation is done using 70 empirical data from 35 samplesderived from liquid blending of 4 types of base oils (B.1, B.2, B.3 and B.4) and olefincopolymers (OCPs), varied in the range of 5-30 % of weight. Kinematic viscosity is measuredat 40oC and 100oC using a cannon automatic viscometer series 2000 (CAV 2000)according to ASTM method D 445. Validation of the equation (Developed-Wright’s method)is performed over all of liquid-binary mixtures of base oil-OCPs, and the accuracy isindicated by percent average absolute deviation (%AAD). The results show that the additionof specific constants could minimize the deviations of estimated values. The averagedeviation of Developed-Wright’s method on kinematic viscosity estimation at 40oC and100oC becomes 2.056 % and 1.917% respectively, lower than Wright’s method which are8.341 % and 14.696%; meanwhile the maximum deviation reaches 5.821 % and 4.657%,lower than Wright’s method which are 21.256 % and 25.265% respectively. These valuesindicate that the Developed-Wright’s method has better accuracy.

Study of the Transport Properties of the Critical Binary Mixture Triethylamine − Water with an Ionic Impurity

The binary liquid mixture of triethylamine + water (TEA–W) has a lower consolute point at a critical composition of 32.27 mass. % triethylamine. The shear viscosity (η) and the electrical conductivity (σ) in the single phase region of this system with added (K+, Cl–) ions at various concentrations are measured in the vicinity and far from the critical temperature TC. For the pure system without KCl salt, the viscosity measurements yield an enhancement, as expected, for the Ising criticality with a crossover to a regular behavior. Shear viscosity data are consistent with a power-law divergence η = η0(Qζ0)zt–y predicted by the mode-coupling and dynamic renormalization group theories. In the temperature range ∆T = TC – T < 2 ºC, the electrical conductivity (σ) exhibits a monotonous deviation from the Vogel–Fulcher–Tammann (VFT) behavior. This anomaly is described by a power law t1 –α, where t is the reduced temperature (T –TC)/TC, and α is the critical exponent of the specific heat anomaly at constant pressure. For the electrolyte mixtures, the obtained critical exponent values are in the range of those expected by the theoretical calculations for the Ising 3D universality class. By combining the viscosity and the electrical conductivity data, the value of the computed Walden product has been determined, and the salt dissociation degrees, as well as the Debye screening length, have been estimated.

Feedforward and cascade forward networks for viscosity prediction for binary mixtures of ammonium-based ionic liquids and water

Ionic liquids have been attracting great interest due to some properties, such as low vapor pressure, thermal and chemical stability, non-flammability and the possibility of designing ionic liquids for specific purposes. The development of new processes and the substitution of traditionally used solvents, however, depend on the availability of data for the substances involved, either experimental or modeling data. Neural networks are robust models that can be used for optimization, pattern classification and recognition, property prediction and many other applications. They can use experimental data to, after enough training, learn functional relationships between variables and then generalize them for unseen cases. In this work, neural networks were trained and applied in the prediction of viscosity for binary mixtures of ammonium-based ionic liquids and water using a group contribution approach. The input variables were the temperature, the ionic liquid mass fraction and the amount of each group used to describe the ionic liquids structures. The influence of the hidden neuron number and the addition of an extra hidden layer was investigated. Furthermore, 13 training algorithms were tested. Feedforward and cascade forward networks were compared. The average absolute relative deviations for the testing set varied from almost 200% to 0.1999% depending on the selected parameters. The results showed neural networks can be used successfully to predict viscosity data, but a careful selection of architecture and training algorithm is required.

Calculating osmotic pressure of liquid mixtures by association theory for sustainable separating of solvents by membrane processes

Recent years, the separation of organic liquid mixtures achieved by organic solvent nanofiltration (OSN), organic solvent reverse osmosis (OSRO), and organic solvent forward osmosis (OSFO) has gained a great momentum. In the methods, it is of particular importance to know the osmotic pressure of liquid mixtures for the correct process design. Although the Van’t Hoff law is frequently employed to estimate the osmotic pressure of such mixtures, unprecedented serious errors might be added to the results. In this study, the osmotic pressure of numerous binary liquid mixtures is predicted using the original definition of osmotic pressure along with the cubic plus association (CPA) equation of state (EoS) and the Van’t Hoff equation at various temperatures and compositions. CPA EoS considers hydrogen bonding effects in associating compounds (those with hydrogen bonds such as water and alcohols). The obtained results reveal that unlike the Van’t Hoff equation (the average deviation = 19.95 bar), the original definition of osmotic pressure with the aid of CPA EoS (the average deviation = 3.86 bar) can properly predict the osmotic pressure of the studied mixtures. Our findings are beneficial for various techniques utilized in the separation of organic liquid mixtures.

Thermodynamic and spectroscopic investigations on binary liquid mixtures containing tri-n-butylamine with 2-alkanols

ABSTRACT Experimental thermodynamic and spectroscopic investigations on binary liquid mixtures containing tri-n-butylamine with 2-propanol, 2-butanol and 2-pentanol have been discussed in this article. The aforesaid binary mixtures have been examined over the entire range of composition at a temperature range of 293.15–308.15 K with a temperature step of 5 K and at 0.1 MPa pressure. To explore the mixtures thermodynamically, the density () and speed of sound (u) at various compositions and temperatures have been measured. Experimental values of these two properties have been used to find out various thermodynamic parameters, viz., excess molar volumes (), excess isentropic compressibilities (), apparent molar volumes (), partial molar volumes (), excess partial molar volumes () and partial molar volumes at infinite dilution (). These parameters are analysed in terms of form and degree of unlike interactions. Along with this, these parameters are also examined to figure out the effect of chain length and temperature on interactions. Further, the computed excess parameters have also been correlated with the compositions using the Redlich–Kister-type polynomial. Similar to excess parameters, the density and speed of sound have also been correlated to compositions using the Jouyban–Acree model. Apart from this, the mixtures were also analysed using FTIR spectroscopy studies.

Thermodynamic properties of binary liquid mixtures of isoamyl alcohol with heterocyclic compounds at varying temperatures

The current article presents the experimental density ( ρ ) and viscosity ( η ) values were re ported as a function of mole fraction for the binary liquid mixtures of isoamyl alcohol (IAA) + heterocyclic components (NCHC) namely; piperidine, pyrrole, pyridine, morpholine, and quinoline at the temperatures T = (293.15 to 313.15) K with 10 K intervals under atmospheric pressure (0.1 MPa). Based on experimental data, the excess molar volume ( V E ), viscosity deviation ( ∆η ) was calculated. These values were correlated to the Redlich-Kister (R-K) model at measured temperatures. The obtained excess molar volume was negative deviations and deviation in viscosity was positive at the above said temperatures. From these results, the new H-bond, OH- π interaction, and molecules fitting in studied unlike molecules had been determined. Further, the influence of temperature on ρ, η, V E and ∆η were also reported. .

Introducing hydrogen bonding contribution to the Patel-Teja thermal conductivity equation of state for hydrochlorofluorocarbons, hydrofluorocarbons and hydrofluoroolefins

The hydrogen bonding contribution has been added to the Patel-Teja thermal conductivity equation of state for the first time to compute the thermal conductivity of the liquid mixtures containing hydrochlorofluorocarbons, hydrofluorocarbons and hydrofluoroolefins. The coefficients of the pure fluids are determined by using 4 strategies. Then an appropriate mixing rule and the cross association terms have been used, and the present model is used for binary and multicomponent mixtures of the liquid phase. The accuracy of this model has been determined through the thermal conductivities of 12 binary liquid mixtures and 1 ternary liquid mixture. Furthermore, the model is used with and without binary interaction parameters to test the predictions of the present thermal conductivity equation of state. The predictions of this model show that the application of hydrogen bonding contribution and the first strategy results in generally low deviations for the liquid mixtures (Overall AAD% is 7.15% and 6.18% without and with binary interaction parameters, respectively).

Energy and power performances of binary mixtures of ionic liquids in planar and porous electrodes by molecular dynamics simulations

Binary mixtures of ionic liquids are interesting alternatives to tailor ionic liquids properties. Some of them have been proposed as electrolytes for supercapacitors. Herein, we performed molecular dynamics simulations of planar and porous electrodes with binary mixtures of ionic liquids comprising the 1-ethyl–3-methyl–imidazoliumbis(trifluoromethane–sulfonyl)imide ([EMIM][NTf2]) and 1-ethyl–3-methyl–imidazoliumtetrafluoroborate ([EMIM][BF4]), increasing the mole fraction of the latter (xBF4) from 0 to 1. The energy densities calculated from the simulations increase monotonically with xBF4, accordingly with available experimental results [Angew. Chem. Int. Ed. 2015, 54, 1 – 5]. Considering that the electrode simulations were dealt with the constant potential model, the characteristic charging times were calculated for planar and porous electrodes. The devices containing only [EMIM][NTf2] charge slower than electrolytes with xBF4 > 0.0, and the fastest charging happens in xBF4 = 1.0 V. These features are related to the higher [NTf2]-electrode interaction and also to the smaller size of [BF4]−. For porous electrode, the calculated Ragone plot indicates that [EMIM][BF4] outperforms all the other electrolytes with a voltage of 3.0 V in terms of energy and power densities. In the system of best performance, there are considerable contributions of co-ion desorption and counter-ion adsorption mechanisms in the negative and positive electrodes, respectively.

Thermodynamic and Spectral Investigation of Binary Liquid Mixtures Of 2-Isopropoxy Ethanol with Amines at (298.15, 303.15 and 308.15) K

Thermodynamic and Spectral Investigation of Binary Liquid Mixtures Of 2-Isopropoxy Ethanol with Amines at (298.15, 303.15 and 308.15) K

Relaxation to steady states of a binary liquid mixture around an optically heated colloid.

We study the relaxation dynamics of a binary liquid mixture near a light-absorbing Janus particle after switching on and off illumination using experiments and theoretical models. The dynamics is controlled by the temperature gradient formed around the heated particle. Our results show that the relaxation is asymmetric: The approach to a nonequilibrium steady state is much slower than the return to thermal equilibrium. Approaching a nonequilibrium steady state after a sudden temperature change is a two-step process that overshoots the response of spatial variance of the concentration field. The initial growth of concentration fluctuations after switching on illumination follows a power law in agreement with the hydrodynamic and purely diffusive model. The energy outflow from the system after switching off illumination is well described by a stretched exponential function of time with characteristic time proportional to the ratio of the energy stored in the steady state to the total energy flux in this state.

Density, speed of sound, refractive index and relative permittivity of methanol, propan-1-ol or pentan-1-ol + benzylamine liquid mixtures. Application of the Kirkwood-Fröhlich model

Densities (ρ), speeds of sound (c), relative permittivities at 1 MHz (εr) and refractive indices at the sodium D-line (nD) at T = (293.15 K to 303.15 K) and p = 0.1 MPa are reported for binary liquid mixtures alkan-1-ol + benzylamine. Methanol, propan-1-ol and pentan-1-ol are the alkan-1-ols studied in this work. The values of the excess molar volume (VmE), excess isentropic compressibility (κSE), excess speed of sound (cE), excess refractive index (nDE), excess relative permittivity (εrE) and its temperature derivative (∂εrE/∂T)p are calculated, and they are adjusted to Redlich-Kister polynomials. The VmE values are negative, indicating a predominance of the solvation between unlike molecules and structural effects. εrE values indicate a positive contribution from the creation of (alkan-1-ol)-benzylamine interactions, and the positive value for the methanol mixture emphasises the importance of solvation. Calculations on excess molar refractions point out to weaker dispersive interactions than in the ideal mixture, which may be explained by the mentioned solvation effects. The Kirkwood-Fröhlich model has been applied to the mixtures, and the Kirkwood correlation factors suggest an important relative weight, especially in the methanol system, of linear-like molecules in the solutions, which is in accordance with the positive contribution of the formed multimers to εrE due to their good effective response to the electric field.

Probing the Intermolecular Interactions in Binary Liquid Mixtures of 1-Tert-butoxy-2-propanol with Amines Through Volumetric, Ultrasonic and FT-IR Spectroscopic Studies at Different Temperatures

Probing the Intermolecular Interactions in Binary Liquid Mixtures of 1-Tert-butoxy-2-propanol with Amines Through Volumetric, Ultrasonic and FT-IR Spectroscopic Studies at Different Temperatures

Inhomogeneous phase separation kinetics in liquid binary mixtures: Sensitivity to initial local composition †

The kinetics of phase separation subsequent to a finite temperature quench is assumed to be driven by diffusion on the altered free energy surface and is generally assumed to be slow. The situation can be different in phase separating liquid binary mixtures, especially for systems characterized by the large difference in mutual interactions between solute and solvent molecules. In such cases, the phase separation kinetics could be fast and may get completed within a short time (ns) scale. As a result, in these systems, one may observe diverse dynamical features arising out of local heterogeneity leading to the onset of phase separation through pattern formation, spinodal decomposition, nucleation, and growth. By using a coarse-grained analysis, we examine phase separation kinetics in each spatial grid and indeed observe important effects of initial heterogeneity on the subsequent evolution. Interestingly, we observe slower separation kinetics for those regions that correspond to the composition at the minimum of the high-temperature surface. The heterogeneous dynamics has been captured here through the non-linear susceptibility function, which shows a pattern similar to what is observed in the supercooled liquid. Each grid shows somewhat different dynamics in the three-stage (exponential, power-law, and logarithmic regime) phase separation dynamics. The late stage of phase separation kinetics is usually attributed to the coarsening of the phase-separated domains. However, in a liquid binary mixture, the late-stage power-law decay undergoes a further change. A new dynamical regime arises characterized by a logarithmic time dependence, which is due to the “smoothening” of the rough interface of already well-separated phases. This can also be described as opposite to the roughening transition described by Chui and Weeks [Phys. Rev. Lett. 40, 733 (1978)]. This reverse roughening transition can explain the logarithmic time dependence observed in the simulation.

Ultrasonic velocities and refractive indies of binary liquid mixtures of 1, 4-dioxane with 1 – alkanols (C3, C4, C6 , C8 ) at 303.15 K

Density (ρ), ultrasonic velocities (u) and refractive indices (n) of the binary mixture between cyclic ether with 1-propanol, 1-butanol, 1-hexanol, 1-octanol for the entire concentration range have been measured at 303.15K, furthermore, deviation in refractive indies from ideal mixture, molar refraction, deviation in molar refraction from ideal values for these mixture has also been evaluated. The deviations from ideality of the acoustical parameters are explained on the basis of molecular interaction between the component molecules in these binary liquid mixtures. The molecular refraction (Rm), excess molecular refraction ( ) and excess molar volume (VE) were calculated from the experimental data. The results are discussed in term of molecular interactions between the components of the binary mixtures.  Â

Ultrasonic and Thermodynamical Study of Molecular Interactions in Binary Liquid Mixtures at Different Temperatures

Ultrasonic and Thermodynamical Study of Molecular Interactions in Binary Liquid Mixtures at Different Temperatures

Speed of Sound, Density, Viscosity and Related Thermodynamic Excess Properties of Binary Liquid Mixtures Containing Butyl Carbitol with 1-Butanol, Toluene and Diethylmalonate at 308.15 and 318.15 K

In present communication, measurements of experimental density, viscosity and ultrasonic velocity of binary liquid mixtures of butyl carbitol with 1-butanol, toluene and diethylmalonate have been carried out at 308.15 and 318.15 K at atmospheric pressure over the entire composition range of mole fractions. To study the intermolecular interactions present in these liquid mixtures, thermodynamic parameters like VE, ΔKS, Δη, ΔLf, ΔVf and ΔZ have been calculated. The excess functions and their deviations from ideality have also been correlated using Redlich-Kister type polynomial equation by the method of least-squares. The variations of thermodynamic parameters with composition and temperature have been discussed in terms of molecular interaction in these liquid mixtures. Further, IR spectra of these liquid mixtures have also been recorded and the obtained results have been used to analyze the mixing behaviour of the components.

Ultrasonic, Refractometry, FT-IR and DFT Studies on Hydrogen Bonding Interactions of Ethylene Glycol/Hexanol Binary Mixtures

The density (ρ), ultrasonic velocity (U), viscosity (η) and refractometry (nD) measurements are performed on the ethylene glycol/hexanol binary liquid mixtures in the range of temperatures 298.15-323.15 K. Various parameters such as adiabatic compressibility (β), acoustic impedance (Z), intermolecular free length (Lf), internal pressure (π) and relaxation time (τ) were calculated based on the experimentally determined values. The excess parameters were calculated to interpret the hydrogen bond networks and environment associated with the liquid solution. The interaction energy between the mixture components is analyzed using the DFT-B3LYP calculations using 6-311+G(d,p), 6-311++G(d,p) basis sets. The FT-IR spectra support the hydrogen bond in the system. The optimization energy, dipole moment of the components were also represented to correlate the measured parameters. The various theories of ultrasonic velocities and mixing rules for refractive index values were also attempted to estimate the ultrasonic speed, refractive index values of the ethylene glycol/hexanol binary system.

High-Resolution, Sensitivity-Enhanced Active Resonator Sensor Using Substrate-Embedded Channel for Characterizing Low-Concentration Liquid Mixtures

Sensitivity and resolution are important parameters that pose a significant challenge in using microwave microfluidic sensors to monitor low-concentration binary liquid mixtures. This work presents a microwave split-ring resonator (SRR) sensor equipped with a substrate-embedded fluidic channel and an active feedback loop to enhance sensitivity and resolution, respectively. The substrate-embedded channel eliminated the impact of the liquid-carrying tubes’ wall and maintained a significant interaction between the liquid in the channel and the electromagnetic (EM) field confined between the SRR and ground plane. Therefore, embedding the channel inside the substrate of the SRR sensor, operating at 2.63 GHz, enhanced the sensitivity by 60%. The constructive energy from the active feedback loop boosted the quality factor of the passive SRR by over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100\times $ </tex-math></inline-formula> (from 116 to 13 000), which significantly enhanced the resolution of the sensor. As a proof of concept, two prototypes of the sensor having different substrate-embedded channels with cross-sectional diameters of 1 and 0.762 mm were fabricated and used to detect low concentrations of ethanol (0–0.08 vol%) and salt (0–200 mM) in water. Embedding the channel inside the substrate of the active SRR sensor achieved a linear correlation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R^{2} = 0.99$ </tex-math></inline-formula> ) between the resonant frequency and the concentration of ethanol and salt in water with high sensitivity (19.95 MHz/vol% for ethanol and 4.35 kHz/mM for salt) and resolution (0.001 vol% for ethanol and 2.298 mM for salt). The achieved results demonstrate the feasibility of using the active SRR microwave sensor with a substrate-embedded channel for monitoring ethanol in fermentation broths and electrolytes in human sweat.