Liquid Mixtures Research Articles

Molecular dynamics studies on the thermodynamic and structural properties of hydrogen bonds in a novel mixture of dual amino acid ionic liquid – H2O

Amino acid ionic liquid - H2O mixtures have been widely used in recent years. Molecular dynamics (MD) simulations were used to investigate the nanostructures and interactions of two kinds of amino acid ionic liquids, 3–propyl-tributyl-alanine phosphate ([aP4443][Gly]) and 3-propyl-tributyl-alanine phosphate ([aP4443][Ala]) at different water molar fractions (xw = 0 – 0.95). Analysis of volume property showed that there were hydrogen (H) bonds between water molecules and ionic liquids, and the nanostructures of the mixture changed dramatically at about xw = 0.7. MD simulations showed that with the increase of water concentration, the structural correlations between anion - cation, cation - water, anion - water and water - water weakened and the relaxation time of H bonds decreased. The water molecule oxygen atoms competed with the anion carboxyl group to form H bonds with the amino group of the cation. Strong H bonds were also observed between anions and water molecules. Water molecules had different aggregation states at different water concentrations. In the concentrated ionic liquids – H2O mixtures, the anions and cations formed a stable network structure, and the H bonds in the system mainly consisted of H bonds between anions - cations. When 0.7 > xw ≥ 0.5, the H bonds between anion - water were the main component of H bonds in the system. When xw ≥ 0.7, the number of water - water H bonds in the mixture increased rapidly, the diffusion coefficients of the anions and cations increased exponentially, and the stable network of the ionic liquids was destroyed. The ion aggregation region was gradually divided by water molecules. When xw ≥ 0.9, water molecules were interconnected to form a large water network structure, and ionic liquids were gradually dissolved in the water molecules.

Studies on Intermolecular Interactions in Binary Liquid Mixtures of 2-Methyl-1-butanol with Glycol Ethers {CH3(OCH2CH2)nOH}, n = 1,2,3 at Different Temperatures: A Volumetric, Acoustic and Transport Study

Studies on Intermolecular Interactions in Binary Liquid Mixtures of 2-Methyl-1-butanol with Glycol Ethers {CH3(OCH2CH2)nOH}, n = 1,2,3 at Different Temperatures: A Volumetric, Acoustic and Transport Study

Computation of Ultrasonic Speed in Binary Liquid Mixture of Acetone and Carbon tetrachloride using Empirical Theories at Different Temperatures

Experimental ultrasonic velocities of binary liquid mixture of acetone and carbon tetra chloride at temperatures 286.15 K, 289.15 K and 293.15 have been evaluatedat 2 MHz as a function of molar concentrations. The experimental values were compared with various theories for analysis of ultrasonic velocity in binary liquid mixtures such as Nomoto theory (NOM), ideal mixing relation (IMR) of Van Dael andVangeel, Impedance Relation (IDR), Rao’s Specific Velocity Method (Rao) and Junjie’s relations (JR). Chi-square test and average percentage error were applied to investigate the relative applicability of these theories to the present systems. The variation of thermo acoustical parameters of the systems with the mole fraction has been discussed in term of molecular interactions.

Molecular Rotors for In Situ Viscosity Mapping during Evaporation of Confined Fluid Mixtures.

Numerous formulation processes of materials involve a drying step, during which evaporation of a solvent from a multicomponent liquid mixture, often confined in a thin film or in a droplet, leads to concentration and assembly of nonvolatile compounds. While the basic phenomena ruling evaporation dynamics are known, precise modeling of practical situations is hindered by the lack of tools for local and time-resolved mapping of concentration fields in such confined systems. In this article, the use of fluorescence lifetime imaging microscopy and of fluorescent molecular rotors is introduced as a versatile, in situ, and quantitative method to map viscosity and concentration fields in confined, evaporating liquids. More precisely, the cases of drying of a suspended liquid film and of a sessile droplet of mixtures of fructose and water are investigated. Measured viscosity and concentration fields allow characterization of drying dynamics, in agreement with simple modeling of the evaporation process.

Characteristics of velocity, bubble's radius, and pressure in liquid and gas bubble mixture

The study focuses on the formation of gas bubbles, a crucial phenomenon that significantly impacts the hydrodynamics in liquid–gas reactors. This phenomenon has been observed in industrial engineering, leading to the development of model equations that describe the velocity of a liquid–gas mixture, pressure, and deviation in the gas bubble's initial radius. Kudryashov–Sinelshchikov (KS) established coupled equations (CEs) to describe the dynamics of the liquid–gas mixture. Here, the study aims to investigate the behavior of velocity, deviation in the bubble radius, and pressures by deriving exact solutions of the KSCEs and representing them graphically. The findings show that the velocity can take negative or positive values, representing interfacial velocity or superficial velocity for both liquid and gas, respectively. The pressure may also be negative or positive, corresponding to the shrinking or stretchering of the liquid surface, respectively. The dynamics of the velocity and the deviation in the bubble radius exhibit similar qualitative behavior, while the pressure shows a variant behavior. The dominant parameters are found to be the gas bubble's initial radius and the polytropic exponent. The stability of the steady-state solution is also analyzed. This study contributes to the existing literature by examining the CEs, which have not been studied until now.

Molecular Interaction Study in the Binary Liquid Mixture of PEO and DMF by Ultrasonic Technique

The non‐destructive ultrasonic technique is a great employ for knowing the solute–solvent interaction in the polymer blend. By the ultrasonic velocity and attenuation evaluation, the visco‐elastic behaviors of the polymer solution have been assessed and compared with the results of conventional dynamic mechanical analysis. In the present research work, a comprehensive ultrasonic investigation of molecular interaction in a polymeric mixture of Poly (ethylene oxide) PEO and dimethyformamide (DMF) at 333 K has been executed by using the information provided by the literature. For this purpose, ultrasonic waves of two different frequencies such as 2 and 5 MHz have been implemented. Several acoustical parameters such as adiabatic compressibility, acoustic impedance, relaxation time, and ultrasonic attenuation coefficient (𝛼/𝑓2) are explored. Thermodynamic parameters like relative association and intermolecular free path length are also estimated. The evaluated values have been associated with the previous experimental results. The non‐ideal approach of the solution is analyzed and discussed in detail.

Effective removal of personal care product residues from aqueous media using hydrophobic deep eutectic solvents: Experimental and computational approach

Personal care product (PCP) residues - classified under micropollutants (MPs)- are widely found in aquatic environments, posing trace-level toxicity. Traditional water treatment techniques struggle to remove these toxins effectively. Deep eutectic solvents (DESs), the liquid mixtures typically composed of hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs), have recently emerged as a viable alternative for extracting pollutants from water. Among DESs, hydrophobic deep eutectic solvents (HDESs) exhibit low water miscibility and unique solvent properties. The main objective of this study is to synthesize HDESs to effectively eliminate 2-naphthol and methylparaben- two of the significant chemical contaminants in PCPs- from aqueous media. HDESs were prepared by mixing different terpenes (menthol and thymol) and long-chain carboxylic acids at varying molar ratios. They were characterized using different spectroscopic and thermal techniques. The density and viscosity of the pure DESs were measured as afunction of temperature. Experimental studies were carried out using the liquid–liquid extraction (LLE) method, and the factors influencing the efficiency of extraction were optimized.Considering the limited number of studies on the extraction mechanism of MPs from aqueous media, this study employs comprehensive computational methods, including density functional theory (DFT) and the COnductor-like Screening MOdel for Real Solvents (COSMO-RS), to provide a detailed interpretation of the extraction mechanism. A series of successive extractions were conducted to reduce the DES usage to ensure economic viability. The reusability of the best-performed DES was explored. Additionally, the regeneration of one of the DESs was accomplished through activated carbon-based recovery.---------------------------------------------------------------------------------------------------------------------

Binding potential and wetting behavior of binary liquid mixtures on surfaces.

We present a theory for the interfacial wetting phase behavior of binary liquid mixtures on rigid solid substrates, applicable to both miscible and immiscible mixtures. In particular, we calculate the binding potential as a function of the adsorptions, i.e., the excess amounts of each of the two liquids at the substrate. The binding potential fully describes the corresponding interfacial thermodynamics. Our approach is based on classical density functional theory. Binary liquid mixtures can exhibit complex bulk phase behavior, including both liquid-liquid and vapor-liquid phase separation, depending on the nature of the interactions among all the particles of the two different liquids, the temperature, and the chemical potentials. Here we show that the interplay between the bulk phase behavior of the mixture and the properties of the interactions with the substrate gives rise to a wide variety of interfacial phase behaviors, including mixing and demixing situations. We find situations where the final state is a coexistence of up to three different phases. We determine how the liquid density profiles close to the substrate change as the interaction parameters are varied and how these determine the form of the binding potential, which in certain cases can be a multivalued function of the adsorptions. We also present profiles for sessile droplets of both miscible and immiscible binary liquids.

Investigation of Excess Thermo‐Acoustic Behavior of Binary Liquid Mixture with Various Temperatures Using Ultrasonic Technique

AbstractUltrasonic methods have been very fruitful in studying the physical properties of binary liquid combinations. In this present study, the thermoacoustic behavior of benzyl propionate with dimethyl sulfoxide (DMSO) is observed using ultrasound, density, and viscosity at different temperatures between 308 and 328 K with a phase of 10 °C. Benzyl propionate is a sweet‐smelling liquid that is used in the botanical and fruit fragrance industries, as well as in the flavoring of organic products. DMSO is a dipolar aprotic, naturally soluble compound used for slow drug synthesis, device synthesis, and drug delivery to the body. Estimated values such as adiabatic compressibility, intermolecular free length, internal pressure, and free volume are determined from arbitrary ultrasonic velocity, density, and viscosity data. The same excess parameters of adiabatic compressibility, intermolecular free length, internal pressure, and free volume support finding the nature of the reaction. The sort of interactions has been accounted for utilizing these qualities. In the present work, benzyl propionate with dimethyl sulfoxide has been characterized by using ultrasonic waves and since this wave is a well‐known tool for NDT, so the mixture is properly characterized. These thermoacoustic parameters with different concentrations of DMSO at different temperatures have been used to study the complex formation and binding through intermolecular forces.

Organogel as Drug Delivery System: Review

Background: Gels are employed as a carrier medium/network for the delivery of topical medicines. Due to number of benefits gels are gaining attention day by day as a drug delivery system. Among gels Organogelare preferably active for incorporating lipophilic and hydrophilic drugs within the same gel network. Aim: To emphasize about the basics of Organogel. Their introduction types, composition, properties, methods of preparation and advantages and applications and most importantly as topical drug delivery system. Definition: The Organogel comes under the semi solid preparations with a definition of having two phases,one of which is organic liquid which gets immobilized by the other, that is an organogelators. Composition: Organogel are, “mixture of lipophilic liquid and solid lipid, in which solid lipid having concentrations (<10%) can entangle bulk liquid oil by formingthreedimensionalnetwork by the physical interaction of self-assembled organogelatorsin the bulk oil”2. Properties: Generally Organogel are thermodynamically stable system, viscoelastic, biphasic system, no irritating, have low degree of hydration in comparison to hydrogels. Exhibit morphological and rheological properties Method of Preparation: Solid fiber Matrix and fluid filled matrix are most common methods adopted for Organogel preparations. Characterization: viscoelasticity, pH, Firmness, In vitro drug, release, stability, phase transition, and structural features,Invitro release, skin permeability were discussed along with different factors that affectOrganogel. Applications: Organogel are used for both oral and topical delivery of number of drugs. They are used for local as well as are capable of systemic percutaneous absorption due to their lipophilic nature and penetration potentiates by the presence of penetration enhancer3. Keywords: Organogels, Organogelator, Solvents, Drug delivery system

Properties of Antiferroelectric Mixtures Differing in the Amount of Added Racemate

Novel three-component liquid crystalline mixtures composed of chiral and achiral (racemic) liquid crystalline materials were designed and studied by polarizing optical microscopy, differential scanning calorimetry, and UV–VIS spectroscopy. The compositions of liquid crystalline mixtures were developed based on the composition of a two-component (binary) mixture marked as W-1000 with the following phase sequence: Cr ↔ SmCA* ↔ SmC* ↔ SmA* ↔ Iso. This mixture has an antiferroelectric (SmCA*) phase over a wide temperature range and exhibits a helical pitch inversion in this phase. All newly obtained mixtures occur in a wide temperature range of the SmCA* phase, while the ferroelectric (SmC*) phase and the orthogonal (SmA*) phase occur in a narrow temperature range. The new mixtures also have a very long helical pitch in the antiferroelectric phase and a short helical pitch in the ferroelectric phase.

Prediction of Fick Diffusion Coefficients in Binary Mixtures of Liquids with Dissolved Gases at Infinite Dilution─A Review

Prediction of Fick Diffusion Coefficients in Binary Mixtures of Liquids with Dissolved Gases at Infinite Dilution─A Review

Predictive, correlative and machine learning models for estimation of viscosity of liquid mixtures

Among the various thermodynamic and transport properties, viscosity is a crucial thermophysical property that plays a vital role in heat and mass transfer, design and calculations, research and development, and numerous industrial applications. Predicting the viscosity behaviour of this highly significant transport property in liquids and liquid mixtures has been a challenging task due to its sensitivity to temperature and concentration variations. In the current investigation, 42 binary liquid mixtures have been investigated and 9 predictive and 4 correlative approaches, along with the machine learning algorithm - Random Forest, have been utilized to predict the viscosity at varying temperatures and concentrations. Percentage Average Absolute Deviation (%AAD) has been used to carry out a comparative analysis to assess the predictive efficacy of these different methodologies. The findings indicate that the Dey-Biswas model outperforms all the predictive models with a Grand %AAD value of 3.41. The Grunberg-Nissan and Wijk give the best overall performance in correlative models having a Grand %AAD of 1.17 with Random Forest also demonstrating consistent predictive efficacy with better Grand %AAD values.

Determination of Electrical and Mechanical Properties of Liquids Using a Resonator with a Longitudinal Electric Field

The possibility of determining the elastic modules, viscosity coefficients, dielectric constant and electrical conductivity of a viscous conducting liquid using a piezoelectric resonator with a longitudinal electric field is shown. For the research, we chose a piezoelectric resonator made on an AT-cut quartz plate with round electrodes, operating with a shear acoustic mode at a frequency of about 4.4 MHz. The resonator was fixed to the bottom of a 30 mL liquid container. The samples of a mixture of glycerol and water with different viscosity and conductivity were used as test liquids. First, the frequency dependences of the real and imaginary parts of the electrical impedance of a free resonator were measured and, using the Mason electromechanical circuit, the elastic module, viscosity coefficient, piezoelectric constant and dielectric constant of the resonator material (quartz) were determined. Then, the container was filled with the test sample of a liquid mixture so that the resonator was completely covered with liquid, and the measurement of the frequency dependences of the real and imaginary parts of the electrical impedance of the loaded resonator was repeated. The dependences of the frequency of parallel and series resonances, as well as the maximum values of the electrical impedance and admittance on the conductivity of liquids for various viscosity values, were plotted. It was shown that these dependences can be used to unambiguously determine the viscosity and conductivity of the test liquid. Next, by fitting the theoretical frequency dependences of the real and imaginary parts of the electrical impedance of the resonator loaded with the liquid under study to the experimental dependences, the elastic module of the liquid and its dielectric constant were determined.

Thermodynamic properties of P-methyl acetophenone with cyclohexylamine, cyclohexanol, and cyclohexane at various temperatures (strong and weak interactions)

ABSTRACT The density, viscosity and sound velocity of the binary liquid mixtures of P-methyl acetophenone with cyclohexylamine, cyclohexanol, and cyclohexane are measured over the complete composition range at temperatures of 303.15–313.15 K and at atmospheric pressure of 0.1 M. Excess molar volume, excess isentropic compressibility and viscosity deviation are calculated from the experimental measurements. The sign and magnitude of the derived parameters reveal the nature and type of interactions between the constituent molecules in the binary mixtures. Thermodynamic properties for this work reveal association interactions between dissimilar molecules in the binary systems P-methyl acetophenone + cyclohexylamine and P-methyl acetophenone + cyclohexanol systems, whereas dispersion forces cause the opposite trend in the other binary system P-methyl acetophenone + cyclohexane.

Optimized Design of Pipe Elbows for Erosion Wear

Multiphase flows are widely used to transport solid–liquid mixtures in oil and gas fields. The pipeline structures used can suffer damage from the high-pressure sand-carrying fracturing fluid, causing erosion and wear failures in the engineering field. In this work, an erosion model that considers particle turbulent kinetic energy and the effect of the design’s structural parameters on the erosion wear of spatial pipe structures is established using computational fluid dynamics (CFD). Structural parameters such as the bending diameter ratio, bending angle and spatial angle are discussed, and the location and degree of each parameter with regard to the erosion rate are obtained. The results show that the included angle of the pipe elbow has the greatest influence on erosion wear among the structural parameters. Several typical anti-erosion optimization models are compared and analysed, and a corrugated anti-erosion structure based on a bionic structure is further proposed. It is found that the anti-erosion performance of the T-type blind long header pipe is better in terms of the numerical value of the erosion rate, while for the erosion cloud diagram, the anti-erosion performance of the corrugated structure is superior. Finally, some suggestions for the application of the anti-erosion structure in the engineering field are given, and technical support is provided for the anti-erosion structure design and practical application of space pipeline systems in the future.

Ionogels based on protic ionic liquid - lithium salt mixtures

The effect of the addition of lithium nitrate on the liquid range and electrical conductivity of mixtures of a protic ionic liquid, ethylammonium nitrate (EAN) with LiNO3 is reported in this work. Moreover, changes in these properties upon confinement in silica-based matrices are also analysed and related to variations on the microstructure of the mixtures. Our results show that gelation of the mixtures induces amorphous behaviour in all the samples, but no significant changes in the thermal stability are detected. However, important differences on the electrical conductivity of the liquid and gel states of the mixtures were observed. While this magnitude decreases with the addition of salt in the liquid samples for all the temperatures it increases at low concentrations of LiNO3 up to a maximum in the gelled samples with the lowest concentration of added salt (0.1 mol of salt by kg of EAN). High resolution magic angle spinning (HRMAS) NMR shows that the addition of lithium nitrate increases the mobility (both rotational and translational motion) of the cation EA+ within the ionogel and the diffusion of the cation provides evidence of the presence of two different populations of the same molecules experiencing two distinct apparent diffusion coefficients (bi-exponential decay of magnetization in diffusion NMR experiments), while it is mono-exponential in the pure ionic liquid. The Li+ cation is shown to display a higher mobility (both rotational and translational motion) in the ionogel than in the neat ionic liquid. The frustration of the formation of solvation complexes due to the confinement is suspected to be behind this behaviour.

Thermophysical properties of binary liquid mixtures at various temperatures, supported by FTIR spectral studies and correlation with the Jouyban–Acree model (allyl alcohol, benzyl aldehyde, benzylamine and benzyl alcohol)

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for activation of viscous flow for binary mixtures of allyl alcohol (C) with benzyl aldehyde (C1), benzylamine (C2) and benzyl alcohol (C3) components in selected compositions were determined from the measured values of densities (ρ), viscosities (η) and speeds of sound (u) of pure components and their mixtures at 303.15–313.15 K. These results were analysed by different theoretical models, such as PFP and Jouyban–Acree model. The effect of various functional groups on the excess properties was discussed in terms of disruption of H-bonding and dipole–dipole interaction between the components of the mixtures. The thermodynamic results of the present investigation have been correlated with FTIR spectral studies and have obtained a good agreement.

Physicochemical properties, theoretical modelling and molecular interaction analysis in ternary liquid mixtures containing 1-propanol, 1,3-diaminopropane and ethyl acetate at temperature 298.15–318.15 K

In the present report, density (ρ), viscosity (η), speed of sound (u) and refractive index (nD) of ternary liquid mixture containing 1-propanol (1P) (1) + 1,3-diaminopropane (1,3-DAP) (2) + ethyl acetate (EAc) (3) were measured at five different temperatures (T = 298.15 to 318.15 K) and at 0.1 MPa pressure. Data of ρ, η, u and nD were used to compute the excess molar volume, VmE, deviation in viscosity, Δη, deviation in ultrasonic speed, Δu, excess isentropic compressibility, ksE, excess free volume, VfE, excess intermolecular free length, LfE, excess available volume, VaE, and deviation in refractive index, ΔnD, and these computed physicochemical properties were fitted to Singh equation. The VmE data were fitted to the Nagata and Cibulka equations. Further, Kohler model, Tsao-Smith model, Radojkovic model, Jacob-Fitzner model and Rastogi model were used to calculate the VmE values. The speed of sound data was analyzed by various correlations such as Van Dael, Nomato, Impedance dependence, Schaaff’s collision factor theory (CFT) and Jacobson’s free length theory (JFLT). Various correlations like Heller, Arago-Biot, Lorentz-Lorenz, Erying, Newton, Gladstone-Dale, and Weiner were used to correlate nD data.

A state-of-the-art theoretical method for estimating ultrasonic velocity in ionic liquid mixtures: An extension of McAllister's interaction model

McAllister’s Interaction Model has been extended to predict ultrasonic velocities in eight binary mixtures of ionic liquids and water at temperatures T = 288.15 K, 298.15 K, and 308.15 K.The ionic liquids chosen for the current study are [BMim][TfO], [BMpyr][TfO], [BMpy][TfO], [BMim][dca], [HMim][dca], [BMpyr][dca], [Mpy][MSO4], and [EEpy][ESO4]. The interactions considered in present cases have been investigated for a range of variations from three-body interactions to nine-body interactions. The experimental values of ultrasonic velocities for all the mixturesat temperatures T = 288.15 K, 298.15 K, and 308.15 Kare compared with the computed values. The differences between the experimental and theoretically predicted velocities are determined in terms of absolute percentage deviation. It is worth mentioning that McAllister’s Model of interactions has been extended, for consideration, from three-body interactions to nine-body interactions among constituent molecules of binary mixtures and applied for the prediction of ultrasonic velocities in binary mixtures of water and ionic liquids for the first time. The extended Huckel theory (EHT) is used to calculate the charge distributions in eight ionic liquids and water molecules to understand the active sites available for interactions on each constituting molecule of the binary mixtures under investigation. The results we obtained complemented our decision to extend McAllister’s interactions model (MAIM) to higher orders (four-body to nine-body interactions). The results obtained (using extended MAIM) report an excellent agreement with experimental velocity values for nine-body interactions for all the systems under study. It is also pointed out that McAllister’s assumption that the free energies of activation are the additive quantity for viscosity investigation in organic liquid mixtures is also valid in the case of ultrasonic velocity studies for ionic liquids and water mixtures. Considering McAllister’s conjecture that rather than a planar system of interactions among solvent-solute molecules, a three-dimensional approach to intermolecular interactions can be more appropriate, authors have confirmed the validity of McAlliter’s conjecture by successfully investigating three-dimensional multi-body (in the present case: 9-body) interactions in the binary mixtures of ionic liquids and water.