Transport Properties Of Solutions Research Articles

Borate Species, Volumetric and Transport Properties of Aqueous Lithium Metaborate Solution from 288.15 to 318.15 K

The present work reports acidity (pH), Ranman spectrum, densities (ρ) and viscosity (η) of aqueous lithium metaborate solution at different temperatures. Polyborate distributions in aqueous LiB(OH)4 solution were calculated using measured pH values and literature equilibrium constants. Combining Raman spectra and polyborate distributions result, the polyborate species were ascertained in solution. The apparent molar volumes (Φv), standard molar volumes ($$\Phi _{v}^{0}$$), apparent molar expansibilities ($$\Phi _{E}^{0}$$), and coefficient of thermal expansion (α) in aqueous lithium metaborate solution have been calculated from the density data. The viscosity data have been analyzed by Jones–Dole equation. Different thermodynamic parameters have been used to explore solute–solute, solute–solvent interactions and effect of concentration and temperature. All the parameters calculated from density and viscosity indicate that the lithium metaborate is water structure breaker.

Effect of temperature on transport properties of cysteine in water

Molecular dynamics simulations have been performed to study the transport properties of the dilute solution of cysteine in water at different temperatures. Structural analysis of the system has been carried out using radial distribution functions between different atoms of the solvent and solute. The self-diffusion coefficients of the solute and solvent are estimated from the slope of the mean square displacement vs the time plot using Einstein’s equation and their binary diffusion coefficients from Darken’s relation. The temperature dependency of diffusion is demonstrated via Arrhenius plots. We have further extended our work to study the effects of the system size on diffusion and to calculate the viscosity coefficients of both the solvent and solution. The calculated values are in close agreement with the previously reported results available in literature.

Theoretical analysis of mass transfer during anodic dissolution of tungsten rotating disk electrode in alkaline solutions

The mass transfer during the electrochemical dissolution of metals with the participation of electrolyte anions and the formation of stable anionic complex is analyzed by the example of tungsten anodic dissolution in the alkaline solutions. The distributions of ionic concentrations, partial current densities of ions and potential over the solution layer near the anode are determined as a result of numerical solution of the problem. The results of numerical solution are compared to the results of analytical solution and experimental data available from the literature. It is shown that the numerical solution of the problem with regard for migration, convection and concentration dependences of transport properties of solution agrees well with the experimental data. A complex role of ion migration in this process is revealed.

Optimization of Thermoelectric Transport Properties of Nb-doped Mo1-xWxSeTe Solid Solutions

Optimization of Thermoelectric Transport Properties of Nb-doped Mo_1-<i>_x</i>W<i>_x</i>SeTe Solid Solutions

Structural, Thermodynamic, and Transport Properties of Aqueous Reline and Ethaline Solutions from Molecular Dynamics Simulations.

Deep eutectic solvents (DESs) are a new generation of green solvents, which are considered an environmentally friendly alternative to ionic liquids and volatile organic compounds. The addition of controlled amounts of water to DESs has a significant effect on their microscopic structure and thus on their thermodynamic and transport properties. In this way, DESs can be modified, leading to solvents with improved characteristics. In this work, molecular dynamics (MD) simulations are performed to obtain a better understanding of the relation between the microscopic structure, molecular interactions, and thermophysical properties of aqueous reline and ethaline solutions at temperatures ranging from 303.15 to 363.15 K. For both reline and ethaline solutions, the hydrogen bond (HB) networks disappear with increasing mass fraction of water, and the intensity of radial distribution function (RDF) peaks decreases. For a mass fraction of water of 40%, most of the HBs between the compounds of reline and ethaline are broken, and DESs are fully dissolved in water. Consequently, a monotonic decrease in viscosities and an increase in self-diffusion coefficients are observed. Ionic conductivities show a nonmonotonic behavior with increasing water content. Up to 60% water mass fraction, the ionic conductivities increase with increasing water content. A further increase in the mass fraction of water decreases conductivities. For all studied systems, the HB network and the peaks of RDFs show relatively small changes for water mass fractions below 5% and beyond 40%. The MD results show that viscosities decrease with temperature, while diffusivities and ionic conductivities increase. The effect of the temperature on the structure of DES–water mixtures is negligible.

Pore-scale modeling of carbonates

Abstract Carbonate rocks display complex pore textures with heterogeneities that extend over several length scales. Identifying and capturing the significant pore space properties in a computationally tractable model is therefore nontrivial. Pore-scale models bridge predictions of transport properties from sub-pore to core scale and attempts have been made to render such methods cost-effective. This chapter reviews several methods for fabricating pore-scale models of carbonate rocks and discusses approaches to simulating their fluid flow and solute transport properties. The advantages and limitations of each method in reducing the reservoir development uncertainties are explained. We argue that pore-scale models can play an important role in predicting the petrophysical properties of carbonate rocks. Even more importantly, they provide sensitivity analyses of pore-scale features on macroscopic transport observations and offer explanations for anomalous flow behaviors.

Insights into the Transport Properties of Electrolyte Solutions in a Hierarchical Carbon Electrode by Molecular Dynamics Simulations

We report here the transport properties obtained through molecular dynamics simulations of a 1.5 M dimethyl sulfoxide (DMSO) lithium hexafluorophosphate (LiPF6) electrolyte solution confined in a n...

Thermodynamic and transport properties of ionic liquids, 1-alkyl-3-methylimidazolium thiocyanate in the aqueous lithium halides solutions

Thiocyanate based ionic liquids, [RMIM][SCN], as fluorine free and low toxic were used effectively in different areas of resaerch. In this work, the thermodynamic and transport properties of aqueous solutions of the synthesized ionic liquids based on thiocyanate anion, [RMIM][SCN] (R = butyl, hexyl and octyl) have been investigated at T = (288.15–318.15) K. Also, effect of LiX (X = Cl−, Br−) salts on the investigated properties have been studied at T = 298.15 K. In this respect, density, speed of sound and viscosity of the solutions have been measured and these properties were used to calculate the apparent molar volume, Vφ, and apparent molar isentropic compressibility κφ. The properties were correlated with corresponding empirical relations to achieve standard partial molar volume, Vφ0, partial molar isentropic compressibility, κφ0, and viscosity B-coefficient. These parameters were used to analysis of the interactions between components. In order to separate Vφ0 contributions of the ILs in binary solutions, the scaled particle theory was used at T = (288.15–318.15) K. The results show that the hydrophobic hydration interactions are dominant interactions.

Structures and transport properties of metastable solid solutions (NaSbTe2)1-x(GeTe)x

In contrast to the solid solution series (LiSbTe2)1-x(GeTe)x, compounds with compositions (NaSbTe2)1-x(GeTe)x are not thermodynamically stable at room temperature, but can be obtained as metastable phases by quenching melts with x ≤ 0.5. For x > 0.5 and in slowly cooled melts, samples are inhomogeneous. Despite the metastability, the lattice parameters of (NaSbTe2)1-x(GeTe)x show a Vegard-like behavior. The limited tendency toward forming solid solutions is due to the fact that the ionic radius of Na+ is much larger than that of Ge2+ or Li+ and thus the lattice parameter of NaSbTe2 (a = 6.32 Å) being significantly larger than that of LiSbTe2 (a = 6.11 Å). Measurements of transport properties revealed an increasing Seebeck coefficient with increasing GeTe content. Electrical and thermal conductivities of all members of the series (NaSbTe2)1-x(GeTe)x with x ≤ 0.5 are low with ∼15 mS cm−1 and 0.5 W m−1 K−1, respectively, which is consistent with the inherently low electrical conductivity of NaSbTe2. Nevertheless, this model system explains both the low thermoelectric performance of other chalcogenides with high Na contents and the widely recognized potential of Na as doping agent in thermoelectric materials.

Effect of mixed anions on the transport properties and performance of an ionic liquid-based electrolyte for lithium-ion batteries

Abstract In this work, the physical, transport and electrochemical properties of various electrolytic solutions containing the 1-propyl-1-methylpyrrolidinium bis[fluorosulfonyl]imide ([C3C1pyr][FSI]) mixed with the lithium bis[(trifluoromethyl)sulfonyl]imide (Li[TFSI]) over a wide range of compositions are reported as a function of temperature at atmospheric pressure. First, the ionicity, lithium transference number, and transport properties (viscosity and conductivity) as well as the volumetric properties (density and molar volume) were determined as a function of lithium salt concentration from 293 to 343 K. Second, the self-diffusion coefficient of each ion in solution was measured by nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradients (PFG). Moreover, an analysis of the collected nuclear Overhauser effect (NOE) data along with ab initio and COSMO-RS calculations was conducted to depict intra and intermolecular neighbouring within the electrolytic mixtures. Based on this analysis, and as expected, all activation energies increase with the Li[TFSI] concentration in solution, and all activation energies were determined from the self-diffusion data for all ions. Interestingly, regardless of the composition in solution, these activation energies were similar, except for those determined for the [FSI]− anion. The activation energy of [FSI]− self-diffusion relatively decreases compared to the other ions as the lithium salt concentration increases. Furthermore, the lithium transference was strongly affected by the lithium salt concentration, reaching an optimal value and an ionicity of approximately 50 % at a molality close to 0.75 mol · kg−1. Finally, these electrolytes were used in lithium-ion batteries (i.e. Li/NMC and LTO/NMC), demonstrating a clear relationship between the electrolyte formulation, its transport parameters and battery performance.

Ion Transport and the True Transference Number in Nonaqueous Polyelectrolyte Solutions for Lithium Ion Batteries.

Nonaqueous polyelectrolyte solutions have been recently proposed as high Li+ transference number electrolytes for lithium ion batteries. However, the atomistic phenomena governing ion diffusion and migration in polyelectrolytes are poorly understood, particularly in nonaqueous solvents. Here, the structural and transport properties of a model polyelectrolyte solution, poly(allyl glycidyl ether-lithium sulfonate) in dimethyl sulfoxide, are studied using all-atom molecular dynamics simulations. We find that the static structural analysis of Li+ ion pairing is insufficient to fully explain the overall conductivity trend, necessitating a dynamic analysis of the diffusion mechanism, in which we observe a shift from largely vehicular transport to more structural diffusion as the Li+ concentration increases. Furthermore, we demonstrate that despite the significantly higher diffusion coefficient of the lithium ion, the negatively charged polyion is responsible for the majority of the solution conductivity at all concentrations, corresponding to Li+ transference numbers much lower than previously estimated experimentally. We quantify the ion–ion correlations unique to polyelectrolyte systems that are responsible for this surprising behavior. These results highlight the need to reconsider the approximations typically made for transport in polyelectrolyte solutions.

A Comparative Study of Water and Bromide Transport in a Bare Loam Soil Using Lysimeters and Field Plots

The purpose of this methodological study was to test whether similar soil hydraulic and solute transport properties could be estimated from field plots and lysimeter measurements. The transport of water and bromide (as an inert conservative solute tracer) in three bare field plots and in six bare soil lysimeters were compared. Daily readings of matric head and volumetric water content in the lysimeters showed a profile that was increasingly humid with depth. The hydrodynamic parameters optimized with HYDRUS-1D provided an accurate description of the experimental data for both the field plots and the lysimeters. However, bromide transport in the lysimeters was influenced by preferential transport, which required the use of the mobile/immobile water (MIM) model to suitably describe the experimental data. Water and solute transport observed in the field plots was not accurately described when using parameters optimized with lysimeter data (cross-simulation), and vice versa. The soil’s return to atmospheric pressure at the bottom of the lysimeter and differences in tillage practices between the two set-ups had a strong impact on soil water dynamics. The preferential flow of bromide observed in the lysimeters prevented an accurate simulation of solute transport in field plots using the mean optimized parameters on lysimeters and vice versa.

The effect of pharmaceutically active ionic liquids, 1-methyl-(3-hexyl or octyl) imidazolium ibuprofenate on the thermodynamic and transport properties of aqueous solutions of glycine at T = 298.2 K and p = 0.087 MPa

The influence of two innovative ionic liquids consisting ibuprofenate anion as active pharmaceutical ingredient ionic liquids (API-ILs) on the volumetric, ultrasonic, viscometric, conductometric and refractometric properties of aqueous solutions of glycine has been surveyed. To reach this purpose, the densities, sounds velocity, viscosities, electrical conductivities and refractive indices of ternary solutions of (glycine + API-ILs, 1-methyl-3-hexylimidazolium ibuprofenate [C6mim][Ibu] or 1-methyl-3-octylimidazolium ibuprofenate, [C8mim][Ibu] + water) have been determined at different concentrations of API-ILs and T = 298.2 K. The experimental data have been employed to calculate the properties such as partial apparent molar volume Vϕ0, partial molar volume of transfer ΔtrVϕ0, partial molar isentropic compression κφ0, ion association constant KA, molar refraction RD, viscosity B-coefficients, and hydration number nH. All of these properties were discussed in the terms of the competitive interactions existing between glycine-[C6mim][Ibu] or [C8mim][Ibu] in aqueous media and the hydration properties of glycine.

Volumetric, acoustic and transport properties of ternary solutions of l-serine and l-arginine in aqueous solutions of thiamine hydrochloride at different temperatures

The volumetric, acoustic and viscometric properties are used for investigating the interactions of l-serine and l-arginine in aqueous solutions of a vitamin, namely, thiamine hydrochloride, over a temperature range of (293.15–313.15) K and at atmospheric pressure. The limiting apparent molar volume, V0ϕ, and empirical parameter, Sv, is evaluated from apparent molar volume, Vϕ. Similarly, limiting apparent molar isentropic compression, K0ϕ,s, and slope, Sk, is evaluated from apparent molar isentropic compression, Kϕ,s. The corresponding transfer properties (ΔtrV0ϕ and ΔtrK0ϕ,s) from water to aqueous vitamin solutions are also evaluated. The viscosity data has also been used to analyze relative viscosity, ƞr, viscosity B-coefficients and temperature derivative of B-coefficients, dB/dT. The various calculated parameters assist to procure valuable information regarding the presence of different kinds of intermolecular interactions in the ternary (l-serine/l-arginine + water + thiamine-HCl) solutions.

Charge and Peptide Concentration as Determinants of the Hydrogel Internal Aqueous Environment.

Self-assembling peptides are a promising class of biomaterials with desirable biocompatibility and versatility. In particular, the oligopeptide (RADA)4, consisting of arginine (R), alanine (A), and aspartic acid (D), self-assembles into nanofibers that develop into a three-dimensional hydrogel of up to 99.5% (w/v) water; yet, the organization of water within the hydrogel matrix is poorly understood. Importantly, peptide concentration and polarity are hypothesized to control the internal water structure. Using variable temperature deuterium solid-state nuclear magnetic resonance (2H NMR) spectroscopy, we measured the amount of bound water in (RADA)4-based hydrogels, quantified as the non-frozen water content. To investigate how peptide polarity affects water structure, five lysine (K) moieties were appended to (RADA)4 to generate (RADA)4K5. Hydrogels at 1 and 5% total peptide concentration were prepared from a 75:25 (w/w) blend of (RADA)4:(RADA)4K5 and similarly analyzed by 2H NMR. Interestingly, at 5% peptide concentration, there was lower mobile water content in the lysinated versus the pristine (RADA)4 hydrogel. Regardless of the presence of lysine, the 5% peptide concentration had higher non-frozen water content at temperatures as low as 217 ± 1.0 K, suggesting that bound water increases with peptide concentration. The bound water, though non-frozen, may be strongly bound to the charged lysine moiety to appear as immobilized water. Further understanding of the factors controlling water structure within hydrogels is important for tuning the transport properties of bioactive solutes in the hydrogel matrix when designing for biomedical applications.

Contribution to the evaluation of solute transport properties in a karstic aquifer (Yucatan, Mexico)

In the process of solute transport, dispersivity and hydrodynamic dispersion coefficients are important factors that define the distribution and migration of dissolved salts in the aquifer. Tracer tests were carried out in wells located in the northeast coast of Yucatan, Mexico, whereby only the freshwater thickness of the aquifer was analyzed. Sodium chloride (NaCl) was used as a tracer. Groundwater flow velocity was estimated with the Drost dilution point method. To analyse the solute transport, the analytical model for instantaneous injection was chosen, which is derived from the advection–dispersion equation, and the dispersivity and longitudinal dispersion coefficients were determined. The results indicate that the longitudinal dispersivity and hydrodynamic dispersion of the aquifer vary from 2.56 to 2,500 m and between 1 × 10−3 and 1 × 10−2 m2/s, respectively. In the areas of Telchac Puerto, Dzilam Bravo and San Felipe, advection is the most important solute transport mechanism, while El Cuyo has lower velocity ranges than other locations in the study area and salts tend to disperse. Groundwater flow velocity varies between 3.1 × 10−7 and 8.65 × 10−5 m/s, associated with the flow in the karstic aquifer matrix, with maximum values ​​of 1.5 × 10−4 m/s, associated with the karstification of the aquifer. Groundwater flow velocity increases towards the coast, which is consistent with the fact that the aquifer discharges to the sea. It is observed that in the first 10 m of aquifer, the velocities are higher than those determined in deeper layers, up to an order of magnitude.

Thermodynamic and transport properties of aqueous solutions containing cholinium l-alaninate and polyethylene glycol dimethyl ether 250: Evaluation of solute-solvent interactions and phase separation

Cholinium amino acids ([Ch][AA]) are novel, low toxic and biocompatible ionic liquids (ILs) which utilized widely in biotechnological processes. Since, the most of these processes were done in an aqueous media, it is vital to achieve better understanding of the interactions between ILs with other species in this media. In this respect, this work is focused on the investigation of physicochemical properties of the cholinium l-alaninate ([Ch][l-Ala]) in water and in the presence of polyethylene glycol di-methyl ether 250 (PEGDME250) with different mass fractions 0.025–0.125 at T = (288.15–318.15) K under atmospheric pressure (≈85 kPa). Density (ρ), speed of sound (u), viscosity (η), and refractive index of the studied aqueous solutions were experimentally measured. The obtained values from the density and acoustic studies were used for calculating the limiting values for apparent molar volume (Vφ0), apparent molar isentropic compressibility (κφ0), and also the transfer molar volume (ΔtranVφ0) and isentropic compressibility (Δtranκφ0) of [Ch][l-Ala] from water to aqueous PEGDME250 solutions. Also, viscosity A and B-coefficients were obtained from intercept and slope of the linear plot of viscosity data versus IL molarity. Moreover, the hydration number (nH) was computed from the isentropic compressibility and viscosity data. Finally, the solute-solvent interactions in the investigated solutions were evaluated on the basis of changing the above thermodynamic properties from aqueous binary to ternary solutions consist of the [Ch][l-Ala] and PEGDME250. The results indicated that the IL-water interactions become stronger in the presence of PEGDME250 compared to pure water; and in above a critical concentration this ternary solution can be separated into two-phases.

Optimizing Nonbonded Interactions of the OPLS Force Field for Aqueous Solutions of Carbohydrates: How to Capture Both Thermodynamics and Dynamics.

Knowledge on thermodynamic and transport properties of aqueous solutions of carbohydrates is of great interest for process and product design in the food, pharmaceutical, and biotechnological industries. Molecular simulation is a powerful tool to calculate these properties, but current classical force fields cannot provide accurate estimates for all properties of interest. The poor performance of the force fields is mainly observed for concentrated solutions, where solute–solute interactions are overestimated. In this study, we propose a method to refine force fields, such that solute–solute interactions are more accurately described. The OPLS force field combined with the SPC/Fw water model is used as a basis. We scale the nonbonded interaction parameters of sucrose, a disaccharide. The scaling factors are chosen in such a way that experimental thermodynamic and transport properties of aqueous solutions of sucrose are accurately reproduced. Using a scaling factor of 0.8 for Lennard-Jones energy parameters (ϵ) and a scaling factor of 0.95 for partial atomic charges (q), we find excellent agreement between experiments and computed liquid densities, thermodynamic factors, shear viscosities, self-diffusion coefficients, and Fick (mutual) diffusion coefficients. The transferability of these optimum scaling factors to other carbohydrates is verified by computing thermodynamic and transport properties of aqueous solutions of d-glucose, a monosaccharide. The good agreement between computed properties and experiments suggests that the scaled interaction parameters are transferable to other carbohydrates, especially for concentrated solutions.

Polarizable Molecular Dynamics and Experiments of 1,2-Dimethoxyethane Electrolytes with Lithium and Sodium Salts: Structure and Transport Properties

The structure and transport properties of electrolyte solutions of 1,2-dimethoxyethane (DME) having salts of Li+ with bis(trifluoromethanesulfonyl)imide ([TFSI]-) or Na+ with [TFSI]- are investigated with polarizable molecular dynamics and experiments. Polarizable force fields for Li+ and Na+ with DME and [TFSI]- were developed based on quantum chemistry calculations, ab initio molecular dynamics simulations, and thermodynamic liquid-state properties. Simulation results for density, viscosity, self-diffusion coefficient, and conductivity of the electrolytes all agree well with the trends and magnitudes of available experimental data for a wide range of salt concentrations. As the concentration of salt increases, the electrolytes become more viscous and molecular species become less mobile. Ionic conductivity does not change monotonically with salt concentration and exhibits a maximum between 0.5 and 1.0 M for both Li[TFSI] and Na[TFSI] electrolytes. Comparatively, both cations are solvated by 5-6 DME or [TFSI]- oxygen atoms and exhibit similar diffusivities and conductivities. The solvation shell of Na+ is found to be more weakly bound and to have a lower binding residence time than that of Li+. The transport of Li+ therefore is more vehicular, through the motion of the solvation shell, while the transport of Na+ is based more on exchange, through the replacement of solvating species. The atomistic insight provided by this work can be used as the basis for future rational design of improved electrolyte solvents for lithium-oxygen, sodium-oxygen, and lithium-sulfur batteries.

Modeling the Transport and Volumetric Properties of Solutions Containing Polymer and Electrolyte with New Model

A new theoretical model based on the local composition concept (TNRF-mNRTL model) was proposed to express the short-range contribution of the excess Gibbs energy for the solutions containing polymer and electrolyte. This contribution of interaction along with the long-range contribution of interaction (Pitzer-Debye-Huckel equation), configurational entropy of mixing (Flory-Huggins relation) and Eyring absolute rate theory were used to fit the viscosity values of ternary aqueous solutions of polymer + electrolyte with considering temperature dependency. The local composition models which are available for correlating the thermodynamic properties of ternary polymer + electrolyte solutions (ternary-Wilson, ternary-modified NRTL, and ternary-modified Wilson) with Eyring absolute rate theory were also used for fitting the viscosity values of ternary solutions for the first time. THe fitting quality of Eyring-TNRF-mNRTL model was compared with these models. The equations of apparent molar volume were also derived from TNRF-mNRTL, ternary-Wilson, ternary-modified NRTL, and ternary-modified Wilson models. These equations were used for correlating the apparent molar volume and density values of ternary polymer + electrolyte solutions.