Thermodynamic Properties Of Aqueous Solutions Research Articles

Speeds of Sound in Binary Mixtures of Water and Carbon Dioxide at Temperatures from 273 K to 313 K and at Pressures up to 50 MPa

Knowledge of thermodynamic properties of aqueous solutions of CO2 is crucial for various applications including climate science, carbon capture, utilisation and storage (CCUS), and seawater desalination. However, there is a lack of reliable experimental data, and the equation of state (EOS) predictions are not reliable, particularly for sound speeds in low CO2 concentrations typical of water resources. For this reason, we have measured speeds of sound in three different aqueous solutions containing CO2. We report speeds of sound in the single-phase liquid region for binary mixtures of water and CO2 for mole fractions of CO2 of 0.0118, 0.0066 and 0.0015 at temperatures from 273.15 K to 313.15 K and at pressures up to 50 MPa, measured using a dual-path pulse-echo apparatus. The relative standard uncertainties of the sound speeds are 0.05 %, 0.03 % and 0.01 % at 0.0118, 0.0066 and 0.0015 CO2 mole fractions, respectively. The change in sound speeds as functions of composition, pressure and temperature are analysed in this study. We find that dissolution of CO2 in water increases its sound speeds at all conditions, with the greatest increase occurring at the highest mole fractions of CO2. Our sound speed data agree well with the limited available experimental data in the literature but deviate from the EOS-CG of Gernert and Span by up to 7 % at the lowest temperatures, highest pressures, and highest CO2 mole fraction. The new low-uncertainty sound speed data presented in this work could provide a basis for development of an improved EOS and in establishing reliable predictions of the change in thermodynamic properties of seawater-like mixtures due to absorption of CO2 gas.

Influence of ice formation on the dynamic and thermodynamic properties of aqueous solutions

Influence of ice formation on the dynamic and thermodynamic properties of aqueous solutions

Studies of radial distribution function and second virial coefficient for surfactant decyltrimethylammonium bromide in aqueous solutions at 298.15 K: Evidence for cation–cation hydrophobic interactions effect

Excess internal pressure of solution and excess partial molar volume of solute data embedded in the parameter reversible isothermal work (W) have been used to calculate the ion–ion pair correlation functions (gij(r), r being distance) and the thermodynamic properties of aqueous solutions of decyltrimethylammonium bromide (C10TAB) in concentration range 0.01 – 0.14 mol∙kg–1. It is observed that gij(r) exhibits a peak at critical micelle concentration (cmc), while the virial coefficient term (gij(r) – 1) also goes through a maximum. Using Friedman's methodology and McMillan–Mayer theory of solutions, these results have been examined. With the help of concept of Gurney cosphere around the ions, the overlap of solvation shells (water molecules) as the concentration of ions increases have been used to probe water– structure effects as water–structure making/breaking. Coefficients Aij are estimated (Coulombic term, a core repulsive term, a cavity formation term and overlap of cosphere term) at various concentrations of ionic surfactant and at a radial distance of 20 Å for a micellar entity. Further analysis indicates that gij parameter (that is, representing cation–cation interaction g++) dominate over g+– (representing ion–solvent interaction) in solution phase. Thus for a self–assembly process (formation of micelle with aggregation number) in a solution phase is being characterized by a peak in gij(r) function at cmc and aggregation number of ≈ 38, area under the peak, while the virial coefficient variation indicates a dominance of cation–cation interaction and cosphere water–structural effects. It is emphasized that the approach adopted by us to use excess PV work to estimate gij(r) is better to understand the thermodynamic process involved in self–assemblies and micelle formation.

Influence of ice formation on the dynamic and thermodynamic properties of aqueous solutions

Water dynamics in solutions with biological or non-biological solutes has been intensely studied when both components (solvent and solute) are amorphous. Here, we apply broadband dielectric spectroscopy combined with calorimetric measurements to analyze the dynamics of the aqueous solutions tri-propylene glycol (3PG) and ε-poly (lysine) (ε-PLL), after their water becomes semi-crystalline. Various crystallization levels were explored by conducting experiments with different annealing times at temperatures above the glass transition temperature (Tg). We find that the amount of ice depends on both the time and temperature of the annealing, and that this, in turn, affects Tg and dynamics of the amorphous part of the samples. However, it should be noted that the observed differences are relatively small for the degrees of crystallinity we have studied (up to about 26 wt% of the water). This also implies that the dynamic crossover of the water relaxation from a high temperature non-Arrhenius behavior to a low temperature Arrhenius dependence is unaffected by the partial crystallization and still occurs as a single crossover at the calorimetric Tg. Thus, we cannot detect two different crossovers, as commonly observed for other types of two-component systems, such as two glass formers.

Novel Binary Mixtures of Alkanolamine Based Deep Eutectic Solvents with Water-Thermodynamic Calculation and Correlation of Crucial Physicochemical Properties.

This paper demonstrates the assessment of physicochemical and thermodynamic properties of aqueous solutions of novel deep eutectic solvent (DES) built of tetrabutylammonium chloride and 3-amino-1-propanol or tetrabutylammonium bromide and 3-amino-1-propanol or 2-(methylamino)ethanol or 2-(butylamino)ethanol. Densities, speeds of sound, refractive indices, and viscosities for both pure and aqueous mixtures of DES were investigated over the entire range of compositions at atmospheric pressure and T = (293.15 ‒ 313.15) K. It was concluded that the experimental data were successfully fitted using the Jouyban–Acree model with respect to the concentration. Obtained results showed that this mathematical equation is an accurate correlation for the prediction of aqueous DES properties. Key physicochemical properties of the mixtures—such as excess molar volumes, excess isentropic compressibilities, deviations in viscosity, and deviations in refractive indices—were calculated and correlated by the Redlich–Kister equation with temperature-dependent parameters. The non-ideal behavior of the studied systems were also evaluated by using the Prigogine−Flory−Patterson theory and the results were interpreted in terms of interactions between the mixture components.

Challenges and opportunities for using formate to store, transport, and use hydrogen

Abstract In this perspective article, the synthesis and thermodynamic properties of aqueous solutions of formate salts (FS, HCO2−) are described in relationship to the concept of H2 carriers. The physiochemical properties of solid FS, aqueous formate solutions, and aqueous bicarbonate solutions set the limitations for storage capacity, deliverable capacity, and usable H2 capacity of these H2 carriers, respectively. These parameters will help in the design of systems that use H2 carriers for storage and transport of H2 for fuel cell power applications. FS, as well as admixtures with formic acid (FA, H2CO2), have potential to address the goals outlined in the U.S. Department of Energy's H2@scale initiative to store in chemical bonds a significant quantity of energy (hundreds of megawatts) obtained from large scale renewable resources.

Isopiestic Method for Solution Model Verifications and Binodal Determinations

Testing a theoretical model by using precise experiments is one of the important subjects in natural sciences. The isopiestic method at constant temperature is one of the most important and widely used experimental methods for determining thermodynamic properties of aqueous solutions. It has been used for the precise measurements of solvent activities and solute molalities for hundreds of binary and higher-order aqueous solutions. It has also been applied to a few binary nonaqueous solutions. On the other hand, the Zdanovskii–Stokes–Robinson (ZSR) rule is the simplest isopiestic molality relation for mixed electrolyte and nonelectrolyte aqueous solutions related to the corresponding single aqueous solutions and thus the isopiestic method has been used as the perfect experimental method for its direct and precise verifications. Here, we review our isopiestic measurements used for solution model verifications. The experimental systems include unsaturated and saturated aqueous solutions, unsaturated methanol solutions, unsaturated mixed solvent systems, unsaturated liquid alloys, unsaturated molten salt mixtures, and unsaturated molten oxide mixtures. Additionally, the isopiestic principle and preliminary experiments are also described for the binodal determination of liquid–liquid bi-phasic solutions, taking binary liquid alloys as examples.

Persistent negative temperature response of mesophyll conductance in red raspberry (Rubus idaeus L.) leaves under both high and low vapour pressure deficits: A role for abscisic acid?

Plant, Cell & Environment (2017) 40: 1940–1959 Version of Record online: 14 AUG 2017, DOI: 10.1111/pce.12997

Vapor Pressure Osmometry, Volumetry, and Compressibility Properties for Solutions of Several Imidazolium Based Ionic Liquids in (Glycine + Water) Solutions

In this study, the effect of glycine on the thermodynamic properties of aqueous solutions containing ionic liquids 1-butyl-3-methylimidazolium chloride, [C4mim]Cl, 1-hexyl-3-methylimidazolium chloride, [C6mim]Cl, 1-butyl-3-methyl-imidazolium trifluoromethanesulfonate, [C4mim][CF3SO3], has been studied. For this purpose, first with help of the vapor pressure osmometery (VPO) method the water activity measurements have been performed on the ternary aqueous systems of (glycine + [C4mim]Cl, [C6mim]Cl, and [C4mim][CF3SO3]) at T = 308.15 K. The influence of the IL nature on the vapor–liquid equilibria behavior of the investigated systems has been studied. The VPO measurements of these solutions show that due to the unfavorable IL-glycine interactions, the negative deviations from the semi-ideal state and in conclude the soluting-out effects have been observed in these solutions. The soluting-out phenomena appears by aqueous biphasic system formation in the case of aqueous [C4mim][CF3SO3] + glycine system and pr...

Persistent negative temperature response of mesophyll conductance in red raspberry (Rubus idaeus L.) leaves under both high and low vapour pressure deficits: a role for abscisic acid?

The temperature dependence of mesophyll conductance (gm ) was measured in well-watered red raspberry (Rubus idaeus L.) plants acclimated to leaf-to-air vapour pressure deficit (VPDL) daytime differentials of contrasting amplitude, keeping a fixed diurnal leaf temperature (Tleaf ) rise from 20 to 35°C. Contrary to the great majority of gm temperature responses published to date, we found a pronounced reduction of gm with increasing Tleaf irrespective of leaf chamber O2 level and diurnal VPDL regime. Leaf hydraulic conductance was greatly enhanced during the warmer afternoon periods under both low (0.75 to 1.5kPa) and high (0.75 to 3.5kPa) diurnal VPDL regimes, unlike stomatal conductance (gs ), which decreased in the afternoon. Consequently, the leaf water status remained largely isohydric throughout the day, and therefore cannot be evoked to explain the diurnal decrease of gm . However, the concerted diurnal reductions of gm and gs were well correlated with increases in leaf abscisic acid (ABA) content, thus suggesting that ABA can induce a significant depression of gm under favourable leaf water status. Our results challenge the view that the temperature dependence of gm can be explained solely from dynamic leaf anatomical adjustments and/or from the known thermodynamic properties of aqueous solutions and lipid membranes.​.

Molecular dynamic simulations study of the effect of salt valency on structure and thermodynamic solvation behaviour of anionic polyacrylate PAA in aqueous solutions

The effect of salt concentration and valency on intermolecular structure and solvation thermodynamic properties of aqueous solution containing polyacrylicacid (PAA) chains and multi-valent salts calcium chloride (CaCl2) and aluminium chloride (AlCl3) as a function of charge density was investigated using atomistic molecular dynamic simulations with explicit solvent. Salt-free solution favours the self-association of uncharged (acidic form) PAA chains facilitated by inter-chain hydrogen bonds. The ionised (charged) PAA chains are not associated in salt-free aqueous solutions and undergo self-association in the salt solutions due to bridging effect induced by condensed salt ions in agreement with scattering investigations available in literature. The collapse behaviour of PAA in presence of CaCl2 and re-expansion behaviour of PAA chains in case of AlCl3 salt solutions are observed. The rigidity of PAA chains decrease with increase in salt concentration, in agreement with experimental results available in literature. The trivalent salt favours relatively the greater extent of shrinking of PAA chains as well as inter-chain interactions as compared to divalent salts as evident from radius-of-gyration, H-bond and pair-wise solvation enthalpy data. The conformation and hydration behaviour of the acid form of PAA chains are not significantly altered by added salt ions. The hydration behaviour of ionised PAA chains is significantly reduced by added salts due to screening effect of the condensed salt ions. The pair correlation functions of solutions species such as Ca2+, Al3+, Na+ and Cl− with respect to PAA oxygen show the greater affinity of PAA units with the higher valency Al3+ ions over Ca2+ and Na+ in solution. With increase in concentration of AlCl3 and CaCl2 salts, a decrease in effective charge density of ionised PAA chains is observed from the existence of unfavourable PAA–water, PAA–Ca2+ and PAA–Al3+ interactions.

Thermodynamic properties of aqueous solutions of [EMIM] thiocyanate and [EMIM] dicyanamide

Thermodynamic behavior of aqueous solutions of two ionic liquids (ILs), [EMIM][SCN] and [EMIM][DCA], was thoroughly characterized. Vapor–liquid equilibria (water activity), mixing enthalpy, density, and viscosity were systematically measured in the entire composition range and/or specifically in the highly dilute IL region, as a function of temperature in the range from (288.15 to 318.15)K. Pertinent information available in the literature was gathered and critically examined. Data on system energetics, measured in this work and selected from the literature, were simultaneously correlated with an NRTL-type model. Despite complicated courses of excess energetic functions, their compact, thermodynamically consistent and adequate representation was achieved and the model description was proved to provide reasonable extrapolations. Excess volumes (positive) and viscosity deviations (negative) as functions of composition and temperature were correlated with Padé approximants with T-dependent parameters yielding adequate representation of data even for the M-shaped curves encountered for the excess volume of (water+[EMIM][SCN]). The aqueous solutions of [EMIM][SCN] and [EMIM][DCA] were found to exhibit a closely similar energetic behavior. Both systems display large negative excess Gibbs energy and S-shaped excess enthalpy and excess heat capacity which are positive in the IL dilute region and change to negative and close-to-zero, respectively, as the IL content increases. The inferred excess entropy is markedly positive, reflecting vast disorganization of nano-scale structures upon mixing the ILs with water. A detailed inspection of the energetic functions of the two systems revealed consistently more positive values for [EMIM][SCN] indicating that [DCA]− is slightly more hydrophilic anion than [SCN]−. Comparison to [EMIM][tricyanomethanide] studied previously showed that [DCA]− and [SCN]− are considerably more hydrophilic than [TCM]−.

Thermodynamic Study of a Complex System for Carbon Capture: Butyltriacetonediamine + Water + Carbon Dioxide

Different thermodynamic properties of aqueous solutions of butyltriacetonediamine (BuTAD), unloaded and loaded with carbon dioxide, are studied experimentally. For unloaded mixtures of BuTAD and water, protonation equilibrium constants between 283 and 333 K and liquid–liquid equilibria between 313 and 353 K, including the lower critical point, are determined at atmospheric pressure. Furthermore, the solubility of carbon dioxide in aqueous solutions of BuTAD between 313 and 393 K is determined at low loadings with an analytic method based on headspace gas chromatography and at high loadings with a synthetic method using a high pressure view cell. In the loaded system, solid precipitation, liquid–liquid phase split, and the presence of metastable states are observed in certain ranges. The data is interesting for assessing the aqueous solution of BuTAD as solvent for carbon capture. A short-cut method is used for comparing the new solvent with an aqueous solution of monoethanolamine (MEA) with respect to the...

Thermodynamic properties of 1-butyl-3-methylimidazolium salicylate as an active pharmaceutical ingredient ionic liquid (API-IL) in aqueous solutions of glycine and L-alanine at T = (288.15–318.15) K

Thermodynamic properties of aqueous solutions of some amino acids, glycine and l-alanine with a novel ionic liquid containing salicylate anion, 1-butyl-3-methylimidazolium salicylate, [BMIM][SAL] as an active pharmaceutical ingredient ionic liquid (API-IL) have been investigated by volumetric, ultrasonic, refractometric and viscometric properties at T=(288.15–318.15K). The standard partial molar volume Vϕ0, partial molar volume of transfer ΔtraVφ0, Hepler’s constant (∂2Vϕ0/∂T2)p and apparent molar isentropic compressibility κφ have been calculated from density and speed of sound data. Viscosity and refractive index data were used for determination of viscosity B-coefficients (B), hydration number nH and molar refraction RD parameters. These parameters are helpful to study the structure promoting and solvation behaviour of the API-IL and various interactions present in the ternary solutions of (amino acid+[BMIM][SAL]+water).

Physicochemical properties of an anticonvulsant drug sodium valproate in aqueous and in mixed aqueous solutions at different temperatures

The study of fundamental thermodynamic properties of aqueous solutions is very important to derive the information about (solute+solvent) and (solute+solute) interactions. Sodium valproate is a very important drug used for treatment of epilepsy, anorexia nervosa, panic attack, anxiety disorder etc. In this communication we report apparent molar volume of solute (Vϕ), limiting apparent molar volume of solute (Vϕ0), limiting apparent molar expansivity of solute (Eϕ0), thermal expansion coefficient (α∗), double derivative of limiting apparent molar volume (∂2Vϕ0/∂T2), Jones–Dole equation viscosity A, B and D coefficients, temperature derivative of B coefficient i.e., (dB/dT) and hydration number (nH) for aqueous solutions of sodium valproate and solutions of sodium valproate in aqueous solutions of sodium chloride and dextrose. The above parameters have been obtained from measured values of densities (ρ) and absolute viscosities (η) for aqueous binary mixtures of sodium valproate and for the ternary mixtures of sodium valproate in 0.06mol⋅kg−1 aqueous solutions of sodium chloride and in 0.06mol⋅kg−1 aqueous solutions of dextrose in the concentration range (0.01 to 0.1)mol⋅kg−1 as a function of temperature at T/K=(288.15, 298.15 and 308.15) and at atmospheric pressure. The values of limiting apparent molar volume of transfer (ΔtrVϕ0), and viscosity B-coefficient of transfer (ΔtrB) have also been calculated. The transition state theory was used to obtain the Gibbs free energy of activation of viscous flow per mole of solvent (Δμ10#) and per mole of solute (Δμ20#).. The related activation parameters like ΔS20# and ΔH20# have also been derived. Co-sphere overlap model has been used to understand the results in terms of molecular interactions (hydrophilic, hydrophobic and ionic interactions). The results have been interpreted in terms of complex drug – water – co-solute (NaCl and Dextrose) interactions.

Simultaneous prediction of the thermodynamic properties of aqueous solution of ethylene glycol monoethyl ether using artificial neural network

In this work, an artificial neural network (ANN) model for simultaneous prediction of the density, viscosity, thermal expansion coefficient, excess molar volume, and viscosity deviation of the aqueous solution of ethylene glycol monoethyl ether (EGMEE) covering the whole mole fractions at temperatures from 293.15 to 333.15K under atmospheric pressure has been used. A total of 75 data points of thermodynamic properties at several temperatures and mole fractions, have been applied to train and test the model. This study reveals that the ANN model shows an excellent alternative for simultaneous prediction of the thermodynamic properties of the aqueous solution of EGMEE with mean square error (MSE<0.0051%) and high coefficient of determination (R2≥0.9913). The results also represent that the ANN model performs better than the Redlich–Kister type equations for estimating of the thermodynamic properties of the aqueous solution of EGMEE with the overall improvement of 99% for more cases. Comparison between the ANN model results and those of achieving from some previous methods indicates that this work can prepare a simple method for simultaneous prediction of the thermodynamic properties of the aqueous solution of EGMEE in a better accord with experimental data.

Thermodynamic properties of aqueous solutions of sodium ibuprofen at 293.15–318.15 K

The enthalpies of solution and dilution of aqueous solutions of sodium ibuprofen (NaIBP) with concentrations of m < 1.4 mol/kg water are measured at 293.15, 298.15, 308.15, and 318.5 K using an isoperibolic calorimeter. The heat capacity of NaIBP in the temperature range of 273.15–528.15 K is measured using a DSC 204 F1 Phoenix differential scanning calorimeter (NETZSCH, Germany). The virial coefficients of the enthalpies of aqueous solutions of NaIBP are derived in terms of the Pitzer model, and the thermodynamic properties of both the solutions and the solution components are calculated over the range of compound solubility. The variation in these characteristics as a function of concentration and temperature is analyzed.

Calculating the thermodynamic properties of aqueous solutions of alkali metal carboxylates

A modified Robinson-Stokes equation with terms that consider the formation of ionic hydrates and associates is used to describe thermodynamic properties of aqueous solutions of electrolytes. The model is used to describe data on the osmotic coefficients of aqueous solutions of alkali metal carboxylates, and to calculate the mean ionic activity coefficients of salts and excess Gibbs energies. The key contributions from ionic hydration and association to the nonideality of solutions is determined by analyzing the contributions of various factors. Relations that connect the hydration numbers of electrolytes with the parameters of the Pitzer-Mayorga equation and a modified Huckel equation are developed.

Thermodynamic properties of binary aqueous solutions of orthophosphate salts, sodium, potassium and ammonium at T = 298.15 K

In this investigation, the thermodynamic properties of the aqueous solutions of orthophosphate salts M3−nHnPO4 H2O with n=0, 1, or 2 and M=Na+, K+ or NH4+ at 298.15K are determined. The water activity measurements for NaH2PO4(aq), Na2HPO4(aq), Na3PO4(aq); KH2PO4(aq), K2HPO4(aq), K3PO4(aq), (NH4)H2PO4(aq), (NH4)2HPO4(aq) and (NH4)3PO4(aq) are effectuated from dilution to saturated solution using the hygrometric method. The activity coefficients are evaluated using ionic-interaction model. The mineral solubility of these phosphate salts is investigated at T=298.15K. The prediction of solubility is made for minerals and other solid phases in aqueous solutions of phosphates. Correlating and predicting the phase behavior in such systems is a difficult task, partially caused by chemical reactions in the liquid phase but also due to the possible formation of one or more solid phases. Solid phases, molality of saturated binary solutions ms(exp) and logarithm of solubility product K°sp are also determined at 298.15K. The standard molar Gibbs energies of dissolution ΔG°diss, formation ΔGf Calc° and the literature ΔGf Ref°, of solid phases crystallizing from saturated phosphate salts solutions are evaluated.This investigation allows understanding physicochemical nature and structure of phosphate solutions, in particular, questions of anion or cation hydration, especially at higher concentrations, ion-pairing formation, and the possibility of phosphate complex formation.

Molecular dispersion energy parameters for alkali and halide ions in aqueous solution.

Thermodynamic properties of aqueous solutions containing alkali and halide ions are determined by molecular simulation. The following ions are studied: Li(+), Na(+), K(+), Rb(+), Cs(+), F(-), Cl(-), Br(-), and I(-). The employed ion force fields consist of one Lennard-Jones (LJ) site and one concentric point charge with a magnitude of ±1 e. The SPC/E model is used for water. The LJ size parameter of the ion models is taken from Deublein et al. [J. Chem. Phys. 136, 084501 (2012)], while the LJ energy parameter is determined in the present study based on experimental self-diffusion coefficient data of the alkali cations and the halide anions in aqueous solutions as well as the position of the first maximum of the radial distribution function of water around the ions. On the basis of these force field parameters, the electric conductivity, the hydration dynamics of water molecules around the ions, and the enthalpy of hydration is predicted. Considering a wide range of salinity, this study is conducted at temperatures of 293.15 and 298.15 K and a pressure of 1 bar.