Water Binary System Research Articles

Polythermal density and viscosity, nanoparticle size distribution, binding with human serum albumin and radical scavenging activity of the C60-l-arginine (C60(C6H13N4O2)8H8) aqueous solutions

The paper presents novel data on concentration and temperature dependences of density (ρ), viscosity (η), nanoparticle dimensions of the C60-l-arginine derivative in aqueous solutions. Moreover, the binding of the C60-arginine with human serum albumin (HSA) and radical scavenging activity of the C60–l-arginine derivative in reaction with diphenylpicrylhydrazyl (DPPH) were studied. The structural characteristics of the C60-Arg–water binary system were obtained on the basis of molecular dynamics method.

Forward-headed structure change of acetic acid–water binary system by stimulated Raman scattering**Project supported by the National Natural Science Foundation of China (Grant Nos. 11574113, 11374123, and 11104106), Science and Technology Planning Project of Jilin Province, China (Grant Nos. 20180101238JC, 20170204076GX, 20180101006JC, 20190103041JH, and 20190201260JC), and Post-Doctoral Innovative Talent Support Program, China (Grant Nos. BX20180127 and 2019M651192).

The acetic acid–water binary system is a classical hydroxy–carboxy mixed system, while new and interesting phenomena appear under stimulated Raman scattering (SRS). Compared with the weaker signal of the acetic acid–water binary system obtained in spontaneous Raman scattering, SRS provides a finer band and a relatively distinct structural transition point. The structural transformation points are respectively at 30% and 80% by volume ratio under the condition of spontaneous Raman spectroscopy, while they are respectively at 15% and 25% under the condition of SRS. This phenomenon is attributed to the generation of laser induced plasma and shockwave induced dynamic high pressure environment during SRS.

A new computational method for drug solubility prediction in methanol + water mixtures

General solubility prediction models were developed using both classic least square and a novel method, in order to predict the solubility of the solutes in methanol + water binary solvent system. The novel approach to the regression analysis was investigated using an error minimization method. This aim was achieved by using a user-defined loss function regression, instead of the classic least square regression approach. To examine the results of the novel methodology, previous solubility data of 41 solutes were used for comparison. Both least square and novel methods were applied to the Jouyban-Acree model, Jouyban-Acree model in combination with Abraham parameters, and the modified Wilson model. The generally trained versions of the mentioned models produced more accurate predictions using the novel method than the least square method that has been confirmed by t-test analyses. The Jouyban-Acree model was the most accurate model among other generally trained models. Finally, the results were validated using a cross-validation analysis which produced the acceptable prediction accuracy of 24.6% mean percentage deviation (MPD) for the new methodology against 32.1% of the least square method. Also a new arithmetically transformed version of aforementioned models was introduced in this study to make the calculations easier to execute.

Study the effect of organic promoters on thermodynamics behaviour for refrigerant gas clathrate hydrate

The present work consists of an experimental and theoretical investigation dealing with hydrate formation for the binary system (water+ refrigerant gas) and ternary systems (water+ refrigerant gas+ promoter) at constant initial conditions (pressure and temperature). Isochoric method (constant volume) search was used in current study to measure the formation data (pressure, temperature) for hydrate. Refrigerant R134a gas and different organic promoters such as benzene and cyclohexane were used in this study. For ternary systems at the different concentrations of promoters shifted hydrate formation data when benzene and cyclohexane decree pressure and increasing temperature. Many objective functions were obtained from kinetic models such as the amount of gas consumed (Δn), the growth rate (r (t)), and conversion of the water to hydrate. The gas consumed (Δn) of the binary system increased lead to increase in hydrate formation, also the hydrate growth rate (r(t)) and increase water conversion to hydrate. The gas consumed in the presence of cyclohexane was higher than at using benzene as a promoter. The experimental results show that the presence of different promoters in the ternary systems have an effect on thermodynamic promotion of refrigerant hydrates formation. The promotion effect increased with increasing the concentration of promoter in the select range. Also, the results manifested that benzene and cyclohexane had a clear effect in reducing the pressure and raising the temperature of the hydrate formation. The storage capacity was investigated. It has been noticed that the existence of the promoters in the hydrate formation system led to a slight increase in the storage capacity with maximum value about (78.66) V/V.

Volumetric and compressibility studies and phase equilibria of aqueous biphasic systems of alcohols using phase diagram

The solubility data of Na2S2O3·5H2O in various concentrations of water and ethanol/1-propanol/2-propanol/2-methyl-2-propanol have been obtained to plot triangular phase diagrams and to determine the liquid–liquid–solid equilibria at 298.15 K. The density and sound velocity measurements were carried out for binary systems (water–salt, water–ethanol/1-propanol/2-propanol/2-methyl-2-propanol) and ternary systems (water–ethanol/1-propanol/2-propanol/2-methyl-2-propanol-Na2S2O3) to investigate volumetric and compressibility properties. The obtained data was used to determine the acoustic parameters including adiabatic compressibility (βs), excess molar volume (VE), intermolecular free length (Lf), specific acoustic impedance (Z), relative association (RA), solvation number (Sn) of water–alcohols, water–salt and water–alcohol–salt at 298.15 ± 0.05 K to evaluate equilibrium effects. Based on which, the salting-out of studied alcohols and phase forming ability of Na2S2O3 through its bond making and breaking properties, intermolecular interactions were reported. The density, sound velocity and adiabatic compressibility of ternary system suggest phase separation phenomenon is bond breaking and bond making process with hydrogen bonding and hydrophobic interaction. The phase formation ability of systems composed of different alcohols is in order of 2-methyl-2-propanol > 1-propanol > 2-propanol > ethanol.

Stability, solubility and thermodynamic properties of dimorphs of furosemide-4,4′-bipyridine cocrystals in organic solvents

In this work, pure form I and form II of furosemide-4,4′-bipyridine (FS-4BPY) 2:1 cocrystals were prepared. Both polymorphs were characterized by optical microscopy, powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The relative stability of the two forms was estimated from their solubility data in 2-propanol by the gravimetric method. Moreover, the thermodynamically stable form with lower solubility, form II, was further investigated in different pure and binary solvents from 293.15 K to 333.15 K under atmospheric pressure. In pure solvent system, the solubilities of forms II cocrystals increase with rising temperature and follow the order of acetone > ethanol > 1-propanol ≈ 1-butanol > 2-propanol > acetonitrile. In 2-propanol–water binary solvent system, the co-solvency phenomenon was observed and the maximum solubility of form II is higher than that in pure solvents. The experimental solubility data were correlated by the modified Apelblat model, the CNIBS/R–K model, the Jouyban–Acree model and the NRTL model, and all models give satisfactory correlations. Finally, the apparent dissolution thermodynamic properties, including the dissolution Gibbs energy, the dissolution enthalpy and the dissolution entropy, were calculated based on the NRTL model. The results indicate that the dissolution processes of form I and form II of FS-4BPY cocrystals in selected solvents are all spontaneous, endothermic, and entropy-driven.

Functionalized zeolite-solvent catalytic systems for microwave-assisted dehydration of fructose to 5-hydroxymethylfurfural

Abstract This study investigates the structure-performance relationships in different zeolite-solvent systems that are suitable for microwave-assisted dehydration of food waste-derived fructose to 5-hydroxymethylfurfural (HMF). Different types of zeolites (MFI, BEA, and Y) were examined as acid catalysts. Water was first tested as the greenest solvent (baseline), followed by dimethyl sulfoxide (DMSO), acetone, γ-valerolactone (GVL), and propylene carbonate (PC)/water (1:1 v/v) binary solvent systems. The results showed that the HMF yield was independent of particle size of MFI zeolite in water. The secondary porosities improved the HMF yield, while byproducts formation (via rehydration or polymerization) was also increased due to the enlarged channels in zeolites. All tested zeolites showed higher fructose conversion, HMF yield, and HMF selectivity in organic-water solvent systems than in water. The synergistic effects of the substrates, catalysts, and solvent-product interactions in the hydrophobic Y zeolite/DMSO system yielded the highest fructose conversion (72.4%) and HMF yield (49.2%). This study advances our understanding of green solvents and functionalized zeolites for microwave-assisted biomass conversion in sustainable biorefinery.

Impact of water on the [C4C1im][Ac] ability for the CO2/CH4 separation

The water impact on the CO2 and CH4 solubilities and their selectivity in [C4C1im][Ac] was evaluated for [C4C1im][Ac]:H2O molar ratios of 5:1, 2:1, 1:1, and 1:2, for temperatures ranging from (293 to 363) K and pressures up to 70 MPa. In addition, density and excess molar volumes of [C4C1im][Ac] + water binary systems were measured aiming at understanding the impact of the solvent structure on the gas solubilities. Water is shown to improve the IL capability to solubilize CO2, with equimolar molar ratios leading to enhanced solubilities for pressures up to 5 MPa, whereas [C4C1im][Ac]:H2O molar ratios of 5:1 and 2:1 present higher CO2 solubility at higher pressures. The impact of water on the solubility of methane, on the other hand, is small, with only a slight enhancement of methane solubility at high pressures observed. The favorable impact of water, on the carbon dioxide solubility, lead to enhanced CO2/CH4 ideal selectivity.

Phase diagram and composition of water based crystalline phases in hydrogen – Water binary system

In this work the original approach developed in our group is applied to describe the phase diagram on p–T plane and phases composition for hydrogen – water system in a wide pressure and temperature range and for prediction of composition and thermodynamic properties of hydrogen hydrates. The p–T phase diagram was calculated for pressure up to 2.5 GPa and temperature from 200 to 330 K, and the following phases have been found to be stable within this region: H2 clathrate hydrate of cubic structure II, H2 filled ices Ih, Ic, II. The obtained monovariant equilibrium lines are found to be in a good agreement with known experimental and theoretical data. Calculated solid phase compositions are also in a good agreement with previous results.

Physico-chemical properties of C70-l-threonine bisadduct (C70(C4H9NO2)2) aqueous solutions

The paper is devoted to the physico-chemical investigation of the C70-Thr aqueous solutions. In the framework of our study, we measured densities (ρ), viscosities (η), refraction indexes (nD) and surface tension (γ) in a wide range of concentrations. Experimental data on size distribution and ζ-potentials of the C70-Thr associates in aqueous solutions were obtained in the concentration range C = 0.001–5 g·dm−3 at 298.15 K. Using experimental data on the decreasing of the ice crystallization temperature in the C70-Thr–water binary system, the excess thermodynamic functions were calculated. Additionally, the structural and dynamic characteristics of the C70-Thr–water binary system were obtained on the basis of molecular dynamics method.

Measurement and Correlation of Solubility and Thermodynamic Properties of Vinpocetine in Nine Pure Solvents and (Ethanol + Water) Binary Solvent

The solid–liquid equilibrium data of vinpocetine in nine pure solvents and ethanol–water binary system at temperatures ranging from 283.15 to 323.15 K was experimentally measured by gravimetric method under atmospheric pressure. For the different types of investigated solvent, the solid–liquid equilibrium solubility of vinpocetine increased with augmented temperature. Experimental solubility was fitted with several thermodynamic models including the modified Apelblat model, λh model, and nonrandom two-liquid (NRTL) model, as well as the combined nearly ideal binary solvent/Redlich–Kister model. All the fitted values were in satisfactory agreement with the experimental results. The thermodynamic parameters were calculated by the activity coefficients of vinpocetine in different solvents, which were obtained by NRTL model. The results demonstrated that the mixing process of vinpocetine with experimental solvents was spontaneous and entropy-driven.

Structure, Microscopic Ordering, and Viscous Properties of Amorphous Poly(n‐alkylsilsesquioxane) Liquids and Solids Synthesized by Cosolvent‐Free Hydrolytic Polycondensation of n‐Alkyltrimethoxysilanes

Poly(n‐alkylsilsesquioxane) [poly(R‐SQ)] liquids with R = Et, Pr, or Bu are prepared from acid‐catalyzed n‐alkyltrimethoxysilane – water binary systems through hydrolytic polycondensation followed by aging. The resultant liquids contain a lot of SiOH groups whereas the viscosities remain almost constant during storage at room temperature over a month. Heat treatment for 1 day at 200 °C in N2 yields poly(Et‐SQ) and poly(Pr‐SQ) solids whereas poly(Bu‐SQ) remains viscous. High‐energy X‐ray diffraction measurements confirm that all samples are amorphous and nonporous. The total structure factor S(Q) of poly(R‐SQ)s and amorphous silica are similar, apart from the prominent prepeak observed for poly(R‐SQ)s at Q ≈ 0.5 − 0.7 Å−1. This prepeak undergoes a distinct shift to lower Q with an increase in the alkyl chain length. These observations indicate the presence of microscopic inhomogeneity consisting of silica‐rich and alkyl‐rich domains and their ordering with a periodicity of ≈9 − 12 Å both in liquid and solid forms of poly(R‐SQ). Thermal curing modifies S(Q) of poly(Et‐SQ) only slightly. The overall shapes of the total correlation function T(r) are similar between poly(R‐SQ)s and a‐SiO2, suggesting the similarity of short‐range order of Si−O network between these materials.

The influence of bromide-based ionic liquids on solubility of {LiBr (1) + water (2)} system. Experimental (solid + liquid) phase equilibrium data. Part 1

In this work, nine ILs are investigated as anti-crystallization additives to (LiBr+water) binary systems conventionally used as a working pair in absorption refrigeration technology. The solubility of {LiBr (1)+IL (2)+water (3)} ternary systems within wide temperature and composition range was determined by the dynamic method. In this work, the following ILs: 1-ethyl-1-methylmorpholinium bromide, [C1C2MOR][Br], 1-butyl-1-methyl-morpholinium bromide, [C1C4MOR][Br], 1-hexyl-1-methylmorpholinium bromide, [C1C6MOR][Br], 1-butyl-3-methylimidazolium bromide, [C1C4IM][Br], 1-ethyl-1-methyl-piperidinium bromide, [C1C2PIP][Br], 1-butyl-1-methylpiperidinium bromide, [C1C4PIP][Br], 1-butyl-1-methyl-pyrrolidinium bromide, [C1C4PYR][Br], 1-butylpyridinium bromide, [C4Py][Br] and tri(ethyl)-butylammonium bromide, [N2,2,2,4][Br] were investigated. The experimental (solid+liquid) phase equilibria have been determined for different IL to LiBr mass fractions from w2=(0.1 to 0.3). For all of the tested system, the transition point between lithium bromide dihydrate and monohydrate form was observed. Additionally, the simple model based on the multicomponent Redlich-Kister equation and a reference state of pure chemical compounds was used to successfully describe solubility of lithium bromide in aqueous systems containing an ionic liquid. The influence of ILs cation's core on the crystallization temperature of aqueous lithium bromide system was discussed and the best IL as an anti-crystallization additive has been proposed.

Commentary concerning the “Measurement, correlation of the solubility and solution thermodynamics of 2-cyanoguanidine in (methanol + water) binary solvent systems from T = (283.15 to 343.15) K”

Errors are discovered regarding the published equation coefficients of Zhang and co-workers [J. Chem. Thermodynamics 89 (2015) 233–239] for mathematically describing the solubility behavior of 2-cyanoguanidine in neat solvents using the λh equation. The back-calculated values using the published equation coefficients are not the mole fraction solubility as stated in the published paper. Furthermore, the λ and h parameters were re-analysed according to the experimental solubility data.

Diethylmethylamine-Based Protic Ionic Liquids and Their Binary Mixtures with Water As Fuel Cell Electrolyte

Protic ionic liquids (PILs) have attracted much attention as a designer material for manifold applications but most promising used as fuel cell electrolytes due to containing active proton in the cationic structure. However, ultimate product of the fuel cell reaction is water, thus, it is very interesting to investigate the effect of water on the properties of PILs for applying as fuel cell electrolytes. In this study, PILs were synthesized through neutralization of a tertiary amine, diethylmethylamine (dema) with sulphuric acid (H2SO4) and trifluoroacetic acid (CF3COOH). Binary mixtures of these PILs and water were prepared with a wide range of composition. The physicochemical and electrochemical properties of these PILs and their binary mixtures, such as density, viscosity, conductivity, thermal properties, ATR-FTIR, NIR, theoretical calculation and cyclic voltammetry (CV), have been studied in detail. The excess molar volume and excess viscosities were derived from density and viscosity and fitted to Redlich-Kister polynomial equation to confirm the presence and nature of interactions between PILs and water binary system. Analysis of FTIR-ATR and NIR spectra for the binary mixtures of [dema]CF3COO and water also indicated that there is a strong interaction between ionic species and water. From quantum chemical calculations using density functional theory (DFT), the electron density distribution around the ion pair of [dema]CF3COO is made and confirmed that there is a strong interaction between cation and anion not only due to strong hydrogen bond but also coulombic interaction. Conductivity of pure [dema]HSO4 was lower than [dema]CF3COO, however, conductivity of [dema]HSO4 and water binary mixtures was higher than the binary mixtures of [dema]CF3COO at room temperature when mole fraction of water was 0.90. From Walden plot (log Λ vs logη-1), it was revealed that [dema]HSO4 and its binary mixtures resemble good PILs, on the other hand, [dema]CF3COO and its binary mixtures are poor PILs, presumably due to high ΔpK a of [dema]HSO4. Finally, electrochemical properties of PILs and their binary mixtures have been analyzed by CV measurements. It is found that there is a strong effect of water on the OCP of PILs. However, these PILs and binary mixtures could be useful as fuel cell electrolytes.

Density, excess molar volume, and COSMO-RS study of reactive aqueous solutions containing formaldehyde

In this study, the densities of formaldehyde (FA) + water (H2O) binary systems with formaldehyde fractions (xFA) of 0.05–0.27 at temperatures (T) of 293.15, 298.15, and 313.15 K were measured at 0.1 MPa, as well as those of a formaldehyde + water + methanol (MeOH) ternary system with xFA of 0.05–0.27 and xMeOH of 0.09–0.64. A thermodynamic model was combined with the conductor-like screening model for real solvents (COSMO-RS) coupled with a chemical reaction equilibrium and mass balance to describe the species distribution in the above solutions containing poly (oxymethylene) glycols ((HO(CH2O)nH, MGnn ≥ 1) and poly (oxymethylene) hemiformals (CH3O(CH2O)nH, HFn, n ≥ 1) produced by the reactions of FA with H2O and MeOH, respectively. The densities and volumes of these unknown oligomers, MGn and HFn, were computed by the COSMO-RS method and were correlated with the polymerization degree, n, and temperature, T. Furthermore, the densities of the FA + H2O and FA + H2O + MeOH solutions were calculated based on the species distribution and COSMO-RS simulations, which reproduced the experimental data well. Finally, the excess molar volumes of the FA + H2O and FA + H2O + MeOH systems were studied for the first time.

Solubility of 2,5-Furandicarboxylic Acid in Eight Pure Solvents and Two Binary Solvent Systems at 313.15–363.15 K

2,5-Furandicarboxylic acid (FDCA) serves as a monomer in various polyesters and is often obtained through the oxidation of 5-hydroxymethylfurfural. The solubility data of FDCA are of great value for the reaction process analysis and separation technology. The experimental solubility of FDCA in eight pure solvents (water, methanol, acetonitrile, acetic acid, ethyl acetate, methyl isobutyl ketone (MIBK), 1-butanol, and isobutanol) and two binary solvent systems (water + acetonitrile and water + acetic acid) in the temperature range of 313.15–363.15 K was determined. In pure solvents and binary mixtures, the solubility of FDCA increased with the increasing temperature. The order from largest to smallest solubility in pure solvents was as follows: methanol, 1-butanol, isobutanol, acetic acid, water, MIBK, ethyl acetate, and acetonitrile. The mole fraction of FDCA in binary mixtures increased first and then decreased with the increasing mole fraction of water. The solubility data were correlated with the UNIQU...

Thermodynamic Properties of l-Aspartates of Alkali and Alkali-Earth Metals in Aqueous Solutions at 298.15 and 310.15 K and Specific Cation Effects on Biomolecule Solvation

Vapor pressure osmometry was applied to the systems calcium l-aspartate ((S)-aminobutanedioic acid calcium salt) + water for varying molalities of Ca–l-Asp (mCa–l-Asp = 0.01–1.02 mol·kg−1) and guanidinium hydrochloride (methanamidine hydrochloride) + sodium L–aspartate ((S)–aminobutanedioic acid sodium salt) + water, varying the molalities of GndmCl and Na–l-Asp (mNa–l-Asp = 0.1, 0.25, 0.4, 0.57 mol·kg−1 and mGndmCl = 0.1–1.1 mol·kg−1) at T = 298.15 K and 310.15 K. From vapor pressure osmometry, activities of water, and the corresponding osmotic coefficients of the mixtures Ca–l-Asp + water and Na–l-Asp + GndmCl + water have been calculated, both being directly related to the chemical potentials of the different species and therefore to their Gibbs energy. Mean molal ion activity coefficients were obtained from experimental data fits with the Pitzer equations and the corresponding dual and triple interaction parameters were derived for the Ca–l-Asp + water binary system. β(2) Pitzer parameters different from zero are required for Ca–l-Asp in water to reproduce the osmotic coefficient decrease with increasing concentration. Mean Spherical Approximation parameters accounting for Coulomb and short range interactions that describe the calcium and magnesium aspartates and glutamates are given. The decrease in the chemical potential of the aspartates corresponds to the Hofmeister series: NaAsp > Mg(Asp)2 > CaAsp. A strong interaction between amino acid and salt due to specific dispersion interactions in amino acid salt systems containing guanidinium based salt has been revealed that is in agreement with MD and half-empirical quantum-chemical calculations.

Pressure-Drop Method for Detecting Bubble and Dew Points of Multicomponent Mixtures at Temperatures of up to 573 K

Filled or empty tubular reactors have been at the heart of many chemical processes in academia and industry. Understanding the phase behavior in such reactors is essential to improving the conversion and selectivity of a given chemical transformation and to minimizing energy consumption. This study shows that the pressure-drop method is a simple and effective technique for measuring vapor–liquid phase equilibria at temperatures of up to 573 K. The basis of the pressure-drop method is flowing the fluid through a capillary with a relatively small inner diameter. The pressure drop between the inlet and outlet of the capillary depends on the phase state of the fluid (gas and/or vapor). In this article, pure propan-2-ol and the binary system propan-2-ol + water have been investigated to validate the method at high temperatures for these fluids. The binary system water + acetonitrile was then measured to demonstrate that the phase equilibrium of a thermally reactive mixture can also be determined by using the p...

Controlling the Organization of Colloidal Sphero-Cylinders Using Confinement in a Minority Phase.

We demonstrate experimentally that a phase-separating host solvent can be used to organize colloidal rods into different cluster and network states. The rods are silica sphero-cylinders which are preferentially wet by the water-rich phase of an oil–water binary liquid system. By beginning with the rods dispersed in the single-fluid phase and then varying the temperature to enter the demixed regime, a precisely chosen volume of water-rich phase can be created. We then show how this can be used to create independent clusters of rods, a percolating network, a network of clusters or a system that undergoes hindered phase separation. These different modes are selected by choosing the relative volumes of the rods and the water-rich phase and by the timing of the temperature change.