Physical Properties Of Aqueous Solutions Research Articles

The Effect of Modulated Millimeter Electromagnetic Waves of Non-Thermal Intensity on the Physical Properties of Aqueous Solutions

The Effect of Modulated Millimeter Electromagnetic Waves of Non-Thermal Intensity on the Physical Properties of Aqueous Solutions

Physical characterization of genipin complexes coupled with multivariate data analysis to assess formed pigments

The potential of electrophoretic mobility and dynamic light scattering (DLS) was investigated to assess pigment formation in aqueous solution after the genipin reaction with different amino acids by separate. Absorbance, mobility, hydrodynamic size, polydispersity index, and conductivity of the aqueous solutions were measured after the reaction. Only complexes derived from genipin and leucine, tyrosine, arginine, lysine, and glycine developed dark blue colors. From all measured variables, complex size was correlated with their blue color intensity, and darkest blue complexes showed the highest hydrodynamic size (1073–4179 nm). Moreover, size pigments below 1 µm were obtained for all amino acids at different concentrations of genipin and amino acid, except for arginine. A partial least squares (PLS) model for size was built and exhibited a good ability to describe the distribution in blue complexes formed after the reaction of genipin and excess of amino acid (mM): (R2adj = 0.88; RMSE = 0.94). Electrophoretic mobility and DLS coupled with multivariate analysis is a useful tool as it can give reliable assessment of the physical properties of aqueous solutions of genipin pigments.

The evolution of solvation symmetry and composition in Zn halide aqueous solutions from dilute to extreme concentrations.

The emergence of cation-anion species, or contact ion pairs, is fundamental to understanding the physical properties of aqueous solutions when moving from the ideal, low-concentration limit to the manifestly non-ideal limits of very high solute concentration or constituent ion activity. We focus here on Zn halide solutions both as a model system and also as an exemplar of the applications spanning from (i) electrical energy storage via the paradigm of water in salt electrolyte (WiSE) to (ii) the physical chemistry of brines in geochemistry to (iii) the long-standing problem of nucleation. Using a combination of experimental and theoretical approaches we quantify the halide coordination number and changing coordination geometry without embedded use of theoretical equilibrium constants. These results and the associated methods, notably including the use of valence-to-core X-ray emission spectroscopy, provide new insights into the Zn halide system and new research directions in the physical chemistry of concentrated electrolytes.

Physical properties of aqueous solutions of 1-propanol near its pequliar point

The work is devoted do the investigation of ultrasound absorption in aqueous solutions of 1- and 2-propanols near their peculiar points. It is assumed that the anomalous ultrasound absorption is caused by the formation of unstable nuclei of a new phase. It is noted, that the concentrations xp(MLS) and xp(US), where the intensities of molecular light scattering and ultrasound absorption take their maxima respectively as well as the point where the concentration curves for differ temperatures intersect are close to each other. A theoretical model for the ultrasound absorption by a nucleus is constructed. The characteristic size of nucleus and the typical time decay for its radial vibrations are estimated. The behavior of the ultrasound absorption coefficient is analyzed on resonance frequencies (f∼10 MHz) and ones removed from them (f≫10MHz). All characteristic experimental peculiarities of the resonance and classic absorption are reproduced with satisfactory accuracy in the framework of the model proposed.

Design of Model Fluids for Flow Characterization Experiments Involving Mixing of Dissimilar Fluids—Refractive Index Matching and Physical Properties

Aqueous solutions of glycerol are widely used as model fluids in flow phenomena experiments. The design of these experiments involves the description of the physical properties of liquids and the refractive index matching using a salt, i.e., calcium chloride. The first part of this paper describes the physical properties of aqueous solutions of glycerol. Refractive index, viscosity, and density were measured for a mass fraction of glycerol in a range from 0 to 1 and compared to the data in the literature. In the second part, calcium chloride was added to aqueous solutions of glycerol, and the variations of density, viscosity, and refractive index with the mass fraction of calcium chloride were reported, which is a new contribution to literature. The main novelties of this work are (1) the development and validation of a set of equations to predict the rheological and physical properties of model fluids for flow studies involving dissimilar fluids; (2) the introduction of an algorithm to match the refractive index of fluids using calcium chloride. The model fluids are designed for large throughput experiments of industrial units, and low-cost solutions were considered. A Matlab script is provided that enables the easy implementation of this method in other works.

Dielectric and physical properties of aqueous solutions of 1,3-dimethylurea at 298.15 K

The complex dielectric function ε*(ω) = ε'(ω)-jε“(ω) is studied for aqueous solutions of 1,3-dimethylurea (1,3-DMU) at constant temperature 298.15 K across the frequency range 20 Hz to 2 MHz. Dielectric properties are measured using Agilent E 4980 precision LCR meter with a four terminal liquid test fixture (Agilent-16452). From measured dielectric data, the frequency dependent electric modulus M*(ω), electrical conductivity σ*(ω) and complex impedance spectra Z*(ω) were obtained. Effects of concentration variation of 1,3-DMU in distilled water on dielectric and electrical properties are discussed to gain information about the self-aggregative nature of 1,3-dimethylurea and dissociation process in aqueous solutions. Density, viscosity, and refractive index of all the solutions are measured and reported.

Radiothermal radiation method for aqueous solutions

For the first time, an ultra-high-sensitivity method for measuring radio-thermal radiation was developed and used in practice in order to establish the difference in the physical properties of aqueous solutions of substances in the millimeter region of the spectrum. The method is used to study the dynamics of the dielectric properties of aqueous solutions depending on the composition of the base substance and its concentration. The dynamics of dielectric properties establishes a one-to-one correspondence between the number and concentration of ions of the dissolved basic substance contained in water and the number of water molecules involved in cooperative interaction, which gives a consistent microscopic picture of ion-water cooperative interactions in the studied aqueous solutions of K2SO4 and Cs2SO4. The density of water molecules perturbed by the ions of the base substance contained in the hydration shell at normal concentrations is proportional to the number of ions, while the transition to weaker solutions leads to the creation of multilayer hydration shells. This means that the number of perturbed water molecules, depending on the number of ions, increases according to a law different from linear. In accordance with the experimental data, the values of the absorption coefficients of aqueous solutions were determined in a wide range of concentrations for alkali metal sulfates. It is noted that alkali metal sulfates have physical properties that generalize the dynamics of dielectric constants depending on the concentration of the base substance. A monotonic increase in the values of the absorption coefficients of solutions with a decrease in the concentration of basic substances in the region of high dilutions was established with individual dynamics for each basic substance, reflecting the total hydration changes in salt solutions. Research has shown that the proposed method for measuring radio-thermal radiation fixes a significant difference in the values of the dielectric constants of aqueous solutions at high dilutions from their values for water.

Relating the physical properties of aqueous solutions of ionic liquids with their chemical structures.

The physical properties of an aqueous solution of a macromolecule primarily depend on its chemical structure and the mesoscopic aggregates formed by many of such molecules. Ionic liquids (ILs) are the macromolecules that have caught significant research interests for their enormous industrial and biomedical applications. In the present paper, the physical properties, such as density, viscosity, ionic conductivity of aqueous solutions of various ILs, have been investigated. These properties are found to systematically depend on the shape and size of the anion and the cation along with the solution concentration. The ionic conductivity and viscosity behavior of the solutions do not strictly follow the Walden rule that relates the conductivity to the viscosity of the solution. However, the modified Walden rule could explain the behavior. A simple calculation based on the geometry of a given molecule could shed the light on the observed results.

Amphiphilic PVCL/TBCHA microgels: From synthesis to characterization in a highly selective solvent

Thermoresponsive copolymer microgels based on the biocompatible monomer N-vinylcaprolactam (VCL) and the hydrophobic comonomer 4-tert-butylcyclohexylacrylate (TBCHA) with highly tunable comonomers ratio were for the first time synthesized by miniemulsion polymerization. Their physical properties in aqueous solution and at the solid interface were characterized using dynamic light scattering (DLS), atomic force microscopy (AFM) and dissipative particle dynamics (DPD) simulations. The results show a significant decrease of the swelling rate of the obtained microgels with an increase of the amount of the hydrophobic comonomer. In the case when the fraction of TBCHA is equal or higher than the fraction of VCL, the microgels become almost insensitive to the temperature changes, and the amount of water inside the microgels appeared to be diminishingly small. In the opposite case, if the VCL fraction is major, the copolymer microgels preserve their softness and deformability while being adsorbed onto a solid surface. At the same time, all samples have shown a good colloidal stability and a low polydispersity in size. Thus, the presented polymerization technique is applicable for the fabrication of microgels using hydrophobic monomers, which are not accessible by conventional precipitation polymerization. We demonstrate that the mechanical properties and the temperature-responsiveness of the copolymer microgels can be precisely adjusted by the content of the hydrophobic comonomer.

Generation of Tautomers Using Micro-p Ka's.

Solutions of organic molecules containing one or more heterocycles with conjugated bonds may exist as a mixture of tautomers, but typically only a few of them are significantly populated even though the potential number grows combinatorially with the number of protonation and deprotonation sites. Generating the most stable tautomers from a given input structure is an important and challenging task, and numerous algorithms to tackle it have been proposed in the literature. This work describes a novel approach for tautomer prediction that involves the combined use of molecular mechanics, semiempirical quantum chemistry, and density functional theory. The key idea in our method is to identify the protonation and deprotonation sites using estimated micro-p Ka's for every atom in the molecule as well as in its nearest protonated and deprotonated forms. To generate tautomers in a systematic way with minimal bias, we then consider the full set of tautomers that arise from the combinatorial distribution of all such mobile protons among all protonatable sites, with efficient postprocessing to screen away high-energy species. To estimate the micro-p Ka's, we present a new method designed for the current task, but we emphasize that any alternative method can be used in conjunction with our basic algorithm. Our approach is therefore grounded in the computational prediction of physical properties in aqueous solution, in contrast to other approaches that may rely on the use of hard-coded rules of proton distribution, previously observed tautomerization patterns from a known chemical space, or human input. We present examples of the application of our algorithm to organic and drug-like molecules, with a focus on novel structures where traditional methods are expected to perform worse.

Rheological behavior and physical properties of aqueous solutions of carrageenan and acacia gum

Polysaccharides are widely used as thickening, stabilizing, and gelling agents for the control of the texture, flavor, microstructure, and shelf-life of foods. This work contributes to the study of the physical properties and rheological behavior of binary and ternary solutions of carrageenan and acacia gum. Experiments were performed to determine properties such as density, refractive index, and viscosity. The results showed that those properties studied increased with increasing biopolymer concentration and decreased with increasing temperature. Experimental data were modeled to describe the combined effects of temperature and biopolymer concentration on the density, refractive index, and dynamic viscosity of these solutions. The properties were measured in the temperature range from 298.15 to 308.15 K. Suitable polynomial functions were successfully fitted to the experimental data. Classical rheological models (Bingham, power law, Casson, and Herschel-Bulkley) were tested for binary and ternary aqueous solutions containing carrageenan. Pseudoplastic behavior was observed, and the solutions were accurately modeled through a power-law model.

Measurement and correlation of the physical properties of aqueous solutions of ammonium based ionic liquids

In this study, thermo physical properties such as density, viscosity, refractive index and surface tension of aqueous solutions of tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH) and tetrabutylammonium hydroxide (TBAOH) was investigated as a function of temperature. These properties were measured in temperatures ranging from 298.15 to 333.15 K and the temperature was increased by an interval of 5 K from 298.15 K and after 303.15 K, it was increased by an interval of 10 K, while the concentrations of all the aqueous solutions were changed from 2.5 to 30 mass percent. The results revealed that the measured properties of all aqueous ILs are inversely related to temperature, while the increase in concentration had different effects on these properties. In the case of density, an increase in the concentration of ILs TMAOH and TEAOH increased their density, while the increase in the concentration of TPAOH and TBAOH decreased their density. On the other hand, the viscosities and refractive indices of all aqueous ILs increased with an increase in concentration, but the surface tensions decreased with the increase in concentration. The derived properties including thermal expansion and excess molar volume of all the aqueous ILs were determined using density data. The thermal expansion data showed an increasing trend with an increase in the temperatures and concentrations of ILs whereas the negative values of excess molar volumes decreased with an increase in temperatures. The correlation of thermo physical properties with temperatures exhibits a good agreement between experimental and predicted values.

Measurement of Solubility and Physical Properties of Aqueous Solution of 2-(Diethylamino)ethanol for CO2 Capture

Nowadays, climate change is the main concern due to the huge amount of carbon dioxide (CO2) emitted into the atmosphere. The sources of this gas are from power generation and natural gas processing. Now, the effective technology to remove CO2 is absorption with amine solutions. The conventional amine solution is monoethanolamine (MEA). However, it also has some disadvantages like low capacity and high energy requirement for regeneration. To overcome these drawbacks, novel solvents have been developed to improve the performance for CO2 capture. Consequently, the objectives of this work are to measure the solubility of CO2 in an aqueous solution of 2-(Diethylamino)ethanol (DEAE) as a novel solution at the temperature from 30 °C to 80 °C, CO2 partial pressures ranging from 5 to 100 kPa and concentration from 3 to 5 M and to measure the physical properties such as density and viscosity from 0-1 mole fraction. The solubility results of CO2 in DEAE solution are compared with those of aqueous solution of MEA. For solubility, the results report that DEAE provides higher performance which is up to 861% higher than that of MEA. For physical properties, the results present that the densities of DEAE decrease with an increase in mole fraction and temperature. Also, the viscosities of all range of mole fraction of DEAE decrease as temperature increases. However, the viscosities increase with mole fraction of DEAE up to 0.4 and becomes lower. This means that DEAE process can be designed and applied for the absorption equipment to save more energy and cost for carbon capture.

Effect of NaCl and KCl on volumetric and acoustic behaviour of procaine hydrochloride in aqueous solution at different temperatures (288.15, 298.15 and 308.15) K

Physical properties of aqueous solutions of drugs are required to assess the biological activity of that particular drug in treatment of the disease. The most important of the physical parameters are density and speed of sound. From this point of view, we have measured densities and speeds of sound of procaine hydrochloride (Procaine·HCl) in aqueous and in 0.06mol·kg−1 and 0.1mol·kg−1 aqueous solutions of sodium chloride and potassium chloride at three different temperatures i.e. T=(288.15, 298.15 and 308.15)K in the concentration range of (0.01–0.1)mol·kg−1. Density and speed of sound data were used to evaluate different thermodynamic properties such as apparent molar volume (Vϕ) of solute, isentropic compressibility (κs) of solution, apparent molar isentropic compressibility (κϕ) of solute i.e. procaine hydrochloride (Procaine·HCl) in water and in aqueous solutions of 0.06 and 0.1mol·kg−1 sodium chloride and potassium chloride. The limiting apparent molar expansivity (Eϕ0) of procaine hydrochloride and coefficient of thermal expansion (α∗) of procaine hydrochloride have also been estimated. Infinite dilution values of Vϕ and κϕ were also obtained from extrapolation to zero molality and have been utilized in obtaining transfer volumes (ΔtrVϕ0) and transfer compressibilities (Δtrκϕ0) of procaine hydrochloride from water to aqueous solutions of 0.06mol·kg−1 and 0.1mol·kg−1 sodium chloride and potassium chloride at different temperatures. The results are interpreted in terms of different interactions between solute and solvent molecules (solute-solute and solute-solvent interaction).

Relationship between Side-Chain Polarity and the Self-Assembly Characteristics of Perylene Diimide Derivatives in Aqueous Solution.

Perylene‐3,4,9,10‐tetracarboxylic acid diimides (PDIs) have recently gained considerable interest for water‐based biosensing applications. PDIs have been studied intensively in the bulk state, but their physical properties in aqueous solution in interplay with side‐chain polarity are, however, poorly understood. Therefore, three perylene diimide based derivatives were synthesized to study the relationship between side‐chain polarity and their self‐assembly characteristics in water. The polarity of the side chains was found to dictate the size and morphology of the formed aggregates. Side‐chain polarity rendered the self‐assembly and photophysical properties of the PDIs—both important for imminent water‐based applications—and these were revealed to be especially responsive to changes in solvent composition.

Physical properties of aqueous solutions of potassium l-prolinate from 298.15 to 343.15 K at atmospheric pressure

In this paper, experimental physical properties such as density, refractive index, and viscosity of aqueous potassium l-prolinate (KPr) as a solvent for CO2 capture were investigated. Different concentrations of aqueous KPr in terms of mass fractions (0.05, 0.10, 0.20, 0.30, and 0.40) were studied over a temperature range 298.15–343.15 K. The obtained results showed that all physical properties increase with increasing the concentration of the solution (isothermally), and decrease as the solution temperature rises for any given concentration. The experimental data of density, refractive index, and viscosity were correlated using empirical correlations as a function of both, temperature and concentration. Coefficient of thermal expansion and activation energy were calculated from the experimental density and viscosity data, respectively, in the same temperature range. Thermal expansion coefficient slightly increases with increase in the temperature and concentration, while activation energy increases with the rise in concentration of amino acid salt.

Investigation on the Physical Properties of Aqueous Solution of Acid Functional Room Temperature Ionic Liquids

Investigation on the Physical Properties of Aqueous Solution of Acid Functional Room Temperature Ionic Liquids

Measurement and correlation of physical properties of aqueous solutions of tetrabutylammonium hydroxide, piperazine and their aqueous blends

The density, viscosity and refractive index of aqueous solutions of tetrabutylammonium hydroxide (TBAOH), piperazine (PZ) and their aqueous blends are determined at several temperatures (303.15 to 333.15K). All these measured physicochemical properties decreases with an increase in temperature. The density data is used to calculate the coefficient of thermal expansion and excess molar volume of all aqueous binary and ternary solutions. The coefficient of thermal expansion increases with increase in temperatures and concentrations. The negativity of excess molar volume for all the aqueous solution decreased with increase in temperature. Each physical property is correlated with temperature by least square method and the corresponding coefficients for each property are presented. The prediction values from correlations for the physical properties are in good agreement with the experimental values.

Thermodynamic Modeling of Apparent Molal Volumes of Metal Nitrate Salts with Pitzer Model

The apparent molal volumes of selected metal nitrate salts, Al(NO3)3, Fe(NO3)3, and Mn(NO3)2, in water have been assessed from the available density measurements of their aqueous solutions at 25 °C over a wide molality range. The values of ϕV have been fitted to the Pitzer model using its volumetric contributions. The model parameters β(0)V, β(1)V, CφV, and V̅0 were determined for each aqueous electrolyte, over the composition range from 0 to about 3.5 mol·kg–1 H2O. The new experimental data and parameters obtained will be useful to extend the present database of electrolyte solutions as well as its application areas, allowing management of many physical properties of aqueous solutions in a numerical way in various end-uses.

Absorption of Green House Gas (CO2) and Physical Properties of Aqueous Solutions of 2-Amino-2-Hydroxymethyl-1, 3-Propanediol and Di-Ethanolamine (AHPD+DEA) at Elevated Pressures

Absorption of Green House Gas (CO2) and Physical Properties of Aqueous Solutions of 2-Amino-2-Hydroxymethyl-1, 3-Propanediol and Di-Ethanolamine (AHPD+DEA) at Elevated Pressures