scholarly journals Dielectric Characteristics, Electrical Conductivity and Solvation of Ions in Electrolyte Solutions

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5617
Author(s):  
Vladimir V. Shcherbakov ◽  
Yuliya M. Artemkina ◽  
Irina A. Akimova ◽  
Irina M. Artemkina
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Aqueous Solutions ◽  
High Frequency ◽  
Electrolyte Solutions ◽  
Effect Of Temperature ◽  
Polar Solvents ◽  
Dielectric Characteristics ◽  
Dissociation Degree ◽  
Temperature Dependences

Solvation and association of ions in solutions largely depend on the dielectric properties of the solvent, the distance between ions in solutions, and temperature. This paper considers the effect of temperature on static dielectric constant (DC), dipole dielectric relaxation (DR) time, and limiting (ultimate) high frequency (HF) electrical conductivity (EC) of water and some polar solvents. In the investigated temperature range (0–370 °C), the static DC and DR time of water decrease, and limiting HF EC passes through a maximum at 250–300 °C with temperature growth. The dielectric characteristics of methanol, ethanol, and propanol behave in a similar way. It is shown that the existence of an HF EC temperature maximum is due to the different nature of the temperature dependences of DC and DR time. It is suggested that the same dependences are responsible for the presence of a maximum in the temperature dependences of the dissociation degree and the ionic product of water. The influence of non-electrolytes concentration as well as metal salts on the dielectric properties of their aqueous solutions is considered. The limiting HF EC of water determines the specific EC value of aqueous electrolyte solutions. Analysis of the absorption of microwave energy by polar solvents, as well as aqueous solutions of non-electrolytes and electrolytes, at a frequency of 2455 MHz is carried out. The optimal conditions for high-frequency heating of solutions have been established. The distance between ions in aqueous solutions of inorganic salts and in non-aqueous solutions of ionic liquids is calculated. It is shown that the maximum on the concentration dependence of the specific EC can be related to ions association.

scholarly journals REGULARITIES IN ELECTRICAL CONDUCTIVITY OF AQUEOUS SOLUTIONS OF SOME INORGANIC ACIDS

2018 ◽  
Vol 59 (2) ◽  
pp. 26
Author(s):  
Yuliya M. Artemkina ◽  
Yuriy D. Zagoskin ◽  
Nikita M. Kuznetsov ◽  
Vladimir V. Shcherbakov
Keyword(s):  
Electrical Conductivity ◽  
Aqueous Solutions ◽  
Electric Conductivity ◽  
High Frequency ◽  
Analytical Equation ◽  
Acid Solutions ◽  
Specific Electric Conductivity ◽  
Inorganic Acids ◽  
Wide Range ◽  
Temperature Dependences

The concentration and temperature dependences of the specific electric conductivity (EC) of aqueous solutions of HCl, HBr, HNO3, HClO4, H2SO4 and HBF4, H2SiF6, and H2TiF6 were analyzed. It was shown that at a temperature of 298 K maximum specific EC of solutions of acids does not exceed the value of the limit high-frequency EC of water. The analytical equation allowing on the basis of maximum EC and corresponding to it concentration to calculate the EC of acid solutions in a wide range of concentrations and temperatures was obtained.

scholarly journals Study of the effect of temperature on the electrical conductivity of aqueous solutions of amino acids

2019 ◽  
Vol 57 (1) ◽  
pp. 91-94
Author(s):  
Vera A. Petrukhina ◽  
◽  
Pavel I. Fedorov ◽  
Tatiana A. Kirillova ◽  
Ludmila Yu. Tcareva ◽  
...  
Keyword(s):  
Experimental Data ◽  
Amino Acids ◽  
Electrical Conductivity ◽  
Amino Acid ◽  
Aqueous Solutions ◽  
Arrhenius Equation ◽  
Effect Of Temperature ◽  
Acid Solutions ◽  
Hydrogen Ions ◽  
Amino Acid Solutions

It is well-known fact that water is a universal solvent due to its physicochemical properties and dielectric constant. Therefore, the majority of substances with a crystalline structure and the structure close to it are well soluble in water due to the dissociation of molecules into ions. Amino acids are organic ampholytes – substances capable of being in ionic forms in water. The quantitative and qualitative composition of ampholytes depends on the structure and composition of amino acids and pH of solution. The interaction of amino acid ions in solution with hydrogen ions and hydroxyl leads to the formation of complex cations and anions. The presence of amino and carboxyl groups in amino acid molecules contributes to the formation of inter-ion positively and negatively charged complexes which leads to the decrease in their mobility and electrical conductivity of solutions. It is observed with increasing concentration of amino acid solutions. The conductivity of amino acid solutions is also influenced by temperature which has a non-linear relationship. We have proposed the approach based on studying the effect of temperature on the equivalent electrical conductivity at infinite dilution λ∞ and describing the experimental data λ∞(Т) by the exponential Arrhenius equation. This article studies the possibility of describing the experimental data λ∞(Т) for aqueous solutions of a number of amino acids by this equation. It is shown that the Arrhenius equation with the found activation energy values adequately describes the dependences of limiting equivalent conductivity on temperature for aqueous solutions of valine, leucine, isoleucine, threonine, lysine, methionine, phenylalanine, L-aspartic and D-aspartic acids, histidine, arginine.

Features of frequency dependence of electrical conductivity and dielectric properties in lignins from conifers and deciduous trees

Holzforschung ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 1113-1122
Author(s):  
Sergey Khviyuzov ◽  
Konstantin Bogolitsyn ◽  
Aleksandr Volkov ◽  
Gennadiy Koposov ◽  
Maria Gusakova
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Electric Field ◽  
High Frequency ◽  
Low Frequency ◽  
Adsorbed Water ◽  
Deciduous Trees ◽  
Hydroxyl Groups ◽  
Electrophysical Properties ◽  
Functional Nature

AbstractLignins are among the most common plant polymers and demonstrate pronounced electrical conductivity properties due to their conjugated polymolecular aromatic structure and polyfunctional nature. Electrical conductivity and dielectric properties of lignins from conifers and deciduous trees in the range of electric field frequencies from 10−2 to 107 Hz were investigated by means of dielectric spectroscopy. Characteristic parameters of static and high frequency electrical conductivity were calculated. To study the influence of the lignins functional nature on their electrophysical properties, the study determined three types of relaxators (separate charges or charge systems in the structure of a substance changing their position in space when exposed to an external alternating electric field) in the structure of the lignin macromolecule. Low-frequency relaxators are associated with oscillations of methoxyl groups. Mid-frequency relaxators correspond predominantly to phenolic hydroxyl groups and to hydroxyl groups of adsorbed water. High-frequency relaxators correspond to the hopping of π-electrons along the chain of conjugated bonds of a benzene ring. Differences in the structure and functional nature of lignins from conifers and deciduous trees cause different contributions of low-frequency relaxators. As a result, these features form differences in the electrophysical properties of lignins from conifers and deciduous trees.

Influence of Electrochemically Exfoliated Graphite Addition on the Dielectric Properties of Epoxy/Montmorillonite Nanocomposites

2021 ◽  
Vol 326 ◽  
pp. 3-15
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
High Frequency ◽  
Small Polaron ◽  
Exfoliated Graphite ◽  
Dielectric Losses ◽  
Correlated Barrier Hopping ◽  
Eeg Changes ◽  
Hopping Model ◽  
Temperature Conduction

The influence of hydrophilic electrochemically exfoliated graphite (EEG) and hydrophobic reduced EEG (rEEG) on the electrical conductivity, dielectric properties, and high-frequency dielectric losses of epoxy-based composites with montmorillonite was described. It was confirmed, that the addition of EEG changes the low-temperature conduction mechanism. The electrical conductivity in composite with EEG and montmorillonite was described by correlated barrier hopping model, whereas for composites with montmorillonite and rEEG two models were used: non-overlapping small polaron tunneling and correlated barrier hopping. The addition of EEG drastically changes the activation energy of charge carriers motions from 2.68 to 0.83 eV, whereas the addition of rEEG only to 2.43 eV. Also composite with EEG was characterized by highest high-frequency dielectric losses.

scholarly journals Investigation of temperature effect on the electrical conductivity of alcohol solutionssodium and potassium alcoholates

2020 ◽  
Vol 61 (1) ◽  
pp. 81-85
Author(s):  
Vera A. Petrukhina ◽  
◽  
Pavel I. Fedorov ◽  
Ksenia A. Konnova ◽  
Maria V. Yakimova ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Aqueous Solutions ◽  
Temperature Dependence ◽  
Isopropyl Alcohol ◽  
Effect Of Temperature ◽  
Inorganic Salts ◽  
Equivalent Conductivity ◽  
Solutions Of Electrolytes ◽  
Weak Electrolytes ◽  
Sodium And Potassium

Earlier, we studied the electrical conductivity of inorganic salts in a number of alcohols (ethanol, propanol-2, and butanol-1) at room temperature and found that alcoholic solutions of inorganic salts are weak electrolytes. It is known that an increase in the temperature of salt solutions leads to an increase in electrical conductivity due to an increase in the mobility of their ions in the solvent medium. To study the temperature dependence of the electrical conductivity of aqueous solutions of electrolytes, we proposed an approach based on the study of the effect of temperature on the equivalent electrical conductivity of solutions at infinite dilution λ∞. Using this approach, we studied the electrical conductivity of aqueous solutions of a number inorganic salts (nitrates, acetates, and phosphates), carboxylic acids, and amino acids as a function of temperature. It was found that for these solutions the dependence λ∞(Т) is described by the exponential Arrhenius equation λ∞ = Аexp(-E/(RT)). This equation was used to describe the temperature dependence of the ultimate equivalent conductivity for solutions of a number of inorganic salts (calcium and nitrate calcium, cadmium, lithium and potassium iodides, chloride, iodide and ammonium nitrate, silver nitrate and sodium bromide) in ethanol. This article investigated and demonstrated the possibility of describing the experimental data λ∞(Т) for solutions of ethylates, propylates and isopropylates of sodium and potassium in the corresponding alcohols (ethylates in ethanol, propylates in propanol, isopropylates in isopropyl alcohol) using the same equation.

scholarly journals Investigation of temperature effect on the electrical conductivity of solutions inorganic salts in ethanol

2020 ◽  
Vol 61 (1) ◽  
pp. 76-80
Author(s):  
Vera A. Petrukhina ◽  
◽  
Ksenia A. Konnova ◽  
Maria V. Yakimova ◽  
Nikolay I. Koltsov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Aqueous Solutions ◽  
Temperature Dependence ◽  
Arrhenius Equation ◽  
Calcium Nitrate ◽  
Effect Of Temperature ◽  
Inorganic Salts ◽  
Salt Solutions ◽  
Weak Electrolytes

The electrical conductivity of the solutions depends on the nature of the solute and solvent. For a solvent, the main parameter is the dielectric constant. Since the dielectric constant of alcohols is much less than the dielectric constant of water, the electrical conductivity of alcoholic solutions of salts is less than the electrical conductivity of their aqueous solutions. Therefore, alcoholic solutions of inorganic salts are weak electrolytes. We previously studied the electrical conductivity of inorganic salts in a number of alcohols (ethanol, propanol-2 and butanol-1) at room temperature. It is of interest to study the effect of temperature on the electrical conductivity of salts in alcohols. Obviously, an increase of temperature salt solutions leads to an increase in their electrical conductivity. To study the temperature dependence of the electrical conductivity of aqueous solutions electrolytes, we proposed an approach based on the study of the effect of temperature on the equivalent electrical conductivity of solutions at infinite dilution λ∞. Using this approach, we studied the electrical conductivity of aqueous solutions of a number of inorganic salts, carboxylic acids, and amino acids as a function of temperature. It has been established that for these solutions the dependence λ∞(Т) is described by the exponential Arrhenius equation λ∞ = Аexp(-E/(RT)). However, such studies have not been conducted for alcoholic salt solutions. In this regard, this article explores the possibility of describing the experimental data λ∞(Т) for solutions of certain inorganic salts in ethanol by this equation. It is shown that the Arrhenius equation with the found activation energies adequately describes the temperature dependence of the ultimate equivalent conductivity for solutions of a number of inorganic salts (chloride and calcium nitrate, cadmium iodide, lithium and potassium chloride, chloride, iodide and ammonium nitrate, silver nitrate and sodium bromide) in ethyl alcohol.

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