Shcherbakov Vladimir V, Artemkina Yuliya M, Akimova Irina A, Artemkina Irina M
Department of General and Inorganic Chemistry, Mendeleev University of Chemical Technology, Miusskaya sq. 9, 125047 Moscow, Russia.
Materials (Basel). 2021 Sep 27;14(19):5617. doi: 10.3390/ma14195617.
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.
溶液中离子的溶剂化和缔合在很大程度上取决于溶剂的介电性质、溶液中离子间的距离以及温度。本文研究了温度对水和一些极性溶剂的静态介电常数（DC）、偶极介电弛豫（DR）时间以及极限（最终）高频（HF）电导率（EC）的影响。在所研究的温度范围（0 - 370°C）内，水的静态DC和DR时间随温度升高而降低，极限HF EC在250 - 300°C时随温度升高出现最大值。甲醇、乙醇和丙醇的介电特性表现出相似的规律。研究表明，HF EC温度最大值的存在是由于DC和DR时间的温度依赖性性质不同。有人认为，相同的依赖性导致了水的离解度和离子积的温度依赖性中出现最大值。考虑了非电解质浓度以及金属盐对其水溶液介电性质的影响。水的极限HF EC决定了电解质水溶液的比电导率值。对极性溶剂以及非电解质和电解质水溶液在2455 MHz频率下对微波能量的吸收进行了分析。确定了溶液高频加热的最佳条件。计算了无机盐水溶液和离子液体非水溶液中离子间的距离。结果表明，比电导率浓度依赖性中的最大值可能与离子缔合有关。
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