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Electron absorption spectra of saturated chlorine solutions in melts of alkaline metal chlorides depending on temperature
- Authors: Kolobov A.Y.1,2, Potapov A.M.2, Khokhlov V.A.2
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Affiliations:
- JSC «DINUR»
- Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences
- Issue: No 5 (2025)
- Pages: 455-466
- Section: Articles
- URL: https://bakhtiniada.ru/0235-0106/article/view/309551
- DOI: https://doi.org/10.31857/S0235010625050045
- ID: 309551
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Abstract
Electronic absorption spectra of saturated chlorine solutions in molten alkali metal chlorides were recorded in the range from the melting point of the salt to 1000°C. An SF-26 spectrophotometer converted for high-temperature measurements was used to record the spectra. The illuminator was separated from the main body and a silite high-temperature furnace with windows was placed between the illuminator and the monochromator. Quartz optical cells with a absorbing layer thickness of 0.8, 1.0 and 1.5 mm were used to conduct the experiments. The thinnest cuvette (0.8 mm) was used to record the spectrum of dissolved chlorine in molten cesium chloride, since the solubility of chlorine in it is maximum and, accordingly, the optical density of such a melt is also maximum. It was found that in all salts the absorption spectrum consists of a single broad absorption band with a maximum in the region of 26000–28000 cm-1. In the range of 13000–8000 cm-1 absorption is practically absent. With increasing temperature, as well as when passing from sodium chloride to cesium chloride, the absorption maximum shifts to the region of lower energies. The solubility of chlorine in molten salts increases with increasing temperature, which indicates the endothermicity of the dissolution process. The thermodynamic characteristics of this process were calculated based on the solubility values. The process of dissolution of Cl2 in molten alkali metal chlorides is characterized by a positive change in entropy and enthalpy. This indicates the dissolution of chlorine not in the form of simple Cl2 molecules, but rather the formation of their associates with ions of the salt medium. With increasing temperature and transition in the series of salt-solvents from NaCl to CsCl, the change in Gibbs energy shifts toward smaller (more negative) values, which corresponds to an increase in the solubility of chlorine in the same direction. And in the same direction, both the physical and chemical (formation of ions) components of the total solubility of the gas increase. A conclusion is made about the predominant chemical mechanism of chlorine dissolution in molten alkali metal chlorides.
About the authors
A. Y. Kolobov
JSC «DINUR»; Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences
Email: art.kolobov@yandex.ru
Pervouralsk city, Sverdlovsk region; Yekaterinburg
A. M. Potapov
Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences
Email: art.kolobov@yandex.ru
Yekaterinburg
V. A. Khokhlov
Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences
Author for correspondence.
Email: art.kolobov@yandex.ru
Yekaterinburg
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