2024 - Sustainable Industrial Processing Summit
SIPS 2024 Volume 16. Intl. Symp on Electrochemistry, Molten Salts, Corrosion, Recycling and Battery
| Editors: | F. Kongoli, C.A. Amatore, R. Fehrmann, G. Kipouros, I. Paspaliaris, G. Saevarsdottir, R. Singh, R. Gupta, M. Halama, D. Macdonald, F. Wang, M. Barinova, F. Ahmed, C. Gaidau, X. Guo, K. Kolomaznik, H. Ozgunay, K. Tang, N.N. Thanh, S. Yefremova, K. Aifantis, Z. Bakenov, C. Capiglia, V. Kumar, A. U. H. Qurashi, A. Tressaud, R. Yazami |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2024 |
| Pages: | 243 pages |
| ISBN: | 978-1-998384-34-1 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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CHLORINE SOLUTIONS IN MOLTEN ALKALI CHLORIDES
Artem Kolobov1; Alexei Potapov2; Vladimir Khokhlov2;1JSC «DINUR», Pervouralsk, Russian Federation; 2INSTITUTE OF HIGH TEMPERATURE ELECTROCHEMISTRY, Ekaterinburg, Russian Federation;
Type of Paper: Regular
Id Paper: 174
Topic: 13
Abstract:
In various technological processes using molten salts, molecular chlorine is released or absorbed. When conducting scientific research involving melts, there are often cases, in which an oxidizing atmosphere of chlorine is necessary, or chlorine is a reaction product. This raises the question concerning the mechanism of chlorine solubility and its influence on the processes being studied. Thus, the purpose of this work is to establish the mechanism of chlorine dissolution in molten alkali metal chlorides.
The purpose of this work is to establish the mechanism of chlorine dissolution in molten alkali metal chlorides.
Electronic absorption spectra of saturated chlorine solutions in molten NaCl, NaCl - KCl, KCl, CsCl were recorded in the temperature range from the melting point of salt to 1000 °C with an interval of approximately one hundred degrees. The work was carried out using an SF-26 spectrophotometer (Russia) adapted for operation with high-temperature melts.
In all salts studied, the long-wavelength edge of the absorption band was reliably detected. With increasing temperature, this absorption edge shifted to longer wavelengths in all chlorides. For sodium chloride and an equimolar mixture of sodium and potassium chlorides, it was possible to record a wide plateau with a maximum shifted to the region of higher energies compared to the absorption maximum of chlorine gas. For the other salts, the maximum could not be recorded; this is due to the large absorption of the salt - solvent.
From the data [1 - 7] it is known that the solubility of chlorine in the studied melts is several mole percent. This is significantly higher than the solubility of inert gases, so it is reasonable to assume that the simplest type of polyhalide compounds Cl3- is formed in the melt. In addition, we have established a shift in the position of the maximum of the chlorine band in the melt to the high-frequency region [8]. This shift confirms the formation of Cl3- complexes in the melt.
In accordance with the theory of molecular orbitals, the sharing of valence electrons in such a complex leads to the formation of axial three-center molecular orbitals. Filling them with electrons in accordance with the principle of minimum energy ensures the stability of such a group of atoms. The stability of such particles at high temperatures can probably be explained by the fact that the anions of the molten salt are not solvated and have high activity.
On the other hand, the close coincidence of the maxima in molten salts with the maximum absorption of chlorine gas, as well as a slight shift of the maximum and an increase in solubility with temperature, allow us to draw a conclusion about the predominant inert gas mechanism of chlorine dissolution. Based on the data presented, it can be concluded that both physical dissolution and chemical interaction with the formation of particles of the Cl3- type take place.