Keywords
cyclic voltammetry, molten salt, rare earths, square wave voltammetry
Abstract
Cyclic voltammetry (CV), square wave voltammetry (SWV) and other electroanalytical methods have been applied to molten chloride salts to study metal ion behavior. These studies have been useful for understanding and optimizing the electrowinning of metals. Notable ions that have been studied are rare earth and actinide metal ions in LiCl-KCl salts. However, the behavior of lanthanum (La3+) ions in some molten chlorides or chloride mixtures (e.g., CaCl2) has not been studied. CV experiments were conducted to evaluate La3+ behavior in CaCl2-LiCl and CaCl2 and were compared to La3+ behavior in LiCl-KCl and CaCl2-NaCl eutectics from other studies. The electrochemical reaction was checked for reversible, quasi-reversible, and irreversible transitions in scan rate by examining the relationship between the scan rate applied and the peak current and potential for La3+ reduction. Properties such as diffusion coefficient (Do) and electrons exchanged (n) were calculated from data. The electrochemical setup was also checked for radial diffusion based on the calculated La3+ diffusion coefficient and electrode radius, which led to the observation that natural convection possibly affected the La3+ reduction peak at low scan rates. For more accurate electroanalytical measurements of La3+ reduction, CV curves with and without LaCl3 added to CaCl2 and CaCl2-LiCl were compared to establish baselines for the La3+ reduction peak. The impact of resistance (IR) compensation on the La3+ reduction peak was also explored. Techniques and practices that improved electroanalytical measurements include placing the electrolytic cell in a Faraday cage, distancing electrodes from the heating coils, and melting the chlorides twice prior to measurements.
Original Publication Citation
Schvaneveldt, M., Fuller, R., & Rappleye, D. (2022). Electroanalytical measurements of lanthanum (III) chloride in molten calcium chloride and molten calcium chloride and lithium chloride. Journal of Electroanalytical Chemistry, 918, 116442. https://doi.org/10.1016/j.jelechem.2022.116442
BYU ScholarsArchive Citation
Schvaneveldt, Mark H.; Fuller, Ranon; and Rappleye, Devin, "Electroanalytical Measurements of Lanthanum (III) Chloride in Molten Calcium Chloride and Molten Calcium Chloride and Lithium Chloride" (2022). Faculty Publications. 7195.
https://scholarsarchive.byu.edu/facpub/7195
Document Type
Peer-Reviewed Article
Publication Date
2022-05-28
Publisher
Elsevier
Language
English
College
Ira A. Fulton College of Engineering and Technology
Department
Chemical Engineering
Copyright Status
© 2022. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/ For version of record, visit https://doi.org/10.1016/j.jelechem.2022.116442 at the Journal Electroanalytical Chemistry.
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