Journal Article

Kinetic and thermodynamic properties of La(III) on Molybdenum electrode in LiCl–KCl–LaCl3 melts

Wu, Hong-Jun, Ji, De-Bin, Li, Gang-Hui, Tan, Heng-Yu, Liang, Rui-Long

2025

Overview

The kinetic and thermodynamic properties of La(III) in LiCl–KCl–LaCl 3 melts on inert electrode (Mo) were investigated by different electrochemical methods. The reduction of La(III) into metallic La on the Mo electrode is a quasi-reversible process that can transfer three electrons in a single step. In the temperature range of 723–848 K, the diffusion coefficient and reaction activation energy of La(III) in LiCl–KCl–LaCl 3 melts were calculated using Cyclic voltammetry (CV) and Chronopotentiometry (CP). Moreover, relationships between the diffusion coefficient with temperature were formulated as follows: ln D 0  = − 3.32/ T  + 5.27 (CV) and ln D 0  = − 4.7/ T  − 5.89 (CP). The dependence of exchange current density of La(III)/La(0) on the experimental temperatures was constructed by Tafel (ln j 0  = − 2.04/ T  − 1.93) and Linear polarization (LP) (ln j 0  = − 2.74/ T  − 0.912). The apparent electrode potentials, Gibbs free energy, and activity coefficient of La(III)/La(0) were estimated using Open-circuit chronopotentiometry (OCP). Different LaCl 3 concentrations were added to LiCl–KCl melts, and the ion concentration of La(III) in the melts was determined using Normal Pulse Voltammetry (NPV). The obtained results had a relative error of less than 10% when compared to the ICP results. It shows that the results obtained by NPV detection are accurate and reliable. Graphical abstract

• Publisher: Springer Netherlands,Springer Nature B.V
• Subject: Activity coefficients / Chemistry / Chemistry and Materials Science / Clean technology / Diffusion coefficient / Electrochemistry / Electrode polarization / Electrodes / Electrons / Experiments / Fossil fuels / Gibbs free energy / Industrial Chemistry/Chemical Engineering / Ion concentration / Lanthanum chlorides / Linear polarization / Lithium chloride / Melts / Molybdenum / Nuclear energy / Nuclear fuels / Physical Chemistry / Potassium chloride / Process controls / Research Article / Solar energy / Temperature / Thermodynamic properties / Thermodynamics / Voltammetry