Highly efficient and facile electrochemical separation of Zr from LiCl–KCl molten salt using a bismuth electrode
摘要
The selective recovery of Zr is crucial for recycling Zr from spent nuclear fuel. This work systematically investigated the electrochemical behavior of Zr on W and Bi electrodes by multiple electrochemical methods. Cyclic voltammetry (CV) confirmed that the diffusion coefficients of Zr(IV) and Zr(II) both increase with increasing temperature, and their diffusion activation energies are 44.3 kJ mol−1 and 34.8 kJ mol−1, respectively. CV, square wave voltammetry (SWV), and chronopotentiometry (CP) revealed the formation of two distinct intermetallic compounds on the Bi film electrode. The kinetic parameters were measured on liquid Bi electrode via linear polarization (LP) and Tafel plots, and the activation energy of the electrode reaction was calculated to be 22.7 kJ mol−1 and 24.4 kJ mol−1, respectively. Furthermore, open-circuit potentiometry (OCP) was employed to obtain the thermodynamic parameters, indicating that (Zr–Bi)solution formation is thermodynamically favored over other Zr–Bi alloys. Potentiostatic electrolysis performed on the liquid Bi demonstrated that the extraction efficiency and current efficiency for Zr are significantly enhanced at elevated temperatures, achieving remarkable values of 99.7% and 98.03%, respectively, at 873 K. This research establishes a fundamental basis and provides a promising strategy for the efficient recovery of Zr from spent nuclear fuel, contributing to the sustainable development of nuclear energy.