Electro-Deposition Behavior in Methanesulfonic-Acid-Based Lead Electro-Refining

The lead (Pb) electro-refining in the green methanesulfonic acid (MSA) system presents an alternative route to the conventional fluosilicic-acid-based Pb electro-refining. Herein, we investigated the electro-deposition behavior of the MSA-based Pb electro-refining by electrochemical measurement and apparent characterization techniques. The operational principle of the Pb deposition was preliminarily understood by performing cyclic voltammetry (CV) complemented with SEM–EDS detection. The results indicated the thermodynamic priority of the efficient Pb 2+ /Pb reduction reaction over the H + /H 2 one. The impact of various factors such as MSA concentration, scanning rate, and temperature on the effectiveness of Pb electro-deposition were investigated by linear sweep voltammetry and electrochemical impedance spectroscopy. Further numeric calculation and model analysis helped acquire in-depth kinetics and mechanism knowledge, such as the discharge form of divalent Pb(II), reversibility of the electrode process, apparent activation energy, reaction order and deposition reaction kinetics. Overall, this work revealed important electrochemical mechanism, principle, and kinetics of the Pb deposition in the MSA-based electro-refining process and would offer a significant guidance in condition optimization of its practice. Graphical Abstract