Open AccessIn situ synchrotron X‐ray diffraction investigation of the evolution of a PbO 2 /PbSO 4 surface layer on a copper electrowinning Pb anode in a novel electrochemical flow cell
Author(s) -
Clancy Marie,
Styles Mark J.,
Bettles Colleen J.,
Birbilis Nick,
Chen Miao,
Zhang Yansheng,
Gu Qinfen,
Kimpton Justin A.,
Webster Nathan A. S.
Publication year - 2015
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577514027659
Subject(s) - electrowinning , anode , materials science , synchrotron , electrolyte , analytical chemistry (journal) , electrochemistry , copper , rietveld refinement , electrode , metallurgy , chemistry , crystallography , crystal structure , optics , physics , chromatography
This paper describes the quantitative measurement, by in situ synchrotron X‐ray diffraction (S‐XRD) and subsequent Rietveld‐based quantitative phase analysis and thickness calculations, of the evolution of the PbO 2 and PbSO 4 surface layers formed on a pure lead anode under simulated copper electrowinning conditions in a 1.6 M H 2 SO 4 electrolyte at 318 K. This is the first report of a truly in situ S‐XRD study of the surface layer evolution on a Pb substrate under cycles of galvanostatic and power interruption conditions, of key interest to the mining, solvent extraction and lead acid battery communities. The design of a novel reflection geometry electrochemical flow cell is also described. The in situ S‐XRD results show that β‐PbO 2 forms immediately on the anode under galvanostatic conditions, and undergoes continued growth until power interruption where it transforms to PbSO 4 . The kinetics of the β‐PbO 2 to PbSO 4 conversion decrease as the number of cycles increases, whilst the amount of residual PbO 2 increases with the number of cycles due to incomplete conversion to PbSO 4 . Conversely, complete transformation of PbSO 4 to β‐PbO 2 was observed in each cycle. The results of layer thickness calculations demonstrate a significant volume change upon PbSO 4 to β‐PbO 2 transformation.