Time filter

Source Type

Zhang Y.-C.,Kunming University of Science and Technology | Chen B.-M.,Kunming University of Science and Technology | Yang H.-T.,Kunming University of Science and Technology | Guo Z.-C.,Kunming University of Science and Technology | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

Anodic behaviors and oxygen evolution kinetics of Pb-0.8%Ag and Al/Pb-0.8%Ag anodes during the initial 24 h zinc electrowinning were investigated with cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS). The results reveal that the anodic behaviors and reaction kinetics of the two anodes vary a lot during the anodic polarization which indicate the formation and stabilization of anodic layer. Compared with conventional Pb-0.8%Ag anode, Al/Pb-0.8%Ag anode has longer time of anodic polarization. At the very beginning of anodic polarization, the two anodes all exhibit higher potential of oxygen evolution reaction (OER) since the reaction is controlled by the transformation step of intermediates. Then, its OER potential is largely diminished and OER rate is deduced from the formation and adsorption of the first intermediate (S-OHads). In the prolonged anodic polarization, the anodic potential of Al/Pb-0.8%Ag gradually decreases and the final value is more stable than that of conventional Pb-0.8%Ag anode. On the anodic layer after 24 h of anodic polarization, the OER potential is controlled by the formation and adsorption of intermediate. The microstructures of Al/Pb-0.8%Ag and Pb-0.8%Ag anodes after 24 h of anodic polarization were analyzed by scanning electron microscope (SEM). © 2014 The Nonferrous Metals Society of China.


Zhang Y.,Kunming University of Science and Technology | Chen B.,Kunming University of Science and Technology | Guo Z.,Kunming University of Science and Technology | Guo Z.,Kunming Hendera of Science and Technology Co.
Acta Metallurgica Sinica (English Letters) | Year: 2014

The Al/Pb-0.8%Ag and Al/Pb-0.75%Ag-0.03%Co (in mass fraction) anodes used in zinc electrowinning are prepared through the electrodeposition of lead methanesulfonate electrolyte onto an aluminum matrix. The results of anode polarization curves, Tafel curves, and EIS characterizations indicated that the Al/Pb-0.75%Ag-0.03%Co anode has higher electrocatalytic activity and corrosion resistance than the Al/Pb-0.8%Ag anode. SEM observations on the fruit surfaces demonstrated the crystals on the Al/Pb-0.8%Ag anode are larger than on the Al/Pb-0.75%Ag-0.03%Co anode. After 24 h of anodic polarization, SEM observations and XRD analysis showed that the MnO2-PbO2 layer on the Al/Pb-0.75%Ag- 0.03%Co anode surface is characterized by dendritic crystals, and the PbSO4-PbO2 layer under the MnO2-PbO2 layer is characterized by uniform and chaotic orientation tetragonal symmetry crystallites of PbSO4. However, the MnO2-PbO2 layer on the Al/Pb-0.8%Ag anode surface is characterized by granular crystals, and the PbSO4-PbO2 layer under the MnO2-PbO2 layer is characterized by well-organized orientation crystallites of PbSO4, which are concentrated in certain zones. © The Chinese Society for Metals and Springer-Verlag Berlin Heidelberg 2014.

Loading Kunming Hendera of Science and Technology Co. collaborators
Loading Kunming Hendera of Science and Technology Co. collaborators