Anodic passivation of Pb-Ag-Nd anode in fluoride-containing H2SO4 solution

作者:Zhong Xiao-cong; Jiang Liang-xing*; Liu Fang-yang; Li Jie; Liu Ye-xiang
来源:Journal of Central South University (English Edition), 2015, 22(8): 2894-2901.
DOI:10.1007/s11771-015-2823-0

摘要

An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that PbF2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is beta-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.).