Influence of Mn2+ ions on the corrosion mechanism of lead-based anodes and the generation of heavy metal anode slime in zinc sulfate electrolyte
- 84 Downloads
The influence of Mn2+ ions on the generation of heavy metal anode slime during zinc electrolysis industry was extensively investigated using several electrochemical methods, electron microscope technologies, and particle size analysis. Results showed that the Mn2+ could obviously promote oxygen evolution reaction (OER) and thereby weaken oxidation efficiency of Mn2+ (ηMnO2) and dissolution of Pb2+. The significant improvement in kinetic parameters for OER was found in electrolytes of 1 and 3 g/L Mn2+, but became unstable as the Mn2+ concentration increased to 10 g/L. This result was correlated with much different properties of oxide layers that its changes of microstructure are involved in, since it confirmed that the positive role of compact oxide layers in contributing to high corrosion resistance and activity for OER, but excessive Mn2+, resulted in its micromorphology of overthickness and instability. Such differences resulted from the effect of the Mn2+ concentration fluctuation on kinetic rates of the nucleation growth process. The formation and adsorption of intermediate MnO2–OHads identified as the controlled step for Mn2+ catalyzing OER was also recommended. The generation mechanism of anode slime was found to be changed in essence due to varying Mn2+ concentrations. In electrolyte of 1 g/L Mn2+, results revealed that the root cause of excessive small suspended anode slime (around 20 μm) was the change of the initial pathway of Mn2+ electro-oxidation, whereas, it showed great improvement in the settling performance as the Mn2+ concentration was increased to 10 g/L. Considering the potential of optimizing Mn2+ concentrations as a cleaner approach to control anode slime, deepening the understanding of the impact mechanism of Mn2+ can provide new insights into intervention in the generation of anode slime.
KeywordsOxygen evolution reaction Heavy metal Anode slime Cleaner approach
This work was supported by the National Key R&D Program of China (2017YFC0210402), National Major Science and Technology Program for Water Pollution Control and Treatment (2017ZX07402004), Natural Science Foundation of China (51304178, 41673114), and the Central Level, Scientific Research Institutes for Basic R&D Special Fund Business (Chinese Research Academy of Environmental Sciences, 2016YSKY034, 2016YSKY-015), and by Funds of State Key Laboratory of Environmental Criteria and Risk Assessment (SKLECRA201754).
- Adcock PA (2017) Zinc electrowinning in the presence of iron (II). J Entomol 48(1):25–35Google Scholar
- Houlachi G, Ghali E, Li X, Lafront A, Wei Z (2015) Influence of silver content on corrosion resistance of lead anodes during potential decay by electrochemical noise measurements. Innov Corros Mater Sci 5:43–52Google Scholar
- Ivanov I, Stefanov Y (2002) Electroextraction of zinc from sulphate electrolytes containing antimony ions and hydroxyethylated-butyne-2-diol-1, 4: part 3. The influence of manganese ions and a divided cell. Hydrometallurgy 64(3):181–186. https://doi.org/10.1016/S0304-386X(02)00039-7 CrossRefGoogle Scholar
- Jaimes R, Miranda-Hernández M, Lartundo-Rojas L, González I (2015) Characterization of anodic deposits formed on Pb-Ag electrodes during electrolysis in mimic zinc electrowinning solutions with different concentrations of Mn (II). J Hydrometall 156:53–62. https://doi.org/10.1016/j.hydromet.2015.05.008 CrossRefGoogle Scholar
- Kelsall G, Guerra E, Bestetti M (2000) Effects of manganese (II) and chloride ions in zinc electrowinning reactors. Proc Electrochem Soc 14:350–361Google Scholar
- Lai YQ, Li Y, Lv XJ, Li J, Liu YX (2011) Electrochemical performance of a Pb/Pb-MnO2 composite anode in sulfuric acid solution containing Mn2+. Hydrometallurgy s115–116(4):64–70Google Scholar
- Liu CX, Shen QF, Xiong M, Shan Y, He SF (2011) Inhibition behaviour of a mixed additive upon zinc electrowinning from sulphate solutions containing germanium. Adv Mater Res 291-294:1479–1483. https://doi.org/10.4028/www.scientific.net/AMR.291-294.1479 CrossRefGoogle Scholar
- Liu JH, Chen BM, Guo ZC, Zhang YC, Xu RD (2013) Effect of the current density on oxygen overpotential and corrosion rate of the Al/Pb-Ag-Co anodes for zinc electrowinning. Adv Mater Res 634-638(1):1718–1723. https://doi.org/10.4028/www.scientific.net/AMR.634-638.1718 CrossRefGoogle Scholar
- Xu RD, Huang LP, Zhou JF, Zhan P, Guan YY, Kong Y (2012) Effects of tungsten carbide on electrochemical properties and microstructural features of Al/Pb-PANI-WC composite inert anodes used in zinc electrowinning. Hydrometallurgy s125–126(7):8–15. https://doi.org/10.1016/j.hydromet.2012.04.012 CrossRefGoogle Scholar
- Yang HT, Liu HR, Guo ZC, Chen BM, Zhang YC. Huang H, Li XL, Fu RC, Xu RD (2013) Electrochemical behavior of rolled Pb-0.8% Ag anodes. Hydrometallurgy 140:144–150Google Scholar
- Zhong XC, Gui JF, Yu XY, Liu FY, Jiang LX (2014) Influence of alloying element Nd on the electrochemical behavior of Pb-Ag anode in H2SO4 solution. Acta Phys -Chim Sin 30(3):492–499Google Scholar