含氟锌电积体系用Pb/3D-PbO2基复合阳极的制备及稳定性调控优化

The gradually increasing concentration of fluoride in zinc electrowinning system leads to corrosion deterioration of lead-based anode and purity reduction of zinc product. Therefore, this project puts forward a composite anode with Pb/3D-PbO2 as substrate and CeO2-PbO2-MnO2 as anodic layer, aiming at enhancing the bond stability of substrate/anodic layer and inner stability of anodic layer, and further improving its corrosion resistance in fluoride-containing zinc electrowinning system. This project investigates the growth process of 3D-PbO2 structure on Pb surface, the growth pattern of 3D-PbO2 could be revealed, and the regulation method of 3D-PbO2 structure parameter could be established; The deposition behavior of CeO2, PbO2, MnO2 in 3D-PbO2 structure would also be studied, with the reveal of match-control mechanism of deposition dynamic of CeO2, PbO2 and MnO2, the co-deposition of these oxides could be achieved. In addition, the regulation method of composition and structure of anodic layer could be established; Furthermore, the influence of 3D-PbO2 structure parameter, composition and structure of anodic layer on the composite anode stability would be clarified. Based on the investigation listed above, the stability optimization method of composite anode could be obtained, and the controlled preparation theory of Pb/3D-PbO2/CeO2-PbO2-MnO2 would be built. This project would enrich and develop the stability regulation theory of metal/oxide electrodes, provide theoretical and technical support for development and application of lead-based anode in zinc electrowinning system containing fluoride.

锌电积电解液氟浓度逐步攀升，铅阳极腐蚀加剧，阴极锌品质降低。本项目提出Pb/3D-PbO2为基底、CeO2-PbO2-MnO2为氧化膜层的复合阳极，以提高铅阳极基底/氧化膜层结合稳定性和氧化膜层内部稳定性，进而改善其在含氟锌电积体系的耐腐蚀性能。研究Pb表面3D-PbO2生长过程，揭示3D-PbO2生长规律，建立3D-PbO2结构参数调控方法；研究CeO2、PbO2、MnO2在3D-PbO2结构上的沉积行为，阐明各组元沉积动力学匹配控制机制，实现三组元共沉积，建立氧化膜层组成和结构调控方法；明确3D-PbO2结构参数和氧化膜层组成、结构对复合阳极稳定性的影响，建立复合阳极稳定性优化方法，形成复合阳极可控制备理论。本项目的实施将丰富和发展金属/氧化物电极稳定性调控理论，为含氟锌电积体系用铅阳极的开发与应用提供理论和技术支撑。

锌电积电解液氟浓度逐步攀升，铅阳极腐蚀加剧，阴极锌品质降低。本项目提出Pb/3D-PbO2为基底、CeO2-PbO2-MnO2为氧化膜层的复合阳极，以提高铅阳极基底/氧化膜层结合稳定性和氧化膜层内部稳定性，进而改善其在含氟锌电积体系的耐腐蚀性能。前期研究发现在乙二醇-侵蚀剂-痕量水体系和低共熔溶剂体系均难以获得具有丰富孔洞结构的3D-PbO2，项目调整方案，提出在Pb基底构筑3D-Pb结构以替代3D-PbO2结构，并进一步开展了以下研究：3D-Pb结构的构建与表征、3D-Pb结构对Pb阳极在H2SO4溶液和含Mn2+ H2SO4溶液中性能的影响，以及3D-Pb/PbO2-CeO2-MnO2的制备及性能表征。主要结果如下：1) 在低Pb2+浓度(~0.15 mol L-1)电沉积条件下可获得杨桃状3D-Pb结构，而在高Pb2+浓度(≥ 0.3 mol L-1)条件下可获得立椎状3D-Pb结构。Pb2+沉积主要受Pb2+扩散传质控制，调控Pb2+浓度和传质条件可控制3D-Pb结构参数；2) 在160 g L-1 H2SO4模拟电解过程中，立锥状3D-Pb(Pyra-Pb)结构有助于提高氧化膜层厚度，显著减缓金属基底的晶界腐蚀。此外，Pyra-Pb结构可提高氧化膜层表面积和PbO2含量，进而降低阳极电位约40 mV；3) 在含锰硫酸模拟电解过程中，Pyra-Pb结构可减小氧化膜层厚度、提高膜层表面致密度，进而提高Pb阳极氧化膜层内部稳定性。在含4和6 g L-1 Mn2+电解液中，Pyra-Pb结构可分别降低阳极电位约70 mV和100 mV。此外，Pyra-Pb结构可显著减少含铅阳极泥的生成量；4) 采用复合共沉积方法在立锥状3D-Pb结构表面制备PbO2-CeO2-MnO2镀层，获得3D-Pb/氧化物复合阳极。CeO2的存在可减缓3D-Pb/氧化物复合阳极在含氟电解体系的腐蚀速率。然而，3D-Pb/PbO2-CeO2-MnO2阳极表面PbO2含量低，膜层厚度大，欧姆电阻大。因此，在模拟电解过程中3D-Pb/PbO2-CeO2-MnO2阳极电位高于3D-Pb/PbO2阳极。综合考虑阳极耐腐蚀性和析氧电位，3D-Pb/PbO2-CeO2复合阳极更适于含氟锌电极体系。