期刊
HYDROMETALLURGY
卷 156, 期 -, 页码 53-62出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.hydromet.2015.05.008
关键词
Zinc electrowinning; Lead-silver electrodes; Anodic potential; Anodic deposits; Oxygen evolution
资金
- PAPIIT-DGAPA-UNAM [IN112212]
- CONACYT [0167485]
This paper studies the influence of Mn(II) ion concentration on the characteristics of the films formed during water oxidation on Pb-Ag (0.5%). Tests were performed in an electrolytic bath whose composition was similar to that used in industrial electrowinning of zinc: 180 g/L H2SO4, 75 g/L Zn2+, with amounts of Mn(II) ranging from 2 to 12 g/L A constant oxidation current density of 300 A/m(2) was applied for 96 h to Pb-Ag electrodes in order to form the anodic films. These films are composed of manganese oxides, and lead sulfates and oxides, determined by SEM-EDX analysis. In order to associate the corresponding reactions involved with each corrosion product, the anodic films were also potentiostatically formed as a function of time, and characterized by polarization curves obtained immediately after the film formation. It is shown that alpha-MnO2, an electrocatalytic phase that favors both the reaction of oxygen evolution and Mn(II) oxidation, forms within the first 10 min, even at relatively low concentrations of Mn (2 g/L). After 1 h, the layer thickness increases and the catalytic effect tends towards its own inhibition; likewise, as the amount of Mn increases, the layers become more cracked and brittle, causing electrolyte penetration through the cracks of oxide layers, which results in the activation of the Pb-Ag surface anode. (C) 2015 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据