ÔØ Å ÒÙ× Ö ÔØElectrodeposition of lead-cobalt composite coatings electrocatalytic for oxygen evolution and the properties of composite coated anodes for copper electrowinning Please cite this article as: Barmi, Maryam Jozegholami, Nikoloski, Aleksandar N., Electrodeposition of lead-cobalt composite coatings electrocatalytic for oxygen evolution and the properties of composite coated anodes for copper electrowinning, Hydrometallurgy (2012), doi: 10.1016/j.hydromet.2012.08.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. , which is significantly less than the 122 mV dec -1 measured on the conventional PbCaSn anodes. The composite anodes exhibited consistently lower oxygen evolution potentials than the conventional type and the potential remained relatively stable throughout the polarisation period. The reduction in the operating anode potential can be attributed to the presence of cobalt in the surface layer while the decrease in the Tafel slope shows that this reduction can be related to a change in the mechanism of the oxygen evolution reaction. Corrosion rates estimated from 16 h tests showed that the composite coated anodes are more stable than the conventional type during short periods of operation. It was also observed that for the Pb-Co coated anode, both the rate of corrosion and the overpotential for the oxygen evolution reaction can be further reduced by the addition of organic additives such as thiourea. : electrowinning, overpotential, anode, lead, cobalt, thiourea
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INTRODUCTIONLead based anodes have been used in the electrowinning of base metals for more than a century due to their low cost and availability. However, the conventional types of lead based anodes, such as PbCaSn, operate at relatively high oxygen overpotential, which results in significant energy consumption, and suffer from corrosion which takes place at a slow rate during the electrowinning process. It is reported that 20-25% of the overall cell energy consumption in tankhouses using conventional lead based anodes is attributed to oxygen evolution overpotential (Schmachtel et al., 2008). On the other hand, the slow corrosion is adding to the cost of anode replacement but, also, leads to contamination of the cathodes with lead from the corrosion product which lowers the quality of the produced cathodes.The development of anodes that can evolve oxygen from acidic sulphate solutions at lower overpotential than on the conventional lead based anode has a long history in the hydrometallurgical research field. This was revisited in the present study, with particul...