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|Title:||Corrosion and passivation of Pb in CO solutions|
|Authors:||El-Egamy, S S|
Badawy, W A
|Abstract:||The electrochemical behaviour of lead in carbonate solutions has been investigated using impedance, cyclic voltammetry and open-circuit potential measurements. Under open-circuit conditions, the lead electrode has been passivated by the formation of PbCO3 film. The rate of passivation is found to be dependent on the carbonate ion concentration. The reciprocal capacitance, the polarization resistance and the equilibrium electrode potential are found to increase with time following a simple logarithmic law Cyclic voltammograms of Pb in 0.15 M Na2CO3 display three anodic current peaks. The peaks correspond to the oxidation of Pb into PbCO3 the transformation of PbCO3 into PbO, and then the further oxidation of PbO into PbO2. On reversing the scan, two reduction peaks could be observed. The first is due to the reduction of PbO2 into PbO and the, second corresponds to the transformation of PbO into PbCO3. The peak currents are found. to be dependent on both the sweep rate and electrolyte concentration. The non-linear dependence of the peak current on the sweep rate indicates that the passivation process is irreversible and controlled by several factors other than diffusion of Pb2 + ions.|
|ISSN:||0975-0991 (Online); 0971-457X (Print)|
|Appears in Collections:||IJCT Vol.03(1) [January 1996]|
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