Anodic oxidation of lead in aqueous carbonate solutions. I. Film formation and dissolution at pH = 12

Abstract

. Can. J. Chem. 66, 2652Chem. 66, (1988. The anodic oxidation of lead has been studied using rotating disk electrodes, under voltammetric and potentiostatic conditions, in aqueous carbonate solutions at pH = 12. The solid films formed on the electrode surface have been identified by X-ray diffractometry. Two distinct surface layers are formed: a compact layer composed of two separate phases, plumbonacrite (Pb100(OH)6(C03)6) and hydrocerussite (Pb3(0H)2(C03)2); and a more dispersed layer of hydrocerussite. The plumbonacrite in the compact layer is formed directly on the electrode surface by a solid-state growth process. The hydrocerussite component of this compact layer appears to form by conversion of the outer layers of plumbonacrite. The dispersed layer is formed by deposition from solution. The extent of deposition is controlled by the rate of transport of soluble pb2+ species to the bulk of solution. Chem. 66, 2652Chem. 66, (1988. Operant dans des solutions aqueuses de carbonate, a un pH de 12, dans des conditions voltam&triques ainsi que potentiostatiques et faisant appel a des electrodes a disque tournant, on a ttudit l'oxydation anodigue du plomb. Utilisant la diffraction des rayons-X, on a identifie les films solides qui se forment h la surface de 1'Clectrode. A cette surface, il se forme deux couches distinctes : une couche compacte composee de deux phases sCparCes, de la plumbonacrite (Pb10)(OH)6(C03)6) et de l'hydrocerussite (Pb3(0H)2(C03)2) ainsi qu'une couche plus dispersee d'hydrocerussite. La plumbonacrite presente dans la couche compacte se forme directement sur la surface de 1'Clectrode par un processus de croissance ? i 1'Ctat solide. I1 semble que la composante hydrockrussite de cette couche compacte se forme par la conversion des couches exterieures de plumbonacrite.La couche dispersee se forme par une deposition a partir de la solution. Le taux de dkposition est contrBlC par la vitesse de transport des espkces Pb2+ h partir de la solution.[Traduit par la revue]

On the role of NO2− ions in passivity breakdown of Zn in deaerated neutral sodium nitrite solutions and the effect of some inorganic inhibitors

“…In addition, an increase in the electrode rotation speed increases the rate of transport of soluble Zn 2+ species away from the anode surface and decreases the concentration of the dissolved species close to the anode surface. Consequently, the extent of ZnO formation on the electrode surface decreases, thereby an increase in peak current is observed [40]. Moreover, Fig.…”

Anodic oxidation of lead in aqueous carbonate solutions. II. Film formation and dissolution in the pH range 9 to 14

“…Also, our measurements of the corrosion potential (ECORR) of lead in carbonate solutions (5) yielded values in the range -0.540 V < ECoRR < -0.350 V. Consequently, we have studied the dissolution and film formation processes occurring on lead at potentials up to 0 mV (vs. SCE). This value is over 0.600 V more positive than our previous anodic limit (6). potentials were measured, and are quoted, against the saturated calomel electrode.…”

“…cedures have been described previously (6). All the experiments were At pH = 13.9, the current passes through a minimum and performed at rotating disk electrodes of surface area -1.6 cm2.…”