EletrodeposiÃÃo de chumbo sobre Carbono VÃtreo, em sistema Ãcido, Alcalino e com a influÃncia do Etileno Glicol

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The electrodeposition of lead, on glassy carbon, from acid (HBF4) and alkaline media (KOH) and on the influence of the ethylene glycol, in concentration varied, has been studied by technique electrochemistry as it has been studied by technique electrochemistry as: cyclic voltammetry, chronoamperometry, while cyclic voltammetry was used to characterize the system and to diagnose of the nucleation, the second were recorded to obtain the nucleation mechanism, under stationary and convective conditions. Structural information on the electrodeposited was obtained by optical microscopy was used to determine the surface morphology. The experimental results clearly show that the deposition of lead, on a glassy carbon substrate is a diffusion-controlled process with a three-dimensional (3D) growth mechanism. The nucleation is instantaneous and / or, progressive and the number of nucleation sites increases with increasing overpotentials. The analyses of the chronoamperometric responses support the view of a 3D growth and suggest a substantial influence of ethylene glycol concentration on the type of nucleation. Progressive nucleation is observed for the deposition from solutions with low content in leads but as this ethylene glycol concentration and overpotentials increases a tendency towards instantaneous nucleation is revealed. The voltammetry with the glassy carbon electrode has confirmed that the lead electrodeposition is a mass transfer controlled process. The Scharifker and Hills model was used to analyze current transients. A progressive and instantaneous nucleation mechanism was found to fit the experimental results.

ASSUNTO(S)

lead nucleation electrodeposition eletrodeposiÃÃo chumbo electrochemistry nucleaÃÃo eletroquÃmica quimica

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