Kinetics of lead deposition in fluorosilicate electrolyte Part II: Inhibiting effect of horse-chestnut extract (HCE) and of sodium lignin sulphonate-HCE mixtures
Abstract
The kinetics of lead electrodeposition from Betts-type electrolytes were investigated by electrochemical impedance spectroscopy, in the presence of some organic levelling agents: horse chestnut extract (HCE) and mixtures of HCE with sodium lignin sulphonate (LS). The impedance spectra and the polarization curves are influenced by the electrode rotation speed and the electrolyte composition. In Part I, a reaction model for lead electrodeposition was shown to be valid in additive-free fluorosilicate electrolytes or in the presence of LS alone. To account for the specific inhibition observed with HCE, this model is completed by addition of a diffusion-controlled process for adsorption and consumption of the HCE molecules at the cathode during lead deposition.