Kinetic study of bromide adsorption on Hg by a combined equivalent-circuit reaction-mechanism modeling of EIS data

Abstract

A quantitative kinetic description of the adsorption of bromide on mercury is developed by combination of complementary approaches to the adsorption impedance data. Equivalent-circuit modeling is matched with mechanistic models. The resulting descriptions permit the estimation of absolute adsorption and desorption rate constants for Br− on Hg electrode by assuming either a Langmuir or a Frumkin adsorption isotherm. It is found that adsorption–desorption dynamics for the Hg/Br− system is well described by the transfer function based on the Frumkin isotherm, indicating a predominant role of adsorbate–adsorbate interactions.