Collect. Czech. Chem. Commun. 1992, 57, 1005-1014

The Adsorption of Iodide Anion on the Dropping Mercury Electrode in Water + 10% Ethanol Mixture

Luis Pérez Oliva, Pilar Carro, Alberto Hernández Creus and José Morales

Departamento de Química Física, Facultad de Quimica, Universidad de La Laguna, Tenerife, Canary Island (Spain)


The adsorption of iodide anion on the dropping Hg electrode from KI + KF solutions at a constant ionic strength in water and water + 10% ethanol mixture at 25 °C has been studied. Results show that I- adsorption is qualitatively similar in both systems. The adsorption equilibrium in both cases can be described through a Frumkin-type adsorption isotherm, although the corresponding parameters depend on the metal charge density and the solvent composition. In the presence of ethanol, the adsorption of I- ions decreases drastically. This fact appears to be mainly related to changes in the solvent structure, rather than due to the competitive adsorption of solvent molecules and I- anions.