Interfacial behaviour of isopropanol at the Hg electrode from solutions of H2O-isopropanol-HCl

Abstract

The adsorption of isopropanol on mercury in aqueous solutions of HCl at constant chemical potential of the acid has been determined from capacity and electrocapillary measurements. The maximum adsorption occurs at a charge of −2.2 μC cm−2. The Frumkin isotherm is obeyed, the a factor in the isotherm changes from a positive value for mixtures rich in water to a negative value for mixtures rich in alcohol. The standard Gibbs energy of adsorption depends quadratically on the potential. The orientation of the alcohol molecule in the interface is discussed. Keywords: interface, medium effects, adsorption isotherm, aliphatic alcohol, Gibbs energy of adsorption.