Adsorption of C-5 Nitriles at Liquid Metal Electrodes. A Comparison of Adsorption Parameters for Isovaleronitrile at Polarized Surfaces of Mercury and Indium-Gallium Alloy (Eutectic Composition)

HgIn this paper a quantitative study of the adsorption of iso C4H9CN (iso-valeronitrile, IVN) at the interfaces between Hg and In Ga alloy (eutectic composition) electrodes and aqueous solutions is described. The equilibrium charge densities at Hg electrodes were determined from both electrocapillary and impedance measurements, whereas at the In Ga electrode only impedance data could be used. The adsorption parameters for IVN, including the free energy of adsorption (DGads), the lateral interaction parameter a, and the limiting Gibbs excess (Gmax) were calculated and compared with previous data relative to the behaviour of aliphatic compounds at different interfaces. The experimental results are discussed in terms of metal-solvent and metal-adsorbate interactions.