Metal-halide-complex and ligand simultaneous adsorption. Chronocoulometry study in the Cd(II), KI Hg system at several ionic strengths

The previous approach developed to study anion-induced adsorption of Cd(II) halide solutions [10] is applied to the Cd(II)-iodide system at several io nic strengths. The experimental surface excess of Cd(II) is calculated for single step chronocoulmetry and a new expression fur the: change of capacit ive charge during the potential step has been obtained in order to include the change in ligand adsorption promoted by the adsorption of the metal com plexes. As was obtained in bromide medium, the approach allows one to concl ude that the anionic tricoordinate, CdI3- and tetracoordinate, CdI42-, meta l complexes are the adsorbed species on the electrode surface predominating the adsorption of CdI42- as ionic strength became higher.