Electrical double layer and adsorption of iodide ions at the Bi|propylene carbonate interface

The adsorption of I− ions on the Bi(1 1 1) single crystal plane from solutions in propylene carbonate has been investigated by impedance measurement method. The ionic charge due to the specific adsorption has been obtained using the mixed-electrolyte method for both electrode charge and electrode potential as the independent electrical variables. The Gibbs energy of adsorption of ions has been calculated using the different modifications of the virial adsorption isotherm. It was found that under comparable conditions the results obtained at constant electrode potential and at constant electrode charge are coincident and the adsorption of I− anion increases in the sequence of solvents: methanol < ethanol < propylene carbonate. The electrosorption valency has been calculated and it was found that this parameter increases in the sequence: propylene carbonate < ethanol < methanol.