A critique of the adsorption isotherms used in electrochemical processes involving the adsorption of organic compounds

Abstract

The main adsorption isotherms used in electrochemical processes involving the adsorption of organic compounds have been analysed both theoretically and experimentally in order to clarify the models, the limits of their applicability and the validity of the results obtained. The isotherms are divided into two categories: (a) isotherms based on continuous-solvent models and (b) isotherms based on discrete-solvent models. The isotherms of category (a) have, in general, low applicability, while their models do not give a realistic description of the adsorbed phase. However, the discrete-solvent models are closer to the physical reality of the electrode/solution interface, although only the generalized Flory–Huggins isotherms seem to provide both high applicability and believable conclusions concerning the particle–particle interactions of the adsorbed phase.