Equilibria in the Electrical Interfacial Layer Revisited

Equilibrium at the solid-liquid interface is the subject of numerous experimental and theoretical investigations. Several different models describing the structure of the electrical interfacial layer (EIL) and the mechanism of surface reactions are suggested in the literature. At present it seems impossible to decide which of them describe the real situation best. One of the routes towards the solution of this problem is the development of new experimental methods and simultaneous interpretation of different sets of data (e.g., adsorption data, Y0 data, s0 data, z-potential data, etc.). Interpretation based on such an approach may eventually enable differentiation between models and a better choice of appropriate ones. Another route is to refine or develop a new, more realistic and less approximate, theoretical concept. This article presents a review of such efforts (EIL structure, electroneutrality condition, surface potential measurements, capacitors within EIL, enthalpy of surface reactions, colloid stability, etc.), with special emphasis on the role of Nikola Kallay in this field, to whom this article is dedicated on the occasion of his 65th birthday.