THE TRIPLE-LAYER MODEL REVISED

The triple layer model (TLM) and the procedures for searching out its parameters, i.e. statistical optimization and the double extrapolation, have been critically reviewed and modified. The Gouy-Chapman equation and the assumption of constant values for the capacitances have been demonstrated to be inconsistent with the rest of the model. However, the constant capacitance model physically resembles the TLM near the point of zero charge (PZC). A new set of independent variables and functions has been employed. The dependence of these functions on the electrolyte activity and adsorption density at the PZC has been shown to have a very simple analytical form. A new statistical optimization procedure has been developed. It needs no approximations, two adjustable parameters, and an independent knowledge of two or three quantities among surface charge, surface potential, inner layer capacitance, total surface site density and inert electrolyte adsorption density. Only the data around the PZC may be employed to estimate the system constants.