Modifications to the four layer model

Abstract

Two variations of the model BOWDEN described in Chapter B2 are presented here. The original model requires, as an input, the equilibrium concentration of adsorbate. This format is useful for studying the effects of varying the values of the parameters and of varying the conditions used. It can also be useful for comparing the model with data — several publications report adsorption in terms of equilibrium concentration of adsorbate. However it is also convenient to be able to relate adsorption to the initial conditions. This is the format of the present version. This format is also useful for comparing the model with data as there are also many publications in which adsorption is reported in terms of the initial concentration. This version of the model, ZNCL2, is supplied in a form suitable for modelling the reaction of Me²⁺ MeOH⁺, and/or, MeCl⁺ ions with a surface. The reasons for this choice are firstly that this is a common situation, and secondly that it illustrates how to deal with cases in which complexes such as MeCl⁺ may also be involved in the reaction. The algebraic development of the equations used to relate adsorption to the initial concentration is given in Chapter B3.