Simplification of a model for ion adsorption on oxide surfaces

The adsorption equation of Bowden et al. (I 977) was modified so that adsorption at a constant pH could be described by three parameters. One of these parameters represents the maximum adsorption. The second is the product of three characteristics. These are the binding constant for the adsorbing ion; the proportion of the adsorbate present as that ion; and the electrostatic potential in the plane of adsorption before adsorption had started. The third parameter indicates the rate at which the electrostatic potential in the plane of adsorption changes as adsorption increases. With these modifications, the adsorption equation may be linearized and graphs used to estimate the parameters. This simplification may be of value either when there is no data for the charge characteristics of the surface, or when there is insufficient computer expertise to fit more complex models.