Site binding, description

A. (1996 a) Comparison of different site binding models for cation sorption Description of pH dependency, salt dependency and cation proton exchange. J. Colloid Interface Sd. 181 45-59... 

Approaches based on conductance calculations. More direct, these approaches focus in the measured quantity the conductance. There are two main groups of theories. One is based on a tight-binding description of the transport processes where the electron current jij between to adjacent sites i and j, is evaluated by using [26-28] ... 

The site binding model based on reactions (1), (2), (14) and (15), often called surface complexation model (SCM), was, beside the simple site binding models (for example two layer model or constant capacitance model) readily applied to a description of the edl on the metal oxide-electrolyte solution interface. Reactions (14) and (15) describe the adsorption of so-called back-... 

Despite successful applications to many ceramic powder/water interfaces, the site-binding model has several ambiguities in its description of the nature... 

T 0 successfully model the surface charge and surface potential requires an accurate description of surface complexing reactions. For illustration purposes, we use sphalerite, a sulfide mineral, as an example to show the surface site-binding model [28,29]. The first step in the model development is to identify the surface species. In the present case these are = ZnSH, =SZnOH, and =SH2, with representing the surface. The second step involves considerations of all species present in the inner Helmholtz plane for the system of interest. For sphalerite in a simple electrolyte solution (NaCl), as in our example, the species includes =SZnOH — Zn, =SZnOH —Na, and =ZnSH — CP. With all the species being identified, the complexing reactions associated with these species need to be specified and the mass action law applied. These are summarized in Table 1 for the current example. 

A two-site binding model (Eq. 3.4) was also considered. However this proved to be an unsuitable description for all datasets, producing binding parameters with standard errors many times larger than the parameters themselves, and so was disregarded. 

Once the molecules are aligned, a molecular field is computed on a grid of points in space around the molecule. This field must provide a description of how each molecule will tend to bind in the active site. Field descriptors typically consist of a sum of one or more spatial properties, such as steric factors, van der Waals parameters, or the electrostatic potential. The choice of grid points will also affect the quality of the final results. 

---