ABSTRACT
I. Introduction 249 II. Electrical Interfacial Layer 250
III. Langmuir Isotherm 253 A. Empirical approach 254 B. Extended Langmuir isotherm 255
IV. Surface Complexation Model 257 A. Mechanism of surface reactions 258 B. Surface charging 258 C. Adsorption of (large) organic ions 259 D. Adsorption of heavy metals on metal oxides 267 References 271
I. INTRODUCTION
Numerous phenomena in colloidal systems are influenced by interfacial properties. This chapter considers solid-liquid interfaces and will be devoted to metal oxides. One of the most important phenomena in interfacial chemistry is the electrostatic charging of the surface due to interactions with ionic species from the bulk of the solution. In con sidering this problem one should distinguish the conductive metallic surfaces from other solids such as ionic crystals. In past decades, equilibria at metal oxide interfaces have been interpreted on the basis of the surface complexation model (SCM) [1] which is some times called the site binding model. The main feature of this approach is based on inter actions of bulk ions with specified surface groups. The resulting interfacial species are called either surface complexes or associates depending on the nature of the chemical bond. Several reactions may take place at the interface, and this problem is discussed in details in Chapters 4 and 5 of this book.
