ABSTRACT
I. Introduction 164 II. Mechanism of Surface Charge Creation at the Solid-Liquid Interface 165
A. Metal/electrolyte interface 165 B. Semiconductor/electrolyte interface 166 C. Ionic crystal (Agl)/electrolyte interface 166 D. Metal oxide (hydroxide)/electrolyte interface 168
III. Electric Interfacial Layer Models Without Counterion Association 169 A. Constant capacitance 170 B. Diffuse layer 171 C. Stern model 174 D. 1-pK model 174 E. 1-pK multisite approach 177 F. MUSIC 178
IV. Electric Interfacial Layer Models with Counterion Association 180 A. Empirical approach 180 B. Ion selectivity 181 C. Association 182 D. Surface complexation 183
V. Determination of Surface Ionization and Complexation Constants 186 A. Surface charge 187 B. Electrokinetic data 191 C. Adsorption of counterions 196
VI. Specific Adsorption 205 A. Methods 207 B. Proton stoichiometry 211
I. INTRODUCTION
Electrical charges at interfaces play a very important role in many practical applications and are crucial in understanding adsorption, stability, and other properties of colloidal systems. Detailed discussion of electrical aspects of interfacial phenomena can be found in a recent book by Lyklema [1]. Though each colloidal system is as a whole electroneutral, the properties of dispersed and continuous phases determine the charge distribution in the interfacial region. Due to electroneutrality conditions, charge at the solid surface is counterbalanced by an equal but opposite charge in the solution. Surface charge and countercharge at the solid-liquid interface form a so-called electrical interfacial layer (EIL). The structure of the electrical interfacial layer and the origin of the surface charge for different systems have been studied quite intensively in recent years, especially the EIL at the metal/electrolyte interface. The description of the electrical interfacial layer at the metal oxide (hydroxide)/electrolyte interface is much more complicated and less understood.
