ABSTRACT
The term "adsorption" refers to the increase in the concentration of a component at the interphase between two volume phases. Thermodynamics defines the adsorption process as a way to attain equilibrium in a heterogeneous system by simultaneous reactions that increase and decrease the concentration of components in the interface layer. Various hypotheses have been conceived concerning the elementary process that occurs during adsorption of ionic or nonionic, inorganic or organic substances on solids. In the following section the most important results of the adsorption of electrolytes, surfactants, and polymers are summarized, with specific emphasis on aqueous systems.
