Understanding adhesion: A means for preventing fouling

Adhesion of particulate materials is an important step in the formation of fouling. Because the size of such materials is generally less than 1 mu m the phenomenon can be described in terms of colloid chemistry. Accordingly, the net force of interaction between foulants and the surface has been described in terms of DLVO theory (van der Waals attraction and electrostatic double-layer repulsion). However, those forces are sometimes not sufficient to describe the formation of fouling. Recent works have made it possible to calculate the effect of hydrophobic interactions and steric forces, which can also be taken into account. In aqueous media, the various types of interactions can be strongly affected by the pH, the ionic strength, the type of ions, and the presence of polymeric molecules. The objective of this work is to give a general overview of the basic physicochemical factors playing a role in fouling and to outline some practical aspects related to the theoretical reasoning to help prevent or at least mitigate fouling. (C) Elsevier Science Inc., 1997.