INVITED REVIEW STABILITY OF COLLOIDAL DISPERSIONS

The stability of colloidal dispersions has traditionally attracted considerable attention in the chemical literature because of its origins in the physical chemistry of electrostatic and steric interactions between surfaces immersed in liquids. Moreover, progress in the physics and chemistry of stability phenomena has a direct impact on chemical engineering research, since stability of dispersions plays an important role in the rheology and transport properties of charged particles in liquids, separation processes (such as membrane filtration and solid/liquid separation), deposition and particulale fouling phenomena and numerous other processing operations. This paper presents a discussion of physical and chemical factors that affect colloidal stability and, in addition, presents an overview of the status of current research needs in this area. In addition to electrostatic and steric effects, some recent studies on the role of bulk motion of the supporting liquid on stability are also discussed. The emphasis throughout is on the stability of dilute dispersions, in which simultaneous interactions between more than two particles are negligible. Some major research needs in the above areas are also identified.