The capture of colloidal particles on surfaces and in porous material: basic principles

Abstract

The deposition of colloidal particles onto surfaces can be considered a special case of hetero-coagulation. Deposition and detachment kinetics are determined by a combination of colloidal and hydrodynamic factors. For well-defined geometries and for systems in which particle–wall interactions are attractive, the deposition rate can be predicted accurately from first principles. When repulsive interactions are operative, theoretical difficulties arise from a number of sources, such as a coupling between hydrodynamics and electrokinetics, surface charge regulation, and shear-induced modification of configurations of adsorbed polymers. These complications prevent accurate prediction of slow deposition rates. Also, no good a priori models exist to predict detachment rates, although trends can be predicted. Experimental examples will be provided of colloidal particle deposition on flat surfaces in an impinging jet, in which the flow is well defined, and in porous beds consisting of pulp fibers, in which the flow is rather ill defined. Effects of electrolyte and polymers on deposition are discussed.