Particle transfer and deposition from flowing colloid suspensions

Abstract

The phenomenology of colloid particle transport and deposition onto solid interfaces (collectors) is discussed. Various effects influencing particle transfer are considered, including diffusion, convection, geometrical interception and migration under external force (gravity). The role of dynamic tangential specific interactions in particle adsorption and deposition (irreversible adsorption) is elucidated. Certain theoretical approaches describing quantitatively particle deposition kinetics are presented, in particular the general convective-diffusion theory and the “perfect sink” model. Theoretical predictions are compared with experimental results obtained by the rotating disc and stagnation point flow methods based on direct microscope observations of particle deposition in situ. In these experiments, mineral particle (CaCO 3 and BaSO 4) and mono-disperse latex suspensions were used (particle size ranging from 0.2 to 4 μm) and the collector surfaces were made from glass and mica. The influence of particle size, flow intensity, ionic strength, etc. on particle deposition rate is illustrated. The experimental results obtained for high surface coverages (geometrical blocking effects), high ionic strength and flow intensity (desorption effects) and for energy barrier limited deposition kinetics are also discussed. These experiments confirm that our general theory can adequately describe particle deposition kinetics for a broad range of particle size, and flow conditions for collectors of various geometrical shape.