Particle adhesion and removal in model systems. Part 6.—Kinetics of deposition of haematite particles on steel

Abstract

The kinetics of adhesion of uniform colloidal spherical particles of haematite on steel was studied as a function of pH, ionic strength and particle size. It was shown that deposition occurs when the collector and the particles have charges of opposite sign and that the rate of adhesion can be greatly affected by the extent of surface coverage by the adhered particles. The deposition of solids of the same charge as the substrate can be induced if a sufficient amount of an indifferent electrolyte is added. Data were interpreted in terms of existing theories of diffusional deposition; the model of Ruckenstein and of Pfeffer and Happel explained the adhesion of small particles (0.15 µm in diameter). The effect of the electrolyte was considered by using the interaction-force boundary-layer concept combined with the double-layer and dispersion terms.