KINETICS OF MAGNETIC FLOCCULATION .2. FLOCCULATION OF COARSE PARTICLES

For pt.I see ibid., vol.23, p.1447 (1990). In theoretical studies of flocculation kinetics one usually assumes that the flocculation process reaches a steady state very rapidly. This assumption is invalid when a long-range attraction between the particles is present. In this paper the authors show that such a situation occurs for magnetic flocculation, provided that the particles are not too small. A full mathematical description of such a process is very difficult. As an alternative, a modified version of von Smoluchowski ’s model for rapid flocculation is presented, which describes the qualitative features of their experimental observations of aqueous Mn2O3 colloids with a particle diameter of about 0.8 mu m quite well. In particular this model suggests that the deviations from the ’steady-state ’ predictions increase very rapidly with increasing particle size, making these results almost always incorrect for many practical applications of magnetic flocculation. © 1990 IOP Publishing Ltd.