Abstract
The breakup of floes composed of a small number of constituent particles by orifice contractile flow is investigated extensively by measuring the size of broken floes of PSL particles on a Coulter counter. It is found that (1) floes of maximum strength are obtained when they are formed in an electrolyte concentration greater than the critical coagulation concentration, and the strength is independent of the valency of electrolyte; (2) the average size of broken floes and the maximum number of constituent particles in a broken floe are successfully expressed as a function of the energy dissipation at the orifice; and (3) the mechanism of floe breakup in the contractile flow is different from that by ultrasonication (flocs are split into smaller agglomerates in the former case, but particles are ripped off one by one from the surface of flocs in the latter case).
