ABSTRACT
The number of particles per unit volume may change because of aggregation, sedimentation, and/or chemical reactions. The differentiation between the terms flocculation, coagulation, and aggregation is difficult because of their ambivalent usage. Flocculation and coagulation can be conveniently treated as a two-step process: destabilization of dispersed particles resulting in a reduced repulsion between particles and aggregation of colliding destabilized particles. Flocculation kinetics is studied for practical and theoretical reasons, because flocculation rates indicate dispersion stability and provide valuable information on interaction of particles. The degree of flocculation has been defined as the ratio of the number of particles in a system after flocculation to the number of particles present before flocculation. Aggregation in dispersion can be assessed by examining the whole system or its components: the particles in dispersion, the aggregates, and the supernatant liquid the sediment. Heterocoagulation is the term used to describe aggregation of different particles.
