Calculation of the rate of coagulation of hydrophobic colloids in the non-steady state

Abstract

In accurate coagulation measurements, the observed coagulation rate should be extrapolated to time zero to find the rate of formation of doublets from singlet particles. In the theoretical calculation of coagulation rates, generally a steady state is assumed. At the onset of coagulation, however, a transient state is present. The results are given of numerical computations of the transient-state coagulation rate for the cases of Van der Waals attraction only and of Van der Waals attraction combined with double layer repulsion. The duration of the non-steady state is about the same as the one calculated by Von Smoluchowski for the case of no long-range interaction. It is expected that no transient effects will be found in classical coagulation experiments, but they may interfere with rapid (stopped-flow) measurements of the rate of rapid coagulation.