Coagulation rate coefficient in colloidal systems: A hybrid stochastic-deterministic theory

The Smoluchowski's coagulation rate coefficient (k(c-S)) has been used for decades notwithstanding its predictions are not always consistent with experimental data. In this work, k(c-S) and Herrera-Ordonez (k(c-HO)) models, were modified and combined to obtain a hybrid equation k(c-h) for the rate coefficient of rapid coagulation. Modification of k(c-S) consisted in adapting the concepts of diffusion-reaction, such as effectiveness factor F, to the case of particle coagulation which is considered a pseudo-reaction. Unlike the deterministic and stochastic approaches, the hybrid model k(c-h) can fit experimental data for the effects of size and concentration of particles, on kc, using only one adjustable parameter value for all particle sizes. The higher predictability of k(c-h) suggests that their assumptions are more realistic. The behavior of F indicates that the fusion of relatively large particles is more effective than that of small particles to produce the sink effect. (C) 2020 Elsevier Ltd. All rights reserved.