Reversible Agglomeration: A Kinetic Model for the Peptization of Titania Nanocolloids

We formulate a model for the peptization of titania nanocolloids. The model assumes simultaneous agglomeration/deagglomeration with size-independent rate constants. It predicts that the evolution of the particle size exhibits first-order kinetics and that the final particle size scales as R approximately C1/df, where C is the mass concentration of the colloid and df is the fractal dimension. These predictions are tested experimentally. We find that the model provides a quantitative and consistent description of the peptization process over a wide range of experimental variables and that it allows the determination of the aggregation and deaggregation rate constants from the time evolution of the average size. Copyright 1999 Academic Press.