A DYNAMIC LIGHT-SCATTERING STUDY ON AGGREGATION OF RODLIKE COLLOIDAL PARTICLES

The kinetics of aggregation of rodlike iron(III)hydroxide colloids in aqueous solution have been investigated by dynamic light scattering. K NO3 and K2SO4 electrolytes were used in different concentrations as co ntrollers for the aggregation kinetics. The experimental results of th e cluster growth were fitted in the fast regime to the diffusion limit ed aggregation (DLA) and are characterized by a power law with a fract al dimension d(f) = 1.71. Clearly, the slow aggregation shows the expo nential kinetics of the reaction limited aggregation (RLA). In the gro wing curves of the colloid clusters, a transition to a very fast aggre gation kinetic was observed. The transition occured at a typical aggre gate size which was crucially dependent on the colloid concentration. This was taken as an evidence for a percolation process.