HYDROPHOBIC INTERACTION AND STABILITY OF COLLOIDAL SILICA

Quasielastic light scattering and electrophoretic mobility measurements on aggregates of an aqueous silica colloid at a constant pH of 9.2 and constant ionic strength in the presence of a cationic surfactant, tetradecylpyridinium bromide (TPB), are presented. Depending on the amount of TPB added, there exist two regimes of aggregation, namely fast flocculation in the middle concentration region and slow aggregation at the two extremes. A correlation between the electrokinetic behavior and the colloid stability has been observed. By taking into account the hydrophobic interaction with an exponential decay character [J.N. Israelachvili et al., J. Colloid Interface Sci., 98 (1984) 500] the modified DLVO stability theory could successfully interpret the aggregation behavior of the silica colloid studied. © 1990.