Kinetics and size distributions in deaggregation of Titania nanocolloids

Titania is of relevance to chemical synthesis as a catalytic material and catalyst support, and a known photocatalyst with the ability to decompose a variety of pollutants in air and in water. Its ability to use naturally occurring sunlight to attack a variety of combustion pollutants and VOC suggests the possibility of low-cost, low-energy processes based on titania for maintaining a clean air and water environment. A study on the redispersion mechanism of heavily aggregated nanocolloidal titania was carried out to produce stable, well-dispersed nanoparticles. Despite the well-known ill-posed nature of the inverse problem, the combination of methodologies allowed to obtain reliable measures of the size distribution during peptization. Kinetics exhibited nearly first-order kinetics to a steady state size distribution which depended on the pH. An erosion-type mechanism in which colloidally unstable primary particles detach from aggregated clusters was presented. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).