Formation of Titanium Dioxide Nanoparticles Generated without Dispersant in Continuous Aging Tube Reactor

Abstract

A new method for the preparation of TiO2 nanoparticles was introduced, which consisted of a small reactor for controlling the hydrolysis rate and aging tube for decreasing the particle size. In this process, TiO2 nanoparticles were synthesized from the hydrolysis and condensation of TEOT (tetraethylorthotitanate) without HPC (hydroxypropylcellulose) dispersant. The advantages of the HPC dispersant have been reported. In spite of these advantages, however, the resulting particles appeared to be formed of agglomerates of much smaller subunits (2 ~ to 4 ~ nm diameter) and, because of this low density, they exhibited poor sintering characteristics. In this study, the particles prepared by using a continuous reaction method without HPC dispersant had a smaller mean particle size and narrower size distribution than those obtained from the batch or semi-batch process using the dispersant. In the preparation of using continuous aging tube reactor, the particle size of TiO2 decreased with increasing reaction temperature and mole ratio (H2O/TEOT). However, the particle size increased with increasing the diameter of aging tube. The optimal conditions for the formation of nanoparticles were as follows

reaction temperature (42.5 ℃), aging tube diameter (1.5 mm), mole ratio (80), and flow type in aging tube (intermittent type). By using the above optimal conditions, mean particle diameters as small as 40 nm were obtained.