Synthesis of TiO2 nanoparticles by hydrolysis of TEOT and decrease of particle size using a two-stage mixed method

A new preparation method of particles was introduced, which consisted of a semibatch-batch two-stage reaction to decrease the size of TiO2 fine partic les. Using a semibatch process as a first stage, the particle size grew to a certain level (132 nm). Using a batch process as a second stage, however, the particle size decreased about 42 nm. The particles prepared by using a two-stage (semibatch-batch) method had a smaller mean particle size and sm aller standard deviation than those obtained from the single-stage process. In Us work, the statistical experimental method was also used to compare t he various properties of the TiO2 particles according to the six parameters [concentration of TEOT during 1st and 2nd stages, reaction temperature dur ing lst and 2nd stages, the amount of hydroxypropyl cellulose (HPC) during Ist and 2nd stages]. It was found that the optimum conditions for the maxim um reduction of TiO2 Particle size using this method were as follows: (1st TEOT (M): 0.091, 2nd TEOT (M): 0.146, Ist temperature (degreesC): 20.0, 2nd temperature (degreesC): 38.2, Ist HPC (X 10(-2) g/cm(3)): 0.018, 2nd HPC ( X 10(-2) g/cm(3)): 0.290). The experimental results measured by using the above optimum conditions were in agreement with calculated results and prod uced the smallest size (similar to 42 nm in diameter) with the value of DPS (-90 nm). In c addition, we found that the main parameters affecting the d ecrease of particle size were concentration of TEOT and the reaction temper ature during second stage. (C) 2001 Elsevier Science B.V. All rights reserv ed.