Highly dispersed behavior of thermal plasma-synthesized TiO₂ nanoparticles in water

Abstract

Spherical TiO₂ nanoparticles, with mean primary particle sizes of 29 and 53 nm, were synthesized by Ar/O₂ radio frequency (RF) induction thermal plasma pyrolysis of atomized liquid precursors containing titanium tetrabutoxide. In the synthesis of the 29-nm-sized TiO₂ nanopowders, the counter-flow gas was injected against plasma from the bottom of the reactor in order to enhance the quench rate. The plasma-synthesized nanoparticles at 1.0 vol % in solid fraction were dispersed by ultrasonic irradiation in the aqueous solution of polyacrylic acid with an average molecular weight of 8000. The mean aggregate size of the plasma-synthesized powders in aqueous suspension measured by a particle size analyzer corresponded exactly to the mean primary particle size evaluated by examining surface area data and by analyzing scanning electron microscopy (SEM) images, which suggests that the plasma-synthesized TiO₂ nanoparticles were individually dispersed in water.