Study on Dispersion of TiO2 Nanopowder in Aqueous Solution via Near Supercritical Fluids.

Abstract

In this study, we investigated the effects of near supercritical carbon dioxide (SCCO2) parameters, including pressure, temperature, and saturation time on titanium dioxide (TiO2) nanopowder dispersion in water-containing sodium hexametaphosphate (SHMP). The stability and morphology of TiO2 particles dispersed in an aqueous solution were examined using a zeta potential instrument, dynamic light scattering, and transmission electron microscopy. As shown in the results, of particular interest, it was found that near SCCO2’s pressure and saturation time had the strongest impact on TiO2 dispersion in water-containing SHMP. This finding indicated that TiO2’s secondary average particle size was significantly reduced with an increase in near SCCO2’s pressure and saturation time. Additionally, in the presence of SHMP, the zeta potential of the as-prepared dispersion solution reached −53.7 mV because of production of the larger negative static charge repulsion force (resulting from SHMP dissociation) on the TiO2 particle surface. The secondary average size was 127 ± 68 nm, indicating good stability of TiO2 dispersed in water containing an inorganic dispersant.