Study on Dispersion of TiO(2) Nanopowder in Aqueous Solution via Near Supercritical Fluids

[Image: see text] In this study, we investigated the effects of near supercritical carbon dioxide (SCCO(2)) parameters, including pressure, temperature, and saturation time on titanium dioxide (TiO(2)) nanopowder dispersion in water-containing sodium hexametaphosphate (SHMP). The stability and morphology of TiO(2) 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 SCCO(2)’s pressure and saturation time had the strongest impact on TiO(2) dispersion in water-containing SHMP. This finding indicated that TiO(2)’s secondary average particle size was significantly reduced with an increase in near SCCO(2)’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 TiO(2) particle surface. The secondary average size was 127 ± 68 nm, indicating good stability of TiO(2) dispersed in water containing an inorganic dispersant.