Photo-Sinking of Titanium (IV) Oxide Powders

Abstract

The hydrophobic-hydrophilic change of the powder surface due to the decomposition of coated hydrophobic materials is applied to the choice of the photoactive TiO₂ powders. Surface modification treatment with the hydrophobic material let the powders of TiO₂ float on water, though the TiO₂ powders without the treatment sink to the bottom of the beaker. Under irradiation of a UV light, only some part of TiO₂ powders floated have started to drop to the bottom. We have found that the rate of the sinking depends on the decomposition rate of the coated material. As the TiO₂ powders which are effective for photocatalytic reaction can decompose the coated molecules, we can choose the efficient photoactive TiO₂ powders from its sinking rate.