Sub-micro photocatalytic TiO2 particles for a water depollution: comparable removal efficiency to commercial P25 and easy separation via a simple sedimentation

Abstract The sub-micrometer sized TiO2 particles (100~200 nm) were synthesized by a sol-gel and subsequent thermal annealing. The particle size, surface area, pore structure, and crystallinity were varied upon the annealing temperatures (450, 550, 650 oC). The photocatalytic activities of three TiO2 particles annealed at various temperatures (450-, 550-, and 650-TiO2) were examined by performing photocatalytic depollution of three organic model pollutants (methylene blue, methyl orange, and phenol) from aqueous solutions under the UV light irradiation. Among three samples, 550-TiO2 (~200 nm) exhibited the highest photocatalytic activity towards the removals of all three model pollutants. Photocatalytic activity of the 550-TiO2 was compared with a commercial TiO2 (P25, Evonik) at various conditions of loading amounts of particles dispersed in MB solution. Light scattering by dispersed particles at high sample loading conditions was less pronounced in the case of 550-TiO2. Therefore, the sub-micro 550-TiO2 particles can exhibit comparable activity to P25 at high sample loading conditions (2-4 g/L). In addition, the bigger size of 550-TiO2 made it possible to separate them via a simple sedimentation process, showing a potential of sub-micro TiO2 particles as an efficient photocatalysts for water depollution.