| Photocatalytic characteristics of nano-sized TiO₂ powder with rutile phase produced using homogeneous precipitation process at low temperatures (HPPLT) were compared with those of commercial P-25 powder by Degussa Co. The TiO₂ powder by HPPLT showed very higher photoactivity in the removal rate, showing lower pH values in the solution, than the P-25 powder when eliminating metal ions such as Pb and Cu from aqueous metal-EDTA solutions. This can be inferred the more rapid photo-oxidation or -reduction of metal ions from the aqueous solution, together with relatively higher efficiencies in the uses of electron and hole formed on the surface of TiO₂ particle, under UV light irradiation. Also, in the view of the TiO₂ particle morphology, compared to the well-dispersed spherical P-25 particle, the agglomerated TiO₂ particle by HPPLT consists of acicular typed primary particle with the thickness ranged of 3∼7 ㎚, which would be more effective to the photocatalytic reactions without electron-hole recombination on the surface of the TiO₂ particle under the UV light irradiation. It is, therefore, thought that the higher photoactivity of the rutile TiO₂ powder by HPPLT in the aqueous solutions resulted from having its higher specific surface area as well as acicular shape primary particle with very thin thickness. |
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