Photo Decomposition Ability of Acicular Typed TiO_2 Ultrafine Powder with Rutile Phase in Aqueous 4-Chlorophenol Solutions

摘要

Photo decomposition ability of ultra-fine rutile TiO_2 powder was investigated using the photo-catalytic reaction in aqueous 1.0 mmol 4-chlorophenol (4CP) solutions with pH-controlled conditions. Its photo-catalytic characteristics were then compared with those of commercial P-25 powder having mainly anatase phase. When 4CP was completely decomposed by the photo-catalytic reaction, HPPLTed TiO_2 powder was more effective than the P-25 powder regardless of the crystalline structures. As the photo-catalytic reaction time increased, the decomposition of 4CP in the aqueous solution was accompanied with much consumption of OH~- ions. However, in the case of the aqueous solution at pH=4 naturally obtained by mixing of water and 4CP, the photo-catalytic reaction of the HPPLTed TiO_2 powder occurred more actively, compared with in the cases of the more acidic and caustic aqueous solutions. Therefore, it is thought that the decomposition of non-degradable 4CP would take place well at a certain amount of OH~- ion concentration in the aqueous solution, considering to show no difference in the adsorption of 4CP on the surface of TiO_2 particle with various pHs of the solution, when the HPPLTed TiO_2 powder with high surface areas more than 180 m~2/g was used.