Photocatalytic Destruction of Dioxins in Exhaust Fuel Gas and Wastewater

抄録

Dioxins are extremely toxic and it is difficult to treat dioxins with conventional methods. Photocatalytic silica-gel is prepared by coating TiO₂ transparent film on the silica-gel bead. When photocatalytic silica-gel is irradiated with UV light, electron (e^- ) and positive hole (h⁺), in the conduction band and valence band, are formed on the TiO₂ surface. The positive hole is apparently able to oxidize a water molecule to hydroxyl radical (OH•) , while the electron is trapped by O₂ molecule to yield superoxide radical (O₂^-). The electron/hole pairs, hydroxyl radical and superoxide radical, have strong oxidation activity. The oxidation of organic pollutants are mediated by a series of reactions raised by hydroxyl radical and/or superoxide radical on the TiO₂ surface. In this study, we carried out destruction of dioxins in exhaust fuel gases and wastewater by photocatalytic silica-gel/UV system.