In this paper, vertically aligned nanotubes arrays of titanium oxide were fabricated on the surface of titanium substrate by direct anode oxidation with HF being the supporting electrolyte. Under the condition of applying the same bias on the electrodes, a higher anodic photocurrent of the TiO2 nanotubes electrode was obtained than that of TiO2 film electrode, which is due to the larger specific surface area, novel microstructure and higher efficient surface-interface electron migration of nanotube electrode. The degradation of a textile azo dye, Acid Orange 7（AO7）, in aqueous solution with TiO2 nanotubes electrode was carried out using photoelectrocatalytic（PEC） process, comparing with electrochemical process（EP） and photocatalytic（PC）. A significant photo-electrochemical synergetic effect was observed. The reason is attributed to the surface state characteristics and higher separation efficiency of photo-generated charge carrier of nanotube system.
TiO2 and montmorillonite composite photocatalysts were prepared and applied in degradingγ-hexachlorocyclohexane (γ-HCH) in soils. After being spiked withγ-HCH, soil samples loaded with the composite photocatalysts were exposed to UV-light irradiation. The results indicated that the photocatalytic activities of the composite photocatalysts varied with the content of TiO2 in the order of 10%<70%<50%<30%. Moreover, the photocatalytic activity of the composite photocatalysts with TiO2 content 30% was higher than that of the pure P25 with the same mass of TiO2. The strong adsorption capacity of the composite photocatalysts and quantum size effect may contribute to its increased photocatalytic activities. In addition, effect of dosage of composite photocatalysts and soil pH onγ-HCH photodegradation was investigated. Pentachlorocyclohexene, trichlorocyclohexene, and dichlorobenzene were detected as photodegradation intermediates, which were gradually degraded with the photodegradation evolution.
