RATES OF PHOTOCATALYTIC OXIDATION OF CRUDE-OIL ON SALT-WATER ON BUOYANT, CENOSPHERE-ATTACHED TITANIUM-DIOXIDE

The rate of TiO2-photocatalyzed oxidation of crude oils spilled on aqu eous 0.5 M NaCl was determined by measuring the rate Of O2 uptake. The photocatalyst was attached to 100-mum-diameter fly-ash-derived buoyan t cenospheres. Partial hydrophobic coating of the cenospheres assured their retention at the air-oil interface. The rate depended on the nea r-UV (broad band, 365-nm peak) irradiance below 25 W m-2, but varied o nly mildly with irradiance in the 25-45 W m-2 range. It increased upon wave motion imitating agitation of the liquid, and upon increase of t he cenosphere:oil mass ratio. It varied only mildly for different crud es (Arab Heavy, Arab Light, Basrah Light, and Texaco Bruce No. 1). Fro m the measured rates, cleanup times as short as 5-10 days were estimat ed.