Heterogeneous photocatalytic decomposition of polyaromatic hydrocarbons over titanium dioxide

The photocatalytic degradation of a mixture of 16 polyaromatic hydrocarbons (PAHs) was investigated in aqueous suspensions of high surface area TiO2 illuminated with 310–380 nm ultraviolet light. Triethylamine was utilized for extraction of PAH compounds from motor oil contaminated soil and subsequently to increase PAH solubilities in TiO2/water slurries. Minimum steady-state hydroxyl radical (HO•) concentrations generated during photocatalysis were determined directly by electrospray ionization mass spectrometry analysis of a stable spin-trapped HO• adduct. In contrast to organic compounds like trichloroethylene which are readily mineralized over TiO2, the PAHs investigated here were relatively slow to degrade although several compounds (acenaphthylene, anthracene, benzo(a)pyrene, and dibenzo(a,h)anthracene) displayed exceptional decomposition kinetics.