Photodegradation of some oxygenated polycyclic aromatic hydrocarbons

In order to obtain information about the degradability of oxygenated polycy clic aromatic hydrocarbons (oxy-PAHs) in environment photodegradation in ac etonitrile solution was studied on 9,10-phenanthtenequinone, 9-phenanthrene carbaldehyde (phenanthrene-9-carboxaldehyde) and 1,8-naphthalenedicarboxyli c anhydride (1,8-naphthalic anhydride), which are formed by fuel combustion or by photoirradiation of PAHs. A solution of the substrate was irradiated under atmospheric conditions using a xenon lamp. Photodegradation rates an d information about products were obtained using HPLC with fluorescence and photodiode array detectors and GC/MS. 9,10-Phenanthrenequinone rapidly degraded by irradiation of light and yield ed diphenic acid, diphenic acid anhydride, phthalic acid anhydride and some unknown compounds. Diphenic acid was a main product and it was produced at maximum upon 5-hour irradiation when degradation rate approached 100%. Thi s reaction seems not to obey first-order equation. 9-Phenanthrenecarbaldehy de degraded slower than 9,10-phenanthrenequinone and yielded a polar unknow n compound as a main product. While 1,8-naphthalenedicarboxylic anhydride s howed quite stable character under irradiation of light.