Efficient Photodegradation of Phenanthrene under Visible Light Irradiation via Photosensitized Electron Transfer

Abstract

Photoinduced electron transfer between transition metal ions and polycyclic aromatic hydrocarbons (PAHs) was utilized to induce the photodegradation of phenanthrene (PHE), a tricyclic aromatic hydrocarbon, under visible light irradiation (λ > 420 nm). Experimental results indicate that Fe3+ ions possess excellent ability of sensitization in the photodegradation of PHE. In solution, PHE could be oxidated completely by oxygen after 3 h irradiation. The intermediates of PHE photodegradation were detected by gas chromatography−mass spectrometer. Eleven kinds of intermediates were determined, including one decomposition product, five ring-opening products, and other oxidation derivatives. Phenanthrenequinone and (1,1‘-biphenyl)-2,2‘-dicarboxaldehyde were the two main products. Based on the experiment results, a possible mechanism was proposed. In alcohols and acetic acid, the photodegradation efficiency of PHE was low, probably because that active PHE•+ was quenched in these solvents. The impacts of variable f...