Photodegradation mechanisms of 1-nitropyrene, an environmental pollutant: the effect of organic solvents, water, oxygen, phenols, and polycyclic aromatics on the destruction and product yields.

This work describes studies of the photodegradation mechanism of 1-nitropyrene (1-NO(2)Py) in a chemical model system consisting of an organic solvent and known constituents of an aerosol particle. Photoproducts such as 1-hydroxypyrene (1-OHPy), 1-hydroxy-x-nitropyrenes (1-OH-x-NO(2)Py), 1-nitrosopyrene, and 1,6- and 1,8-pyrenediones were identified by high-performance liquid chromatography (HPLC) and HPLC/mass spectrometry (HPLC/MS) techniques, and their quantum yields show a significant dependence on the type of solvent. The photodegradation quantum yield of 1-NO(2)Py, φ((-1-NO2Py)), was larger in toluene, benzene, and polar protic solvents (10(-3)) in comparison with nonpolar and polar aprotic solvents, where the yield is on the order of 10(-4).