Exploring influence of organics on the photodegradation of nitroaromatic compounds: Focus on HONO/NO formations and kinetics

The effects of aromatic carbonyls (ACs), polycyclic aromatic hydrocarbons (PAHs) and phenols (PHs) on the photolysis of nitroaromatic compounds (ArNO 2 ) in the solid phase were explored. The reactive nitrogen gas formation by the photolysis process was investigated in a cylindrical reactor coupled to a NO x analyzer. These organics had an enhanced or inhibited influence on the nitrous acid (HONO) and NO formations by the photolysis of 1-nitropyrene (NPy) and 5-nitrosalicylic acid (NSA), depending on the hydrogen abstraction and donation abilities of organics. Based on the high-performance liquid chromatography (HPLC) results, methyl-2-benzoylbenzoate (MBB), fluoranthene (FLA) and syringaldehyde (SG) showed a promoted effect on the photodegradation of NPy and NSA, as shown by an increase in the photolysis frequency of ArNO 2 ( J ArNO 2 $J_{{\mathrm{ArNO}}_2}$ ) by a factor of 1.19–2.76. Based on experimental results, the HONO source strength by the photolysis of ArNO 2 in organic aerosols was estimated to be lower than 1 ppt h −1 .