Light-induced transformations of aza-aromatic pollutants adsorbed on models of atmospheric particulate matter: Acridine and 9(10-H) acridone

Abstract

The effect of the characteristics of the surface on the phototransformation of acridine, one of the most abundant azapolycyclic compounds encountered in urban atmospheres, and of one of its principal photoproducts, acridone, was studied when adsorbed onto models of the atmospherice particulate matter. For this purpose, relative photodegradation rates were determined from absorption or emission intensities as a function of irradiation times, and some products were isolated and characterized. The relative photodegradation rates of adsorbed acridine show the tendency (NH 4 ) 2 SO 4 > MgO > Al 2 O 3 >SiO 2 . In general, the rates decrease as the fraction of protonated acridine species on the surface increases in MgO, Al 2 O 3 , and SiO 2 , except for (NH 4 ) 2 SO 4 where a fast surface reaction occurs. Oxygen reduces the photodestruction rates by as much as 40 to 60% when compared to an inert atmosphere, implying the participation of an acrideine triplet state in the transformation processes on all surfaces except on (NH 4 ) 2 SO 4 . Acridone, a major product, undergoes a photoinduced tautomerization to 9-hydroxy acridine. The formation of a dihydrodiol, another photoproduct of acridine, is suggested by comparison to reported spectral properties of these compounds. This is formed through a singlet oxygen reaction. Photoproducts showing the absence of the narrow absorption band of 250 nm, characteristic of the π →π* transition in tricyclic aromatics, were detected in small yields but not identified. These results suggest possible photochemical transformation pathways that could lead to the ultimate fate of these pollutants in the environment.

Assessment of azaarenes and azaarones (oxidized azaarene derivatives) in the Dutch coastal zone of the North Sea

“…De Voogt et al (1999) concluded that keto-metabolites are major products in the aquatic fate of benzoquinolines. In the atmosphere similar photochemical transformations have been observed (Negrón-Encarnación and Arce, 2007). In contaminated groundwater hydroxylated N-heterocyclics have been reported to be significantly higher than their parent compounds (Pereira et al, 1988;Reineke et al, 2007).…”

Screening of soil bacteria as potential agents for drugs biodegradation: a case study with clofibric acid

“…In 1976, this molecule was the first pharmaceutical compound detected in the environment, because of its chemical structure similar to the herbicide mecoprop . This drug is considered an environmental compound of concern because of its occurrence and persistence (with an estimated half‐life > 21 years) . It is hardly or not degraded by the conventional technology used in wastewater treatment plants (WWTPs).…”

On the Photochemical Stability of the 9‐Mesityl‐10‐methylacridinium Cation

“…These may arise from singlet-oxygen reactions, especially because mes-acr + has been shown to be a good 1 O 2 sensitizer, [22] and formation of a dioxetane at the acridine group has been reported. [23] A more detailed analysis of the oxygen uptake kinetics is underway to shed more light on the breakdown reactions, and these findings will be reported at a later date. …”