title: Photoenhanced NO2 loss on simulated urban grime.
abstract: The present study focuses on the heterogeneous reaction between gaseous NO(2) and solid pyrene/KNO(3) films, used as a simplified proxy of urban grime. This reaction is investigated under simulated atmospheric conditions with respect to relative humidity, NO(2) concentration and irradiation in a coated-wall flow-tube reactor. The geometric steady-state uptake coefficients γ(geo) for pyrene/KNO(3) films exposed to 50 ppbv of NO(2) ranged from 1.12×10(-7) in the dark to 2.67×10(-6) under near-UV irradiation (300-420 nm) and decreased with increasing NO(2) concentration in the range 30-120 ppbv. NO(2) removal is linearly dependent on light intensity, with release of gas-phase NO and HONO. Analysis of the solid film by ion chromatography and GC-MS showed the formation of nitrite ions and traces of 1-nitropyrene. A light-induced reaction mechanism is proposed. The results discussed herein suggest that PAH-containing urban grime on windows and buildings may be a key player in urban air pollution.
authors.affiliation: Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), UMR5256, Université de Lyon 1, CNRS, Villeurbanne, 69626 France.
authors.forename: Rachid
authors.initials: R
authors.lastname: Ammar
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Monge
authors.forename: Christian
authors.initials: C
authors.lastname: George
authors.forename: Barbara
authors.initials: B
authors.lastname: D'Anna