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Photoenhanced NO 2 Loss on Simulated Urban Grime
Author(s) -
Ammar Rachid,
Monge Maria Eugenia,
George Christian,
D'Anna Barbara
Publication year - 2010
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201000540
Subject(s) - pyrene , chemistry , nitrite , irradiation , relative humidity , ion , inorganic ions , ion chromatography , environmental chemistry , analytical chemistry (journal) , photochemistry , chromatography , meteorology , organic chemistry , physics , nuclear physics , nitrate
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.