Atmospheric Chemistry of Benzyl Alcohol: Kinetics and Mechanism of Reaction with OH Radicals Franc ̧ ois Bernard, † Isabelle Magneron, † Gre ́ gory Eyglunent, † Ve ́ ronique Daë le, † Timothy J. Wallington, ‡ Michael D. Hurley, ‡ and Abdelwahid Mellouki †, * † Institut de Combustion, Aé rothermique, Ré activite ́ et Environnement (ICARE), CNRS (UPR 3021), Observatoire des Sciences de l’Univers en re ́ gion Centre (OSUC), 1C Avenue de la Recherche Scientifique, 45071 Orle ́ ans Cedex 2, France ‡ Systems Analytics and Environmental Sciences Department, Ford Motor Company, Mail Drop RIC-2122, Dearborn, Michigan 48121-2053, United States * S Supporting Information ABSTRACT: The atmospheric oxidation of benzyl alcohol has been investigated using smog chambers at ICARE, FORD, and EUPHORE. The rate coefficient for reaction with OH radicals was measured and an upper limit for the reaction with ozone was established; k OH = (2.8 ± 0.4) × 10 −11 at 297 ± 3 K (averaged value including results from Harrison and Wells) and k O 3 <2 × 10 −19 cm 3 molecule −1 s −1 at 299 K. The products of the OH radical initiated oxidation of benzyl alcohol in the presence of NO X were studied. Benzaldehyde, originating from H-abstraction from the −CH 2 OH group, was identified using in situ FTIR spectroscopy, HPLC-UV/FID, and GC-PID and quantified in a yield of (24 ± 5) %. Ring retaining products originating from OH-addition to the aromatic ring such as o- hydroxybenzylalcohol and o-dihydroxybenzene as well as ring-cleavage products such as glyoxal were also identified and quantified with molar yields of (22 ± 2)%, (10 ± 3)%, and (2.7 ± 0.7)%, respectively. Formaldehyde was observed with a molar yield of (27 ± 10)%. The results are discussed with respect to previous studies and the atmospheric oxidation mechanism of benzyl alcohol. 1. INTRODUCTION Aromatic compounds are ubiquitous in the atmosphere; they are emitted by human activities and natural processes. The atmospheric chemistry of toluene, benzene, and xylenes has been intensively studied over the past few years to assess their contribution to urban air pollution. In the presence of NO X (NO 2 + NO), the degradation of aromatics leads to the formation of ozone and a number of photooxidants as well as secondary organic aerosol affecting air quality. 1−4 Benzyl alcohol (C 6 H 5 CH 2 OH, BzOH) is used in the pharmaceutical, cosmetic, perfume, food flavouring industries, in solvents, and in epoxy resin coatings. It has also biogenic sources and is emitted by fruits such as peachs, 5,6 raspberries 7 and blackberries 8 and in flowers such as petunia. 9−11 It has been also identified in indoor air. 12 There have been two previous studies of the atmospheric chemistry of benzyl alcohol, both were conducted at the National Institute for Occupational Safety and Health. 13,14 In the first investigation, the rate coefficient for reaction with OH radicals, an upper limit for the rate coefficient of reaction with ozone, and identification of benzaldehyde, glyoxal, and 4-oxopentanal as products of OH radical initiated oxidation were reported. 14 In the second investigation, the rate coefficient and oxidation products of the reaction of NO 3 radicals with benzyl alcohol were reported. 13 In the present work, we have conducted an investigation of the reactions of OH and O 3 with benzyl alcohol using the smog chambers at ICARE (Orle ́ ans, France), Ford Motor Company (Dearborn, Michigan), and EUPHORE (European photo- reactor, Valencia, Spain) which complements the previous studies. 2. EXPERIMENTAL SECTION Three smog chambers were used in the present work. At ICARE, the rate coefficients for the reactions of benzyl alcohol with OH radicals and ozone were measured. At FORD, the rate coefficient for OH reaction with benzyl alcohol and the yield of benzaldehyde were determined. At EUPHORE, the mechanism of the OH-initiated oxidation of benzyl alcohol in the presence of NO X was investigated. ICARE Chamber. Kinetic measurements were performed in the 7300 L ICARE Teflon chamber. 15,16 The chamber was surrounded by 24 lamps with a maximum output centered on 365 nm (UV-A T-40 L, Viber Lourmat). Experiments were performed in P ∼ 1013 mbar of air at T = 298 ± 2 K with a relative humidity of ∼5%. Reactants which are liquids under Received: November 13, 2012 Revised: February 27, 2013 Accepted: February 28, 2013 Published: February 28, 2013 Article pubs.acs.org/est © 2013 American Chemical Society 3182 dx.doi.org/10.1021/es304600z | Environ. Sci. Technol. 2013, 47, 3182−3189