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Reactivity of Semivolatile Organic Compounds with Hydroxyl Radicals, Nitrate Radicals, and Ozone in Indoor Air
Author(s) -
Wei Wenjuan,
Mandin Corinne,
Ramalho Olivier
Publication year - 2017
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.21093
Subject(s) - chemistry , ozone , radical , reaction rate constant , environmental chemistry , reactivity (psychology) , particulates , photochemistry , organic chemistry , kinetics , medicine , physics , alternative medicine , pathology , quantum mechanics
ABSTRACT Indoor semivolatile organic compounds (SVOCs) originate from indoor and outdoor sources. These SVOCs partition among different phases and available surfaces, which increases their residence time indoors to several years. SVOCs may also react with indoor oxidants, such as hydroxyl radicals (OH), nitrate radicals (NO 3 ), and ozone. In the present study, the second‐order reaction rate constants of 72 SVOCs in indoor air (gas and particle phases) at room temperature and ambient air pressure were retrieved from the literature. The pseudo–first‐order reaction rate constants of these SVOCs were calculated for the indoor concentration ranges of OH, NO 3 , and ozone. Then, the extent to which the chemical reaction had a meaningful impact on the removal of SVOCs from the indoor environment was quantitatively analyzed. The orders of magnitude of the second‐order rate constant ranged between 10 −15 and 10 −10 cm 3 /(molecule·s) for OH/SVOC reactions, 10 −17 and 10 −12 cm 3 /(molecule·s) for NO 3 /SVOC reactions, and 10 −20 and 10 −16 cm 3 /(molecule·s) for ozone/SVOC reactions in indoor air. Assuming that the highest indoor reactant concentrations were 1.8 × 10 6 molecules/cm 3 (7.3 × 10 −5 ppb) for OH, 2.5 × 10 8 molecules/cm 3 (10 −2 ppb) for NO 3 , and 1.4 × 10 12 molecules/cm 3 (58 ppb) for ozone, the highest pseudo–first‐order rate constants in the gas phase for the studied reactions of OH/SVOCs ( n = 72), NO 3 /SVOCs ( n = 3), and ozone/SVOCs ( n = 14) reached 1.5 h −1 (OH/benzo[a]pyrene), 0.41 h −1 (NO 3 /acenaphthene), and 1.0 h −1 (ozone/aldrin and ozone/heptachlor), respectively. The pseudo–first‐order rate constants in the particle phase for the studied reactions of OH/SVOCs ( n = 13), NO 3 /SVOCs ( n = 6), and ozone/SVOCs ( n = 14) at the high indoor reactant concentrations reached 0.09 h −1 (OH/DEHP), 5.8 h −1 (NO 3 /pyrene), and 11 h −1 (ozone/benzo[ a ]pyrene), respectively. These results indicate that the chemical reactions of some SVOCs in indoor air have a meaningful impact compared to the air exchange rate, which should be considered in future studies on indoor air quality modeling.