ATR-IR Study of Ozone Initiated Heterogeneous Oxidation of Squalene in an Indoor Environment

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• 作者：Dong Fu ; Chunbo Leng ; Judas Kelley ; Guang Zeng ; Yunhong Zhang ; Yong Liu
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：September 17, 2013
• 年：2013
• 卷：47
• 期：18
• 页码：10611-10618
• 全文大小：384K
• 年卷期：v.47,no.18(September 17, 2013)
• ISSN：1520-5851

文摘

There has been a surge of interest in interfacial ozone chemistry for its application in indoor air quality and public health. Squalene, one of the most abundant ozone reactive constituents in an indoor environment, has received increasing attention lately, and a number of studies have been devoted to its heterogeneous interaction with ozone in actual and simulated settings. At present, there is still a large discrepancy in the measurement of the reactive uptake coefficient of ozone onto a squalene surface, and knowledge about this system remains incomplete. In this work, we investigated the ozone initiated heterogeneous oxidation of squalene using attenuated total reflection infrared spectroscopy (ATR-IR). We measured pseudo-first-order rate constants and uptake coefficients based on time dependent absorbance changes in C鈺怌 (1668 cm^鈥?) and C鈺怬 (1730 cm^鈥?) vibration bands. The uptake coefficients are (1.7 卤 0.2) 脳 10^鈥? from the C鈺怌 band and (5.1 卤 0.7) 脳 10^鈥? from the C鈺怬 band. The latter is likely an upper limit of reaction probability for ozone uptake onto squalene. Studies of temperature (5鈥?2 掳C) and relative humidity (0 and 80% RH) dependence revealed that indoor temperatures and RHs did not affect reaction kinetics. The insignificant RH effect is probably due to the weak interaction between water and squalene molecules. We quantitatively characterized the hydrophilicity and redox activity of squalene before and after exposure to ozone for the first time, and observed considerable enhancements in both hydrophilicity and redox activity during reaction. This may imply that ozone initiated heterogeneous oxidation could pose a higher public health risk in an indoor environment, and it may help explain some of the adverse health effects associated with elevated indoor pollutants.