Heterogeneous Interaction of H2O2 with Arizona Test Dust

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• 作者：Atallah El Zein ; Manolis N. Romanias ; Yuri Bedjanian
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：January 16, 2014
• 年：2014
• 卷：118
• 期：2
• 页码：441-448
• 全文大小：341K
• ISSN：1520-5215

文摘

The heterogeneous interaction of H₂O₂ with solid films of Arizona Test Dust (ATD) was investigated under dark conditions and in presence of UV light using a low pressure flow tube reactor coupled with a quadrupole mass spectrometer. The uptake coefficients were measured as a function of the initial concentration of gaseous H₂O₂ ([H₂O₂]₀ = (0.18 鈥?5.1) 脳 10¹² molecules cm^鈥?), irradiance intensity (J_NO2 = 0.002 鈥?0.012 s^鈥?), relative humidity (RH = 0.002 鈥?69%), and temperature (T = 268 鈥?320 K). The initial uptake coefficient was found to be independent of the concentration of H₂O₂ and UV irradiation intensity and to decrease with increasing RH and temperature according to the following expressions: 纬₀ = 4.8 脳 10^鈥?/(1+ RH^0.66) at T = 275 K and 纬₀ = 3.2 脳 10^鈥?/(1 + 2.5 脳 10¹⁰exp(鈭?360/T)) at RH = 0.35% (calculated using BET surface area, estimated conservative uncertainty of 30%). By contrast, the steady state uptake coefficient was found to be independent of temperature, to increase upon UV irradiation of the surface, and to be inversely (纬_SS [H₂O₂]^鈭?.6) dependent on the concentration of H₂O₂. The RH independent steady state uptake coefficient was measured under dark and UV irradiation conditions: 纬_SS(dark) = (0.95 卤 0.30) 脳 10^鈥? and 纬_SS(UV) = (1.85 卤 0.55) 脳 10^鈥?, for RH = (2 鈥?69)% and [H₂O₂]₀ 1.0 脳 10¹² molecules cm^鈥?. The present experimental data support current considerations that uptake of H₂O₂ on mineral aerosol is potentially an important atmospheric process.