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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Reactive uptake of N2O5 by aerosol particles containing mixtures of humic acid and ammonium sulfate
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Reactive uptake of N2O5 by aerosol particles containing mixtures of humic acid and ammonium sulfate

机译：含有腐殖酸和硫酸铵混合物的气溶胶颗粒对N2O5的反应性吸收

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The kinetics of reactive uptake of N2O5 on submicron aerosol particles containing humic acid and ammonium sulfate has been investigated as a function of relative humidity ( RH) and aerosol composition using a laminar flow reactor coupled with a differential mobility analyzer (DMA) to characterize the aerosol. For single-component humic acid aerosol the uptake coefficient, gamma, was found to increase from 2 to 9 x 10(-4) over the range 25-75% RH. These values are 1-2 orders of magnitude below those typically observed for single-component sulfate aerosols (Phys. Chem. Chem. Phys. 2003, 5, 3453-3463;(1) Atmos. Environ. 2000, 34, 2131-2159(2)). For the mixed aerosols, gamma was found to decrease with increasing humic acid mass fraction and increase with increasing RH. For aerosols containing only 6% humic acid by dry mass, a decrease in reactivity of more than a factor of 2 was observed compared with the case for single-component ammonium sulfate. The concentration of liquid water in the aerosol droplets was calculated using the aerosol inorganic model ( for the ammonium sulfate component) and a new combined FTIR-DMA system ( for the humic acid component). Analysis of the uptake coefficients using the water concentration data shows that the change in reactivity cannot be explained by the change in water content alone. We suggest that, due to its surfactant properties, the main effect of the humic acid is to reduce the mass accommodation coefficient for N2O5 at the aerosol particle surface. This has implications for the use of particle hygroscopicity data for predictions of the rate of N2O5 hydrolysis.
机译：使用层流反应器和差动迁移率分析仪（DMA）来表征含腐殖酸和硫酸铵的亚微米气溶胶颗粒上N2O5的反应动力学与相对湿度（RH）和气溶胶组成的关系，以表征气溶胶。对于单组分腐殖酸气雾剂，在相对湿度25-75％的范围内，吸收系数γ从2增加到9 x 10（-4）。这些值比单组分硫酸盐气雾剂通常观察到的值低1-2个数量级（Phys.Chem.Chem.Phys.2003，5，3453-3463;（1）Atmos.Environ.2000，34，2131-2159 （2））。对于混合气雾剂，γ随腐殖酸质量分数的增加而减少，随RH的增加而增加。对于以干重计仅含有6％腐殖酸的气溶胶，与单组分硫酸铵的情况相比，观察到反应性降低了2倍以上。使用无机气溶胶模型（针对硫酸铵组分）和新的组合FTIR-DMA系统（针对腐殖酸组分）计算气溶胶液滴中液态水的浓度。使用水浓度数据分析吸收系数表明，反应性的变化不能仅通过含水量的变化来解释。我们建议，由于其表面活性剂的特性，腐殖酸的主要作用是降低气溶胶颗粒表面N2O5的质量容纳系数。这对于使用颗粒吸湿性数据预测N2O5水解速率具有重要意义。

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