Reactions of Methanesulfonic Acid with Amines and Ammonia as a Source of New Particles in Air
Reactions of Methanesulfonic Acid with Amines and Ammonia as a Source of New Particles in Air
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DOI：
10.1021/acs.jpcb.5b07433
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发表时间：
2016-03-03
影响因子：
3.3
通讯作者：
Finlayson-Pitts, Barbara J.
中科院分区：
文献类型：
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作者：
Chen, Haihan;Varner, Mychel E.;Finlayson-Pitts, Barbara J.
作为气溶胶的重要来源，需要更好地了解气态前体物的新粒子形成（NPF），以准确预测对能见度，气候变化和人类健康的影响。虽然硫酸、胺/NH3和水的三元成核被认为是NPF的重要驱动因素，但越来越多的证据表明在某些条件下甲磺酸（MSA）和胺的贡献。在这里，我们报告的形成的颗粒直径为2.5-10 nm的反应MSA与甲胺（MA），二甲胺（DMA），和NH3在2.3-7.8秒的反应时间在流动反应器中，并比较这些颗粒与先前报道的形成从与三甲胺（TMA）的反应。研究了水蒸气和气态前体物浓度对颗粒数、浓度和粒径的影响。水的存在显著增强颗粒形成和生长。在类似的实验条件下，颗粒数浓度以MA >> TMA近似于DMA >> NH3的顺序降低，其中NH3的效率比DMA低2-3个数量级。进行了可能的中间簇的量子化学计算，以提供洞察水的作用和胺/NH3在颗粒形成中的不同能力。胺/NH3的气相碱性和氢键能力都有助于颗粒形成和生长的潜力。我们的研究结果表明，虽然胺的浓度通常比大气中的NH3低1-3个数量级，但它们仍然在驱动NPF中发挥重要作用。
New particle formation (NPF) from gaseous precursors as a significant source of aerosol needs to be better understood to accurately predict the impacts on visibility, climate change, and human health. While ternary nucleation of sulfuric acid, amines/NH3, and water is recognized as a significant driver for NPF, increasing evidence suggests a contribution from methanesulfonic acid (MSA) and amines under certain conditions. Here we report the formation of particles 2.5-10 nm in diameter from the reactions of MSA with methylamine (MA), dimethylamine (DMA), and NH3 at reaction times of 2.3-7.8 s in a flow reactor and compare these particles with those previously reported to be formed from reaction with trimethylamine (TMA). The effects of water vapor and concentrations of gaseous precursors on the particle number concentration and particle size were studied. The presence of water significantly enhances particle formation and growth. Under similar experimental conditions, particle number concentrations decrease in the order MA >> TMA approximate to DMA >> NH3, where NH3 is 2-3 orders of magnitude less efficient than DMA. Quantum chemical calculations of likely intermediate clusters were carried out to provide insights into the role of water and the different capacities of amines/NH3 in particle formation. Both gas-phase basicity and hydrogen-bonding capacity of amines/NH3 contribute to the potential for particles to form and grow. Our results indicate that, although amines typically have concentrations 1-3 orders of magnitude lower than that of NH3 in the atmosphere, they still play an important role in driving NPF.