Hygroscopic properties of aminium sulfate aerosols
Hygroscopic properties of aminium sulfate aerosols
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DOI：
10.5194/acp-17-4369-2017
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发表时间：
2016-11
影响因子：
6.3
通讯作者：
G. Rovelli;R. E. H. Miles;J. Reid;S. Clegg
中科院分区：
文献类型：
--
作者：
G. Rovelli;R. E. H. Miles;J. Reid;S. Clegg
抽象的。烷基硫酸铵来源于短链胺和硫酸之间的中和反应，并已在大气气溶胶颗粒中检测到。它们的物理化学行为不如其无机等价物硫酸铵，尽管它们在大气过程中发挥作用，如新颗粒的成核和生长以及云滴的形成。在这项工作中，比较蒸发动力学实验技术，使用圆柱形电动平衡，以确定吸湿性能的六个短链烷基硫酸铵，特别是单，二，和三甲基硫酸铵和单，二，和三乙基硫酸铵。这种方法可以在不到10秒的时间内恢复与水活度相关的生长曲线，避免半挥发性成分挥发可能产生的不确定性。测量是在半径大于5 µm的颗粒上进行的，避免了需要用液滴表面张力的假设值来校正液滴表面曲率的平衡测量。平衡溶液液滴组成随水活度的变化在0.5至> 0.98的范围内报告，沿着有溶液密度和折射率的精确参数化。与吸湿性测量相关的水活度的不确定性通常为0.9，小于0.9的不确定性为± 1%，直径增长因子的最大不确定性为± 0.7%。与以前报告的测量结果相比，整个水活度范围内的偏差。
Abstract. Alkylaminium sulfates originate from the neutralisation reaction between short-chained amines and sulfuric acid and have been detected in atmospheric aerosol particles. Their physicochemical behaviour is less well characterised than their inorganic equivalent, ammonium sulfate, even though they play a role in atmospheric processes such as the nucleation and growth of new particles and cloud droplet formation. In this work, a comparative evaporation kinetics experimental technique using a cylindrical electrodynamic balance is applied to determine the hygroscopic properties of six short-chained alkylaminium sulfates, specifically mono-, di-, and tri-methylaminium sulfate and mono-, di-, and tri-ethyl aminium sulfate. This approach allows for the retrieval of a water-activity-dependent growth curve in less than 10 s, avoiding the uncertainties that can arise from the volatilisation of semi-volatile components. Measurements are made on particles > 5 µm in radius, avoiding the need to correct equilibrium measurements for droplet-surface curvature with assumed values of the droplet-surface tension. Variations in equilibrium solution droplet composition with varying water activity are reported over the range 0.5 to > 0.98, along with accurate parameterisations of solution density and refractive index. The uncertainties in water activities associated with the hygroscopicity measurements are typically 0.9 and ∼ ±1 % below 0.9, with maximum uncertainties in diameter growth factors of ±0.7 %. Comparison with previously reported measurements show deviation across the entire water activity range.