Interfacial Tensions of Aged Organic Aerosol Particle Mimics Using a Biphasic Microfluidic Platform
Interfacial Tensions of Aged Organic Aerosol Particle Mimics Using a Biphasic Microfluidic Platform
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DOI：
10.1021/acs.est.5b04880
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发表时间：
2016-02-02
影响因子：
11.4
通讯作者：
Dutcher, Cari S.
中科院分区：
文献类型：
--
作者：
Metcalf, Andrew R.;Boyer, Hallie C.;Dutcher, Cari S.
二次有机气溶胶（SOA）颗粒是大气颗粒物的主要组成部分，但其形成过程和环境特性尚未得到很好的了解。由于内部水相和有机相的分配，这些复杂的颗粒通常包含多个界面。气溶胶界面可以通过改变环境有机蒸气与悬浮颗粒相互作用的方式，深刻影响排放到大气中的可冷凝有机化合物的命运。为了准确预测SOA在大气中的演变，我们必须提高我们对气溶胶界面的理解。在这项工作中，两相微尺度流动被用来测量反应的丙酮醛，甲醛，和硫酸铵水溶液混合物与周围的油相的界面张力。我们的实验表明，作为有机物含量的函数的界面张力的抑制，其对于甲基乙二醛硫酸铵体系随反应时间保持恒定。我们还揭示了一个意想不到的时间依赖性的界面张力在一段时间内的48小时的三元溶液中的丙酮醛和甲醛在硫酸铵水溶液，表明一个更复杂的表面活性的行为，其中溶解的有机物之间存在竞争。从这些界面张力的测量，老化的大气气溶胶与内部液液相分离的形态推断。
Secondary organic aerosol (SOA) particles are a major component of atmospheric particulate matter, yet their formation processes and ambient properties are not well understood. These complex particles often contain multiple interfaces due to internal aqueous- and organic-phase partitioning. Aerosol interfaces can profoundly affect the fate of condensable organic compounds emitted into the atmosphere by altering the way in which ambient organic vapors interact with suspended particles. To accurately predict the evolution of SOA in the atmosphere, we must improve our understanding of aerosol interfaces. In this work, biphasic microscale flows are used to measure interfacial tension of reacting methylglyoxal, formaldehyde, and ammonium sulfate aqueous mixtures with a surrounding oil phase. Our experiments show a suppression of interfacial tension as a function of organic content that remains constant with reaction time for methylglyoxal ammonium sulfate systems. We also reveal an unexpected time dependence of interfacial tension over a period of 48 h for ternary solutions of both methylglyoxal and formaldehyde in aqueous ammonium sulfate, indicating a more complicated behavior of surface activity where there is competition among dissolved organics. From these interfacial tension measurements, the morphology of aged atmospheric aerosols with internal liquid liquid phase separation is inferred.