Physiochemical properties of alkylaminium sulfates: hygroscopicity, thermostability, and density.
Physiochemical properties of alkylaminium sulfates: hygroscopicity, thermostability, and density.
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DOI：
10.1021/es3004377
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发表时间：
2012-03
影响因子：
11.4
通讯作者：
Chong Qiu;Renyi Zhang
中科院分区：
文献类型：
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作者：
Chong Qiu;Renyi Zhang
虽然最近已证明胺的非均相相互作用在大气气溶胶的形成和生长中起重要作用，但关于硫酸铵的物理化学性质的信息很少。在这项研究中，烷基胺硫酸盐（AASs）的吸湿性，热稳定性和密度测量了一个集成的气溶胶分析系统，包括串联差分迁移率分析仪和气溶胶粒子质量分析仪。随着相对湿度的增加，原子吸收光谱气溶胶的粒径呈单调增长，没有明确的潮解点。硫酸铵与AASs的混合降低了AS对应的潮解点。含AASs的颗粒表现出与AS相当或更高的热稳定性。测定了AASs的密度为1.2 ~ 1.5 g cm(-3)，并根据烷基碳与总硫酸盐的摩尔比建立了预测AASs密度的经验模型。我们的研究结果表明，胺在硫酸盐颗粒上的异质吸收可能会大大改变气溶胶的性质。特别是，烷基胺与硫酸铵气溶胶的置换反应导致从结晶相到无定形相的转变，并改善了水分吸收，大大增强了它们的直接和间接气候强迫。
Although heterogeneous interaction of amines has been recently shown to play an important role in the formation and growth of atmospheric aerosols, little information is available on the physicochemical properties of aminium sulfates. In this study, the hygroscopicity, thermostability, and density of alkylaminium sulfates (AASs) have been measured by an integrated aerosol analytical system including a tandem differential mobility analyzer and an aerosol particle mass analyzer. AAS aerosols exhibit monotonic size growth at increasing RH without a well-defined deliquescence point. Mixing of ammonium sulfate (AS) with AASs lowers the deliquescence point corresponding to AS. Particles with AASs show comparable or higher thermostability than that of AS. The density of AASs is determined to be 1.2-1.5 g cm(-3), and an empirical model is developed to predict the density of AASs on the basis of the mole ratio of alkyl carbons to total sulfate. Our results reveal that the heterogeneous uptake of amines on sulfate particles may considerably alter the aerosol properties. In particular, the displacement reaction of alkylamines with ammonium sulfate aerosols leads to a transition from the crystalline to an amorphorous phase and an improved water uptake, considerably enhancing their direct and indirect climate forcing.