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首页> 外文期刊>Atmospheric chemistry and physics >Deliquescence, efflorescence, and phase miscibility of mixed particles of ammonium sulfate and isoprene-derived secondary organic material
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Deliquescence, efflorescence, and phase miscibility of mixed particles of ammonium sulfate and isoprene-derived secondary organic material

机译：硫酸铵和异戊二烯衍生的次生有机材料混合颗粒的潮解，风化和相溶性

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The hygroscopic phase transitions of ammonium sulfate mixed with isoprene-derived secondary organic material were investigated in aerosol experiments. The organic material was produced by isoprene photo-oxidation at 40% and 60% relative humidity. The low volatility fraction of the photo-oxidation products condensed onto ammonium sulfate particles. The particle-phase organic material had oxygen-to-carbon ratios of 0.67 to 0.74 (?±0.2) for mass concentrations of 20 to 30 ?1/4g m−3. The deliquescence, efflorescence, and phase miscibility of the mixed particles were investigated using a dual arm tandem differential mobility analyzer. The isoprene photo-oxidation products induced deviations in behavior relative to pure ammonium sulfate. Compared to an efflorescence relative humidity (ERH) of 30 to 35% for pure ammonium sulfate, efflorescence was eliminated for aqueous particles having organic volume fractions ϵ of 0.6 and greater. Compared to a deliquescence relative humidity (DRH) of 80% for pure ammonium sulfate, the DRH steadily decreased with increasing ϵ, approaching a DRH of 40% for ϵ of 0.9. Parameterizations of the DRH(ϵ) and ERH(ϵ) curves were as follows: DRH(ϵ)Combining double low line ∑i ci,d ϵi valid for 0 ≤ ϵ ≤0.86 and ERH(& varepsilon;)Combining double low line ∑ i ci,e ϵi valid for 0 ≤ ϵ ≤ 0.55 for the coefficients c0,dCombining double low line 80.67, c0,e Combining double low line 28.35, c1,d Combining double low line −11.45, c1, e Combining double low line −13.66, c2,d Combining double low line 0, c2,e Combining double low line 0, c3,d Combining double low line 57.99, c3,e Combining double low line-83.80, c4,d Combining double low line −106.80, and c4,e Combining double low line 0. The molecular description that is thermodynamically implied by these strongly sloped DRH(ϵ) and ERH(ϵ) curves is that the organic isoprene photo-oxidation products, the inorganic ammonium sulfate, and water form a miscible liquid phase even at low relative humidity. This phase miscibility is in contrast to the liquid-liquid separation that occurs for some other types of secondary organic material. These differences in liquid-liquid separation are consistent with a prediction recently presented in the literature that the bifurcation between liquid-liquid phase separation versus mixing depends on the oxygen-to-carbon ratio of the organic material. The conclusions are that the influence of secondary organic material on the hygroscopic properties of ammonium sulfate varies with organic composition and that the degree of oxygenation of the organic material, which is a measurable characteristic of complex organic materials, is an important variable influencing the hygroscopic properties of mixed organic-inorganic particles.
机译：在气溶胶实验中研究了硫酸铵与异戊二烯衍生的次级有机材料混合的吸湿相变。有机材料是通过在40％和60％相对湿度下进行异戊二烯光氧化而制得的。低挥发性分数的光氧化产物冷凝在硫酸铵颗粒上。当质量浓度为20〜30≤1/ 4g m-3时，颗粒相有机材料的氧碳比为0.67〜0.74（α±0.2）。使用双臂串联差动迁移率分析仪研究了混合颗粒的潮解，风化和相溶性。异戊二烯光氧化产物引起相对于纯硫酸铵的行为偏差。与纯硫酸铵的风化相对湿度（ERH）相比为30％到35％相比，有机体积分数 varepsilon;为0.6或更大的水性颗粒的风化被消除。与纯硫酸铵的潮解相对湿度（DRH）为80％相比，DRH随着 varepsilon;的增加而稳步下降，对于 varepsilon; 的DRH达到40％。 0.9。 DRH（＆varepsilon; ）和ERH（＆varepsilon; ）曲线的参数化如下：DRH（＆varepsilon; ）结合双低线∑ i c i，d ＆varepsilon; i 对0≤有效＆varepsilon; ≤0.86和ERH（＆varepsilon; ）组合双低线∑ i c i，e < / i> ＆varepsilon; i 对0≤＆varepsilon; ≤0.55有效，对于系数 c 0， d 结合双低线80.67， c 0， e 结合双低线28.35， c 1， d 组合双低线−11.45， c 1， e 组合双低线−13.66， c 2， d 组合双低线0， c 2， e 组合双低线0， c 3， d 组合双低线57.99， c 3， e 组合双低线83.80， c 4， d 组合双低线−106.80和 c 4， e 组合双低线0。具有热力学含义的分子描述由这些强烈倾斜的DRH（＆varepsilon; ）和ERH（＆varepsilon; ）曲线表明，有机异戊二烯光氧化产物，无机硫酸铵和水形成了即使在较低的相对湿度下也可以混溶的液相。该相混溶性与某些其他类型的第二有机材料发生的液-液分离相反。液-液分离的这些差异与最近在文献中提出的预测一致，即液-液相分离与混合之间的分叉取决于有机材料的氧碳比。结论是，次要有机材料对硫酸铵吸湿性的影响随有机组成的变化而变化，有机物的氧化程度是复合有机材料的可测量特征，是影响吸湿性的重要变量。混合的有机-无机颗粒。

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