Effect of varying experimental conditions on the viscosity of α-pinene derived secondary organic material
Effect of varying experimental conditions on the viscosity of α-pinene derived secondary organic material
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DOI：
10.5194/acp-16-6027-2016
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发表时间：
2016-01-01
影响因子：
6.3
通讯作者：
Bertram, Allan K.
中科院分区：
文献类型：
--
作者：
Grayson, James W.;Zhang, Yue;Bertram, Allan K.
含有二次有机材料（SOM）的颗粒的粘度的知识是有用的预测SOM颗粒的反应速率和扩散。在这项研究中，我们调查的相对湿度和SOM颗粒的质量浓度的函数的SOM颗粒的粘度，在SOM合成。在< aEuro-5aEuro-%相对湿度（RH）下，通过α-蒎烯的臭氧分解产生SOM。使用戳流技术进行实验，该技术测量用针戳材料后SOM的实验流动时间（τ（exp，流量））。在第一组实验中，我们表明，τ（exp，流量）增加了3600倍，作为相对湿度从< aEuro-0.5 RH增加到50 aEuro-% RH，SOM与生产质量浓度为121 aEuro-A μ gaEuro-m（-3）。基于模拟，颗粒的粘度在< aEuro-0.5aEuro-% RH下在6aEuro-aEuro份/千X aEuro-10（5）和5aEuro-aEuro份/千X aEuro-10（7）aEuro-PaaEuro-s之间，并且在50 aEuro- %RH下在3aEuro-aEuro份/千X aEuro-10（2）和9aEuro-aEuro份/千X aEuro-10（3）aEuro-PaaEuro-s之间。在第二组实验中，我们表明，在干燥条件下，tau（exp，流量）减少了45倍，因为生产质量浓度从121增加到14 aEuro-000 aEuro-A μ gaEuro-m（-3）。从模拟的点流实验来看，生产质量浓度为14 aEuro-000 aEuro-A μ gaEuro-m（-3）的SOM的粘度被确定为在4aEuro-aEuro份/千份× aEuro-10（4）和1.5aEuro-aEuro份/千份× aEuro-10（6）aEuro-PaaEuro-s之间，相比之下，在6aEuro-aEuro份/千份× aEuro-10（5）和5aEuro-PaaEuro-s之间，aEuro千分率x aEuro-10（7）aEuro-PaaEuro-s，适用于生产质量浓度为121 aEuro-A mu gaEuro-m（-3）的SOM。结果可以合理化的SOM的化学组成对生产条件的依赖。这些结果强调了SOM的转变特性，不仅与RH和前体类型，而且与生产条件，并建议生产质量浓度和RH的粘度确定时，应考虑比较实验室结果时，这些结果外推到大气中。
Knowledge of the viscosity of particles containing secondary organic material (SOM) is useful for predicting reaction rates and diffusion in SOM particles. In this study we investigate the viscosity of SOM particles as a function of relative humidity and SOM particle mass concentration, during SOM synthesis. The SOM was generated via the ozonolysis of alpha-pinene at < aEuro-5aEuro-% relative humidity (RH). Experiments were carried out using the poke-and-flow technique, which measures the experimental flow time (tau(exp, flow)) of SOM after poking the material with a needle. In the first set of experiments, we show that tau(exp, flow) increased by a factor of 3600 as the RH increased from < aEuro-0.5 RH to 50aEuro-% RH, for SOM with a production mass concentration of 121aEuro-A mu gaEuro-m(-3). Based on simulations, the viscosities of the particles were between 6aEuro-aEuro parts per thousand x aEuro-10(5) and 5aEuro-aEuro parts per thousand x aEuro-10(7)aEuro-PaaEuro-s at < aEuro-0.5aEuro-% RH and between 3aEuro-aEuro parts per thousand x aEuro-10(2) and 9aEuro-aEuro parts per thousand x aEuro-10(3)aEuro-PaaEuro-s at 50aEuro-% RH. In the second set of experiments we show that under dry conditions tau(exp, flow) decreased by a factor of 45 as the production mass concentration increased from 121 to 14aEuro-000aEuro-A mu gaEuro-m(-3). From simulations of the poke-and-flow experiments, the viscosity of SOM with a production mass concentration of 14aEuro-000aEuro-A mu gaEuro-m(-3) was determined to be between 4aEuro-aEuro parts per thousand x aEuro-10(4) and 1.5aEuro-aEuro parts per thousand x aEuro-10(6)aEuro-PaaEuro-s compared to between 6aEuro-aEuro parts per thousand x aEuro-10(5) and 5aEuro-aEuro parts per thousand x aEuro-10(7)aEuro-PaaEuro-s for SOM with a production mass concentration of 121aEuro-A mu gaEuro-m(-3). The results can be rationalized by a dependence of the chemical composition of SOM on production conditions. These results emphasize the shifting characteristics of SOM, not just with RH and precursor type, but also with the production conditions, and suggest that production mass concentration and the RH at which the viscosity was determined should be considered both when comparing laboratory results and when extrapolating these results to the atmosphere.