EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Hygroscopicity of organic compounds as a function of organic functionality, water solubility, molecular weight and organic oxidation level

shuang han1,2, Juan Hong1,2, Qingwei Luo1,2, Hanbing Xu3, Haobo Tan4,5, Qiaoqiao Wang1,2, Jiangchuan Tao1,2, Nan Ma1,2, Yafang Cheng6, and Hang Su6
shuang han et al.
  • 1Institute for Environmental and Climate Research, Jinan University, Guangzhou, Guangdong 511443, China
  • 2Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China
  • 3Experimental Teaching Center, Sun Yat-Sen University, Guangzhou 510275, China
  • 4Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, CMA, Guangzhou 510640, China
  • 5Foshan Meteorological Service of Guangdong, Foshan 528010, China
  • 6Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany

Hygroscopic properties of 23 organic compounds with different physico-chemical properties including carboxylic acids, amino acids, sugars and sugar alcohols were measured using a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA). We converted our experimental GF data of organics at 90% RH to κ to facilitate the comparison and we find that organic compounds with different molecular functionality present quite different hygroscopicity. Compounds with extra functional groups usually show higher hygroscopicity compared to their parental molecular compounds. Moreover, some compounds share the same molecular structure or functionality but vary differently in hygroscopicity. In general, the hygroscopicity of organics increase with functional groups in the following order: (-CH3/-NH2) < (-OH) < (-COOH/C=C/C=O). For highly soluble organics, the hygroscopicity decreases with molecular weight; while for slightly soluble organics which are not fully dissolved in aerosol droplets, their hygroscopicity can be divided into two categories. One is non-hygroscopic compounds, which may not fully deliquesce in the aerosol droplets. The other is moderate hygroscopic compounds, of which the hygroscopicity is mainly limited by their water solubility. Moreover, the hygroscopicity of organic compounds generally increased linearly with O:C ratios, although some of them have the same O:C ratio of but with different hygroscopicity. The experimental determined hygroscopicity are also compared with model predictions using the Extended Aerosol Inorganics Model (E-AIM) and the UManSysProp at 10-90% RH. Both models poorly represent the hygroscopic behavior of some organics, which may due to that the phase transition and intermolecular interactions are not considered in the simulations.

How to cite: han, S., Hong, J., Luo, Q., Xu, H., Tan, H., Wang, Q., Tao, J., Ma, N., Cheng, Y., and Su, H.: Hygroscopicity of organic compounds as a function of organic functionality, water solubility, molecular weight and organic oxidation level, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13985,, 2021.

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