Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations--颗粒学报PARTICUOLOGY

Zhang, C., Zhang, Z., Bu, L., Yang, Y., Xiong, W., & Wang, Y. (2023). Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations. Particuology, 77, 128-135. https://doi.org/10.1016/j.partic.2022.09.005

Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

Chao Zhang ^{a b}, Zhichao Zhang ^a, Longxiang Bu ^a, Yang Yang ^{a b *}, Wei Xiong ^a, Yueshe Wang ^c

a School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
b Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
c State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, 710049, China

10.1016/j.partic.2022.09.005

Volume 77, June 2023, Pages 128-135

Received 25 June 2022, Revised 16 September 2022, Accepted 18 September 2022, Available online 25 September 2022, Version of Record 2 December 2022.

E-mail: yangyang@usst.edu.cn

Highlights

• Interaction between water and surfactant aerosol is studied using MD method.

• Various morphologies are observed for malonic acid (MA) (adipic acid (AA))-H₂O particles.

• Surface propensity of MA and AA depends on temperature and water content.

• Effects of the MD results on hygroscopic properties are discussed.

Abstract

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol particles. However, knowledge on the morphology of surfactant particles after the adsorption of water is insufficient. In this study, the interaction between water and particles composed of surface active malonic acid (MA) or adipic acid (AA) are simulated based on the molecular dynamics method. The key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium state. Results show that demixed structure 1 with the adsorption of water clusters on acid grain, mixed structure and demixed structure 2 with acids coating on water droplet can be observed. With temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then weakens. Near the standard atmospheric temperature (280–330 K), the surface propensity of MA and AA increases with increasing water content and alkyl group, and its sensitivity to temperature and water content varies regularly. Moreover, all surfactants at the particle surface orient their hydrophobic groups toward the gas. These findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

Graphical abstract

Keywords

Aerosol particles; Surfactant; Surface propensity; Hygroscopic growth; Molecular dynamics

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