Numerical study of effects of particle properties on heterogeneous nucleation in air-water vapor mixtures based on molecular dynamics

Y Yu and YT Lu and CW Xu and C Fu, CHEMICAL ENGINEERING SCIENCE, 317, 122105 (2025).

DOI: 10.1016/j.ces.2025.122105

In the control of atmospheric fine particulate matter (PM2.5) pollution, water nucleation technology has gained attention due to its efficiency and environmental protection. However, the initial mechanism of heterogeneous nucleation remains unclear, hindering optimization and application. This study investigates how particle characteristics affect heterogeneous nucleation in air-water vapor mixtures using molecular dynamics (MD) simulations. By simulating the adsorption behavior of water molecules on SiO2 particle under distinct conditions, the effects of supersaturation, particle size and gas composition on the heterogeneous nucleation process were analyzed. The results show that the nucleation process can be partitioned into two distinct phases at high initial supersaturation. During the first phase, a linear growth regime is established as water molecules adsorb onto particle surfaces, forming molecular clusters. In the second phase, the nucleation rate declines due to cluster coalescence. And while supersaturation initially boosts water molecule adsorption capacity, high supersaturation reduces the adsorption rate as surface coverage saturates, revealing dynamic equilibrium's limitation on nucleation efficiency. Increasing particle size improves adsorption and nucleation rates by expanding surface area and enhancing activity. Nitrogen enhances the overall condensation process by promoting the growth rate of water molecules. Cross-scale consistency from molecular adsorption to mesoscopic liquid layer formation was confirmed by comparing ESEM experiments with simulated snapshots. This work clarifies the comprehensive impacts of particle properties and gas environment on nucleation processes at the molecular level, providing a theoretical basis for optimizing industrial waste gas treatment and improving PM2.5 control technology.

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