Nano and Molecular Systems Research Unit, FI-90014 University of Oulu, P. O. Box 3000, Oulu, Finland.
Environ Sci Process Impacts. 2018 Nov 14;20(11):1611-1629. doi: 10.1039/c8em00345a.
The droplet surface plays important roles in the interaction between organic aerosols with clouds and climate. Surface active organic compounds can partition to the droplet surface, depleting the solute from the droplet bulk or depressing the droplet surface tension. This may in turn affect the shape of the droplet growth curve, threshold of aerosol activation into cloud droplets, activated droplet size distributions, and cloud radiative effects. In this work, a new monolayer model along with a traditional Gibbs adsorption isotherm model was used in conjunction with equilibrium Köhler theory to predict cloud condensation nuclei (CCN) activation of both simple and complex surface active model aerosol systems. For the surface active aerosol considered, the monolayer droplet model produces similar results to the Gibbs model as well as comparable results to CCN measurements from the literature, even for systems where specific molecular identities and aqueous properties are unknown. The monolayer model is self-contained and fully prognostic, and provides a versatile, conceptually simple, yet physically based model for understanding the role of organic surfactants in cloud droplet formation.
液滴表面在有机气溶胶与云及气候的相互作用中起着重要作用。表面活性有机化合物可以分配到液滴表面，使溶质从液滴主体中耗尽或降低液滴表面张力。这反过来可能会影响液滴生长曲线的形状、气溶胶进入云滴的激活阈值、激活液滴的尺寸分布和云的辐射效应。在这项工作中，一种新的单层模型与传统的 Gibbs 吸附等温线模型一起，结合平衡 Köhler 理论，用于预测简单和复杂表面活性模型气溶胶系统的云凝结核 (CCN) 激活。对于所考虑的表面活性气溶胶，单层液滴模型产生的结果与 Gibbs 模型相似，与文献中的 CCN 测量结果也相似，即使对于特定分子身份和水相性质未知的系统也是如此。单层模型是自包含的和完全预测性的，它为理解有机表面活性剂在云滴形成中的作用提供了一个通用的、概念上简单的、但基于物理的模型。
