Composition dependent density of ternary aqueous solutions of ionic surfactants and salts : capturing the effect of surfactant micellization in atmospheric droplet model solutions
|Author:||Calderón, Silvia M.1; Prisle, Nønne L.1|
1Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland
|Online Access:||PDF Full Text (PDF, 1.8 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2021062940366
|Publish Date:|| 2021-06-29
Surfactants exist in atmospheric aerosols mixed with inorganic salts and can significantly influence the formation of cloud droplets due to bulk–surface partitioning and surface tension depression. To model these processes, we need continuous parametrizations of the concentration dependent properties of aqueous surfactant–salt solutions for the full composition range from pure water to pure surfactant or salt. We have developed density functions based on the pseudo-separation method and Young’s mixing rule for apparent partial molal volumes for solutions that mimic atmospheric droplets of marine environments. The developed framework requires only model parameters from binary water–salt and water–surfactant systems and includes the effect of salinity on micellization with composition-dependent functions for the critical micelle concentration (CMC). We evaluate different models and data available in the literature to find the most suitable representations of the apparent partial molal volume of sodium chloride (NaCl) in aqueous solutions and the CMC of selected atmospheric and model surfactants in pure water and aqueous NaCl solutions. We compare model results to experimental density data, available in the literature and obtained from additional measurements, for aqueous solutions containing one of the ionic surfactants sodium octanoate, sodium decanoate, sodium dodecanoate or sodium dodecylsulfate mixed with NaCl in different relative ratios. Our model follows the experimental trends of increasing densities with increasing surfactant concentrations or increasing surfactant–salt mixing ratios both, below and above the CMC, capturing the effect of the inorganic salt on the surfactant micellization.
Journal of atmospheric chemistry
|Pages:||99 - 123|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
114 Physical sciences
1172 Environmental sciences
This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme, Project SURFACE (Grant Agreement No. 717022). The authors gratefully acknowledge the financial contribution from the Academy of Finland (Grant Nos. 308238, 314175 and 335649).
|EU Grant Number:||
(717022) SURFACE - The unexplored world of aerosol surfaces and their impacts.
|Academy of Finland Grant Number:||
308238 (Academy of Finland Funding decision)
314175 (Academy of Finland Funding decision)
335649 (Academy of Finland Funding decision)
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