Hygroscopic Growth and Deliquescence of NaCl Nanoparticles Coated with Surfactant AOT
- 19 March 2009
- journal article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 113 (26), 7678-7686
- https://doi.org/10.1021/jp809869r
Abstract
Aerosolized nanoparticles of NaCl coated with variable amounts of surfactant AOT were generated by electrospraying AOT/NaCl aqueous solutions, followed by neutralizing and drying the resulting particles. A tandem differential mobility analyzer was used to select a narrow size distribution of particles with mobility equivalent diameters below 20 nm and monitor their hygroscopic growth as a function of relative humidity. Effects of the particle size and relative amount of surfactant on the hygroscopic growth of NaCl were studied. For pure NaCl nanoparticles, the deliquescence relative humidity (DRH) increased as the particle size was decreased, in full agreement with previous measurements. Below the DRH the NaCl nanoparticles had an equivalent of one-four monolayers of water adsorbed on the surface. The addition of a sub-monolayer AOT coating reduced the DRH and suppressed the hygroscopic growth of the NaCl core. At AOT coverage levels exceeding one monolayer, a clear deliquescence transition was no longer discernible. The Zdanovskii-Stokes-Robinson (ZSR) model failed to predict the observed growth factors of mixed AOT/NaCl nanoparticles reflecting a large contribution of the interfacial interactions between NaCl and AOT to the total free energy of the particles. There were indications that AOT/NaCl nanoparticles prepared by the electrospray aerosol source were enhanced in the relative mass fraction of AOT in comparison with the solution from which they were electrosprayed.Keywords
This publication has 67 references indexed in Scilit:
- Efficiency of cloud condensation nuclei formation from ultrafine particlesAtmospheric Chemistry and Physics, 2007
- Ultrafine Particles Cross Cellular Membranes by Nonphagocytic Mechanisms in Lungs and in Cultured CellsEnvironmental Health Perspectives, 2005
- Exposure Assessment for Atmospheric Ultrafine Particles (UFPs) and Implications in Epidemiologic ResearchEnvironmental Health Perspectives, 2005
- Seasonal Trends of Concentration and Size Distribution of Ultrafine Particles Near Major Highways in Los Angeles Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites ProgramAerosol Science and Technology, 2004
- Formation and growth rates of ultrafine atmospheric particles: a review of observationsJournal of Aerosol Science, 2004
- Translocation of Inhaled Ultrafine Particles to the BrainInhalation Toxicology, 2004
- Impact, Trapping, and Accommodation of Hydroxyl Radical and Ozone at Aqueous Salt Aerosol Surfaces. A Molecular Dynamics StudyThe Journal of Physical Chemistry B, 2003
- Cloud activation of single‐component organic aerosol particlesPublished by American Geophysical Union (AGU) ,2002
- Study of ultrafine particles near a major highway with heavy-duty diesel trafficAtmospheric Environment, 2002
- Experiments and Simulations of Ion-Enhanced Interfacial Chemistry on Aqueous NaCl AerosolsScience, 2000