The hygroscopicity and reactivity of fatty acid atmospheric aerosol proxies are affected by nanostructure

DOI: 10.5194/egusphere-egu21-7326

Authors: Adam Milsom (University of Birmingham) , Adam Squires (University of Bath) , Nicholas Terrill (Diamond Light Source) , Andrew Ward (Central Laser Facility) , Christian Pfrang (University of Birmingham; University of Reading)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: EGU General Assembly 2021
Peer Reviewed: No

State: Published (Approved)
Published: March 2021

Abstract: Atmospheric aerosol hygroscopicity and reactivity play a significant role in determining aerosol fate, and are affected by composition and other physical properties. Organic aerosol emissions contain fatty acids, along with sugars such as fructose. As surfactants, fatty acids organise into a range of nanostructures (3-D molecular arrangements), dependent on water content and mixture composition. In this study, we were able to demonstrate (and quantify) that the chemical reactivity of this proxy is dependent on its 3-D molecular arrangement. Furthermore, we have determined the effect of each observed nanostructure on hygroscopicity by measuring the swelling of these nanostructures as a function of relative humidity. We did this by coating capillaries with a fatty acid/sugar as a mixture for an urban aerosol, and following structural changes with simultaneous Small-Angle X-ray Scattering (SAXS) and Raman microscopy, at a synchrotron X-ray source. SAXS measured the nano-structural parameters required to follow both the reaction kinetics (ozonolysis) and hygroscopic swelling of each nanostructure. Raman microscopy provided complementary kinetic information and supported these findings. We found that the molecular arrangement of surfactant material has an impact on both the chemical kinetics and hygroscopicity. This has implications for the persistence of particulate matter in the urban environment and surfactant material in the atmosphere.

Subject Areas: Chemistry


Instruments: I22-Small angle scattering & Diffraction

Added On: 29/04/2021 08:23

Discipline Tags:

Desertification & Pollution Earth Sciences & Environment Physics Chemistry Organic Chemistry Nanoscience/Nanotechnology

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)