Enhanced aggregation and interfacial adsorption of an aqueous film forming foam (AFFF) in high salinity matrices

Per- and polyfluoroalkyl substances (PFAS) exist in contaminated groundwater, surface water, soil, and sediments from use of aqueous film forming foams (AFFFs). Under these conditions PFAS exhibit unusual behavior due to their surfactant properties, namely, aggregation and surface activity. Environm...

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Bibliographic Details
Published in:Environmental science--processes & impacts 2023-12, Vol.25 (12), p.2181-2188
Main Authors: Steffens, Sophia D, Sedlak, David L, Alvarez-Cohen, Lisa
Format: Article
Language:English
Subjects:
Accumulation
Adsorption
Air-water interface
Environmental factors
Fluorocarbons - analysis
Foams
Groundwater
Groundwater pollution
Micelles
Mixtures
Perfluoroalkyl & polyfluoroalkyl substances
Perfluorochemicals
Salinity
Salinity effects
Sediments
Soil contamination
Soil water
Surface activity
Surface tension
Surface water
Surface-groundwater relations
Water Pollutants, Chemical - analysis
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Summary:Per- and polyfluoroalkyl substances (PFAS) exist in contaminated groundwater, surface water, soil, and sediments from use of aqueous film forming foams (AFFFs). Under these conditions PFAS exhibit unusual behavior due to their surfactant properties, namely, aggregation and surface activity. Environmental factors such as salinity can affect these properties, and complicate efforts to monitor PFAS. The effect of high salinity matrices on the critical micelle concentration (CMC) of a AFFF formulation manufactured by 3M and the surface accumulation of PFAS was assessed with surface tension isotherm measurements and bench-scale experiments quantifying PFAS at the air-water interface. Conditions typical of brackish and saline waters substantially depressed the CMC of the AFFF by over 50% and increased the interfacial mass accumulation of PFAS in the AFFF mixture by up to a factor of 3, relative to values measured in ultrapure water. These results indicate that high salinity matrices increase the aggregation and surface activity of PFAS in mixtures, which are key properties affecting their transport. Saline water increases aggregation and interfacial accumulation of PFAS found in AFFF mixtures, having the potential to affect retention during transport at or near coastal contamination sites.
ISSN:2050-7887
2050-7895
DOI:10.1039/d3em00247k