UC Berkeley

‘Forever chemicals’ is on its way to becoming a household name. Yet as researchers, we arestill identifying the numerous data gaps in our understanding of bio- and chemical transformation, toxicity, transport processes, and physicochemical behavior of the poly- and perfluorinated alkyl substances (PFAS) that have earned this colloquial title. This dissertation addresses how the unusual surfactant properties of PFAS derived from fluorine chemistry impact their behavior in the context of environmental management and treatment technologies.

The physicochemical properties investigated in this work are aggregation, surface activity,and sorptive behavior, all of which have the potential to cause artifacts of removal in treatment systems, as well as unexpected behavior in the environment. The aggregation of PFOS with specific groundwater relevant salts is investigated in order to understand an artifact of PFOS removal in high ionic strength treatment-like matrix. Additionally, the surface activity and interfacial accumulation activity of PFOS is evaluated using the Langmuir-Szyszkowski adsorption model (Chapter 2). This work is expanded upon by investigation of the aggregation and surface accumulation properties of an industrial AFFF, which is more representative of the complex PFAS contamination matrices that may be subject to high salinity conditions in the environment (Chapter 3). Lastly, sorption processes related to PFAS removal in a biobased treatment system are uncovered through a mechanistic investigation of a multi-step oxidative treatment mechanism (Chapter 4).

Overall, this works serves to provide researchers with a more complete picture of the complexitiesassociated with PFAS treatment in relation to their unique surfactant properties.