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Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2022)

‘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.

    Cover page: Surfactant Properties of Per- and Polyfluoroalkyl Substances (PFAS): Implications for Detection, Fate, and Transport in Environmental and Treatment Matrices
    • Article
    • Peer Reviewed
    UC Santa Barbara Previously Published Works (2015)
    The asymmetric synthesis of dragmacidin D (1) was completed in 10 steps. Its sole stereocenter was set by using direct asymmetric alkylation enabled by a C2-symmetric tetramine and lithium N-(trimethylsilyl)-tert-butylamide as the enolization reagent. A central Larock indole synthesis was employed in a convergent assembly of the heterocyclic subunits. The stereochemical evidence from this work strongly supports the predicted S configuration at the 6''' position, which is consistent with other members of the dragmacidin family of natural products.
      Cover page: 10-Step Asymmetric Total Synthesis and Stereochemical Elucidation of (+)-Dragmacidin D.
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2023)
      Fungi and laccase mediator systems (LMSs) have a proven track record of oxidizing recalcitrant organic compounds. There has been considerable interest in applying LMSs to the treatment of perfluoroalkyl acids (PFAAs), a class of ubiquitous and persistent environmental contaminants. Some laboratory experiments have indicated modest losses of PFAAs over extended periods, but there have been no clear demonstrations of a transformation mechanism or the kinetics that would be needed for remediation applications. We set out to determine if this was a question of identifying and optimizing a rate-limiting step but discovered that observed losses of PFAAs were experimental artifacts. While unable to replicate the oxidation of PFAAs, we show that interactions of the PFAA compounds with laccase and laccase mediator mixtures could cause an artifact that mimics transformation (≲60%) of PFAAs. Furthermore, we employed a surrogate compound, carbamazepine (CBZ), and electron paramagnetic resonance spectroscopy to probe the formation of the radical species that had been proposed to be responsible for contaminant oxidation. We confirmed that under conditions where sufficient radical concentrations were produced to oxidize CBZ, no PFAA removal took place.
        Cover page: An Artifact of Perfluoroalkyl Acid (PFAA) Removal Attributed to Sorption Processes in a Laccase Mediator SystemCreative Commons 'BY' version 4.0 license
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