Environmental Fate of Novel Functionalized Hydrofluoroether (HFE) Alcohols
Bibliographic record
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a diverse class of chemicals ubiquitous in the environment due to their chemical stability and application in a wide range of commercial and consumer products. Said stability is owed to the PFAS containing a series of strong carbon-fluorine bonds that are often resistant to environmentally relevant degradation processes. The fate of PFAS is innately related to unique environmental transformations. Therefore, it is imperative to assess novel PFAS structures in various environmental matrices to inform risk assessments based on the complete environmental fate of the chemical. A novel highly functionalized polyfluorinated surfactant, di(polyfluoroether thioether(S)‐oate) sulfonate (diFESOS), containing two hydrofluoroether (HFE) alcohol building blocks, (F7C3OCHFCF2SCH2CH2OH (FESOH)) has been designed for degradation by containing various heteroatom linkages and polyfluorinated carbons. However, the degree to which each functional group impacts the environmental fate of PFAS is investigated in this thesis through structural congeners of FESOH and quantitative structure-activity relationships. Rat in vivo toxicokinetic analysis of diFESOS and FESOH demonstrated faster elimination kinetics than perfluorinated alternatives. Blood of orally dosed rats contained higher levels of metabolites than intravenously dosed rats, highlighting the importance of metabolism in the gut and liver. Terminal metabolites were identified as 2H-3:2 polyfluoroether sulfonic acid (2H-3:2 PFESA) and perfluoropropionic acid (PFPrA). Atmospheric degradation studies exhibited the importance of the thioether functional group to both facilitate faster and more complete degradation. One HFE alcohol congener, MeFESOH (F3COCHFCF2SCH2CH2OH), was observed to degrade to an ultrashort acyl fluoride, and ultimately completely mineralize. Investigating the microbial biodegradation of each HFE alcohol, similar rates were observed, however thioether compounds yielded 2H-x:2 PFECA (x=1,3) products that were resistant to further microbial action. However, 2H-1:2 PFECA and 2H-1:2 PFESA demonstrated the potential to completely mineralize from secondary photolysis in surface water systems. Partitioning properties of each HFE alcohol congener exhibited unique affinities compared to polyfluorinated alternatives, highlighting the importance of investigating heteroatom-linked PFAS. Overall, this work highlights the value of understanding PFAS chemical architecture and how including thioethers, polyfluorinated ethers, and methoxy groups has the potential to facilitate the degradation of PFAS under environmental conditions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".