Adsorption of Single and Multi-Component Per-and Polyfluoroalkyl Substances (PFAS) at Air-Water Interfaces
Bibliographic record
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a class of fluorinated chemicals that are highly persistent in the environment, pose significant health risks, and are widespread due to their use in consumer products and fire-fighting foams. The purpose of this study was to investigate the transport and retention of PFAS in groundwater systems, with a particular focus on their adsorption to air-water interfaces under environmentally relevant conditions. Laboratory experiments were conducted in one-dimensional columns and in a two-dimensional cell to assess the air-water interfacial adsorption of individual PFAS species and PFAS mixtures using a commercial aqueous film-forming foam (AFFF). The results of these experiments showed that at low concentrations, perfluorooctanesulfonic acid (PFOS) adsorption was better predicted by the Freundlich isotherm than the Langmuir isotherm. Varying pore-water velocity revealed that lower velocities increased retardation at lower PFOS concentrations due to the presence of diffusion-limited domains in quasi-saturated conditions. Additionally, PFAS in AFFF mixtures exhibited competitive air-water interfacial adsorption, with more surface-active PFAS reducing the retention of less active components. The two-dimensional cell experiments showed pronounced retardation of PFOS alone, emphasizing the need for multidimensional studies to model PFAS plumes accurately. A gas injection test suggested potential vertical transport of PFOS through adsorption to air bubbles, though further research is required to validate this for remediation applications. Overall, the findings highlight the influence of concentration, velocity, and surfactant mixtures on PFAS transport and emphasize the need for comprehensive site characterization to inform predictive modelling and effective remediation strategies.
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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".