Adsorption of Single and Multi-Component Per-and Polyfluoroalkyl Substances (PFAS) at Air-Water Interfaces

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.

Department dc:contributor.department

Civil Engineering

Year dc:date.issued

2025

Author dc:creator

• Barnes-James, Julia

Advisor dc:contributor.supervisor

• Mumford, Kevin

• Per- and polyfluoroalkyl substances (PFAS)
• Perfluorooctanesulfonic acid (PFOS)
• Groundwater
• Remediation
• Air-sparging
• Environment
• Interfacial adsorption
• Aqueous film-forming foam (AFFF)

Statement dc:rights

• Attribution-NonCommercial-NoDerivatives 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/34270

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/34270