InterPore2026

Improving the Prediction of Interfacial Tension and Adsorption at Fluid−Fluid Interfaces for Mixtures of PFAS and/or Hydrocarbon Surfactants by Considering Synergistic Effect

21 May 2026, 10:05

1h 30m

Poster Presentation (MS02) Environmental Porous Media: Water, Agriculture, and Remediation Poster

Speaker

Martin Witt

Description

Per- and polyfluoroalkyl substances (PFAS) are a family of compounds listed as persistent, mobile and toxic, posing significant risks to human health and ecosystems. Some PFAS, notably those present in Aqueous Film-Forming Foam (AFFF) exhibit significant adsorption at fluid-fluid interfaces (e.g., air-water interfaces), which plays a crucial role in their transport through soil and groundwater [1], [2]. Furthermore, AFFF formulations contain mixtures of PFAS and hydrocarbon surfactants with anionic, cationic, zwitterionic, and non-ionic species.
Current models typically account for competitive adsorption but don’t consider synergistic effect [3], thereby limiting their predictive capabilities for AFFF contamination sources.
This study aims to demonstrate that incorporating synergistic effect between PFAS and other surfactants alters the estimated quantities of PFAS adsorbed at fluid-fluid interfaces, and consequently that transport in soil is, in turn, affected.
Our modelling approach, [4], utilizes Szyszkowski parameters for each component, derived from fitting surface tension versus concentration curves for individual surfactant solutions—maintaining consistency with existing non-synergistic models. Furthermore, we provide new experimental Szyszkowski parameters for specific AFFF-derived PFAS. These values fill a gap in the current literature and can be integrated into both existing and future adsorption models. The adsorption model will be implemented in a transport screening model in the unsaturated zone to assess its impact on PFAS transport in soil.