# Influence of Electrolytes on the Air–Water Interfacial Properties of Perfluoroalkyl Acids (PFAAs)

## TL;DR

This study explores how electrolytes affect the air-water interface properties of PFAAs, which are harmful chemicals, to improve methods for cleaning contaminated water.

## Contribution

The study reveals how electrolytes influence PFAA surface tension and adsorption, offering insights for better remediation techniques.

## Key findings

- Electrolytes reduce surface tension for both long- and short-chain PFAAs.
- Divalent ions like Ca2+ have a stronger effect on surface tension than monovalent ions like Na+.
- Electrolytes enhance adsorption and surface excess concentrations of PFAAs.

## Abstract

Perfluoroalkyl acids
(PFAAs), a subclass of per- and polyfluoroalkyl
substances (PFAS), are widely used but pose significant environmental
concerns due to their toxicity and bioaccumulation. Foam fractionation,
utilizing the amphiphilic nature of PFAS, offers a promising remediation
method by exploiting their migration to air–water interfaces.
The effectiveness of this technique is highly dependent on the air–water
interfacial properties and the adsorption capacity of PFAS at the
interface. This study investigates the impact of electrolytes prevalent
in PFAS-contaminated water on the air–water interfacial properties
of PFAAs, focusing on surface tension and diffusion behavior. Our
results show that electrolytes reduced surface tension for both long-
and short-chain PFAAs, with divalent ions (Ca2+) exhibiting
stronger effects than monovalent ions (Na+). Surface tension
modeling using Gibbs and Extended Langmuir isotherms revealed enhanced
adsorption and increased surface excess concentrations in the presence
of electrolytes, while dynamic surface tension analysis highlighted
the influence of electrolytes on molecular diffusion and adsorption
kinetics at short time scales.