Plasma-assisted degradation of a short-chain perfluoroalkyl substance (PFAS): Perfluorobutane sulfonate (PFBS)

Osakpolo Isowamwen; Rui Li; Thomas Holsen; Selma Mededovic Thagard

doi:10.1016/j.jhazmat.2023.131691

Plasma-assisted degradation of a short-chain perfluoroalkyl substance (PFAS): Perfluorobutane sulfonate (PFBS)

J Hazard Mater. 2023 Aug 15:456:131691. doi: 10.1016/j.jhazmat.2023.131691. Epub 2023 May 23.

Authors

Osakpolo Isowamwen¹, Rui Li¹, Thomas Holsen², Selma Mededovic Thagard³

Affiliations

¹ Department of Chemical and Biomolecular Engineering, Plasma Research Laboratory, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA.
² Department of Civil and Environmental Engineering, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA.
³ Department of Chemical and Biomolecular Engineering, Plasma Research Laboratory, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA. Electronic address: smededov@clarkson.edu.

PMID: 37236102
DOI: 10.1016/j.jhazmat.2023.131691

Abstract

This study investigates the degradation of perfluorobutane sulfonate (PFBS), a chemical compound belonging to a group of per- and polyfluoroalkyl substances (PFAS), by gas-phase electrical discharge plasma. Plasma alone was ineffective in degrading PFBS due to its poor hydrophobicity, which inhibited the compound from accumulating at the plasma-liquid interface, the region of chemical reactivity. To overcome bulk liquid mass transport limitations, a surfactant, hexadecyltrimethylammonium bromide (CTAB), was introduced to interact with and transport PFBS to the plasma-liquid interface. In the presence of CTAB, ∼99% of PFBS was removed from the bulk liquid and concentrated at the interface, where 67% of the concentrate was degraded and 43% of that amount was defluorinated within one hour. PFBS degradation was further improved by optimizing the surfactant concentration and dosage. Experiments with a range of cationic, non-ionic, and anionic surfactants revealed that the PFAS-CTAB binding mechanism is predominantly electrostatic. A mechanistic understanding of the PFAS-CTAB complex formation, its transport to and destruction at the interface is proposed, alongside the chemical degradation scheme, which includes the identified degradation byproducts. This study shows that surfactant-assisted plasma treatment is one of the most promising techniques for destroying short-chain PFAS in contaminated water.

Keywords: CTAB; PFBS; Plasma; Surfactant; Water treatment.