Sonochemical degradation of PFAS in ion exchange regeneration wastes

• Published in: Journal of hazardous materials 2024-06, Vol.471, p.134291-134291, Article 134291
• Main Authors: Fuller, Mark E., Zhao, Yuwei, Hedman, Paul C., Koster van Groos, Paul G., Soto, Anthony, Boodoo, Francis, Yniguez, Jord, McKenzie, Erica R.
• Format: Article
• Language: English
• Subjects: Ion exchange; PFAS; Sonolysis; Still bottoms; Volatile organic fluorine
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.134291

One of the primary technologies currently being deployed for the removal of per- and polyfluoroalkyl substances (PFAS) from water is ion exchange (IX). For regenerable IX resins, concentrated PFAS in the resulting spent brine and/or still bottoms requires further treatment. This research demonstrated that PFAS in spent brine and still bottoms can be effectively degraded sonochemically at 1000 kHz. Overall, PFAS degradation was negatively impacted by high total organic carbon (TOC) and residual methanol (MeOH) solvent (up to 50 g/kg; 5% w:w), but was enhanced by the high chloride. The addition of caustic (up to 1 N NaOH) partially mitigated the inhibition by TOC and MeOH. Sonochemical degradation of individual PFAS compounds resulted in significant mineralization to form inorganic fluoride, but small quantities of volatile organic fluorine species (VOF) were noted. This is believed to be the first report of sonochemical degradation of PFAS in ion exchange regeneration wastes, and indicates the possibility for the application of this technology as part of a complete PFAS capture and destruction treatment train. [Display omitted] •Sonochemical PFAS degradation was observed in high salt resin regeneration wastes.•Elevated chloride enhanced PFAS degradation, while elevated TOC inhibited the process.•TOC inhibition could be partially mitigated by the addition of sodium hydroxide.•Volatile organic fluorine was produced during sonochemical PFAS degradation.