Mechanochemical destruction of per- and polyfluoroalkyl substances in aqueous film-forming foams and contaminated soil

Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic chemicals of concern that exhibit extreme persistence within the environment and possess physicochemical properties that are resistant to targeted degradation. Comprising substantial concentrations of PFASs, aqueous film-forming foams (AFFFs) present a major exposure pathway to the environment having been applied to land at firefighting-training sites globally for decades. This has led to significant contamination of environmental media. Herein, we demonstrate that mechanochemical destruction (MCD) is an effective method for the destruction of PFASs in an AFFF concentrate and an authentic sample of PFAS-contaminated soil derived from a decommissioned firefighting training facility. Both targeted analysis and non-targeted analysis were used in this study to evaluate the degradation of PFASs in complex substrates during MCD treatment. Destruction efficiencies of target PFAS subgroups ranged from 99.88% to 100%. The only additive employed for MCD treatment was quartz sand, which was used only for the liquid AFFF sample, with no additives required for the destruction of PFASs in the contaminated soil. This confirms the viability of MCD for both the remediation of PFAS-contaminated land and the destruction of stockpiled AFFFs. Mechanochemical treatment, or high energy ball milling, was successfully employed to destroy per- and polyfluoroalkyl substances in an aqueous film-forming foam concentrate and an authentic contaminated soil sample.

Automated summary

This study demonstrates that mechanochemical destruction (MCD) is an effective method for the destruction of PFASs in AFFF concentrate and PFAS-contaminated soil. Both targeted and non-targeted analysis were used to evaluate the degradation of PFASs during MCD treatment, showing high destruction efficiencies. The use of MCD could be a viable option for remediation of PFAS-contaminated land and destruction of stockpiled AFFFs.