This project aims to apply the properties of (1) ferro-cavitation and (2) electrosorptive cavitation aqueous treatment technologies developed at the National Research Council of Canada, in conjunction with per- and polyfluoroalkyl substances (PFAS) expert knowledge at McGill University for the remediation of high priority PFAS originated from aqueous film-forming foams (AFFF). The specific objectives are as follows:

1. Development of a synergistic approach for applying a hybrid pulsed electrosorptive cavitation process train to degrade high-priority PFAS toward mineralization in aqueous systems,
2. Elucidation of degradation mechanisms through advanced chemical analysis and quantum modeling, and
3. Scoping of process scale-up of the developed process train for continuous treatment and complete defluorination of high-priority PFAS.

This project furthers the scientific understanding and implementation of two novel cavitation approaches, conceived as a process train to target the remediation of high priority PFAS from AFFF. It applies a mid-to-high frequency sono-Fenton approach called ferro-cavitation, a promising PFAS destruction technology, in combination with a pulsed electrosorptive cavitation technology to target complete defluorination of high-priority PFAS. In the development of a synergistic approach, the hybrid process intends to mimic non-thermal plasma treatment through their disintegration of large PFAS collected at increased gas-liquid interfaces through localized sonolytic bubbles. Sonolytic bubbles at mid-to-high frequencies formed in a sono-Fenton process with ligand addition, summarized as ferrocavitation, will be applied. Pulsed electrosorptive cavitation is outlined as a second unit operation in the process to target the complete removal of PFAS products with a hydrodynamic cavitation process and an electrosorption process for complete defluorination. Degradation mechanisms, determined through chemical analysis and quantum modeling, will be applied to determine optimal empirical conditions and scale-up criteria will be determined through preliminary techno-economic analysis to support the process feasibility.

The success of this project will allow practitioners to manage PFAS environmental risks using a sustainable and fast degradation strategy at reduced costs compared to other technologies. The approach targets the complete on-site destruction of PFAS, avoiding the need for off-site incineration or the formation of toxic fluorinated byproducts. This research will provide a scientific understanding of increased gas-liquid interfaces other than liquid surface effects in plasma treatment with ease in process scaling at reduced equipment costs and enhanced safety in operation. Research outcomes of the study will contribute toward the following:

1. Increased understanding of PFAS degradation using ferro-cavitation, particularly, with ligand addition,
2. Influence of electrosorptive cavitation in complete defluorination of PFAS,
3. Role of pulsations in surface adherence and degradation of PFAS,
4. Determination of molecular reaction kinetics of PFAS for elucidating the mechanism of PFAS removal, and
5. Process scale-up criteria established through techno-economic feasibility analysis.

(Anticipated Project Completion - 2024)