Solvent-Free Nonthermal Destruction of PFAS Chemicals and PFAS in Sediment by Piezoelectric Ball Milling

Abstract

Studies on the destruction of solid per- and polyfluoroalkyl substances (PFAS) chemicals and PFAS-laden solid wastes significantly lag behind the urgent social demand. There is a great need to develop novel treatment processes that can destroy nonaqueous PFAS at ambient temperatures and pressures. In this study, we develop a piezoelectric-material-assisted ball milling (PZM-BM) process built on the principle that ball collisions during milling can activate PZMs to generate ∼kV potentials for PFAS destruction in the absence of solvents. Using boron nitride (BN), a typical PZM, as an example, we successfully demonstrate the complete destruction and near-quantitative (∼100%) defluorination of solid PFOS and perfluorooctanoic acid (PFOA) after a 2 h treatment. This process was also used to treat PFAS-contaminated sediment. Approximately 80% of 21 targeted PFAS were destroyed after 6 h of treatment. The reaction mechanisms were determined to be a combination of piezo-electrochemical oxidation of PFAS and fluorination of BN. The PZM-BM process demonstrates many potential advantages, as the degradation of diverse PFAS is independent of functional group and chain configurations and does not require caustic chemicals, heating, or pressurization. This pioneering study lays the groundwork for optimizing PZM-BM to treat various PFAS-laden solid wastes.

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

“…However, the EOF result found in this study represents double the efficiency of PFAS destruction in comparison to a similar study by Yang and colleagues in which impacted sediment was treated within a planetary ball mill. 28…”

“…28 Of particular signicance in this work, no co-milling agents (e.g., KOH, boron nitride) were added to the soil prior to MCD treatment, unlike comparable studies. [26][27][28] Furthermore, the results observed here revealed higher DEs for a broader range of target PFASs when compared to previous studies that used MCD for the treatment of PFASs in contaminated soils 26,27 and sediments. 28…”

Near-Complete Destruction of PFAS in Aqueous Film-Forming Foam (AFFF) by Integrated Photo-Electrochemical Processes

“…Details of instrument setup were described in our previous publication. 49 Nontargeted analysis of PFAS transformation products was performed on high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC/Q-ToF-MS, SCIEX). The instrument setup was described in Text S2.…”

Electron/hole piezocatalysis in chemical reactions

“…Yang et al (2023) 176 introduced a hexagonal boron nitride for the degradation of solid per- and polyfluoroalkyl compounds (PFAS) under BM. The successful decomposition and defluorination of the solid perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) were observed after 2 h of treatment.…”

“…The degradation pathways of BTH, as shown in Fig.5, involved eight possible intermediate products. A decreased toxicity was observed for these intermediates compared to the pristine BTH.Yang et al (2023)176 introduced a hexagonal boron nitride for the degradation of solid per-and polyfluoroalkyl compounds (PFAS) under BM. The successful decomposition and defluorination of the solid perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) were observed after 2 h of treatment.…”