Destruction and defluorination of PFAS matrix in continuous-flow supercritical water oxidation reactor: Effect of operating temperature

Prospects of complete mineralization of per- and polyfluoroalkyl substances by thermal destruction methods

“…Their PFAS destruction efficiencies vary from low percentages to near-complete decomposition and mineralization. For example, a study reported 100% fluoride recovery through SCWO at 610°C and residence times of 30 seconds [33]. Furthermore, a novel method employing polar aprotic solvents and low temperatures within the range of 80 to 120°C led to the fluorine mineralization in perfluoroalkyl carboxylic acids (PFCAs), ranging from 78 to 100% in 24 hours [27].…”

Hydrothermal Destruction and Defluorination of Trifluoroacetic Acid (TFA)

“…Several end-of-life PFAS destruction technologies have been investigated, including photocatalytic degradation, sonochemical destruction, plasma-based treatment, electrochemical oxidation, and hydrothermal technologies. , Treatment methods that rely on the partitioning behavior of PFAS do not readily degrade TFA. The hydrothermal approaches treat the entire fluid volume and show greater promise; however, the reaction rates and routes for TFA and longer-chain PFCA destruction are only partially understood.…”

“…Hydrothermal methods have been used to destroy PFAS in subcritical water under alkaline conditions and supercritical water under oxidative conditions. ,,− Hydrothermal alkaline treatment (HALT) in batch reactors has been shown to destroy and defluorinate PFAS compounds in various matrices, including AFFF, , spent GAC, contaminated groundwater, and foam fractionate . Endo and Funazukuri have proposed second-order rate constants for PFOA destruction under hydrothermal conditions, and Wu et al have proposed second-order PFOS destruction rate constants (with NaOH) at a fixed T = 350 °C. , TFA is a suitable model compound for studying the reaction kinetic rates and reaction mechanisms; these can be extrapolated for more complex PFCAs ( e.g ., PFOA, PFNA).…”

Structural Features of Styrene-Functionalized Cyclodextrin Polymers That Promote the Adsorption of Perfluoroalkyl Acids in Water

“…Per- and polyfluoroalkyl substances (PFASs) are a class of fluorinated surfactants used in many industrial and consumer products including firefighting foams, food packaging, cookware, waterproof textiles, and personal care products. − PFASs are bioaccumulative and environmentally persistent due to their innate thermal and chemical stability. − Chronic exposure to even trace amounts of some PFASs has been associated with adverse health impacts, such as high cholesterol, thyroid disease, low birth weight, liver damage and kidney cancer. − Our understanding of the negative effects associated with many individual PFASs and PFAS mixtures continues to develop. , Because of their widespread use and environmental persistence, PFAS contamination is now a major health and environmental crisis, affecting water resources around the world. − In March 2023, the U.S. EPA proposed enforceable limits for six PFASs in drinking water . For example, the proposed maximum contaminant levels (MCLs) for two legacy perfluoroalkyl acids (PFAAs), perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are 4 ng L –1 , along with combined limits at similar concentrations for four others. , As PFAS regulations are established around the world, it is clear that PFASs should be phased out for all but the most critical and environmentally containable use cases, while legacy contamination is addressed through environmental remediation and degradation into benign byproducts. − …”