Supercritical Water Oxidation as an Innovative Technology for PFAS Destruction

Krause, Max; Thoma, Eben D.; Sahle-Damesessie, Endalkachew; Crone, Brian C.; Whitehill, Andrew; Shields, Erin P.; Gullett, Brian K.

doi:10.1061/(asce)ee.1943-7870.0001957

Cited by 52 publications

(35 citation statements)

References 33 publications

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“…PFAS destruction is a daunting task because the strong C-F bonds that give PFAS their desirable properties also make these compounds resistant to end-of-life degradation. Harsh PFAS degradation methods include incineration (8), ultrasonication (9,10), plasmabased oxidation (11), electrochemical degradation (12,13), supercritical water oxidation (14), ultraviolet-initiated degradation using additives such as sulfite or iron (15)(16)(17)(18)(19), and other combinations of chemical and energy inputs (20) (table S1). Leveraging the reactivity of perfluoroalkyl species might, however, offer milder alternatives to address the PFAS contamination problem.…”

mentioning

confidence: 99%

Low-temperature mineralization of perfluorocarboxylic acids

Trang

Xue

et al. 2022

Science

168

100

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Per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative pollutants found in water resources at concentrations harmful to human health. Whereas current PFAS destruction strategies use nonselective destruction mechanisms, we found that perfluoroalkyl carboxylic acids (PFCAs) could be mineralized through a sodium hydroxide–mediated defluorination pathway. PFCA decarboxylation in polar aprotic solvents produced reactive perfluoroalkyl ion intermediates that degraded to fluoride ions (78 to ~100%) within 24 hours. The carbon-containing intermediates and products were inconsistent with oft-proposed one-carbon-chain shortening mechanisms, and we instead computationally identified pathways consistent with many experiments. Degradation was also observed for branched perfluoroalkyl ether carboxylic acids and might be extended to degrade other PFAS classes as methods to activate their polar headgroups are identified.

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confidence: 99%

Low-temperature mineralization of perfluorocarboxylic acids

Trang

Xue

et al. 2022

Science

168

100

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“…Thus, it is ideal to utilize other relatively low-cost technologies to reduce PFAS wastewater volume first and concentrate PFAS along with co-contaminants. The wastewater containing highly concentrated PFAS may be transferred to a disposal well deep underground [ 129 , 130 ] or a PFAS-specialized degradation plant for complete destruction. This approach is also expensive, requires further treatment steps, and does not always eliminate the concentrated PFAS streams [ 63 , 131 ].…”

Section: Coupled Membrane Technologymentioning

confidence: 99%

A Review on Removal and Destruction of Per- and Polyfluoroalkyl Substances (PFAS) by Novel Membranes

Das

Ronen

2022

Membranes

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Per- and Polyfluoroalkyl Substances (PFAS) are anthropogenic chemicals consisting of thousands of individual species. PFAS consists of a fully or partly fluorinated carbon–fluorine bond, which is hard to break and requires a high amount of energy (536 kJ/mole). Resulting from their unique hydrophobic/oleophobic nature and their chemical and mechanical stability, they are highly resistant to thermal, chemical, and biological degradation. PFAS have been used extensively worldwide since the 1940s in various products such as non-stick household items, food-packaging, cosmetics, electronics, and firefighting foams. Exposure to PFAS may lead to health issues such as hormonal imbalances, a compromised immune system, cancer, fertility disorders, and adverse effects on fetal growth and learning ability in children. To date, very few novel membrane approaches have been reported effective in removing and destroying PFAS. Therefore, this article provides a critical review of PFAS treatment and removal approaches by membrane separation systems. We discuss recently reported novel and effective membrane techniques for PFAS separation and include a detailed discussion of parameters affecting PFAS membrane separation and destruction. Moreover, an estimation of cost analysis is also included for each treatment technology. Additionally, since the PFAS treatment technology is still growing, we have incorporated several future directions for efficient PFAS treatment.

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“…For water, the supercritical condition is achieved at pressures exceeding 22 mega Pascals (MPa) and temperatures above 374°C (Cengel & Boles, 2002) and is defined by a single fluid phase that is a fraction of the density of water with a tremendous capacity to dissolve gas and organic compounds while precipitating inorganic species. Since its introduction in the 1980s from work at the Massachusetts Institute of Technology, SCWO has been thoroughly reviewed throughout the literature for various applications and potential challenges, and various patents have been pursued and awarded (Hong & Spritzer, 2002;Krause et al, 2022;Kritzer & Dinjus, 2001;Marrone, 2012;Pinkard et al, 2021;Tester et al, 1993;Yesodharan, 2002). Recent research on the applicability of highpressure thermal treatment (e.g., SCWO and alkaline hydrothermal treatment) has demonstrated a high degree of certainty for the complete mineralization of perfluorooctane sulfonic acid (PFOS) in water (Krause et al, 2022;Pinkard et al, 2021;Wu et al, 2019), PFAS within wastewater treatment sludge (Yu et al, 2020), and PFAS associated with aqueous film-forming foam (AFFF) (Hao et al, 2021;Pinkard, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Since its introduction in the 1980s from work at the Massachusetts Institute of Technology, SCWO has been thoroughly reviewed throughout the literature for various applications and potential challenges, and various patents have been pursued and awarded (Hong & Spritzer, 2002;Krause et al, 2022;Kritzer & Dinjus, 2001;Marrone, 2012;Pinkard et al, 2021;Tester et al, 1993;Yesodharan, 2002). Recent research on the applicability of highpressure thermal treatment (e.g., SCWO and alkaline hydrothermal treatment) has demonstrated a high degree of certainty for the complete mineralization of perfluorooctane sulfonic acid (PFOS) in water (Krause et al, 2022;Pinkard et al, 2021;Wu et al, 2019), PFAS within wastewater treatment sludge (Yu et al, 2020), and PFAS associated with aqueous film-forming foam (AFFF) (Hao et al, 2021;Pinkard, 2022). The theorized mechanism of SCWO facilitated destruction is thermal oxidation of PFAS, resulting in fully mineralized carbon dioxide and inorganic fluoride, though instantaneous sequential defluorination reactions related to chemical oxidation and/or reduction via manipulated pH may also occur (Wu et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Validation of supercritical water oxidation to destroy perfluoroalkyl acids

McDonough

Kirby

Bellona

et al. 2022

Remediation Journal

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Some of the same unique physical and chemical properties that make per‐ and polyfluoroalkyl substances (PFAS) desirable for a wide range of commercial applications render them recalcitrant to many liquid treatment technologies. As developments in PFAS‐related toxicological studies increasingly suggest potential adverse human health effects, our industry has made great progress in the past several years on concentrating PFAS into small volume waste streams via adsorption and separation mechanisms. Coupled with residual PFAS‐containing commercial products that are being phased out, management of these concentrated waste streams presents an urgent need for the development and validation of destructive treatment technologies. Here, we field‐validate supercritical water oxidation to treat a concentrated waste stream of 12 perfluoroalkyl acids (PFAAs) with liquid and gaseous analysis, adhering to the recent Other Test Method 45 for stack emission sampling from the United States Environmental Protection Agency (USEPA) and USEPA Method 537.1, with quality control and quality assurance protocols from the Department of Defense/Department of Energy Quality Systems Manual 5.3. Results generated suggest greater than 99.999% destruction and removal efficiency of these 12 PFAAs after two ∼120‐min continuous flow trials, with an overall defluorination percentage of approximately 62.6%.

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Supercritical Water Oxidation as an Innovative Technology for PFAS Destruction

Cited by 52 publications

References 33 publications

Low-temperature mineralization of perfluorocarboxylic acids

Low-temperature mineralization of perfluorocarboxylic acids

A Review on Removal and Destruction of Per- and Polyfluoroalkyl Substances (PFAS) by Novel Membranes

Validation of supercritical water oxidation to destroy perfluoroalkyl acids

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