Removal Of PFOA Research Articles

Enhanced Adsorption and Photocatalytic Removal of Pfoa from Water by F-Functionalized Mof with In-Situ-Growth Tio2: Regulation of Electron Density and Bandgap

Enhanced Adsorption and Photocatalytic Removal of Pfoa from Water by F-Functionalized Mof with In-Situ-Growth Tio2: Regulation of Electron Density and Bandgap

Surfactant Enhanced Electrokinetic Removal of Pfoa from Kaolinite Soil

Surfactant Enhanced Electrokinetic Removal of Pfoa from Kaolinite Soil

Efficient preadsorption–degradation of PFOA in water by a NaClO-assisted electrocoagulation technique using an Fe/Ni foam electrode

A novel strategy of “preadsorption–degradation” for efficient PFOA removal based on the EC-NaClO system with an Fe/Ni foam electrode has been successfully achieved.

Elucidating the removal of organic micropollutants on biological ion exchange resins

Biological ion exchange (BIEX) refers to operating ion exchange (IX) filters with infrequent regeneration to favor the microbial growth on resin surface and thereby contribute to the removal of organic matter through biodegradation. However, the extent of biodegradation on BIEX resins is still debatable due to the difficulty in discriminating between biodegradation and IX. The objective of the present study was to evaluate the performance of BIEX resins for the removal of organic micropollutants and thereby validate the occurrence of biodegradation. The removals of biodegradable micropollutants (neutral: caffeine and estradiol; negative: ibuprofen and naproxen) and nonbiodegradable micropollutants with different charges (neutral: atrazine and thiamethoxam; negative: PFOA and PFOS) were respectively monitored during batch tests with biotic and abiotic BIEX resins. Results demonstrated that biodegradation contributed to the removal of caffeine, estradiol, and ibuprofen, confirming that biodegradation occurred on the BIEX resins. Furthermore, biodegradation contributed to a lower extent to the removal of naproxen probably due to the absence of an adapted bacterial community (Biotic: 49% vs Abiotic: 38% after 24 h batch test). The removal of naproxen, PFOS, and PFOA were attributable to ion exchange with previously retained natural organic matter on BIEX resins. Nonbiodegradable and neutral micropollutants (atrazine and thiamethoxam) were minimally (6%–10%) removed during the batch tests. Overall, the present study corroborates that biomass found on BIEX resins contribute to the removal of micropollutants through biodegradation and ion exchange resins can be used as biomass support for biofiltration.

Evaluation of a drop-in waste volume reduction method for liquid investigation derived waste containing per- and polyfluoroalkyl substances

Development of on-site treatment strategies for PFAS-containing investigation derived waste (IDW) will decrease the potential for secondary release following off-site disposal, lower disposal costs, and promote more effective long-term management of PFAS-laden waste. Herein, we report the application of a simple, drop-in treatment that utilizes one of two PFAS sorbents: bituminous granular activated carbon (GAC) or strong base anion exchange resin (IX) and a small circulation pump to adsorb and concentrate PFAS impacted mass from liquid IDW collected from two sites with disparate water chemistries and synthetic IDW amended with PFAS-containing aqueous film forming foam (AFFF). Bench scale intermittent circulation experiments revealed that bituminous granular activated carbon (GAC, 0.5 mg/mL) removed up to 97.0 ± 1.4% and 96.4 ± 0.5% of PFOS and PFOA, respectively, in both site-derived IDW sources. Improved performance was observed in experimental treatments containing a strong base anion exchange resin (IX, 0.5 mg/mL), where up to 99.4 ± 0.1% and 96.7 ± 0.2% of PFOS and PFOA were removed, respectively. High chloride concentrations (20 g/L) reduced removal of short chain perfluorocarboxylates (PFBA and PFHxA) using GAC or IX, but high salt concentrations had negligible effects on the removal of PFOA, PFBS, PFHxS, or PFOS. Excellent scalability was observed in mesoscale experiments, where the majority of amended PFAS mass was removed from synthetic IDW within five days of vessel circulation using two different PFAS-capture configurations. Combined PFOS and PFOA concentrations were reduced to levels below 0.07 μg/L using either GAC or IX for both configurations. Results generated in this study support the application of this approach as an economical strategy for potential waste volume reduction in IDW destined for off-site disposal.

Enhanced treatment of perfluoroalkyl acids in groundwater by membrane separation and electrochemical oxidation

This work explores the treatment of poly- and perfluoroalkyl acids (PFAAs) in groundwater by coupling membrane separation and electrochemical oxidation (ELOX). A process system engineering approach based on modelling and empirical data was followed. Two nanofiltration (NF90) and reverse osmosis (BW30) membranes were characterized for treating an electrolyte (NaCl and CaSO4) mixture of perfluorocarboxylic acids (PFCAs) containing PFOA, PFHpA, PFHxA, PFPeA and PFBA with initial concentrations of 10 µg L−1 each. Membrane surface charge shielding and concentration polarization negatively influenced NF90 performance, and the BW30 membrane was selected. Electrochemical oxidation with boron doped diamond anodes treated the PFCAs mixture amended with PFOS and 6:2 FTSA, emulating previously pre-concentrated feed and non-preconcentrated feed conditions. Working at different current densities (J) between 20 and 350 A m−2, the removal of PFOA, PFOS and 6:2 FTSA followed first order apparent kinetics, although shorter chain PFCAs initially showed increasing trends because of their simultaneous electrogeneration and degradation. Overall, ΣPFAA electrolysis followed first order kinetics linearly correlated to J in the full range of testing. Unexpectedly, PFAAs electrolysis was faster for the low conductive non-preconcentrated feed, a result that was ascribed to the enhanced direct electron transfer mechanism resulting from the higher cell voltage. For 99.9% PFAAs removal, the total specific cost of treatment was minimized using a cascade of four RO stages and ELOX treatment of the concentrate, to reach ΣPFAA below the Health Advisory Levels recommended by the USEPA in drinking water (<70 ng L−1 sum of PFOA and PFOS).

Removing PFOA and nitrate by quaternary ammonium compounds modified carbon and its mechanisms analysis: Effect of base, acid or oxidant pretreatment.

Acid/base/oxidant pretreatment influenced subsequent quaternary ammonium epoxide compounds modified carbon (QAE-AC) and hence PFOA and nitrate removal. This work discerned that the most favorable QAE-AC protocol for PFOA removal was achieved when the wood carbon pretreated with HNO3 to adjust the carbon's slurry pH to 4.77, and tailored with the QUAB188. For nitrate removal, the most favorable when the carbon was pretreated with NaOH to raise the carbon's slurry pH to 9.34, and then loaded with the QUAB360. Based on experimentally results and molecular model, we found that pore volume, phenolic groups and the surface charge were the main factors affecting the PFOA removal, while the only factor affecting nitrate removal was surface charge. The QUAB's epoxide functionalities have cross-linked with phenolics along the activated carbon's graphene edge sites. QAE is preferentially reacted with the phenolic in the micropores and mesopores of carbon, and some QAE molecules form new "pore-like structures" outside the pores with the graphene planes or other QAE molecules. This pore-like structure hosted adsorption capacity by the quaternary ammonium. The favorable PFOA adsorption sites were in smaller mesopores via both hydrophobic interaction and electrostatic interaction; and nitrate sorption was occurring in the smaller micropores via anion exchange. Therefore, it can be considered that QAE-AC can simultaneously adsorb PFOA and nitrate in water.

PFOA and PFOS removal by ion exchange for water reuse and drinking applications: role of organic matter characteristics

Perfluoroalkyl substances (PFAS) are drinking water contaminants of emerging concern due to their persistence in the environment and tendency to bio-accumulate.

Electrochemical Transformations of Perfluoroalkyl Acid (PFAA) Precursors and PFAAs in Groundwater Impacted with Aqueous Film Forming Foams.

While oxidative technologies have been proposed for treatment of waters impacted by aqueous film forming foams (AFFFs), information is lacking regarding the transformation pathways for the chemical precursors to the perfluoroalkyl acids (PFAAs) typically present in such waters. This study examined the oxidative electrochemical treatment of poly- and perfluoroalkyl substances (PFASs) for two AFFF-impacted groundwaters. The bulk pseudo first order rate constant for PFOA removal was 0.23 L h-1 A-1; for PFOS, this value ranged from 0.084 to 0.23 L h-1 A-1. Results from the first groundwater studied suggested a transformation pathway where sulfonamide-based PFASs transformed to primarily perfluorinated sulfonamides and perfluorinated carboxylic acids (PFCAs), with subsequent defluorination of the PFCAs. Transient increases in the perfluorinated sulfonamides and PFCAs were observed. For the second groundwater studied, no transient increases in PFAAs were measured, despite the presence of similarly structured suspected PFAA precursors and substantial defluorination. For both waters, suspected precursors were the primary sources of the generated fluoride. Assessment of precursor compound transformation noted the formation of keto-perfluoroalkanesulfonates only in the second groundwater. These results confirm that oxidation and defluorination of suspected PFAA precursors in the second groundwater underwent transformation via a pathway different than that of the first groundwater, which was not captured by total oxidizable precursor assay.

New York chooses Cabot for PFOA removal

New York chooses Cabot for PFOA removal

Rapid and high-capacity adsorption of PFOS and PFOA by regenerable ammoniated magnetic particle

Adsorption is well accepted as an effective method for perfluorinated compounds' (PFCs) removal from water among various conventional methods. However, development of adsorbents that combine good performance of PFC removal and regenerability has not yet been realized. This work demonstrated the fabrication and application of an ammoniated magnetic adsorbent for efficient and economical PFOS and PFOA removal. Functional ammonium groups and γ-Fe2O3 were effectively incorporated in the particle with the proposed method. These fabricated magnetic particles presented superior adsorption performance for PFOS and PFOA with short equilibrium time of 120min and high adsorption capacity. The isotherms revealed that the adsorption process belonged to multilayer sorption with their intricate interactions including anion exchange and hydrophobic interaction. The magnetic particle maintained its removal efficacy over a wide pH range of 3-9 or with coexisting substances. Moreover, the regeneration and reuse of the magnetic particle were successfully carried out with PFOS and PFOA removal efficiency sustained higher than 80% in 15 consecutive treatment cycles. Along with the efficient adsorption and easy separation of adsorbents, we expect that this ammoniated magnetic particle can serve as an excellent alternative for PFOS and PFOA removal from water.