Electro-regeneration of PFAS-laden and other spent sorbents

Abstract

An electro-regeneration system for a sorbent includes a vessel having an inlet and an outlet, a pump fluidly coupled to the inlet, an anode positioned at least partially in the vessel, and a cathode positioned at least partially in the vessel. The cathode includes an electrically conductive sorbent. A power source is electrically coupled to the anode and the cathode. Regenerating a PFAS-laden sorbent includes applying current from the power source to the cathode, thereby electrostatically repelling the PFAS from the electrically conductive sorbent, and regenerating the sorbent to yield a regenerated sorbent.

Description

ELECTRO-REGENERATION OF PFAS-LADEN AND OTHER SPENT SORBENTSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 582,655 filed on September 14, 2023, which is incorporated herein by reference in its entirety.STATEMENT OF GOVERNMENT INTEREST

[0002] This invention was made with government support under 2127509 awarded by the National Science Foundation. The government has certain rights in the invention.TECHNICAL FIELD

[0003] This invention relates to electro-regeneration of PFAS-laden and other spent sorbents.BACKGROUND

[0004] Many consumer products are made with fluorinated chemicals called per- and polyfluoroalkyl substances (PFAS) due to their high stability, unique surfactant features, oil and water repellency, and chemical resistance. These chemicals are persistent, non-biodegradable, and bio-accumulable in the aquatic environment. PFAS are highly toxic and, at part per billion concentrations, may lead to cancer, liver damage, and endocrine disruption. Adsorption technology (e.g., granular activated carbons and / or ion exchange resins) has been used for PFAS mitigation. The quick breakthrough of these adsorbents is leading to a pervasive PFAS cycle. Disposing of spent adsorbents in landfills can contribute to PFAS contamination in the leachate. The other environmental endpoint for these PFAS-laden adsorbents involves their disposal in incineration facilities. Treating these materials through combustion processes can result in incomplete breakdown of PFAS, leading to the formation of potentially harmful byproducts (e.g., perfluoroalkanes).SUMMARY

[0005] This disclosure describes systems and methods for in situ electro-regeneration of exhausted PFAS-laden and other spent sorbents, as well as recovery of an enriched effluent forenhanced destructive removal by other techniques (e.g., electrochemical oxidation, advanced oxidation, biological treatment, etc.).

[0006] A first general aspect includes an electro-regeneration system for a sorbent. The electro-regeneration system includes a vessel having an inlet and an outlet, a pump fluidly coupled to the inlet, an anode positioned at least partially in the vessel, and a cathode positioned at least partially in the vessel. The cathode includes an electrically conductive sorbent. A power source is electrically coupled to the anode and the cathode.

[0007] Implementations of the first general aspect may include one or more of the following features.

[0008] The electrically conductive sorbent is laden with per- and polyfluoroalkyl substances (PF AS). The PF AS is adsorbed on a surface of the electrically conductive sorbent. The system is configured to regenerate the electrically conductive sorbent. Applying a current from the power source to the cathode increases a concentration of hydroxide ions on the electrically conductive sorbent, thereby electrostatically repelling the PF AS from the electrically conductive sorbent. Repelling the PFAS from the electrically conductive sorbent may include regenerating the electrically conductive sorbent. The sorbent may include granular activated carbon. The granular activated carbon may include macropores, mesopores, micropores, or a combination thereof. The pump is configured to provide an electrolyte to the vessel. The pump is configured to pump the electrolyte thorough the vessel in a direction against gravity. The system is configured for galvanostatic cycling.

[0009] In a second general aspect, regenerating a PFAS-laden sorbent includes applying current from the power source to the cathode, thereby electrostatically repelling the PFAS from the electrically conductive sorbent, and regenerating the sorbent to yield a regenerated sorbent.

[0010] Implementations of the second general aspect may include one or more of the following features. Electrostatically repelling the PFAS from the electrically conductive sorbent includes increasing a concentration of the PFAS in the electrolyte solution. Applying current may include applying a constant current. The electrically conductive sorbent may include granular activated carbon. The PFAS may include perfluorooctanoic acid.

[0011] The method may include, after regenerating the electrically conductive sorbent, adsorbing additional PFAS on the electrically conductive sorbent. The method may include cycling the system through one or more additional adsorption and regeneration cycles. Cyclingthe system increases surface oxygen groups on the granular activated carbon. The electroregeneration system can be at least partially submerged in the electrolyte.

[0012] In particular, this disclosure describes the regeneration of perfluorooctanoic acid (PFOA, as a model long chain PF AS compound) laden-F400 carbon using electro-assisted upflow rapid small-scale column test (RSSCT) setup. The laboratory column experiments were conducted exploring sequential adsorption and electro-regeneration cycles. The results showed that the electro-regeneration of saturated F400 carbon reinstated up to ~60% of initial capacity. After the 1st regeneration cycle, the regeneration efficiency of spent F400 carbon remained similar following four consecutive adsorption / regeneration cycles. This regeneration technique can be used to reduce waste PFAS-laden adsorbents in landfills and decrease the amount of CO2 emissions associated with the incineration of these sorbents.

[0013] The details of one or more embodiments of the subject matter of this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 depicts an electro-assisted up-flow rapid small-scale column test (RSSCT) setup for regeneration of exhausted PFAS-laden media. The inset depicts regeneration of a PFAS-laden granular activated carbon.

[0015] FIGS. 2A and 2B show PFOA removal breakthrough curves for F400 and electroregeneration efficiency of 100% saturated PFOA-laden F400, respectively. C / Co represents the column effluent concentrations divided by the column influent concentrations.

[0016] FIGS. 3 A and 3B show PFOA breakthrough curves for 100% and 50% saturated F400 and impact of saturation level for electro-regeneration efficiency of PFOA-laden F400, respectively.

[0017] FIG. 4 shows the effect of current on the cumulative increase in regeneration efficiency of F400.

[0018] FIG. 5 shows the effect of electro-regeneration cycles on the regeneration efficiency for PFOA-laden F400. *Saturation PFOA level (50%). Contact time for each sequential cycle: 72 h that is equivalent to 8,640 bed volume.

[0019] FIGS. 6A and 6B show deconvolution of Cis and Oispeaks, respectively, from XPS spectra of pristine F400, 1 cycle, and 4 cycle electro-regenerated F400.DETAILED DESCRIPTION

[0020] This disclosure describes in situ electro-regeneration systems and methods for regeneration of exhausted per- and poly-fluoroalkyl substances (PFAS)-laden and other spent sorbents. In particular, this disclosure describes the efficiency of electro-driven regeneration on PFAS-laden granular activated carbon (GAC), the impact of PF AS saturation level on regeneration efficiency, the reuse capability of regenerated GAC following multiple adsorptionregeneration cycles, and the impact of electro-regeneration process on GAC surface characteristics.

[0021] FIG. 1 depicts an electro-assisted up-flow rapid small-scale column test (RSSCT) system 100 for regeneration of exhausted PFAS-laden media. System 100 includes vessel 102. As depicted, vessel 102 is an electrolytic cell. In other embodiments, vessel 102 is an electroassisted tank. Vessel 102 includes inlet 104 and outlet 106. Anode 108 and cathode 110 are positioned at least partially in vessel 102, with a pre -de fined interelectrode gap. Pump 112 is configured to provide electrolyte to vessel 102 through inlet 104 in an upward direction (e.g., against gravity). Power supply 114 is coupled to anode 108 and cathode 110 through leads 108’ and 110’, respectively. Cathode 110 includes electrically conductive sorbent 116 (e.g., GAC). Spacers 118 can be positioned on one or both sides of electrically conductive sorbent 116.Spacers 118 allow fluid flow thought vessel 102. In one example, spacers 118 are made of glass wool. As depicted in the inset, electrically conductive sorbent 116 can have one or more of macropores 120, mesopores 122, and micropores 124, and can be laden with PF AS 126. As described herein, PF AS adsorbed during adsorption cycle of system 100 can be desorbed during a regeneration cycle. During regeneration, performed galvanostatically under a constant applied current, an electrolyte (e.g., sodium sulfate) is provide to vessel 102 through inlet 104. In this process, the surface charge of electrically conductive sorbent 116 becomes more negatively charged, resulting in the substruction of negatively charged PF AS molecules from the sorbent surface due to electrostatic repulsion forces.

[0022] Regenerating a PFAS-laden sorbent includes applying current from the power source to the cathode, thereby electrostatically repelling the PFAS from the electrically conductivesorbent, and regenerating the sorbent to yield a regenerated sorbent. Electrostatically repelling the PF AS from the electrically conductive sorbent includes increasing a concentration of the PF AS in the electrolyte solution. Applying current may include applying a constant current. The electrically conductive sorbent may include granular activated carbon. The PFAS may include perfhiorooctanoic acid. The method may include, after regenerating the electrically conductive sorbent, adsorbing additional PFAS on the electrically conductive sorbent. The system may be cycled through one or more additional adsorption and regeneration cycles. Cycling the system increases surface oxygen groups on the granular activated carbon. The electro-regeneration system can be at least partially submerged in the electrolyte.

[0023] In situ adsorption / electro-regeneration of PFOA laden-F400 was developed using electro-assisted benchtop up flow RSSCT. The effects of different PFOA saturation levels (50% and 100%) on F400 carbon and the performance of electro-regeneration cycles were examined. With fully saturated F400 carbon (100%), the efficiency of electro-regeneration was significantly lower. Therefore, the regeneration capabilities of F400, when loaded with long chain PFOA, were found to be highly influenced by the saturation level of the adsorbent. For both saturation levels, the electro-regeneration of spent F400 carbon was achieved with a lower energy consumption of less than 1 kWh / kg. After the 1stregeneration cycle, the regeneration efficiency of spent F400 carbon remained similar for the following three consecutive adsorption / regeneration cycles.

[0024] The electro-regeneration process does not result in any noticeable loss of carbon mass, ensuring that the adsorption capacity for PFOA remains consistent over four consecutive adsorption / electro-regeneration cycles. However, changes are observed in the characterization of the carbon surface, particularly in the C-C and O=C-OH bands, along with alterations in the physicochemical structures of the carbon such as surface area and pore size distributions.

[0025] Regeneration can be achieved due at least in part to the primary adsorption of long- chain PFOA molecules on the external surface of the carbon rather than within the interior micropores. This suggests that the electro-regeneration process primarily focuses on desorbing the surface bound PFOA molecules, enabling the regeneration of the carbon adsorbent.EXAMPLESMaterial and methods

[0026] PFOA was selected as the model PF AS compound because of its frequent detection inPF AS contaminated sources. PFOA was purchased from Sigma-Aldrich Chemical Co., Ltd. (St. Louis, MO, USA).I3C4-PFOA, an internal standard, was obtained from Wellington Laboratories (Guelph, ON, Canada) and added to the samples prior to the analysis.

[0027] F400 (Calgon Inc., USA) carbon was used as the adsorbent media, which was grounded and sieved through 140-170 U.S. mesh size (88-105 pm) before use. Additionally, the solutions were prepared in Milli-Q (deionized, DI) water at a resistivity of 18.2 Mflcm at 25 °C. Electro-regeneration reactor design and operation

[0028] The GAC adsorbent media was packed into RSSCT column. The column was packed with 1 cm of glass wool (bottom), 1 cm of F400 (50 mg as mass, middle), and 1 cm of glass wool (top). The electrolytic cell contained an anode (Ti wire: 5 cm long with 0.314 cm diameter) and a cathode (PFOA-laden F400), with a media depth of 1 cm. A nickel wire was used to close the circuit between the power supply and the cathode. The interelectrode gap of anode and cathode was kept at 1.5 cm. The column was operated in up-flow configuration during both adsorption and regeneration cycles.

[0029] Two steps, PFOA adsorption and electro-regeneration cycles of F400 carbon, were sequentially performed. At step I, PFOA solution (5 mg / L) was continuously fed to the column at 2 mL / min flow rate (empty bed contact time [EBCT]= 1.27 min). A high initial PFOA concentration of 5 ppm was used to achieve rapid breakthrough during the adsorption cycle. The experiments were performed up to 18,000 bed volumes (BVs), and with a loading rate of 5.82 gpm / ft2. In step II, in-situ electro-regeneration of the PFOA loaded carbon was conducted following exhaustion of the media’s adsorption capacity. During the electro-regeneration process, the reactor was fed with predetermined sodium sulfate (Na2SO4) solution (250 mM), as the supporting electrolyte. The regeneration cycles were performed galvanostatically under a constant applied current of 1 mA with a TENMA 72-2720 power supply, connected to a digital multimeter Fluke 15B+. The samples were collected from the outlet of the reactor at different time intervals. All electro-regeneration experiments were carried out at room temperature (25 °C) under ambient pH conditions (>pH 8). The changes in pH and conductivity were monitored using Orion Star Al 21 (Thermo) and Traceable 4360 (Control Company), respectively.Adsorbent characterization

[0030] The pristine and electro-regenerated F400 carbon were characterized for change in surface area, pore size, and surface chemistry. The Brunauer Emmett Teller (BET) specific surface area and the pore size distribution of the samples were measured by N2 adsorption / desorption at 77 K using a Tristar II 3020 analyzer (Micromeritics, USA). The elemental analysis of pristine and regenerated F400 carbons was performed using Kratos XPS (Shimadzu Group Company). The spectra were referenced to the C Is binding energy at 284.5 eV. Standard data analysis was performed using the Casa Software.Analytical methods and analysis

[0031] PFOA was analyzed with an Agilent 1290 multisampler liquid chromatograph coupled with 6490 Triple Quadrupole mass spectrometer LC-MS / MS (Agilent, Santa Clara, CA). A Gemini Cl 8 column (100 x 3 mm, Phenomenex, Torrence, CA) was used as the analytical column in conjunction with two Zorbax DIOL guard columns (Agilent, Santa Clara, CA) and one delay LC column (Luna 5 pm Cl 8, Phenomenex, Torrence, CA). The column oven was kept at 40 °C. The mobile phase A was 20 mM ammonium acetate in optima LC / MS grade water, the mobile phase B was 100% optima LC / MS grade methanol, and HPLC rinse solution was 100% HPLC grade acetonitrile. Each sample was spiked with 5 mM of isotopically labeled13C4-PFOA as internal standard (0.5 mL of mass labeled standards + 0.5 mL sample). The injection volume for the analysis was 10 pL. The detection limit of PFOA was 200 ppt.PFOA adsorption and electro-regeneration

[0032] The changes in effluent concentrations during adsorption and electro-regeneration cycles are shown in FIGS. 2A and 2B, respectively. The observed adsorption S-shaped curve in FIG. 2A indicates that the RSSCT system captured the mass transfer zone within the sorbent- packed bed. At the tested feed PFOA concentration of 5 mg / L, the breakthrough of PFOA occurred at 18,000 bed volumes (BVs), which corresponds to a treated volume of 20L. The treated volume of water can significantly increase as the feed water PF AS concentration decreases. Following the 100% saturation of the media with PFOA, a cathodic current of 1 mA was applied to the saturated F400. As shown in FIG. 2B, the applied current and service flow rate (2 mL / min), 43% of the total PFOA desorbed from the carbon surface until reaching 18,000 BVs.

[0033] In the electrified regeneration system described herein, the surface charge of the adsorbent becomes more negatively charged, resulting in the substruction of negatively charged PFOA molecules from the adsorbent surface due to electrostatic repulsion forces. Spent carbon characteristics will remain the same independently of the bed-volume treated and similar volumes can be used in regeneration. Thus, for environmentally relevant concentrations of PF AS usually found in the range of ppb-ppt (orders of magnitude below the experimental conditions of 5 mg / L) concentration factors of x500 can be expected.

[0034] The impact of saturation levels at two different PFOA saturation levels (100% and 50%) on in situ electro-regeneration efficiency in continuous-flow systems is shown in FIG. 3A. As shown in FIG. 3B, the regeneration of F400 was accomplished after 50% (7,000 BVs) and 100% (18,000 BVs) PFOA saturation up to 168 h regeneration time, with a constant flow rate (2 mL / min) and applied current (1 mA). The EC performance of electro-regeneration efficiency was also presented by establishing breakthrough curves at different saturation levels (50% and 100%) in FIG. 3B. The electro-regeneration efficiency calculations for spent F400 carbon confirmed that EC is around 0.70 kWh / kg. The results showed that the electro-regeneration efficiency was 27% lower for fully saturated (100%) F400 carbon as compared to 50% saturation. When the PFOA molecules can reach into the meso- and macropore regions in a short period of time (<50% breakthrough), spent carbon is easier to regenerate. Water cluster formation at oxidized carbon surfaces can favor penetration through the pore throats of spent carbon, and thus strong H-bonds can be formed between water molecules and the hydrophilic tails of PFOA that would inhibit the electro-regeneration efficiency of spent carbon.

[0035] The RSSCT experiments were conducted in the absence and presence of an applied current. As shown in FIG. 4, regeneration efficiency of spent F400 was enhanced with current. While only 17% of PF AS released from the F400 in the absence of current, over 60% was removed through the application of current. The result showed that electro-regeneration of spent F400 exhibited higher regeneration efficiency than conventional salt regeneration.Effect of electro-regeneration cycles on regeneration efficiency

[0036] The stability of the electro-regeneration process was examined over repeated 4 cycles of adsorption / electro-regeneration in the same RSSCT at constant flow rate (2 mL / min), saturation PFOA level (50%), and applied current (1 mA). The efficiency of the electroregeneration of F400 during four consecutive adsorption / regeneration cycles was presented inFIG. 5. After four consecutive cycles, the regeneration efficiency of spent F400 was not significantly changed. This similarity can be due to different factors such as regeneration time, PFOA structure, pore regions and surface charge of adsorbents. Slow diffusion occurs at micropore regions of carbon. Thus, longer regeneration times may be required if PFOA must slowly diffuse out from these microporous regions. Therefore, in a short period of adsorption / and regeneration time, PFOA molecules can reach to the meso- and macropore regions of F400 carbon, whereas it may not be reached on the narrower micropores of carbon.Effect of electro-regeneration on adsorbent characteristics

[0037] During electro-desorption of spent F400, oxidation / reduction reactions can alter the pore structure (especially micropore region) of spent carbon. To understand the impact of electro-regeneration on the F400 structure, the physicochemical properties of pristine F400, 1st and 4th regeneration cycles of F400 were evaluated. Results, presented in Table 1, demonstrate a shift in pore distribution towards smaller meso- and macropores instead of micropores, leading to reduction in the surface area of pristine F400 carbon (1039 m2 / g). Specifically, after the 1st regeneration cycle, the surface area decreased to 678 m2 / g, and further decreased to 429 m2 / g after the 4th regeneration cycle. The total pore volume (Vr) of pristine F400 was decreased after 1st and 4th regeneration cycles. Different than meso- and macropore volume of carbon, a portion of the micropores were diminished after 1st and 4th regeneration cycles.Table 1. Carbon characteristics of pristine F400, after 1st and 4thelectro-regeneration cycles.Pristine F400 After 1stcycle regeneration After 4thcycle regeneration■' Specific surface area calculated with the Brunauer-Emmett-Teller (BET) model,bTotal pore volume calculated from single point adsorption at P / Po = 0.99,cThe pore volume fraction in each pore size range obtained from the density functional theory (DFT) analysis,doxygen content calculated with XPS analyzer.

[0038] Oxygen content of pristine F400 is apparently increased up to 30% after electroregeneration. During electro-regeneration, surface oxygen functional groups are increased.Surface oxygen groups, when present on the carbon surface, have the potential to create a water cluster. This water cluster formation can lead to pore blockage due to the decrease in surface hydrophobicity and the Ti-electron density on the carbon. The changing physicochemical characteristics of GAC at lower current (1 mA) should give a positive effect for the PFOA-laden spent carbon.

[0039] The changes in carbon and oxygen content of F400 following electro- 1st and 4th regeneration cycles were also analyzed by XPS and presented in FIG. 6. After 1st and 4th cycle regeneration, oxygen peaks were clearly increased with decreasing carbon peaks. The amount of oxygen surface groups adhered to the carbon surface also increased. This increase in oxygen surface groups is favorable for selectively desorbing PF AS contaminants. Comparing pristine F400 and the 1st cycle of electro-regeneration, it is observed that the percentage of C-C functional groups on pristine F400 decreased by 29% after the 4thelectro-regeneration cycle. After the 4thelectro-regeneration cycle, there was an increase in the percentage of C-O-C (3%) functional groups. During electro-regeneration cycles, C-Si peaks (24-25%) appeared due to the presence of glass wool, which can be ascribed to attachment of Si on the carbon surface. Besides, O=C-OH (10%) functional groups on the carbon surface were decreased with increasing electroregeneration cycles. The C-0 (8%) and C=O (%4) functional groups were increased after 1stand 4thelectro-regeneration cycles. The XPS spectra analysis confirmed that the oxidation of the carbon surface increases during the electro-regeneration cycles. With the increase in surface oxygen groups, the electro-desorption of PFOA from saturated F400 was enhanced.Energy Consumption (EC)

[0040] Since electrical energy consumption (EC, kWh / g) is an engineering figure of merit in evaluating the operational costs of an electric driven process, the required electrical energy for desorbing PF AS from the surface was calculated using EC values for flow-through operation according to equation (1).where Eceii is the potential differences through the electro-regeneration system (V), I is the applied current (A), t is the charging time (h) and ACmass is the mass of F400 in the RSSCT (g) and 1000 is a conversion factor.

[0041] Although this disclosure contains many specific embodiment details, these should not be construed as limitations on the scope of the subject matter or on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this disclosure in the context of separate embodiments can also be implemented, in combination, in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[0042] Particular embodiments of the subject matter have been described. Other embodiments, alterations, and permutations of the described embodiments are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results.

[0043] Accordingly, the previously described example embodiments do not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.

Claims

WHAT IS CLAIMED IS:

1. An electro-regeneration system for a sorbent, the system comprising: a vessel comprising an inlet and an outlet; a pump fluidly coupled to the inlet; an anode positioned at least partially in the vessel; a cathode positioned at least partially in the vessel, wherein the cathode comprises an electrically conductive sorbent; and a power source electrically coupled to the anode and the cathode.

2. The system of claim 1, wherein the electrically conductive sorbent is laden with per- and polyfluoroalkyl substances (PFAS).

3. The system of claim 2, wherein the PFAS is adsorbed on a surface of the electrically conductive sorbent.

4. The system of claim 3, wherein the system is configured to regenerate the electrically conductive sorbent.

5. The system of claim 4, wherein applying a current from the power source to the cathode increases a concentration of hydroxide ions on the electrically conductive sorbent, thereby electrostatically repelling the PFAS from the electrically conductive sorbent.

6. The system of claim 5, wherein repelling the PFAS from the electrically conductive sorbent comprises regenerating the electrically conductive sorbent.

7. The system of claim 6, wherein the sorbent comprises granular activated carbon.

8. The system of claim 7, wherein the granular activated carbon comprises macropores, mesopores, micropores, or a combination thereof.

9. The system of claim 1 , wherein the pump is configured to provide an electrolyte to the vessel.

10. The system of claim 9, wherein the pump is configured to pump the electrolyte thorough the vessel in a direction against gravity.

11. The system of claim 1, wherein the system is configured for galvanostatic cycling.

12. A method of regenerating a PFAS-laden sorbent, the method comprising: flowing an electrolyte solution through the electro-regeneration system of claim 1, wherein the electrically conductive sorbent is laden with PFAS; applying current from the power source to the cathode, thereby electrostatically repelling the PFAS from the electrically conductive sorbent and regenerating the sorbent to yield a regenerated sorbent.

13. The method of claim 12, wherein electrostatically repelling the PFAS from the electrically conductive sorbent comprises increasing a concentration of the PFAS in the electrolyte solution.

14. The method of claim 12, wherein applying current comprises applying a constant current.

15. The method of claim 12, wherein the electrically conductive sorbent comprises granular activated carbon.

16. The method of claim 15, wherein the PFAS comprises perfluorooctanoic acid.

17. The method of claim 16, further comprising, after regenerating the electrically conductive sorbent, adsorbing additional PFAS on the electrically conductive sorbent.

18. The method of claim 17, further comprising cycling the system through one or more additional adsorption and regeneration cycles.

19. The method of claim 18, wherein cycling the system increases surface oxygen groups on the granular activated carbon.

20. The method of claim 12, wherein the electro-regeneration system is at least partially submerged in the electrolyte.

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