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US-20260125334-A1 - TREATMENT PROCESS FOR PFAS-CONTAINING COMPOUNDS

US20260125334A1US 20260125334 A1US20260125334 A1US 20260125334A1US-20260125334-A1

Abstract

An improved method for separating PFAS substances from contaminated water and polar solvent systems using alkyl quaternary ammonium compound comprising of coagulation, flocculation, or phase separation thereof is disclosed. The aforementioned compounds may form electrostatic complexes that are insoluble in polar solvents aiding in separation.

Inventors

  • Rachel Taylor

Assignees

  • HERITAGE RESEARCH GROUP LLC

Dates

Publication Date
20260507
Application Date
20251219

Claims (20)

  1. 1 . A method of removing at least one polyfluoroalkyl compound from a medium, comprising contacting said medium with a compound of Formula I: wherein R 1 is selected from optionally substituted C 1 -C 30 alkyl and optionally substituted C 2 -C 30 alkenyl; R 2 is selected from optionally substituted C 1 -C 30 alkyl and optionally substituted C 2 -C 30 alkenyl; R 3 and R 4 are each independently selected from optionally substituted C 10 -C 30 alkyl and optionally substituted C 10 -C 30 alkenyl; and X − is a counter anion.
  2. 2 . The method of claim 1 , wherein R 1 is selected from optionally substituted C 1 -C 9 alkyl and optionally substituted C 2 -C 8 alkenyl.
  3. 3 . The method of claim 2 , wherein R 1 is methyl.
  4. 4 . The method of claim 2 , wherein R 2 is selected from optionally substituted C 1 -C 9 alkyl and optionally substituted C 2 -C 8 alkenyl.
  5. 5 . The method of claim 4 , wherein R 2 is methyl.
  6. 6 . The method of claim 1 , wherein R 3 and R 4 are independently selected from optionally substituted C 10 -C 20 alkyl.
  7. 7 . The method of claim 1 , wherein R 1 , R 2 , R 3 and R 4 are all unsubstituted.
  8. 8 . The method of claim 1 , wherein the counter anion is a halogen anion.
  9. 9 . The method of claim 8 , wherein the counter anion is a chloride or bromide anion.
  10. 10 . The method of claim 1 , wherein the medium comprises sand or soil.
  11. 11 . The method of claim 1 , wherein the medium comprises water.
  12. 12 . The method of claim 1 , wherein contacting the polyfluoroalkyl compound with the compound of Formula I results in the formation of an electrostatic complex.
  13. 13 . The method of claim 12 , wherein the electrostatic complex is insoluble in water.
  14. 14 . The method of claim 13 , wherein the electrostatic complex is less dense than water.
  15. 15 . The method of claim 13 , wherein the electrostatic complex is more dense than water.
  16. 16 . The method of claim 1 , wherein the polyfluoroalkyl compound is soluble in water.
  17. 17 . The method of claim 1 , wherein the compound of Formula I is soluble in water.
  18. 18 . The method of claim 1 , wherein the compound of Formula I exhibits a solubility of greater than about 1 mg/L of water.
  19. 19 . The method of claim 1 , wherein the compound of Formula I exhibits a solubility of less than 1 mg/L of water.
  20. 20 . The method of claim 1 , wherein contacting the polyfluoroalkyl compound with the compound of Formula I results in ion exchange and the formation of a new salt species.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/US2024/035609 filed Jun. 26, 2024, which is hereby incorporated herein by reference in its entirety. International Application No. PCT/US2024/035609 claims the benefit of U.S. Provisional Application No. 63/510,639 filed Jun. 28, 2023, which is hereby incorporated herein by reference in its entirety. BACKGROUND Perfluoroalkyl substances and/or polyfluoroalkyl substances (generally referred to as “PFAS”) have been used in consumer products for decades, and because of the strong carbon-fluorine (C—F) bond, these substances do not degrade quickly over time. Traditionally, flocculants and coagulants have been deployed in efforts to remove PFAS from waste streams, leachates, run-off, and other PFAS-laden liquids, soils, or solids. Some chemical approaches to remove PFAS rely on traditional ferric or aluminum chlorides to remove modest PFAS content while requiring up to twice the standard dosing rate. Furthermore, traditional commercial PFAS flocculants such as polydiallyldimethylammonium chloride (polyDADMAC or polyDDA) and Aluminum chloride are ineffective in solvent systems such as methanol and water. Therefore, there remains a need for improved treatment processes for removal of PFAS. SUMMARY In various embodiments, methods for removing at least one polyfluoroalkyl or perfluoroalkyl compound from a medium are disclosed. Unless stated differently, such compounds may be referred to as “PFAS” compounds. Generally speaking, the term PFAS shall embody all types of perfluoroalkyl and polyfluoroalkyl species including, but not limited to, perfluoroalkyl sulfonic acids, polyfluoroalkyl sulfonic acids, perfluoroalkanoic acids, and polyfluoroalkanoic acids. The term “perfluoroalkyl” generally refers alkyl substances in which all carbons (except for the last one bound to a functional group) are saturated with fluorine. The term “polyfluoroalkyl” generally refers to alkyl substances that are mostly saturated with fluorines, but also contain carbon-hydrogen bonds. In some embodiments, a quaternary ammonium salt is used. In certain embodiments, a quaternary ammonium salt may comprise the compound of Formula I: wherein R1 is selected from optionally substituted C1-C30 alkyl and optionally substituted C2-C30 alkenyl;R2 is selected from optionally substituted C1-C30 alkyl and optionally substituted C2-C30 alkenyl;R3 and R4 are each independently selected from optionally substituted C10-C30 alkyl and optionally substituted C10-C30 alkenyl; andX− is a counter anion. In some embodiments, the counterion used in Formula I may comprise a halogen. In such embodiments, the halogen may comprise fluoride ion, chloride ion, bromide ion, and/or iodine ion. In other embodiments, a quaternary ammonium salt may comprise the compound of Formula II: wherein R5 is selected from optionally substituted C1-C30 alkyl and optionally substituted C2-C30 alkenyl;R6 is selected from optionally substituted C1-C30 alkyl and optionally substituted C2-C30 alkenyl;R7 and R8 are each independently selected from optionally substituted C10-C30 alkyl and optionally substituted C10-C30 alkenyl; and Z− is a perfluoroalkanoate anion, a perfluorosulfonate anion, a polyfluoroalkanoate anion, or a polyfluorosulfonate anion. In some embodiments, the counterion used in Formula II may comprise a perfluoroalkanoate anion or a perfluorosulfonate anion. In certain embodiments, the medium comprising at least one PFAS compound for removal comprises sand, soil, and/or water. In still other embodiments, the compound of Formula I or II may be freely soluble in water, have a solubility of greater than about 1 mg/L of water, or have a solubility of less than 1 mg/L of water. In some embodiments, having a solubility of 1 mg/L or less in water is desirable, as formation of insoluble quaternary perfluoroalkanoate or perfluorosulfonate salts results in the efficient removal of PFAS contaminants. During processes of removing PFAS from media, an electrostatic complex may be formed. When formed, an electrostatic complex may be insoluble in water. Such electrostatic complex may have a density less than water or have a density greater than that of water. Additional embodiments of the invention, as well as features and advantages thereof, will be apparent from the descriptions herein. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows examples of the quaternary ammonium adducts that may form in the presence of anionic functional groups. FIG. 2 shows the concentration of PFOA and PFOS after treatment with different quaternary amines. FIG. 3 shows the sum of the concentrations of each PFAS in 10 mL of 1% AFFF solution treated with 100 μL of 5% quat solution. FIG. 4 shows NMR spectra of AFFF overlayed on AFFF treated with Dimethyldidecylammonium chloride, Dimethyldimyristylammonium Bromide, and Dimethyldioctadecyldecylammonium bromide. FIG. 5 shows NMR spectr