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EP-4214164-B1 - METHOD OF ABSORBING ORGANIC CONTAMINANTS BY CROSS-LINKED POLYMERIC AMMONIUM SALTS

EP4214164B1EP 4214164 B1EP4214164 B1EP 4214164B1EP-4214164-B1

Inventors

  • COLEMAN-KAMMULA, M., Seetha
  • FIGULY, D., Garret
  • POWLEY, R., Charles
  • MASSOUDA, Flanagan, Debora

Dates

Publication Date
20260506
Application Date
20210921

Claims (15)

  1. A method for absorbing at least one PFAS molecule from an aqueous medium wherein said at least one PFAS molecule comprises a water soluble fluorinated amphiphilic structure with a carbon chain length that ranges from 4 to 14 carbon atoms which comprises: contacting said at least one PFAS molecule with at least one crosslinked polymeric ammonium salt, or a mixture of said crosslinked polymeric ammonium salts, wherein in said salts about 25% or more of groups which link ammonium nitrogen atoms are group Y, wherein Y is an n-alkylene group or alkyl substituted n-alkylene group, wherein said n-alkylene group or said alkyl substituted n-alkylene group has from 2 to about 20 carbon atoms; from zero to about 75% of the groups which link ammonium nitrogen atoms are group Z, wherein Z is a hydrocarbylene radical containing from 2 to 50 carbon atoms, said hydrocarbylene radical optionally containing or substituted with one or more hydroxyl, ether, amino. thioether, keto, ester, silyl group or heterocyclic rings; and about 25% or more of the ammonium nitrogen atoms are secondary ammonium nitrogen atoms, with the result that said at least one PFAS molecule is absorbed into said at least one crosslinked polymeric ammonium salt, or into said mixture of said crosslinked polymeric ammonium salts.
  2. The method of claim 1 wherein said hydrocarbylene radical contains from 1 to 30 carbon atoms.
  3. The method of claim 1 wherein the at least one crosslinked polymeric ammonium salt has a swell factor of at least about 2 in water.
  4. The method of claim 3 wherein the at least one crosslinked polymeric ammonium salt is combined with an amount of granulated activated carbon.
  5. The method of claim 3 wherein the at least one crosslinked polymeric ammonium salt is a poly(alkylamine) ammonium salt.
  6. The method of claim 5 wherein the poly(alkylamine) ammonium salt is prepared from hexamethylene diamine and 1,10-dibromodecane using DMF/methanol as solvent.
  7. The method of claim 5 wherein the poly(alkylamine) ammonium salt is prepared from polyethylene imine and 1,10-dibromodecane using DMF/methanol as solvent.
  8. The method of claim 1, including the additional steps of: (i) desorbing said at least one PFAS molecule from said at least one crosslinked polymeric ammonium salt, or from said mixture of crosslinked polymeric ammonium salts, by contacting the at least one crosslinked polymeric ammonium salt, or said mixture of crosslinked polymeric ammonium salts, which contains at least one PFAS molecule with an aqueous alkaline solution having a pH in the range of from about 8 to 14 with the result that the PFAS molecules are released from the at least one crosslinked polymeric ammonium salt, or from said mixture of crosslinked polymeric ammonium salts; and (ii) recovering the at least one PFAS molecule, and the at least one crosslinked polymeric ammonium salt or the mixture of crosslinked polymeric ammonium salts.
  9. The method of claim 1, including the additional steps of: (i) desorbing said at least one PFAS molecule from said at least one crosslinked polymeric ammonium salt, or from said mixture of crosslinked polymeric ammonium salts, by contacting the at least one crosslinked polymeric ammonium salt, or said mixture of crosslinked polymeric ammonium salts, which contains said at least one PFAS molecule with an ammonium hydroxide/methanol solution with the result that the at least one PFAS molecule is released from the at least one crosslinked polymeric ammonium salt, or from said mixture of crosslinked polymeric ammonium salts; and (ii) recovering the at least one PFAS molecule and the at least one crosslinked polymeric ammonium salt or the mixture of crosslinked polymeric ammonium salts.
  10. The method of claim 8 or claim 9, wherein the crosslinked polymeric ammonium salt is a poly(alkylamine) ammonium salt and the at least one PFAS molecule is perfluoro-octanoic acid (PFOA).
  11. The method of claim 10 wherein the crosslinked polymeric ammonium salt is a poly(alkylamine) ammonium salt prepared from hexamethylene diamine and 1,10-dibromodecane using DMF/methanol as solvent.
  12. The method of claim 10 wherein the crosslinked polymeric ammonium salt is a poly(alkylamine) ammonium salt prepared from polyethylene imine and 1,10-dibromodecane using DMF/methanol as solvent.
  13. The method of claim 1 wherein said at least one PFAS molecule comprises a telomer alcohol of the type used in aqueous fire-fighting foam compositions.
  14. The method of claim 1 wherein the at least one crosslinked polymeric ammonium salt, or said mixture of crosslinked polymeric ammonium salts are deployed in polar organic chemical integrative samplers (POCIS).
  15. The method of claim 1 wherein the aqueous medium comprises at least one of stagnant pools, wells, rivers, springs, estuarine systems, and industrial and municipal wastewater streams.

Description

BACKGROUND OF THE INVENTION The described and claimed inventive concept(s) relate to the use of cross-linked polymeric ammonium salts for absorbing and desorbing organic contaminants, and, more particularly, to the use of such cross-linked polymeric ammonium salts for absorbing and desorbing at least one or more Per and Polyfluoro Alkyl Substances (PFAS) from water, by changing the pH. Per- and Polyfluoroalkyl substances (PFAS) have been shown to be highly persistent in the environment and in biological tissue and have been correlated with negative health impacts. According to the Agency for Toxic Substances and Disease Registry (ATSDR), PFAS increase cholesterol and suppress the immune system. PFAS can bioaccumulate, some having very long half-lives in humans, and they are found in the blood of a large percentage of the U.S. population. They are very stable chemicals that can persist in soil and water for long periods of time, and they are highly mobile in soils and water. PFAS encompass a whole family of manmade chemicals used in consumer and industrial applications, such as, for example, in the fabrication of non-stick cookware, grease-resistant paper, fast food wrappers, microwave popcorn bags, stain-resistant carpets and fabrics, water-resistant clothing and in cleaning and personal care product formulations and in aqueous film-forming foams (AFFF) for fire suppression. There are more than 3,000 PFAS chemicals that are in current use, or have previously been used, on the global market. While the origin of the environmental contamination is not known in most cases, current focus seems to be on Aqueous Film-Forming Foams (AFFF's) as 75% of the contaminated sites reported to date have some association with AFFF's. PFAS surfactant-containing AFFF formulations have been used extensively to extinguish hydrocarbon fuel fires at military bases, fire training sites, and oil refineries. The available conventional water treatment systems and methods to remove PFAS from water have shortcomings. Granular activated carbon (GAC) adsorption systems and methods used to remove PFAS from water, for example, have been shown to be somewhat effective on the longer-chain PFAS, but are less effective in removing branched and shorter chain compounds. Similar to activated carbon, some conventional anion exchange resins (IX) may be more effective at removing longer chain PFAS than the shorter chain compounds. Other anion exchange resins have shown some success in removing a broader range of PFAS, including the shorter-chain compounds. However, removal of the PFAS to recover the ion exchange resins for re-use can be difficult. In addition, these sorbents have some deficiencies when used to remediate well and river waters. For example, PFAS concentrations in these waters are usually orders-of-magnitude lower than background constituents (ppt being low vs. ppb being high), such as natural organic matter (NOM) and metal ions, which compete with PFAS for sorption sites with the result that PFAS removal is reduced. Though materials containing amine functional groups have been shown to absorb PFAS, in these types of materials, amine functionality and porosity of the sorbents play a key role on PFAS removal efficiency, kinetics, and capacity. The strategy of incorporating swell and de-swell properties has never been reported with amine functionalized PFAS sorbents. There is a critical need, therefore, to develop PFAS sorbents that exhibit rapid PFAS removal of all chain lengths and facile regeneration through de-sorption wherein three design elements are incorporated: (i) provision of a molecular environment that balances lipophilic and hydrophilic forces to attract amphiphilic PFAS molecules; (ii) exhibition of an ability to tune the chain length of lipophilic blocks to match the chain length of the PFAS molecules; and (iii) exhibition of an ability to vary cross-link density thereby affecting swell levels. Some relevant prior art documents are US 5 633 344 A, ATEIA MOHAMED ET AL: "Cationic polymer for selective removal of GenX and short-chain PFAS from surface waters and wastewaters at ng/L levels",WATER RESEARCH, ELSEVIER, AMSTERDAM, NL, vol. 163, 15 July 2019 (2019-07-15), WO 2019/186166 A1, US 2015/053620 A1 and WO 2020/113004 A1. SUMMARY OF THE INVENTION The inventive concept(s) described and claimed herein relate to a method for absorbing, i.e., removing, at least one or more PFAS molecules from an aqueous medium wherein the PFAS molecules comprise fluorinated amphiphilic structures with carbon chain lengths ranging from 4 to 14 carbon atoms. The PFAS molecules are contacted with at least one crosslinked polymeric ammonium salt, or a mixture of said crosslinked polymeric ammonium salts, wherein in the salts about 25% or more of the groups which link ammonium nitrogen atoms are group Y, wherein Y is an n-alkylene group or alkyl substituted n-alkylene group, wherein the n-alkylene group or the alkyl substituted n-alkylene group has