CN-122029132-A - Method and system for oxidative pretreatment of PFAS-containing aqueous solutions

Abstract

Methods, systems and apparatus for disrupting PFAS include oxidatively pre-treating an aqueous foam fractionation solution comprising PFAS to form a pre-treated solution, raising or lowering the pH by mixing the aqueous foam fractionation solution with persulfate and acid or base, and oxidizing the aqueous foam fractionation solution, and then subjecting the pre-treated solution to UV photolysis, such as by directing UV light of 222 nm, 254 nm and/or 185 nm onto the pre-treated aqueous foam fractionation solution. Oxidizing the foam fraction may comprise subjecting the aqueous foam fraction solution to elevated temperature and pressure for a period of time sufficient to perform thermal oxidation or to perform ozone oxidation of the aqueous foam fraction solution.

Inventors

• LIU ZEKUN
• HUANG ZHENGXIN
• J. R.L. Tirado
• T.P. Smith
• M. C. Pirlo

Assignees

• 克拉罗斯技术股份有限公司

Dates

Publication Date

20260512

Application Date

20240712

Priority Date

20230714

Claims (20)

1. 1. A method of disrupting PFAS, comprising: Oxidatively pre-treating an aqueous foam fractionation solution comprising PFAS to form a pre-treated solution, the step of oxidatively pre-treating the aqueous foam fractionation solution comprising: Mixing the aqueous foam fractionation solution with persulfate and acid or base to raise or lower the pH, and then Oxidizing the aqueous foam fractionation solution and then And carrying out UV photolysis on the pretreated solution.
2. 2. The method of claim 1, wherein the UV photolysis comprises directing UV light of 222 nm onto the pre-treated aqueous foam fractionation solution.
3. 3. The method of claim 2, wherein oxidizing the aqueous foam fractionation solution comprises subjecting the aqueous foam fractionation solution to elevated temperature and pressure for a period of time sufficient to perform thermal oxidation.
4. 4. The method of claim 3, wherein the elevated temperature comprises about 100 degrees to about 140 degrees celsius.
5. 5. The method of claim 4, wherein the elevated pressure comprises about 1 to about 5 bar.
6. 6. The method of claim 1, wherein oxidizing the aqueous foam fractionation solution comprises ozone oxidizing the aqueous foam fractionation solution.
7. 7. The method of claim 1, wherein the UV photolysis comprises directing 254 nm UV light onto the pretreated aqueous foam fractionation solution.
8. 8. The method of claim 1, wherein the UV photolysis comprises directing UV light of 185 nm onto the pretreated aqueous foam fractionation solution.
9. 9. The method of claim 1, further comprising separating solid particles from the aqueous foam fractionation solution before and/or after oxidatively pre-treating the aqueous foam fractionation solution.
10. 10. A method of disrupting PFAS, comprising: mixing the aqueous foam fractionation solution with a persulfate salt and an acid or base to raise or lower the pH; The aqueous foam fractionation solution is subjected to a temperature of about 100 to about 140 degrees celsius and a pressure of about 1 to about 5 bars for a time sufficient to effect thermal oxidation, and The pretreated solution was subjected to UV photolysis of about 222 nm.
11. 11. The method of claim 10, wherein the persulfate comprises potassium persulfate, sodium persulfate, and/or aluminum persulfate.
12. 12. The method of claim 11, wherein the persulfate is added to the aqueous foam fractionation solution to achieve a concentration in the aqueous foam fractionation solution of about 100 to about 200 mM.
13. 13. The method of claim 10, wherein an acid is mixed into the aqueous fractionation solution to reduce the pH of the aqueous foam fractionation solution.
14. 14. The method of claim 13, wherein the pH is reduced to between about 2 and about 4.
15. 15. The method of claim 10, wherein a base is mixed into the aqueous foam fractionation solution to raise the pH of the aqueous foam fractionation solution.
16. 16. The method of claim 15, wherein the pH is raised to between about 10 and about 14.
17. 17. A system for pre-treating PFAS-containing water, the system comprising: A pretreatment reactor comprising a pretreatment vessel configured to hold PFAS-containing water under elevated pressure, said pretreatment vessel comprising a heating element to heat said PFAS-containing water contained therein, and A source of persulfate and acid or base configured to deliver persulfate and acid or base to the PFAS-containing water upstream of the pretreatment vessel or the PFAS-containing water within the pretreatment vessel.
18. 18. The system of claim 17, further comprising a settling tank upstream and/or downstream of the pretreatment reactor.
19. 19. The system of claim 17, wherein the pretreatment reactor is also a photo-reactor and further comprises a source of UV light configured to direct UV light onto the PFAS-containing water after pretreatment.
20. 20. The system of claim 19, wherein the source of UV light emits UV light having a peak of about 222 nm.

Description

Method and system for oxidative pretreatment of PFAS-containing aqueous solutions Cross Reference to Related Applications The present application claims priority to "efficient photochemical disruption of PFAS from waste streams" (PROCESSES FOR EFFICIENT PHOTOCHEMICAL DESTRUCTION OF PFAS FROM WASTE STREAMS) filed on 7 months 14 of 2023, U.S. provisional application No. 63/513,782, "PFAS disruption systems and methods" (SYSTEMS AND METHODS OF PFAS DESTRUCTION) filed on 10 months 17 of 2023, U.S. provisional application No. 63/591,040, and "pretreatment of PFAS contaminated water prior to photo-reduction" (PRETREATMENT OF PFAS CONTAMINATED WATER PRIOR TO PHOTOREDUCTION) filed on 18 months 4 of 2024, U.S. provisional application No. 63/635,938, all of which disclosures are incorporated herein by reference. Background Perfluoro and polyfluoroalkyl species (PFASs) are a class of synthetically prepared compounds that have been used for decades in numerous consumer and industrial applications. PFASs have some unique surface characteristics and may also be both hydrophobic and oleophobic. Therefore PFASs is used as a coating aid, lubricant, foaming aid and various surface treatments. They have proven to be particularly useful as flame retardants in the form of Aqueous Film Forming Foams (AFFF). In addition, some PFASs are known to bioaccumulate in plants and animals. There is growing evidence that exposure to PFAS also causes various health problems. In view of these concerns, various regulatory authorities around the world have begun to establish strict limits on the presence of PFAS in food and water. PFASs is a class of chemicals containing perfluoroalkyl or polyfluoroalkyl groups. PFASs definitions and classifications change over time. PFASs is a fluorinated species containing at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atoms attached thereto), i.e., with a few known exceptions, any chemical containing at least one perfluorinated methyl group (-CF 3) or perfluorinated methylene group (-CF 2-) is PFAS. Some of the most important examples of PFASs include perfluorosulfonic acids (PFSAs), such as perfluorooctanesulfonic acid (PFOS), and perfluorocarboxylic acids (PFCAs), such as perfluorooctanesarboxylic acid (PFOA). The fluorotelomer is a fluorocarbon-based oligomer or telomer synthesized by telomerization. Certain fluorotelomers and fluorotelomer-based compounds are sources of environmentally persistent perfluorocarboxylic acids (e.g., PFOA). PFASs have prompted extensive research efforts to reduce their presence in the environment. Many early efforts focused on capture (e.g., from potable water). Recently, however, more effort has been put into destroying these materials. One of the attributes of PFASs is their resistance to decomposition in the environment. PFASs are not readily metabolized by organisms and do not decompose when exposed to visible light or longer wavelength UV radiation that is common in terrestrial environments. Some methods of decomposition PFASs that have proven effective are supercritical water oxidation (SCWO) and treatment PFASs in aprotic polar solvents. SCWO achieves treatment by heating water to 374 ℃ under high pressure (exceeding 3000 psi). Therefore, SCWO is extremely energy consuming and may suffer from clogging problems. The use of SCWO often requires high solids waste because it relies on the heat capacity (btu) generated by the waste to make the process economically efficient. The advantage of SCWO is that it enables a short residence time for effective treatment, which is in the order of 30 seconds to several minutes. The use of alkaline aprotic media disruption PFASs suffers from the practical problem that most waste streams are water-based and therefore difficult to transfer into aprotic media requiring minimal water content. In other cases, it has also been shown that the creation of subcritical water conditions in alkaline environments destroys PFAS compounds. This process, known as hydrothermal alkaline treatment (HALT), operates at a temperature of about 350 ℃ and a pressure of about 2400 psi. Other methods of destroying PFASs involve the use of electrochemical techniques. Electrochemical destruction may destroy long chains PFASs (e.g., PFOS and PFOA), however, shorter chains PFASs are more difficult to destroy. Longer PFASs chains tend to accumulate on the electrodes and are therefore more susceptible to oxidation or reduction. Further work indicated that sonication could cause damage to PFAS. There is a need for an improved process to efficiently and effectively destroy PFAS, especially PFAS in water. Disclosure of Invention Various embodiments disclosed herein include a method system and apparatus for disrupting PFAS with 222 nm UV radiation. For example, certain embodiments include a method of disrupting PFAS comprising adding sulfite to an aqueous solution comprising PFAS, and then irradiating the aqueous solution with 222 nm