Method for degrading perfluorohexane sulfonic acid in wastewater based on ionization irradiation technology

Abstract

The invention provides a method for degrading perfluorohexane sulfonic acid in wastewater based on an ionization irradiation technology, which comprises the following steps: adding a reagent A into the wastewater containing the perfluorohexane sulfonic acid, then carrying out ionization irradiation treatment, and carrying out reduction defluorination on the perfluorohexane sulfonic acid in the wastewater. And adding hydrogen peroxide into the solution obtained after defluorination treatment, and then carrying out second ionization irradiation treatment to finish deep decomposition and mineralization treatment on the perfluorohexane sulfonic acid in the wastewater. The technology disclosed by the invention has the advantages of simple process, mild conditions, high defluorination efficiency, good mineralization effect, easiness in amplification and the like, can be used for performing efficient reduction defluorination and mineralization on the perfluorohexane sulfonic acid in the wastewater, and is suitable for treating various wastewater containing perfluorohexane sulfonic acid pollutants.

Description

Technical Field

[0001] The invention relates to the technical field of environmental engineering, and relates to a method for degrading perfluorohexane sulfonic acid in waste water based on ionizing radiation technology. Background Art

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of man-made organic fluorine compounds that are widely used in the manufacture of flame retardants due to their highly stable molecular structure. Due to their widespread use, PFAS have been frequently detected in the environment and pose a potential threat to the ecological environment and human health. Therefore, measures have been taken at home and abroad to restrict or ban the use of PFAS.

[0003] Perfluorohexane sulfonic acid (PFHxS) is often used as a substitute for PFAS due to its similar properties to PFAS. It is widely used in fire-fighting water film-forming foam (AFFF), metal electroplating, textile and leather processing, interior decoration, polishes and cleaning agents, coating waterproofing, and electronics and semiconductor manufacturing.

[0004] How to effectively remove PFHxS from water is an urgent problem to be solved in the field of water treatment. Since fluorine has the highest electronegativity, the energy required to break the carbon-fluorine bond is large, and since the atomic radius of the covalently bound carbon atom is smaller than that of the fluorine atom, the carbon-carbon bond in PFHxS is fully protected and difficult to decompose and mineralize. At present, most studies focus on the removal of PFAS in water, while there are fewer studies on the removal of PFHxS. For example, the adsorption method can remove some PFAS in some water, but the adsorbed PFAS and adsorbent need to be further treated (see non-patent document 1). Biological method is a commonly used wastewater treatment method, but its removal ability for PFAS is limited, and there is no report of strains that can decompose PFAS. Advanced oxidation method is a commonly used wastewater deep treatment method. Relying on the strong oxidizing radicals such as hydroxyl radicals generated in the process, most of the difficult-to-degrade organic pollutants in water can be removed, but the removal effect of advanced oxidation method on PFAS in water is not ideal. In contrast, the advanced reduction method has shown a certain removal ability for PFAS in water (see non-patent document 2). This study shows that the hydrated electrons generated during ultraviolet irradiation can remove the fluorine in PFAS, resulting in the decomposition of PAFS. However, the penetration ability of ultraviolet in water is weak, and the yield of hydrated electrons is not high. A long irradiation time (≥24h) is required to achieve a relatively satisfactory defluorination efficiency. Ionizing irradiation is a new type of advanced oxidation technology. Compared with conventional advanced oxidation technologies, ionizing irradiation can not only produce oxidative active particles such as hydroxyl radicals, but also reductive active species such as hydrated electrons. Compared with ultraviolet irradiation, ionizing irradiation has stronger penetration ability. Studies have shown that ionizing irradiation can degrade PFAS in water, but the required irradiation dose is high (several hundred kGy), resulting in high energy consumption (non-patent document 3). How to reduce the dose required for ionizing irradiation treatment of PFAS in water and improve the treatment effect is currently the bottleneck that limits whether ionizing irradiation technology can be used to remove PFAS in actual wastewater. It is worth noting that the concentration of PFAS substances in water is usually low, and how to selectively remove PFAS in water in the presence of other organic matter is also a problem that needs to be solved urgently.

[0005] Non-patent literature

[0006] Non-patent literature 1: Park, M., Wu, S., Lopez, IJ, Chang, JY, Karanfil, T. and Snyder, SA 2020. Water Research 170, 115364.

[0007] Non-patent document 2: Bentel, MJ, Liu, Z., Yu, Y., Gao, J., Men, Y. and Liu, J. 2020. Environmental Science & Technology Letters 7(5), 351-357.

[0008] Non-patent document 3: Lassalle, J., Gao, R., Rodi, R., Kowald, C., Feng, M., Sharma, VK, Hoelen, T., Bireta, P., Houtz, EF, Staack, D. 2021. Radiation Physics and Chemistry 189, 109705. Summary of the invention

[0009] In order to solve the above problems, the present invention aims to propose a method for degrading perfluorohexane sulfonic acid in wastewater based on ionizing radiation technology, so as to solve the problem that perfluorohexane sulfonic acid in water is difficult to treat. That is, the present invention proposes a method for degrading perfluoroethane sulfonic acid in wastewater based on ionizing radiation technology. The method constructs a hydrated electron / SO 2 · - / SO 3 · - and hydrated electrons / CO 2 · - These two systems can effectively break the carbon-fluorine bonds in perfluorinated compounds, while achieving efficient defluorination and reducing the energy barrier required for breaking other carbon-fluorine bonds. Subsequently, the defluorinated organic products are further treated by oxidation to further mineralize them into CO 2 and H 2 O. This technology is simple to operate, has excellent treatment effect, and is easy to scale up and apply to actual projects.

[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0011] A method for degrading perfluorohexane sulfonic acid in wastewater based on ionizing radiation technology, characterized in that the steps are as follows:

[0012] (1) adding reagent A to wastewater containing perfluorohexane sulfonic acid, and then subjecting it to ionizing radiation treatment; (2) adding a certain amount of hydrogen peroxide to the solution obtained after the ionizing radiation treatment in step (1), and subjecting it to a second ionizing radiation treatment, thereby completing the degradation treatment of perfluorohexane sulfonic acid in water.

[0013] Furthermore, the reagent A in step (1) is sodium sulfite or sodium formate.

[0014] Furthermore, the molar concentration ratio of the reagent A in step (1) to the perfluorohexane sulfonic acid in the wastewater is 1 to 30.

[0015] Furthermore, the radiation source of the ionizing radiation treatment in step (1) is an electron accelerator, 60 Co or 137 Any of Cs.

[0016] Furthermore, the irradiation dose of the irradiation treatment in step (1) is 1 kGy to 100 kGy, preferably 5 kGy to 30 kGy.

[0017] Furthermore, the mass fraction of the hydrogen peroxide used in step (2) is about 20-40%. The dosage of hydrogen peroxide is 0.02‰-1‰, and the irradiation dose is between 1-50 kGy.

[0018] Furthermore, the irradiation dose in step (2) is preferably 5 to 20 kGy.

[0019] In addition, in step (2), the radiation source of the second ionizing radiation treatment is also an electron accelerator, 60 Co or 137 Any of Cs.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for degrading perfluorohexane sulfonic acid in wastewater based on ionizing radiation technology, which makes full use of the oxidizing and reducing active species generated during electron beam irradiation to first construct a selective hydrated electron / SO 2 · - / SO 3 · - and hydrated electrons / CO 2 · - Reduction system is used to achieve effective defluorination of PFHxS. The structural stability of PFHxS after defluorination decreases, and then an oxidation system based on hydroxyl radicals is constructed to mineralize the defluorinated organic matter, thereby achieving the purpose of degradation. This method is simple to operate, has strong processing capacity and high processing efficiency, and can effectively remove PFHxS in actual water bodies, providing a solution for effectively removing PFHxS in water bodies. DETAILED DESCRIPTION

[0022] The present invention is described in detail below through specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0023] Embodiment 1:

[0024] Artificially prepare 5 mg / L PFHxS wastewater, add 2 mM sodium sulfite to the wastewater, and use 60 Co source was used for irradiation treatment, and irradiation was performed at 10 kGy. 1 mM hydrogen peroxide was added to the treated wastewater, and irradiation was performed again at 5 kGy. The final defluorination rate of PFHxS was 82.4%, and the mineralization rate was 44.1%.

[0025] Embodiment 2:

[0026] Artificially prepare 5 mg / L PFHxS wastewater, add 2 mM sodium formate to the wastewater, and use 60 Co source was used for irradiation treatment, and the irradiation was 20 kGy. 1 mM hydrogen peroxide was added to the treated wastewater, and irradiated again for 5 kGy. The final defluorination rate of PFHxS was 66.2%, and the mineralization rate was 24.1%.

[0027] Embodiment 3:

[0028] Artificially prepare 5 mg / L PFHxS wastewater, add 2 mM sodium sulfite to the wastewater, and use 60 Co source was used for irradiation treatment, and the irradiation was 30 kGy. 2 mM hydrogen peroxide was added to the treated wastewater, and irradiated again for 10 kGy. The final defluorination rate of PFHxS was 85.3%, and the mineralization rate was 78.1%.

[0029] Embodiment 4:

[0030] Artificially prepare 5 mg / L PFHxS wastewater, add 4 mM sodium sulfite to the wastewater, and use 60 Co source was used for irradiation treatment, and irradiation was performed at 15 kGy. 1 mM hydrogen peroxide was added to the treated wastewater, and irradiation was performed again at 20 kGy. The final defluorination rate of PFHxS was 95.1%, and the mineralization rate was 82.1%.

[0031] Embodiment 5:

[0032] Add a certain amount of PFHxS to the effluent of the secondary sedimentation tank of the actual sewage plant to make its concentration 5 mg / L, and then add 2 mM sodium sulfite to the wastewater. 60 Co source was used for irradiation treatment, and irradiation was performed at 10 kGy. 4 mM hydrogen peroxide was added to the treated wastewater, and irradiation was performed again at 20 kGy. The final defluorination rate of PFHxS was 77.1%, and the mineralization rate was 46.2%.

[0033] Embodiment 6:

[0034] A certain amount of PFHxS was added to the effluent of the secondary sedimentation tank of an actual sewage plant to a concentration of 5 mg / L. Then 4 mM sodium formate was added to the wastewater. 60Co source was used for irradiation treatment, and irradiation was performed at 10 kGy. 4 mM hydrogen peroxide was added to the treated wastewater, and irradiation was performed again at 20 kGy. The final defluorination rate of PFHxS was 68.2%, and the mineralization rate was 22.1%.

[0035] Determination methods and instruments

[0036] Fluoride ion concentration in wastewater:

[0037] The fluoride ion concentration (mg / L) in the wastewater was determined using a fluoride ion selective electrode and an ion chromatograph.

[0038] Defluorination rate:

[0039] The calculation method is the percentage calculated by dividing the fluoride ion concentration in the wastewater by the total fluoride ion concentration in the PFAS structure.

[0040] Concentration of organic carbon in wastewater TOC:

[0041] The concentration of organic carbon in the wastewater was analyzed using a total organic carbon analyzer.

[0042] Mineralization rate:

[0043] The result is obtained by (1-TOC concentration in the solution after the reaction is completed / TOC concentration in the solution at the beginning of the reaction).

[0044] From the results of the above embodiments, it can be seen that the method of degrading perfluorohexane sulfonic acid in wastewater based on ionizing irradiation technology of the present invention uses the active species produced by the synergistic effect of ionizing irradiation and sulfite / formate to complete the primary defluorination of perfluorohexane sulfonic acid, thereby reducing the carbon-fluorine bond energy in perfluorohexane sulfonic acid. Then the deep decomposition and mineralization of perfluorohexane sulfonic acid are completed by the subsequent oxidation of hydroxyl radicals. It can be seen from the above embodiments that the method can effectively achieve the defluorination and mineralization of perfluoro compounds, especially in Example 3, the defluorination rate of PFHxS is 85.3% and the mineralization rate is 78.1%; in Example 4, the defluorination rate of PFHxS is 95.1% and the mineralization rate is 82.1%. Such results can be fully applied to actual life production. In addition, from the perspective of the treatment method, the method is simple to operate, has strong treatment capacity, can effectively remove PFHxS in actual water bodies, and can efficiently reduce, defluorinate and mineralize perfluorohexane sulfonic acid in wastewater. It can be seen that it is suitable for the treatment of various wastewaters containing perfluorohexane sulfonic acid pollutants.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0046] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0047] The above is a detailed introduction to the method for degrading perfluorohexane sulfonic acid in wastewater based on ionizing radiation technology provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for degrading perfluorohexane sulfonic acid in wastewater based on ionizing radiation technology, characterized in that: The steps are as follows, (1) adding reagent A to wastewater containing perfluorohexane sulfonic acid, and then performing ionizing radiation treatment; (2) adding a certain amount of hydrogen peroxide to the solution obtained after the ionizing radiation treatment in step (1), and then performing a second ionizing radiation treatment, thereby completing the degradation treatment of perfluorohexane sulfonic acid in water.

2. The method according to claim 1, characterized in that In step (1), the reagent A is sodium sulfite or sodium formate.

3. The method according to claim 1, characterized in that In step (1), the molar concentration ratio of the reagent A to the perfluorohexane sulfonic acid in the wastewater is 1 to 30.

4. The method according to claim 1, characterized in that: In step (1), the radiation source of the ionizing radiation treatment is an electron accelerator, 60 Co and 137 Any of Cs.

5. The method according to claim 1, characterized in that In step (1), the ionizing radiation treatment has an irradiation dose of 1 kGy to 100 kGy.

6. The method according to claim 1, characterized in that In step (2), the mass fraction of the hydrogen peroxide is 20-40%, and the dosage of the hydrogen peroxide is 0.02‰-1‰.

7. The method according to claim 1, characterized in that In step (2), the irradiation dose of the second irradiation treatment is 1 to 50 kGy.

8. The method according to claim 1, characterized in that: In step (2), the radiation source of the second ionizing radiation treatment is an electron accelerator, 60 Co and 137 Any of Cs.