Fluorine-modified hydrothermal carbon material, preparation method thereof and application of fluorine-modified hydrothermal carbon material in repairing perfluoro / polyfluoroalkyl compound contaminated water body

Abstract

This invention belongs to the field of water treatment technology, specifically relating to a fluoride-modified hydrothermal carbon material, its preparation method, and its application in the remediation of water bodies contaminated with perfluorinated / polyfluoroalkyl compounds. The invention involves a hydrothermal reaction of an aqueous solution of carbohydrates to obtain a hydrothermal solid product; the hydrothermal solid product is then calcined in a protective gas atmosphere to obtain a preliminary hydrothermal carbon product; the preliminary hydrothermal carbon product is mixed with an inorganic strong alkali and then calcined in a protective gas atmosphere to obtain activated hydrothermal carbon; the activated hydrothermal carbon is then mixed with a fluoride and then calcined in a protective gas atmosphere to obtain a fluoride-modified hydrothermal carbon material. The fluoride-modified hydrothermal carbon material provided by this invention can simultaneously and efficiently remove complex pollutants such as PFOA and PFOS formed by PFAS in polluted water bodies. The method is simple, low-cost, and widely applicable to the treatment of typical PFAS complex pollution in water bodies such as groundwater near fluoride plants.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a fluorine-modified hydrothermal carbon material, its preparation method, and its application in the remediation of water bodies polluted by perfluorinated / polyfluoroalkyl compounds. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are aliphatic organofluorine compounds in which hydrogen atoms in the molecular structure are partially or completely replaced by fluorine. All carbon atoms in the carbon chain of PFAS are sp. 3 The hybridized CF bonds formed by these compounds have high bond energies, thus PFAS exhibit high thermal stability and chemical inertness. They are widely used in the textile, industrial, and equipment sectors as surfactants, flame retardants, fluororubbers, and textile finishing agents, and are also frequently added to personal care products. As typical PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) possess certain carcinogenic, neurotoxic, reproductive, and genotoxic properties. They can accumulate through the food chain, posing a threat to human health.

[0003] With the development of the industrial economy and the impact of human activities, environmental pollutants generally exist in the form of complex pollution. Currently, PFAS have been detected in the atmosphere, soil, surface water, groundwater, human tissues, and animal and plant bodies worldwide. A recent study shows that PFAS are prevalent in surface water and groundwater globally, existing in complex pollution forms.

[0004] Currently, the main technologies used to treat PFAS-contaminated water include adsorption, photocatalysis, nanofiltration, advanced reduction, and electrolysis. Adsorption is the most commonly used method due to its economic efficiency and ease of operation. Hydrothermal carbon and other carbon-based materials have diverse structures and various excellent properties, making them good adsorbents for treating PFAS pollution. However, in practical applications, they suffer from drawbacks such as slow adsorption rates and limited adsorption capacity. Summary of the Invention

[0005] The purpose of this invention is to provide a fluorine-modified hydrothermal carbon material, its preparation method, and its application in the remediation of water bodies polluted by perfluorinated / polyfluoroalkyl compounds. The fluorine-modified hydrothermal carbon material provided by this invention can achieve simultaneous and efficient removal of complex pollutants such as PFOA and PFOS formed by PFAS in polluted water bodies. The preparation method of the fluorine-modified hydrothermal carbon material provided by this invention is simple and low in cost, and is widely applicable to the treatment of typical PFAS complex pollution in water bodies such as groundwater near fluoride plants.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing fluorine-modified hydrothermal carbon materials, comprising the following steps: A hydrothermal reaction is carried out on an aqueous solution of a carbohydrate to obtain a hydrothermal solid product; the hydrothermal solid product is then subjected to a first calcination in a protective gas atmosphere to obtain a preliminary product, hydrothermal carbon. The carbohydrate includes one or more of glucose, fructose, xylose, cellulose, chitosan, and chitin. The preliminary product hydrothermal carbon was mixed with an inorganic strong alkali and then subjected to a second calcination in a protective gas atmosphere to obtain activated hydrothermal carbon. The activated hydrothermal carbon and fluoride are mixed and then subjected to a third calcination in a protective gas atmosphere to obtain a fluorine-modified hydrothermal carbon material. The fluoride includes one or more of ammonium fluoride, potassium fluoride, and sodium fluoride.

[0007] Preferably, the mass ratio of the activated hydrothermal carbon to the fluoride is 1:(0.1~15); the third calcination temperature is 950~1100℃ and the time is 1~3 h.

[0008] Preferably, the concentration of the aqueous solution of the carbohydrate is 60~120g / L; the temperature of the hydrothermal reaction is 150~200℃ and the time is 8~12 h; the temperature of the first calcination is 600~800℃ and the time is 1~3 h.

[0009] Preferably, the inorganic strong base includes sodium hydroxide and / or potassium hydroxide; the mass ratio of the preliminary product hydrothermal carbon to the inorganic strong base is 1:(2~4); the second calcination temperature is 950~1100℃ and the time is 1~3 h.

[0010] This invention provides a fluorine-modified hydrothermal carbon material prepared by the preparation method described in the above technical solution.

[0011] This invention provides the application of the fluorine-modified hydrothermal carbon material described above in the remediation of water bodies polluted by perfluorinated / polyfluoroalkyl compounds.

[0012] Preferably, the water bodies polluted by perfluorinated / polyfluoroalkyl compounds include surface water or groundwater; the water bodies polluted by perfluorinated / polyfluoroalkyl compounds are water bodies polluted by a combination of perfluorinated / polyfluoroalkyl compounds.

[0013] Preferably, the perfluoro / polyfluoroalkyl compound contaminating the water includes perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

[0014] Preferably, in the water body polluted by the perfluorinated / polyfluoroalkyl compound complex: the concentration of perfluorooctanoic acid is 0.1~5 mg / L, and the concentration of perfluorooctane sulfonic acid is 0.1~5 mg / L.

[0015] Preferably, the application includes: mixing the fluorine-modified hydrothermal carbon material with water polluted by perfluorinated / polyfluoroalkyl compounds for adsorption reaction; the dosage of the fluorine-modified hydrothermal carbon material is 0.1~0.5 g / L, and the adsorption reaction time is 2~360 min.

[0016] This invention provides a method for preparing fluorine-modified hydrothermal carbon material, comprising the following steps: reacting an aqueous solution of a carbohydrate with a hydrothermal reaction to obtain a hydrothermal solid product; calcining the hydrothermal solid product in a protective gas atmosphere to obtain a preliminary hydrothermal carbon product, wherein the carbohydrate includes one or more of glucose, fructose, xylose, cellulose, chitosan, and chitin; mixing the preliminary hydrothermal carbon product with an inorganic strong alkali and then calcining it in a protective gas atmosphere to obtain activated hydrothermal carbon; and mixing the activated hydrothermal carbon with a fluoride and then calcining it in a protective gas atmosphere to obtain a fluorine-modified hydrothermal carbon material, wherein the fluoride includes one or more of ammonium fluoride, potassium fluoride, and sodium fluoride. The fluorine-modified hydrothermal carbon material prepared by this invention introduces fluorine (F) into the carbon skeleton of the carbon-based adsorbent material, utilizing the adsorption mechanism of the F-F interaction to effectively achieve rapid and high-capacity removal of PFAS, effectively improving the adsorption and removal efficiency of PFAS, and exhibiting excellent performance in the treatment of PFAS-polluted water bodies. Compared with the prior art, this invention has the following beneficial effects: (1) The fluorine-modified hydrothermal carbon material prepared by the present invention can achieve simultaneous and efficient removal of composite pollutants such as PFOA and PFOS formed by PFAS in water. (2) The rapid and efficient adsorption performance of the fluorine-modified hydrothermal carbon material prepared in this invention is mainly due to the strong dipole interaction between the CF chain of PFAS and the -F group on the material surface. This interaction creates a selective hydrophobic microenvironment that preferentially adsorbs PFAS, making it particularly suitable for the remediation of water bodies polluted by perfluorinated / polyfluoroalkyl compounds with complex water matrix characteristics. The results of the examples show that, in this invention, the performance of unfluorinated material AHC and fluorinated material in removing PFOA and PFOS was compared. The fluorinated material exhibited higher removal efficiency, indicating that the introduction of fluorine groups enhances the selectivity of PFAS. The FF interaction is the core mechanism for the selective adsorption of PFAS by the fluorine-modified material. (3) The carbon source for preparing the fluorine-modified hydrothermal carbon material in this invention is glucose, which is widely available, inexpensive, and sustainable; (4) The fluorine-modified hydrothermal carbon material prepared by the present invention can be recycled and reused, and has the advantage of long-term stability; (5) The fluorine-modified hydrothermal carbon material prepared by the present invention is suitable for groundwater or surface water and has a wide range of applications.

[0017] In summary, the fluorine-modified hydrothermal carbon material prepared by this invention exhibits excellent performance in removing perfluorinated / polyfluoroalkyl compound (PFAC) complex pollution, is easy to operate, and has low cost. It has broad application prospects in the remediation of surface water or groundwater polluted by PFAC complex pollution. Attached Figure Description

[0018] Figure 1 EDS spectrum of fluorine-modified hydrothermal carbon material (AHC-F5); Figure 2 The image shows the removal effect of fluorine-modified hydrothermal carbon materials on PFOA and PFOS. Figure 3 The image shows the removal effect of fluorine-modified hydrothermal carbon material AHC-F5 on PFOA and PFOS. Detailed Implementation

[0019] This invention provides a method for preparing fluorine-modified hydrothermal carbon materials, comprising the following steps: A hydrothermal reaction is carried out on an aqueous solution of a carbohydrate to obtain a hydrothermal solid product; the hydrothermal solid product is then subjected to a first calcination in a protective gas atmosphere to obtain a preliminary product, hydrothermal carbon. The carbohydrate includes one or more of glucose, fructose, xylose, cellulose, chitosan, and chitin. The preliminary product hydrothermal carbon was mixed with an inorganic strong alkali and then subjected to a second calcination in a protective gas atmosphere to obtain activated hydrothermal carbon. The activated hydrothermal carbon and fluoride are mixed and then subjected to a third calcination in a protective gas atmosphere to obtain a fluorine-modified hydrothermal carbon material. The fluoride includes one or more of ammonium fluoride, potassium fluoride, and sodium fluoride.

[0020] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0021] This invention involves a hydrothermal reaction of an aqueous solution of a carbohydrate to obtain a hydrothermal solid product. The hydrothermal solid product is then subjected to a first calcination under a protective gas atmosphere to obtain a preliminary product, hydrothermal char. The carbohydrate includes one or more of glucose, fructose, xylose, cellulose, chitosan, and chitin. In this invention, glucose is preferred. The aqueous solution of the carbohydrate is prepared from the carbohydrate and water, which can be deionized water. The concentration of the aqueous solution is preferably 60-120 g / L, more preferably 80-115 g / L, further preferably 95-110 g / L, and in the examples, it can be 108 g / L. In this invention, the hydrothermal reaction is carried out in a hydrothermal reactor. The temperature of the hydrothermal reaction is preferably 150-200 °C, more preferably 160-190 °C, and in the examples, it can be 180 °C. The duration of the hydrothermal reaction is preferably 8-12 h, and in the examples, it can be 10 h. After the hydrothermal reaction is completed, a hydrothermal reaction liquid is obtained. Preferably, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain an initial solid product. The initial solid product is then washed and dried sequentially to obtain a hydrothermal solid product. The washing reagents preferably include anhydrous ethanol and water sequentially, and each washing reagent is preferably used 1 to 3 times. In this invention, the first calcination is carried out in a tube furnace. The protective gas can be nitrogen. The temperature of the first calcination is preferably 600-800 °C, more preferably 650-750 °C, and in the embodiment, it can be 700 °C; the first calcination time is preferably 1-3 hours, and in the embodiment, it can be 2 hours.

[0022] After obtaining the preliminary product hydrothermal carbon, the present invention mixes the preliminary product hydrothermal carbon with an inorganic strong alkali and performs a second calcination in a protective gas atmosphere to obtain activated hydrothermal carbon. In the present invention, the inorganic strong alkali preferably includes sodium hydroxide and / or potassium hydroxide, and in the examples, it can be potassium hydroxide. The mass ratio of the preliminary product hydrothermal carbon to the inorganic strong alkali is preferably 1:(2~4), more preferably 1:(2.5~3.5), and in the examples, it can be 1:3. The mixing is preferably grinding, and the present invention does not have special requirements for the specific implementation of the grinding. In the present invention, the second calcination is carried out in a tube furnace. The protective gas can be nitrogen. The temperature of the second calcination is preferably 950~1100℃, more preferably 1000~1050℃. The time of the second calcination is preferably 1~3 h, and in the examples, it can be 2 h. After the second calcination is completed, an initial calcined product is obtained. The present invention preferably cools the initial calcined product and washes it with water until it is neutral (pH value is 7), and then dries it to obtain the activated hydrothermal carbon. The washing is preferably done with deionized water.

[0023] After obtaining activated hydrothermal carbon, the present invention mixes the activated hydrothermal carbon and fluoride and then performs a third calcination in a protective gas atmosphere to obtain fluorine-modified hydrothermal carbon material. The fluoride includes one or more of ammonium fluoride, potassium fluoride, and sodium fluoride. In the present invention, the fluoride is preferably ammonium fluoride. The mass ratio of the activated hydrothermal carbon to the fluoride is preferably 1:(0.1~15), more preferably 1:(1~15), and even more preferably 1:(3~15). In the embodiments, it can be 1:5, 1:10, or 1:15. The mixing is preferably grinding, and the present invention does not have special requirements for the specific implementation of the grinding. In the present invention, the third calcination is carried out in a tube furnace. The protective gas can be nitrogen. The temperature of the third calcination is preferably 950~1100℃, more preferably 1000~1050℃. The time of the third calcination is preferably 1~3 h, and in the embodiments, it can be 2 h. After the third calcination is completed, an initial calcined product is obtained. Preferably, the initial calcined product is cooled and washed with water until neutral (pH 7), and then dried to obtain the fluorine-modified hydrothermal carbon material. Deionized water is preferably used for washing.

[0024] This invention provides a fluorine-modified hydrothermal carbon material prepared by the preparation method described in the above technical solution.

[0025] This invention provides the application of the fluorine-modified hydrothermal carbon material described above in the remediation of water bodies polluted by perfluorinated / polyfluoroalkyl compounds.

[0026] In this invention, the water bodies polluted by perfluorinated / polyfluoroalkyl compounds may include surface water or groundwater. Preferably, the water bodies polluted by perfluorinated / polyfluoroalkyl compounds are complex polluted water bodies. The complex polluted water bodies preferably include perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

[0027] In this invention, in the water body polluted by the perfluorinated / polyfluoroalkyl compounds: the concentration of perfluorooctanoic acid (PFOA) is preferably 0.1~5 mg / L, more preferably 0.5~3 mg / L, and even more preferably 1~2 mg / L; the concentration of perfluorooctane sulfonic acid (PFOS) is 0.1~5 mg / L, more preferably 0.5~3 mg / L, and even more preferably 1~2 mg / L. The pH value of the water body polluted by the perfluorinated / polyfluoroalkyl compounds can be 3~11, preferably 4~10, and even more preferably 5~7.

[0028] In this invention, the preferred application includes: mixing the fluorine-modified hydrothermal carbon material with water polluted by perfluorinated / polyfluoroalkyl compounds for an adsorption reaction. The dosage of the fluorine-modified hydrothermal carbon material is preferably 0.1~0.5 g / L, more preferably 0.15~0.3 g / L, and even more preferably 0.2~0.25 g / L. The adsorption reaction time is preferably 2~360 min, more preferably 2~120 min. The adsorption reaction temperature is room temperature.

[0029] In this invention, the fluorine-modified hydrothermal carbon material and water contaminated with perfluorinated / polyfluoroalkyl compounds are mixed and subjected to an adsorption reaction to obtain remediated water and adsorbed fluorine-modified hydrothermal carbon material. Preferably, this invention further includes regenerating the adsorbed fluorine-modified hydrothermal carbon material to obtain regenerated fluorine-modified hydrothermal carbon material. The regenerated fluorine-modified hydrothermal carbon material is then recycled for remediation of water contaminated with perfluorinated / polyfluoroalkyl compounds. In this invention, the reagent used for regeneration is preferably methanol. The purity of the methanol is ≥99.9%. The regeneration preferably includes immersing the adsorbed fluorine-modified hydrothermal carbon material in methanol for regeneration, followed by drying. The regeneration is carried out under shaking conditions, with a shaking speed preferably of 150-200 rpm and a regeneration time preferably of 2-3 hours. The drying can be vacuum drying, with a vacuum drying time preferably of 55-60°C. In this invention, the fluorine-modified hydrothermal carbon material is recycled 2-10 times, and in this example, it can be recycled 5 times.

[0030] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 I. Preparation of Fluorine-Modified Hydrothermal Carbon Materials: Step 1: Dissolve glucose in deionized water and stir until completely dissolved to obtain a glucose solution with a concentration of 108 g / L; Step 2: Place the glucose solution obtained in Step 1 in a hydrothermal reactor, heat at 180 °C for 10 h, centrifuge, and wash three times each with anhydrous ethanol and water. Step 3: After drying the product obtained in Step 2, place it in a tube furnace and calcine it at 700 °C for 2 h under a nitrogen atmosphere to obtain the preliminary product hydrothermal carbon (HC). Step 4: Grind and mix HC and KOH at a mass ratio of 1:3 and place them in a tube furnace. Calcine at 1000℃ for 2 h under a nitrogen atmosphere. Step 5: After cooling the product from Step 4, wash it with deionized water until the pH reaches 7, and then dry it to obtain activated hydrothermal carbon (AHC). Step 6: Grind and mix AHC and ammonium fluoride at a mass ratio of 1:0.1~1:15 (1:5, 1:10 and 1:15 are used in this example respectively), place them in a tube furnace, and calcine at 1000 °C for 2 h under a nitrogen atmosphere; Step 7: After cooling the product from Step 6, wash it several times with deionized water and dry it. The resulting product is the fluorine-modified hydrothermal carbon material (AHC-F) with different fluorine modification amounts. x (x=0.1~15), in this embodiment, the mass ratio of AHC to ammonium fluoride is 1:5, 1:10, and 1:15, and the resulting fluorine-modified hydrothermal carbon materials are AHC-F5 and AHC-F, respectively. 10 AHC-F 15 .

[0032] Table 1 shows the fluorine content of hydrothermal carbon and fluorine-modified hydrothermal carbon (AHC-F5) determined by combustion pyrolysis-ion chromatography. Figure 1 EDS spectra of the fluorine-modified hydrothermal carbon material (AHC-F5). Table 1 and Figure 1 Characterization results show that a fluorine-modified hydrothermal carbon material with a certain fluorine content was successfully prepared using the above steps, with the fluorine content of AHC-F5 being approximately 0.1%.

[0033] Table 1. Fluorine content of hydrothermal carbon and fluorine-modified hydrothermal carbon (AHC-F5) determined by combustion pyrolysis-ion chromatography.

[0034] II. Application of Fluorine-Modified Hydrothermal Carbon Materials in the Efficient Treatment of Water Polluted by Perfluorinated / Polyfluoroalkyl Compounds: This embodiment also provides the application of the above-mentioned fluorine-modified hydrothermal carbon material in the efficient treatment of water bodies polluted by perfluorinated / polyfluorinated alkyl compounds. The specific application method is as follows: Step 1: Add 20 mL of water containing 1 mg / L PFOA and 1 mg / L PFOS to a glass reaction flask. The initial pH of the polluted water in this experiment was 6.2 ± 0.15. Add 4 mg of fluoride-modified hydrothermal carbon material (AHC-F5, AHC-F...). 10 AHC-F 15 ); Step two: After sealing, the borosilicate glass bottle was shielded from light with aluminum foil and placed in a constant-temperature shaker at 150 rpm and 25°C for 2 minutes and 2 hours. The results were obtained as shown in Table 2. Figure 2 The data in the middle. Figure 2 The image shows the removal effect of fluorine-modified hydrothermal carbon material on PFOA and PFOS.

[0035] Table 2. Removal effect of fluorine-modified hydrothermal carbon materials on PFOA and PFOS

[0036] Table 2 and Figure 2 The results showed that fluorine-modified hydrothermal carbon materials with different amounts of fluorine modification could achieve a removal efficiency of 99% for both PFOA and PFOS in the composite pollution system, enabling rapid and efficient removal of PFOA and PFOS composite pollution from water bodies simultaneously. Specifically, after 2 min of shaking adsorption, the fluorine-modified hydrothermal carbon material adsorption system achieved a removal rate of 99% for both 1 mg / L PFOA and 1 mg / L PFOS, while the hydrothermal carbon itself only achieved a removal rate of about 22% for PFOA. The fluorine-modified hydrothermal carbon exhibited a significant advantage in rapid and efficient adsorption, with comparable removal rates for PFOA and PFOS.

[0037] III. Stability Study of Fluorine-Modified Hydrothermal Carbon Materials in the Efficient Treatment of Water Polluted by Perfluorinated / Polyfluoroalkyl Compounds: Step 1: Add 20 mL of water containing 1 mg / L PFOA, 1 mg / L PFOS and 4 mg of fluorine-modified hydrothermal carbon material AHC-F5 to a glass reaction flask; Step 2: After sealing, the borosilicate glass bottle is shielded from light with aluminum foil and then placed in a constant temperature shaker at 150 rpm and 25 ℃ for 2 h. Step 3: Centrifuge and collect the used adsorbent, then regenerate it in 10 mL of methanol (99.9%), shake at 150 rpm for 2 h, and then vacuum dry at 60 °C overnight; Step four involves using the regenerated material in the next round of PFOA / PFOS adsorption reaction, with the entire cycle repeated five times. Results were obtained through testing. Figure 3 The data in the middle. Figure 3 The image shows the removal effect of fluorine-modified hydrothermal carbon material AHC-F5 on PFOA and PFOS. Figure 3 The results show that the fluorine-modified hydrothermal carbon material AHC-F5 can completely remove PFOA and PFOS in five cycles of experiments, demonstrating high stability.

[0038] As can be seen from the above embodiments, the fluorine-modified hydrothermal carbon material provided by the present invention has excellent performance in removing perfluorinated / polyfluoroalkyl compound complex pollution, is easy to operate, and has low cost. It has broad application prospects in the remediation of surface water or groundwater and other water bodies polluted by perfluorinated / polyfluoroalkyl compounds.

[0039] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for producing a fluorine-modified hydrothermal carbon material, characterized by, Includes the following steps: A hydrothermal reaction is carried out on an aqueous solution of a carbohydrate to obtain a hydrothermal solid product; the hydrothermal solid product is then subjected to a first calcination in a protective gas atmosphere to obtain a preliminary product, hydrothermal carbon. The carbohydrate includes one or more of glucose, fructose, xylose, cellulose, chitosan, and chitin. The preliminary product hydrothermal carbon was mixed with an inorganic strong alkali and then subjected to a second calcination in a protective gas atmosphere to obtain activated hydrothermal carbon. The activated hydrothermal carbon and fluoride are mixed and then subjected to a third calcination in a protective gas atmosphere to obtain a fluorine-modified hydrothermal carbon material. The fluoride includes one or more of ammonium fluoride, potassium fluoride, and sodium fluoride.

2. The production method according to claim 1, characterized by, The mass ratio of the activated hydrothermal carbon to the fluoride is 1:(0.1~15); the third calcination temperature is 950~1100℃, and the time is 1~3 h.

3. The production method according to claim 1, characterized by, The concentration of the aqueous solution of the sugar substance is 60~120g / L; the temperature of the hydrothermal reaction is 150~200 ℃ and the time is 8~12 h; the temperature of the first calcination is 600~800 ℃ and the time is 1~3 h.

4. The method of claim 1, wherein, The inorganic strong base includes sodium hydroxide and / or potassium hydroxide; the mass ratio of the preliminary product hydrothermal carbon to the inorganic strong base is 1:(2~4); the second calcination temperature is 950~1100℃ and the time is 1~3 h.

5. Fluorine-modified hydrothermal carbon material prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the fluorine-modified hydrothermal carbon material according to claim 5 in the remediation of water bodies polluted by perfluorinated / polyfluoroalkyl compounds.

7. Use according to claim 5, characterized in that, The water bodies polluted by perfluorinated / polyfluoroalkyl compounds include surface water or groundwater; the water bodies polluted by perfluorinated / polyfluoroalkyl compounds are water bodies polluted by a combination of perfluorinated / polyfluoroalkyl compounds.

8. Use according to claim 7, characterized in that, The water bodies polluted by perfluorinated / polyfluoroalkyl compounds include perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

9. Use according to claim 8, characterized in that, In the water body polluted by the perfluorinated / polyfluoroalkyl compounds: the concentration of perfluorooctanoic acid is 0.1~5 mg / L, and the concentration of perfluorooctane sulfonic acid is 0.1~5 mg / L.

10. The use according to any one of claims 6 to 9, characterized in that, The application includes: mixing the fluorine-modified hydrothermal carbon material with water polluted by perfluorinated / polyfluoroalkyl compounds for adsorption reaction; the dosage of the fluorine-modified hydrothermal carbon material is 0.1~0.5 g / L, and the adsorption reaction time is 2~360 min.

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