Method for degrading perfluorinated compounds in sludge

Abstract

The invention discloses a method for degrading perfluorinated compounds in sludge, which comprises the following steps: adding an indole polymer solution into a sludge extracting solution containing the perfluorinated compounds, and carrying out degradation reaction on the perfluorinated compounds under illumination, the structure of the indole polymer is as follows: # imgabs0. Compared with a small molecule indole derivative containing long-chain alkyl and amido with positive charges, the indole polymer provided by the invention has higher stability, and can continuously and stably generate hydration electrons and efficiently degrade PFOA (perfluorooctanoic acid); compared with polyindole, PFCs in a polluted water body can be effectively captured, a self-assembled inclusion is formed with the polyindole, the degradation effect is improved, and the dosage of raw materials is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of environmental governance, and in particular to a method for degrading perfluorinated compounds in sludge. Background Art

[0002] Among various environmental pollutants, perfluorinated compounds (PFCs) are widely used in textile, printing and dyeing, fire protection and other fields. However, perfluorinated compounds are new persistent organic pollutants. The large-scale production and use of perfluorinated compounds has caused increasingly serious water and soil environmental pollution, and has attracted widespread attention from researchers at home and abroad.

[0003] Among them, perfluorooctanoic acid (PFOA) is one of the most representative perfluorinated compounds. Due to the properties of perfluorinated compounds such as antimicrobial metabolism, hydrophobicity and lipophobicity, and extremely high stability, they pose a serious threat to water bodies, soil environments, and ecosystems. Therefore, PFCs degradation technology has become an important challenge in the current field of environmental governance.

[0004] At present, the methods commonly used to degrade PFCs mainly include advanced oxidation, electrochemical oxidation, photocatalytic degradation, ultrasonic degradation, thermal cracking and hydrated electron reduction defluorination, etc. The reaction device based on photo-induced hydrated electron reduction defluorination is simple, the degradation is fast and thorough, and it has low energy consumption. It is the most efficient method among the existing technologies for degrading PFCs.

[0005] Among them, the use of indole derivatives to generate hydrated electrons to degrade PFCs is also a research focus of future PFCs degradation technology. However, the existing technology uses small molecule indole derivatives or polyindole, which has the disadvantages of large amount of raw materials and poor degradation effect, which limits the development of PFCs degradation technology to a certain extent. Therefore, developing more efficient new technologies for the treatment of PFCs pollution on this basis is a research hotspot and key in this field. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects and shortcomings of the prior art and provide a method for degrading perfluorinated compounds in sludge. The molecular structure of the indole polymer used for degrading perfluorinated compounds of the present invention contains a long-chain alkyl group and a positively charged quaternary ammonium salt, which can effectively capture PFCs in polluted water, form a self-assembled inclusion body with PFOA, continuously and stably generate hydrated electrons and efficiently degrade PFOA.

[0007] The object of the present invention is to provide a method for degrading perfluorinated compounds in sludge, comprising the following steps: An indole polymer solution is added to the sludge extract containing perfluorinated compounds, and the perfluorinated compounds are degraded by light reaction; The structure of the indole polymer is shown below:

[0008] Wherein, R1, R2, R3 and R4 are independently selected from H or , R5, R6 are independently selected from H or C 10~22 , and R5 and R6 are not H at the same time; the number average molecular weight of the indole polymer is 3000~8000 g / mol.

[0009] In some embodiments of the present invention, the structure of the indole polymer is as follows: , , or

[0010] The number average molecular weight of the indole polymer is 3000-8000 g / mol.

[0011] In some embodiments of the present invention, the mass ratio of the perfluorinated compound to the indole polymer is 1:10-40.

[0012] In some embodiments of the present invention, the pH value of the sludge extract containing perfluorinated compounds is 4.0-7.0.

[0013] In some embodiments of the present invention, the temperature of the light irradiation reaction is 25±2° C. and the time is 4 to 8 hours.

[0014] In some embodiments of the present invention, the light source of the illumination reaction is a low-pressure mercury lamp.

[0015] In some embodiments of the present invention, the content of perfluorinated compounds in the sludge extract containing perfluorinated compounds is 3.02×10 -3 mg / L, and the content of the indole polymer in the indole polymer solution is 0.6-1 mg / L.

[0016] Another object of the present invention is to provide a method for preparing a method for degrading perfluorinated compounds in sludge, wherein the method for preparing the indole polymer comprises the following steps: S1. Chlorinating indolecarboxylic acid and reacting with alkyl hydroxyethyl ammonium chloride to obtain an indole derivative; S2. dissolving the indole derivative in acetonitrile to form an acetonitrile solution of the indole derivative, dropping the acetonitrile solution of the indole derivative into an acetonitrile solution of ferric chloride, stirring the reaction, and purifying to obtain an indole polymer; In some embodiments of the present invention, the indolecarboxylic acid is selected from at least one of indole-4-carboxylic acid, indole-5-carboxylic acid, indole-6-carboxylic acid, and indole-7-carboxylic acid; In some embodiments of the present invention, the alkyl hydroxyethyl ammonium chloride is selected from at least one of tetradecyl dimethyl hydroxyethyl ammonium chloride, octadecyl dimethyl hydroxyethyl ammonium chloride, behenyl dimethyl hydroxyethyl ammonium chloride, and di(decyl) dimethyl hydroxyethyl ammonium chloride.

[0017] In some embodiments of the present invention, in S1, the chlorination reagent is selected from SOCl2.

[0018] In some embodiments of the present invention, in S1, the temperature of the chlorination is 80-100° C. and the time is 15-25 hours.

[0019] In some embodiments of the present invention, in S1, the mass ratio of indolecarboxylic acid to alkylhydroxyethylammonium chloride is 1.1-1.5:1.

[0020] In some embodiments of the present invention, in S1, the mass ratio of the indolecarboxylic acid to the chlorination reagent is 1:1.1-1.5.

[0021] In some embodiments of the present invention, in S1, the reaction temperature is 110-130° C. and the reaction time is 10-20 hours.

[0022] In some embodiments of the present invention, in S2, the mass ratio of the indole derivative to ferric chloride is 1:2-4.

[0023] In some embodiments of the present invention, in S2, the stirring reaction is carried out at room temperature for 8 to 16 hours.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with small molecule indole derivatives containing long-chain alkyl groups and positively charged amine groups, the indole polymers of the present invention have higher stability, can continuously and stably generate hydrated electrons and efficiently degrade PFOA.

[0025] (2) Compared with polybenzazole, the indole polymer of the present invention contains long-chain alkyl groups and positively charged quaternary ammonium salts in its molecular structure, which can effectively capture PFCs in sludge and form self-assembled inclusions with PFOA, significantly improving the degradation effect and reducing the amount of raw materials used, thereby reducing energy consumption and costs.

[0026] (3) The present invention uses an indole polymer with a moderate molecular weight to effectively improve the degradation effect of PFOA. If the molecular weight of the indole polymer is too large, it cannot form a self-assembled inclusion body with PFOA. If the molecular weight of the indole polymer is too small, it cannot continuously and stably generate hydrated electrons and efficiently degrade PFOA.

[0027] (4) The indole polymer provided by the present invention has stable properties and has no significant effect on the degradation of PFCs in complex environmental conditions. Therefore, the method for degrading PFCs in sludge provided by the present invention has a wide range of applications. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the concept of the present invention and the technical effects produced in combination with the embodiments, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the present invention. The test methods used in the embodiments are all conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can all be reagents and materials obtained from commercial channels.

[0029] Example 1 This embodiment provides an indole polymer, and the preparation method thereof comprises the following steps: S1. 10 parts by mass of indole-4-carboxylic acid and 11 parts by mass of SOCl2 were added to a reaction bottle respectively, 40 parts by mass of N,N-dimethylformamide was added, the reaction was carried out at 100°C for 15 hours, 9.1 parts by mass of tetradecyldimethylhydroxyethylammonium chloride was added, the mixture was stirred for 1 hour, 1 mL of triethylamine was added, the reaction was carried out at 120°C for 15 hours, the crude product after the reaction was filtered, rotary evaporated to dryness, and separated and purified by silica gel column to obtain an indole derivative.

[0030] S2. Dissolve 10 parts by weight of the above indole derivative in 50 mL of acetonitrile to form an acetonitrile solution of the indole derivative, drop the acetonitrile solution of the indole derivative into 50 mL of acetonitrile solution containing 20 parts by weight of ferric chloride, stir and react at room temperature for 10 hours, wash the product repeatedly with methanol, and dry to obtain an indole polymer with a number average molecular weight of 8000 g / mol; the structural formula of the indole polymer is as follows: .

[0031] Example 2 This embodiment provides an indole polymer, and the preparation method thereof comprises the following steps: S1. 10 parts by mass of indole-4-carboxylic acid and 15 parts by mass of SOCl2 were added to a reaction bottle respectively, 40 parts by mass of N,N-dimethylformamide was added, and the mixture was reacted at 90°C for 20 h. Then 8.3 parts by mass of dioctyldimethylhydroxyethylammonium chloride was added, and the mixture was stirred for 1 hour. 1 mL of triethylamine was added, and the mixture was reacted at 110°C for 18 hours. The crude product after the reaction was filtered, rotary evaporated to dryness, and separated and purified by silica gel column to obtain an indole derivative.

[0032] S2. Dissolve 10 parts by weight of the above indole derivative in 50 mL of acetonitrile to form an acetonitrile solution of the indole derivative, drop the acetonitrile solution of the indole derivative into 50 mL of acetonitrile solution containing 25 parts by weight of ferric chloride, stir and react at room temperature for 12 hours, wash the product repeatedly with methanol, and dry to obtain an indole polymer with a number average molecular weight of 7260 g / mol; the structural formula of the indole polymer is as follows: .

[0033] Example 3 This embodiment provides an indole polymer, and the preparation method thereof comprises the following steps: S1. Add 12 parts by mass of indole-4-carboxylic acid and 16 parts by mass of SOCl2 into a reaction bottle respectively, add 40 parts by mass of N,N-dimethylformamide, react at 80°C for 24 hours, then add 8 parts by mass of di(decyl)dimethylhydroxyethylammonium chloride, stir for 1 hour, add 1 mL of triethylamine, react at 110°C for 20 hours, filter the crude product after the reaction, evaporate to dryness, and separate and purify it by silica gel column to obtain an indole derivative.

[0034] S2. 12 parts by weight of the above indole derivatives were dissolved in 50 mL of acetonitrile to form an acetonitrile solution of indole derivatives, and the acetonitrile solution of indole derivatives was dropped into 50 mL of acetonitrile solution containing 36 parts by weight of ferric chloride, and the reaction was stirred at room temperature for 10 hours. The product was repeatedly washed with methanol and dried to obtain an indole polymer with a number average molecular weight of 6974 g / mol; the structural formula of the indole polymer is as follows: .

[0035] Example 4 This embodiment provides an indole polymer, and the preparation method thereof comprises the following steps: S1. Add 10 parts by mass of indole-5-carboxylic acid and 14 parts by mass of SOCl2 into a reaction bottle respectively, add 40 parts by mass of N,N-dimethylformamide, react at 100°C for 12 hours, then add 7.1 parts by mass of octadecyldimethylhydroxyethylammonium chloride, stir for 1 hour, add 1 mL of triethylamine, react at 130°C for 10 hours, filter the crude product after the reaction, rotary evaporate to dryness, and separate and purify it by silica gel column to obtain an indole derivative.

[0036] S2. Dissolve 10 parts by weight of the above indole derivative in 50 mL of acetonitrile to form an acetonitrile solution of the indole derivative, drop the acetonitrile solution of the indole derivative into 50 mL of acetonitrile solution containing 40 parts by weight of ferric chloride, stir and react at room temperature for 16 hours, wash the product repeatedly with methanol, and dry to obtain an indole polymer with a number average molecular weight of 3000 g / mol; the structural formula of the indole polymer is as follows: .

[0037] Example 5 This embodiment provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 10 parts by mass of the solution of the indole polymer prepared in Example 1 were dispersed in the sludge extract, the content of the indole polymer in the solution of the indole polymer was 0.6 mg / L, and the pH of the solution was adjusted to 6.0 using 0.1M NaOH and HCl, the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 6 h. 2 mL was sampled every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0038] Example 6 This embodiment provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 18 parts by mass of the solution of the indole polymer prepared in Example 2 were dispersed in the sludge extract, the content of the indole polymer in the solution of the indole polymer was 1 mg / L, and the pH of the solution was adjusted to 5.0 using 0.1M NaOH and HCl, and the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 5 h. 2 mL was sampled every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0039] Example 7 This embodiment provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 40 parts by mass of the solution of the indole polymer prepared in Example 3 were dispersed in the sludge extract, the content of the indole polymer in the solution of the indole polymer was 0.8 mg / L, and the pH of the solution was adjusted to 7.0 using 0.1M NaOH and HCl, and the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 8 h. 2 mL was sampled every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0040] Example 8 This embodiment provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 30 parts by mass of the indole polymer solution prepared in Example 4 were dispersed in the sludge extract, the content of indole polymer in the indole polymer solution was 0.7 mg / L, and the pH of the solution was adjusted to 4.0 using 0.1M NaOH and HCl, and the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 4 h. 2 mL was sampled every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0041] Comparative Example 1 This comparative example provides a polybenzazole, and its preparation method comprises the following steps: Take 50 mL of acetonitrile and put it into a three-necked flask, then slowly add 0.04 mol of ferric chloride and stir thoroughly to dissolve. Then add 30 mL of acetonitrile solution containing 0.01 mol of indole dropwise under a nitrogen atmosphere. The mixed solution was shaken at 300 rpm for 15 hours. The shaken solution was passed through a 0.22 μm organic filter membrane by vacuum filtration, and polybenzazole particles were retained on the filter membrane. The polybenzazole particles were repeatedly washed with methanol and 60°C hot water to remove impurities. Then, vacuum dried at 70°C for 10 hours. Finally, the polybenzazole was ground using an agate mortar and passed through a 100-mesh sieve to obtain polybenzazole.

[0042] Comparative Example 2 This comparative example provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 10 parts by mass of the polybenzazole solution prepared in Comparative Example 1 were dispersed in the sludge extract, the content of polybenzazole in the polybenzazole solution was 0.6 mg / L, and the pH of the solution was adjusted to 6.0 using 0.1M NaOH and HCl, and the prepared reaction solution was magnetically stirred for 1 h and then transferred to a cylindrical quartz glass reactor for photodegradation under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 6 h. 2 mL was sampled every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0043] Comparative Example 3 This comparative example provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 10 parts by mass of the solution of indole derivatives prepared in step S1 of Example 1 were dispersed in the sludge extract, the content of indole derivatives in the solution of indole derivatives was 0.6 mg / L, and the pH of the solution was adjusted to 7.0 using 0.1M NaOH and HCl, the prepared reaction solution was magnetically stirred for 1 h and then transferred to a cylindrical quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 5 h. 2 mL of the sample was taken every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0044] Comparative Example 4 This comparative example provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 18 parts by mass of the solution of indole derivatives prepared in step S1 of Example 2 were dispersed in the sludge extract, the content of indole derivatives in the solution of indole derivatives was 1 mg / L, and the pH of the solution was adjusted to 5.0 using 0.1M NaOH and HCl, the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 4 h. 2 mL of the sample was taken every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0045] Comparative Example 5 This comparative example provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3 mg / L, 30 parts by mass of the solution of indole derivatives prepared in step S1 of Example 3 were dispersed in the sludge extract, the content of indole derivatives in the solution of indole derivatives was 0.8 mg / L, and the pH of the solution was adjusted to 4.0 using 0.1M NaOH and HCl, the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 7 h. 2 mL of the sample was taken every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0046] Comparative Example 6 This comparative example provides a method for degrading perfluorinated compounds in sludge, which specifically comprises the following steps: The content of perfluorinated compounds in the sludge extract containing 1 part by mass of PFOA was 3.02×10 -3mg / L, 40 parts by mass of the solution of indole derivatives prepared in step S1 of Example 4 were dispersed in the sludge extract, the content of indole derivatives in the solution of indole derivatives was 0.7 mg / L, and the pH of the solution was adjusted to 6.0 using 0.1M NaOH and HCl, the prepared reaction solution was magnetically stirred for 1 h and then transferred to a quartz glass reactor, and photodegradation reaction was carried out under the irradiation of a 36W low-pressure mercury lamp. The temperature of the photodegradation reaction was controlled at 25±2°C, and the reaction time was 8 h. 2 mL of the sample was sampled every 30 minutes, extracted with 200 mL of methanol, and the remaining content of PFOA was detected by high performance liquid chromatography-mass spectrometry (HPLC-MS / MS), and the degradation rate of PFOA was calculated.

[0047] The degradation rates of PFOA in Examples 5 to 8 and Comparative Examples 2 to 6 are shown in Table 1: Table 1. Degradation rates of PFOA in Examples 5-8 and Comparative Examples 2-6.

[0048]

[0049] The stability test of the present invention is mainly performed by repeating Examples 5 to 8 and Comparative Examples 2 to 6 for 10 times to degrade PFOA, and then testing the degradation effects of Examples 5 to 8 and Comparative Examples 2 to 6 on PFOA again. The specific results are shown in Table 2: Table 2. Stability tests of Examples 5-8 and Comparative Examples 2-6.

[0050]

[0051] As shown in Tables 1-2, the indole polymers provided in Examples 1-4 have better degradation effects on perfluorinated compounds than polyindole and small molecule indole derivatives; in addition, the indole polymers provided by the present invention are stable in nature, and after being used for 10 times to degrade PFOA, the photodegradation reaction of PFOA still has a high degradation rate, and the degradation effect does not change significantly.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for degrading perfluorinated compounds in sludge, characterized in that: The steps include: An indole polymer solution is added to the sludge extract containing perfluorinated compounds, and the perfluorinated compounds are degraded by light reaction; The structure of the indole polymer is shown below: ； Wherein, R1, R2, R3 and R4 are independently selected from H or , R5, R6 are independently selected from H or C 10~22 , and R5 and R6 are not H at the same time, and the number average molecular weight of the indole polymer is 3000~8000 g / mol.

2. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The structure of the indole polymer is shown below: 、 、 or .

3. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The mass ratio of the perfluorinated compound to the indole polymer is 1:10-40.

4. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The pH value of the sludge extract containing perfluorinated compounds is 4.0-7.

0.

5. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The temperature of the light reaction is 25±2°C and the time is 4 to 8 hours.

6. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The light source of the illumination reaction is a low-pressure mercury lamp.

7. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The content of perfluorinated compounds in the sludge extract containing perfluorinated compounds is 3.02×10 -3 mg / L, and the content of the indole polymer in the indole polymer solution is 0.6-1 mg / L.

8. The method for degrading perfluorinated compounds in sludge according to claim 1, characterized in that: The preparation method of the indole polymer comprises the following steps: S1. Chlorinating indolecarboxylic acid and reacting with alkyl hydroxyethyl ammonium chloride to obtain an indole derivative; S2. dissolving the indole derivative in acetonitrile to form an acetonitrile solution of the indole derivative, dropping the acetonitrile solution of the indole derivative into an acetonitrile solution of ferric chloride, stirring the reaction, and purifying to obtain an indole polymer; The indolecarboxylic acid is selected from at least one of indole-4-carboxylic acid, indole-5-carboxylic acid, indole-6-carboxylic acid and indole-7-carboxylic acid; The alkyl hydroxyethyl ammonium chloride is selected from at least one of tetradecyl dimethyl hydroxyethyl ammonium chloride, octadecyl dimethyl hydroxyethyl ammonium chloride, behenyl dimethyl hydroxyethyl ammonium chloride and di(decyl) dimethyl hydroxyethyl ammonium chloride.

9. The method for degrading perfluorinated compounds in sludge according to claim 8, characterized in that: In S1, the chlorination reagent is selected from SOCl2; The mass ratio of the indole carboxylic acid to the alkyl hydroxyethyl ammonium chloride is 1.1-1.5:

1.

10. The method for degrading perfluorinated compounds in sludge according to claim 8, characterized in that: In S2, the mass ratio of the indole derivative to ferric chloride is 1:2-4; The stirring reaction is carried out at room temperature for 8 to 16 hours.

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