A sludge biochar-based catalyst and a method for preparing the same

Abstract

The application relates to the technical field of catalysts, and particularly discloses a sludge biochar-based catalyst and a preparation method thereof.The sludge biochar-based catalyst comprises the following components in parts by weight: 108-112 parts of biochar powder, 75-95 parts of calcium-loaded polypropylene fiber, wherein the biochar powder is obtained by sequentially subjecting a precursor to pyrolysis, washing, drying and grinding; the components of the precursor comprise dewatered sludge and zinc chloride, the dosage ratio of the zinc chloride to the dewatered sludge is 12.5 mmol:1 g, and the calcium-loaded polypropylene fiber is polypropylene fiber with calcium silicate loaded on the surface.The application can adsorb and solidify phosphate ions in sewage through the calcium-loaded polypropylene fiber, improve the removal efficiency of bisphenol A, and improve the purification treatment effect on the sewage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, and more particularly to a sludge biochar-based catalyst and a preparation method thereof. BACKGROUND

[0002] Bisphenol A is a widely used chemical product, and is also a typical endocrine disruptor. Bisphenol A can enter the human body through various pathways such as the digestive tract, respiratory tract, and skin, interfere with the human endocrine system, and may cause diseases related to reproduction and fertility, and even cancer in severe cases. Therefore, means need to be taken to treat bisphenol A in pollutants.

[0003] In related technologies, there is a method for oxidative degradation of bisphenol A, which uses sludge biochar and persulfate to promote the degradation of bisphenol A in wastewater. The biochar is prepared as follows: (1) mixing dewatered sludge and zinc chloride solution to obtain a precursor; the components of the precursor include dewatered sludge and zinc chloride, and the amount ratio of zinc chloride to dewatered sludge is 12.5 mmol:1 g; (2) pyrolyzing the precursor in a nitrogen atmosphere at 500°C for 2h, then washing with hydrochloric acid and deionized water in sequence, and then drying and grinding to obtain the sludge biochar.

[0004] In view of the above related technologies, the inventors believe that although the scheme in the related technologies can promote the degradation of bisphenol A, in actual implementation, various inorganic ions often exist in wastewater. When the wastewater contains phosphate ions, it is difficult to fully remove bisphenol A in the wastewater according to the method in the related technologies, which is not conducive to improving the treatment effect of the wastewater. SUMMARY

[0005] When the wastewater contains phosphate ions, it is difficult to fully remove bisphenol A in the wastewater according to the method in the related technologies, which is not conducive to improving the treatment effect of the wastewater. In order to improve this defect, the present application provides a sludge biochar-based catalyst and a preparation method thereof.

[0006] In a first aspect, the present application provides a sludge biochar-based catalyst, which adopts the following technical scheme:

[0007] A sludge biochar-based catalyst, the sludge biochar-based catalyst includes the following components by weight: 108-112 parts of biochar powder, 75-95 parts of calcium-loaded polypropylene fiber, the biochar powder is obtained by sequentially subjecting a precursor to pyrolysis, washing, drying, and grinding; the components of the precursor include dewatered sludge and zinc chloride, the amount ratio of zinc chloride to dewatered sludge is 12.5 mmol:1 g, and the calcium-loaded polypropylene fiber is a polypropylene fiber with calcium silicate loaded on the surface.

[0008] By adopting the technical scheme, the biochar powder and the calcium-loaded polypropylene fiber are compounded to obtain the sludge biochar-based catalyst. When the sludge biochar-based catalyst and the persulfate salt are used together to catalytically degrade bisphenol A in wastewater, the calcium silicate on the surface of the calcium-loaded polypropylene fiber can electrostatically adsorb phosphate ions in the wastewater, and the calcium silicate is based on the polypropylene fiber, so that the high specific surface area characteristics of the fiber material are fully utilized, and the solidification of the phosphate ions is realized. By adsorbing and solidifying the phosphate ions, it is difficult for the phosphate ions to quench the free radicals generated in the wastewater treatment process, and the competitive adsorption of the phosphate ions and bisphenol A on the surface of the biochar powder is also reduced, so that the removal efficiency of bisphenol A is improved, and the purification treatment effect on the wastewater is improved.

[0009] Preferably, the calcium-loaded polypropylene fiber is prepared by the following method:

[0010] (1) The carboxylated polypropylene fiber is immersed in a sodium metasilicate solution with a mass fraction of 15% for 30 minutes, and then suction filtration is performed to obtain a silicon-loaded polypropylene fiber; the carboxylated polypropylene fiber is polypropylene fiber with carboxyl groups grafted on the surface, and the carboxyl groups are provided by acrylic acid;

[0011] (2) The silicon-loaded polypropylene fiber is immersed in a calcium chloride solution with a mass fraction of 5% for 5 hours, and then suction filtration is performed again, and the obtained product is washed with water and dried to obtain a calcium-loaded polypropylene fiber.

[0012] By adopting the technical scheme, the carboxylated polypropylene fiber is first immersed in the water glass, and the carboxyl groups on the surface of the fiber react with sodium metasilicate to produce silicic acid, which enhances the adhesion of the fiber surface and carries a part of sodium metasilicate on the fiber surface. Then, the reaction of sodium metasilicate and calcium chloride produces calcium silicate precipitate on the surface of the fiber, and the calcium-loaded polypropylene fiber is obtained.

[0013] Preferably, the carboxylated polypropylene fiber is prepared by the following method:

[0014] (1) Acrylic acid, ferrous ammonium sulfate, sulfuric acid and a solvent are mixed to obtain a modification liquid; in the modification liquid, the mass fractions of acrylic acid, ferrous ammonium sulfate and sulfuric acid are 40%, 2% and 0.5% respectively, the rest is made up to 100% by the solvent, and the solvent is a mixture of water and ethanol in a volume ratio of 4:1;

[0015] (2) The polypropylene fiber and the modification liquid are mixed in a weight ratio of 1:80, and electron beam irradiation is performed on the mixture at a dose of 20-80 kGy per gram of polypropylene fiber. After the irradiation is completed, the fiber is taken out, washed and dried to obtain carboxylated polypropylene fiber; the polypropylene fiber is waste polypropylene fiber.

[0016] By adopting the technical scheme, the polypropylene fiber is grafted with acrylic acid under the action of electron beam irradiation, and carboxylated polypropylene fiber is obtained. The method realizes the reuse of waste polypropylene fiber, and helps to reduce the production cost.

[0017] Preferably, the irradiation dose of the electron beam is set as 60-80 kGy per gram of polypropylene fiber.

[0018] By adopting the technical scheme, the range of the electron beam irradiation dose is preferred, which helps to increase the number of carboxyl groups on the surface of the carboxylated polypropylene fiber, improve the carrying capacity of the carboxylated polypropylene fiber for sodium metasilicate, increase the total amount of calcium silicate on the surface of the calcium-loaded polypropylene fiber, and improve the adsorption effect of the calcium-loaded polypropylene fiber on phosphate ions.

[0019] Preferably, the precursor is prepared by the following method:

[0020] (1) The sludge is dried and ground to obtain dewatered sludge; zinc chloride is added to water to obtain a zinc chloride solution with a concentration of 5 mol / L;

[0021] (2) The dewatered sludge and the aging solution are mixed at a ratio of 2.5 L of the aging solution per kilogram of the dewatered sludge, and then sealed and placed for 24 h to obtain the precursor.

[0022] By adopting the technical scheme, the aging solution containing zinc chloride is mixed with the dewatered sludge, the dewatered sludge absorbs the aging solution by using the water absorption property of the dewatered sludge, and the evaporation of water is reduced by sealing and placing, so as to promote the full penetration of zinc chloride, realize the aging treatment of the sludge, and obtain the precursor.

[0023] Preferably, the components of the precursor further include iron chloride, and the iron chloride is added to water together with the zinc chloride in step (1) of preparing the precursor.

[0024] By adopting the technical scheme, the iron chloride is added to the precursor, which helps to increase the specific surface area of the biochar powder and improve the catalytic removal effect of the biochar powder on bisphenol A.

[0025] Preferably, the components of the precursor further include an auxiliary carbonization agent, and the auxiliary carbonization agent is mixed with the dewatered sludge and the aging solution after sealing and placing in step (2) of preparing the precursor. The amount of the auxiliary carbonization agent is 20% of the dewatered sludge, and the components of the auxiliary carbonization agent include phosphoric acid and lignin.

[0026] By adopting the technical scheme, the auxiliary carbonization agent is added in the precursor, and the auxiliary carbonization agent contains phosphoric acid and lignin. The lignin contains a large amount of aromatic rings, and has a high degree of aromatization itself. The phosphoric acid can catalyze the formation and condensation of carbon aromatic rings. Therefore, the addition of the phosphoric acid and the lignin is beneficial to improve the degree of aromatization of the biochar. The bisphenol A contains two benzene rings in the molecule, and is a typical aromatic compound. The improvement of the degree of aromatization of the biochar improves the compatibility of the biochar powder and the bisphenol A, and thus the adsorption of the biochar powder to the bisphenol A is enhanced, which is helpful to improve the removal efficiency of the bisphenol A.

[0027] Preferably, the auxiliary carbonization agent is prepared by mixing a base material and a 50% phosphoric acid solution in a weight ratio of 3:2, and then being kept at 130°C for 90 min to obtain the auxiliary carbonization agent. The base material includes straw powder or poplar powder.

[0028] By adopting the technical scheme, the straw powder or the poplar powder is preferably used as the raw material for producing the auxiliary carbonization agent. The poplar powder has a higher lignin content than the straw powder, and thus is beneficial to the aromatization of the biochar. Although the corn straw powder has a lower lignin content, it is widely available in rural areas and has a low cost. Therefore, the corn straw powder can also be used under the premise of saving cost and local availability.

[0029] Preferably, the base material includes dewatered papermaking sludge.

[0030] By adopting the technical scheme, the lignin content in the dewatered papermaking sludge is usually higher than that in the straw powder and the poplar powder. Under the premise of facilitating local availability, the appropriate use of the dewatered papermaking sludge not only helps to reduce the production cost, but also is beneficial to improve the degree of aromatization of the biochar, and thus is helpful to improve the compatibility of the biochar powder and the bisphenol A, and to improve the removal effect of the bisphenol A.

[0031] In a second aspect, the application provides a preparation method of a sludge biochar-based catalyst, which adopts the following technical scheme.

[0032] The preparation method of the sludge biochar-based catalyst includes the following steps.

[0033] (1) The precursor in any of the above is placed in an oven and dried at 160°C for 36h, and then pyrolyzed in a nitrogen atmosphere at 500°C for 2h to obtain biochar;

[0034] (2) After the biochar is cooled, it is first soaked and washed with nitric acid for 24h, and then washed with deionized water. Then, the biochar is filtered, dried and ground to obtain biochar powder. The biochar powder is mixed with calcium-loaded polypropylene fibers to obtain a sludge biochar-based catalyst.

[0035] By adopting the technical scheme, the application soaks the biochar by nitric acid, and the soaking and washing of the nitric acid can increase the number of carbonyl groups on the surface of the biochar, and the carbonyl groups can promote the generation of singlet oxygen in the catalytic oxidation system of sodium persulfate, and the increase of the number of carbonyl groups helps to improve the removal effect of bisphenol A.

[0036] In summary, the application has the following beneficial effects:

[0037] 1. The application uses calcium-loaded polypropylene fibers to adsorb and solidify phosphate ions in wastewater, making it difficult for phosphate ions to quench free radicals generated during the wastewater treatment process, and reducing the competitive adsorption of phosphate ions on the surface of biochar powder and bisphenol A, thereby improving the removal efficiency of bisphenol A and improving the purification treatment effect of wastewater.

[0038] 2. The application limits the auxiliary carbonization agent to agricultural waste or wood processing waste, which contains lignin and cellulose, and lignin contains a large number of aromatic groups. Using waste with high lignin content as an auxiliary carbonization agent helps to increase the number of aromatic groups in biochar powder, thereby improving the compatibility of biochar powder and bisphenol A, and helping to improve the removal effect of bisphenol A.

[0039] 3. The method of the application soaks the biochar by nitric acid, and the soaking and washing of the nitric acid can increase the number of carbonyl groups on the surface of the biochar, and the carbonyl groups can promote the generation of singlet oxygen in the catalytic oxidation system of sodium persulfate, so the increase of the number of carbonyl groups helps to improve the removal effect of bisphenol A. DETAILED DESCRIPTION

[0040] The application will be further described in detail below in combination with examples, preparation examples and comparative examples. The raw materials involved in the application can be obtained by market purchase.

[0041] Preparation example of calcium-loaded polypropylene fiber

[0042] The following preparation example 1 is used as an example for illustration.

[0043] Preparation example 1

[0044] Before starting to prepare calcium-loaded polypropylene fiber, this preparation example provides a carboxylated polypropylene fiber, which is prepared according to the following method: (1) mixing acrylic acid, ferrous ammonium sulfate, sulfuric acid and solvent to obtain a modification liquid; in the modification liquid, the mass fractions of acrylic acid, ferrous ammonium sulfate and sulfuric acid are 40%, 2% and 0.5% respectively, the rest is made up to 100% by solvent, and the solvent is a mixture of water and ethanol in a volume ratio of 4:1;

[0045] (2) The polypropylene fiber and the modification liquid are mixed according to a weight ratio of 1:80, electron beam irradiation is performed according to a dose of 10 kGy per gram of polypropylene fiber, and after the irradiation is completed, the fiber is taken out, washed and dried to obtain carboxylated polypropylene fiber; the polypropylene fiber is waste polypropylene fiber, the monofilament diameter of the fiber is 50 μm, and the average length is 16 mm.

[0046] In the preparation example, the calcium-loaded polypropylene fiber is prepared according to the following method:

[0047] (1) The carboxylated polypropylene fiber is added into the water glass with a mass fraction of 15% of sodium metasilicate according to an impregnation ratio of 1:100 (by weight, the same below) for impregnation for 30 min, and then suction filtration is performed to obtain silicon-loaded polypropylene fiber; the carboxylated polypropylene fiber is polypropylene fiber with carboxyl groups grafted on the surface, and the carboxyl groups are provided by acrylic acid;

[0048] (2) The silicon-loaded polypropylene fiber is added into a calcium chloride solution with a mass fraction of 5% according to an impregnation ratio of 1:100 for impregnation for 5 h, and then suction filtration is performed again, and the obtained product is washed with water and dried to obtain calcium-loaded polypropylene fiber.

[0049] As shown in Table 1, the differences between Preparation Examples 1-5 are different radiation doses of electron beams (per gram of polypropylene fiber).

[0050] Table 1 Radiation dose

[0051] Sample Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5 Radiation dose / kGy 10 20 40 60 80

[0052] Preparation example of the precursor

[0053] The following is illustrated by taking Preparation Example 6 as an example.

[0054] Preparation Example 6

[0055] In the preparation example, the precursor is prepared according to the following method:

[0056] (1) The sludge is dried at 105°C, and then ground to obtain dewatered sludge; zinc chloride is added into water to obtain an aging liquid with a zinc chloride concentration of 5 mol / L; the sludge used in this step is domestic sludge taken from a sewage treatment plant;

[0057] (2) The dewatered sludge and the aging liquid are mixed according to a ratio of 2.5 L of the aging liquid per kilogram of the dewatered sludge, and then sealed and left to stand for 24 h to obtain the precursor.

[0058] In the preparation example, the content of lignin in the dewatered sludge is also detected according to the description of “GB / T 35818-2018 Analysis Method of Forestry Biomass Raw Materials Determination of Polysaccharide and Lignin Content”, and the results show that the weight of lignin accounts for 0.7% of the dry weight of the dewatered sludge.

[0059] Preparation Example 7

[0060] The difference between this preparation example and Preparation Example 6 is that the components of the precursor further include iron chloride, which is added into water together with zinc chloride in step (1) of preparing the precursor, and the mass fraction of the iron chloride in the precursor is 2%.

[0061] Preparation Example 8

[0062] The difference between this preparation example and Preparation Example 7 is that 20% of the weight of the dewatered sludge of Preparation Example 7 is replaced by an auxiliary carbonization agent, which is mixed with the dewatered sludge after being sealed and placed and the aging liquid in step (2) of preparing the precursor.

[0063] The auxiliary carbonization agent is prepared by mixing a base material and a 50% phosphoric acid solution in a weight ratio of 3:2, and then incubating at 130°C for 90 min to obtain the auxiliary carbonization agent, wherein the base material is corn straw powder (lignin mass fraction 17.4%) with a mesh size of 200.

[0064] Preparation Example 9

[0065] The difference between this preparation example and Preparation Example 8 is that the base material is poplar powder (lignin mass fraction 25.2%) with a mesh size of 200.

[0066] Preparation Example 10

[0067] The difference between this preparation example and Preparation Example 9 is that 30% of the weight of the domestic sludge is replaced by dewatered papermaking sludge. In the dry weight of the dewatered papermaking sludge, the proportion of lignin is 36.8%.

[0068] Example

[0069] Examples 1-5

[0070] The following is described by taking Example 1 as an example.

[0071] Example 1

[0072] In this example, the sludge biochar-based catalyst is mixed by 108 g of biochar powder and 75 g of calcium-loaded polypropylene fibers.

[0073] In this example, the sludge biochar-based catalyst is prepared by the following steps:

[0074] (1) The precursor of Preparation Example 6 is placed in an oven and dried at 160°C for 36 h, and then pyrolyzed at 500°C in a nitrogen atmosphere for 2 h to obtain biochar;

[0075] (2) After waiting for the biochar to cool, the biochar is soaked and washed with 3 mol / L nitric acid for 24 h, and then washed with deionized water, and then filtered and dried, and then ground to an average particle size of 45 μm to obtain biochar powder, and then mixed with the calcium-loaded polypropylene fiber of Preparation Example 1 to obtain a sludge biochar-based catalyst; in this step, the biochar and the nitric acid are mixed at a ratio of 1 kg:4 L.

[0076] As shown in Table 2, the main difference between Examples 1-5 is that the raw material ratio of the sludge biochar-based catalyst is different.

[0077] Table 2 Raw material ratio of sludge biochar-based catalyst

[0078]

[0079]

[0080] Examples 6-9

[0081] As shown in Table 3, Examples 6-9 differ from Example 5 in that the preparation example of the calcium-loaded polypropylene fiber is different.

[0082] Table 3 Preparation example of calcium-loaded polypropylene fiber

[0083] Sample Example 5 Example 6 Example 7 Example 8 Example 9 Preparation Example Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5

[0084] Examples 10-13

[0085] As shown in Table 4, Examples 10-13 differ from Example 9 in that the preparation example of the precursor is different.

[0086] Table 4 Preparation example of precursor

[0087] Sample Example 9 Example 10 Example 11 Example 12 Example 13 Preparation Example Preparation Example 6 Preparation Example 7 Preparation Example 8 Preparation Example 9 Preparation Example 10

[0088] Comparative Examples

[0089] Comparative Example 1

[0090] The difference between this comparative example and Example 1 is that the components of the sludge biochar-based catalyst only include biochar powder, and the nitric acid used in the soaking and washing of Example 1 is replaced with 3 mol / L hydrochloric acid.

[0091] Comparative Example 2

[0092] The difference between this comparative example and Example 1 is that the calcium-loaded polypropylene fiber is replaced with wollastonite powder of the same mass, and the particle size distribution of the wollastonite powder is d 50 7.72 μm, d 97 31.85 μm, and the specific surface area is 1.41 m 2 / g.

[0093] Comparative Example 3

[0094] The present comparative example differs from Example 1 in that the components of the sludge biochar-based catalyst only include biochar powder.

[0095] Performance detection test method

[0096] Test materials: sludge biochar-based catalysts prepared in Examples 1-13 and Comparative Examples 1-2.

[0097] Test steps:

[0098] (1) Prepare simulated wastewater with a bisphenol A concentration of 10 mg / L and a phosphate ion concentration of 10 mmol / L for standby; in this step, the phosphate ion is provided by sodium phosphate;

[0099] (2) Take 100 L of simulated wastewater, adjust the simulated wastewater to neutral using hydrochloric acid and sodium hydroxide solution, and then add sludge biochar-based catalyst and sodium persulfate to the simulated wastewater; the sludge biochar-based catalyst is added according to the dosage of 10 g of biochar powder per 100 L of simulated wastewater, and the sodium persulfate is added according to the calculated dosage at a concentration of 0.5 mmol / L;

[0100] (3) After 10 min, sample and detect the bisphenol A concentration C in the simulated wastewater.

[0101] Calculate the difference between the concentration C and the initial concentration of bisphenol A, and record the difference value as the bisphenol A removal amount. Then calculate the ratio between the bisphenol A removal amount of each example and comparative example and the bisphenol A removal amount of Comparative Example 1, and record the ratio as the bisphenol A relative removal amount. The results are shown in Table 5.

[0102] Control group settings:

[0103] Use the sludge biochar-based catalyst of Comparative Example 1 as the test material of the control group, and perform the control test according to the following steps: (1) prepare simulated wastewater with a bisphenol A concentration of 10 mg / L and without phosphate ions for standby;

[0104] (2) Take 100 L of simulated wastewater, adjust the simulated wastewater to neutral using hydrochloric acid and sodium hydroxide solution, and then add sludge biochar-based catalyst and sodium persulfate to the simulated wastewater; the sludge biochar-based catalyst is added according to the dosage of 10 g of biochar powder per 100 L of simulated wastewater, and the sodium persulfate is added according to the calculated dosage at a concentration of 0.5 mmol / L;

[0105] (3) After 10 min, sample and detect the bisphenol A concentration c in the simulated wastewater.

[0106] The difference between the concentration c and the initial concentration of bisphenol A is calculated, and the difference is recorded as the removal amount of bisphenol A. Then, the ratio between the measured removal amount of bisphenol A and the removal amount of bisphenol A in Comparative Example 1 is calculated, and the ratio is recorded as the relative removal amount of bisphenol A in the control group. The results are shown in Table 5.

[0107] Table 5 Relative removal amount of bisphenol A

[0108]

[0109] It can be seen from Examples 1-5 and Comparative Example 1 and Table 5 that the relative removal amount of bisphenol A measured in Examples 1-5 is greater than that in Comparative Example 1, indicating that the calcium-loaded polypropylene fiber adsorbs and solidifies the phosphate ions in the sewage, improves the removal efficiency of bisphenol A, and improves the purification treatment effect on the sewage.

[0110] It can be seen from Example 1 and Comparative Example 2 and Table 5 that the relative removal amount of bisphenol A measured in Example 1 is greater than that in Comparative Example 2, indicating that under the test conditions of the present application, the calcium-loaded polypropylene fiber is more easily adsorbed by phosphate ions than the same weight of wollastonite, thereby reducing the interference of phosphate ions and improving the removal efficiency of bisphenol A and the purification treatment effect on the sewage.

[0111] It can be seen from Examples 1, Comparative Example 1 and Comparative Example 3 and Table 5 that soaking and washing the biochar with nitric acid helps to improve the removal effect of bisphenol A, but in the absence of calcium-loaded polypropylene fiber, the phosphate ions still have a relatively obvious interference, resulting in a lower removal efficiency of bisphenol A in Comparative Example 3.

[0112] It can be seen from the control group and Comparative Example 1 and Table 5 that when the simulated sewage does not contain phosphate ions, the combination of biochar powder and persulfate can achieve a good removal effect on bisphenol A.

[0113] It can be seen from Examples 3 and 6-9 and Table 5 that increasing the electron beam irradiation dose helps to increase the number of carboxyl groups on the surface of the carboxylated polypropylene fiber and improve the carrying capacity of the carboxylated polypropylene fiber for sodium metasilicate, which helps to increase the total amount of calcium silicate on the surface of the calcium-loaded polypropylene fiber and improve the adsorption effect of the calcium-loaded polypropylene fiber on phosphate ions. When the electron beam irradiation dose is set to 60-80 kGy per gram of polypropylene fiber, the adsorption effect of the calcium-loaded polypropylene fiber on phosphate ions is better, which helps to reduce the interference of phosphate ions and improve the removal efficiency of bisphenol A.

[0114] It can be seen from the combination of Example 10, Example 9 and Table 5 that the measured relative removal amount of bisphenol A in Example 10 is higher, which indicates that the addition of ferric chloride according to the dosage condition of Example 10 helps to increase the specific surface area of the biochar powder and improves the catalytic removal effect of the biochar powder on bisphenol A.

[0115] It can be seen from the combination of Examples 11-13, Example 10 and Table 5 that the relative removal amount of bisphenol A in Examples 11-13 is successively increased relative to Example 10, which indicates that the addition of phosphoric acid and lignin is conducive to improving the removal efficiency of bisphenol A, and with the increase of the lignin content in the auxiliary carbonization agent, the adsorption of the biochar powder on bisphenol A is also enhanced, and the relative removal amount of bisphenol A in Example 13 is higher.

[0116] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A sludge biochar-based catalyst, characterized in that, The sludge biochar-based catalyst comprises the following components by weight: 108-112 parts of biochar powder, 75-95 parts of calcium-loaded polypropylene fiber, wherein the biochar powder is obtained by sequentially subjecting a precursor to pyrolysis, washing, drying and grinding; the components of the precursor comprise dewatered sludge and zinc chloride, and the ratio of the amount of zinc chloride to dewatered sludge is 12.5 mmol: 1 g; and the calcium-loaded polypropylene fiber is polypropylene fiber loaded with calcium silicate on the surface. The calcium-loaded polypropylene fiber is prepared by the following method: (1) carboxylated polypropylene fiber is immersed in a sodium metasilicate solution with a mass fraction of 15% for 30 min, and then suction filtration is performed to obtain silicon-loaded polypropylene fiber; the carboxylated polypropylene fiber is polypropylene fiber grafted with carboxyl groups on the surface, and the carboxyl groups are provided by acrylic acid; (2) the silicon-loaded polypropylene fiber is immersed in a calcium chloride solution with a mass fraction of 5% for 5 h, and then suction filtration is performed again, and the obtained product is washed with water and dried to obtain calcium-loaded polypropylene fiber; The carboxylated polypropylene fiber is prepared by the following method: (1) acrylic acid, ferrous ammonium sulfate, sulfuric acid and a solvent are mixed to obtain a modification solution; In the modification solution, the mass fractions of acrylic acid, ferrous ammonium sulfate and sulfuric acid are 40%, 2% and 0.5% respectively, the rest is made up to 100% by the solvent, and the solvent is a mixture of water and ethanol in a volume ratio of 4:1; (2) polypropylene fiber and the modification solution are mixed in a weight ratio of 1:80, and electron beam irradiation is performed at a dose of 20-80 kGy per gram of polypropylene fiber, and then the fiber is taken out after irradiation, washed and dried to obtain carboxylated polypropylene fiber; the polypropylene fiber is waste polypropylene fiber.

2. The sludge-biochar-based catalyst according to claim 1, characterized in that, The irradiation dose of the electron beam is set to 60-80 kGy per gram of polypropylene fiber.

3. The sludge-biochar-based catalyst according to claim 1, wherein, The precursor is prepared by the following method: (1) dewatered sludge is obtained by drying and grinding sludge, and zinc chloride is added to water to obtain an aging solution with a zinc chloride concentration of 5 mol / L; (2) 2.5 L of the aging solution is mixed with every kilogram of dewatered sludge, and then the mixture is sealed and left to stand for 24 h to obtain the precursor.

4. The sludge-biochar-based catalyst according to claim 3, characterized in that, The components of the precursor further comprise iron chloride, which is added to water together with zinc chloride in step (1) of preparing the precursor.

5. The sludge-biochar-based catalyst according to claim 3, wherein, The components of the precursor further comprise an auxiliary carbonization agent, which is mixed with the dewatered sludge and the aging solution after sealing and standing in step (2) of preparing the precursor, and the amount of the auxiliary carbonization agent is 20% of the dewatered sludge; the components of the auxiliary carbonization agent comprise phosphoric acid and lignin.

6. The sludge-biochar-based catalyst according to claim 5, characterized in that, The auxiliary carbonization agent is prepared by the following method: a base material and a 50% phosphoric acid solution are mixed in a weight ratio of 3:2, and then heat preservation is performed at 130°C for 90 min to obtain the auxiliary carbonization agent; the base material comprises straw powder or poplar powder.

7. The sludge-biochar-based catalyst according to claim 6, characterized in that, The base material comprises dewatered papermaking sludge.

8. A process for the preparation of a sludge biochar-based catalyst according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: (1) the precursor is dried in an oven at 160°C for 36 h, and then pyrolyzed in a nitrogen atmosphere at 500°C for 2 h to obtain biochar; (2) After waiting for the biochar to cool down, first use nitric acid to soak and wash for 24h, and then use deionized water to wash, then filter, dry and grind the biochar, obtain biochar powder, mix the biochar powder with calcium-loaded polypropylene fibers to obtain a sludge biochar-based catalyst.

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