A composite material for sulfonamide antibiotic treatment, preparation method and application

Abstract

The present invention belongs to the technical fields of biochar preparation, water treatment, and new materials, and discloses a composite material, a preparation method, and an application for the treatment of sulfonamide antibiotics, which include the following steps: preparing sludge biochar SBC; preparing MnO2@OSBC; preparing aminated PCA; preparing PCA-MnO2@OSBC; cutting degreased cotton, ultrasonically cleaning it with deionized water, drying it, dispersing PCA-MnO2@OSBC in a polyvinyl alcohol PVA solution, impregnating the degreased cotton, dropping glutaraldehyde for crosslinking, curing, immersing it in a PCA-MnO2@OSBC suspension, and freeze-drying and heat-treating. The composite material of the present invention has relatively stable physical and chemical properties, can achieve efficient separation and recycling from the aqueous solution after degradation, and can achieve good degradation effects in a variety of typical real water bodies.

Description

Technical Field

[0001] The present invention belongs to the technical fields of biochar preparation, water treatment, and new materials, and particularly relates to a composite material for treating sulfonamide antibiotics, a preparation method, and an application thereof. Background Art

[0002] As the first batch of widely used broad-spectrum veterinary antibiotics, sulfonamide antibiotics account for up to 5.9% of the global consumption, making them the largest category of antibiotics currently in use. Among them, sulfamethoxazole (SMX), as one of the most commonly used sulfonamide antibiotics, is widely used to treat respiratory, gastrointestinal, and urinary tract infections. Since humans and animals have low metabolic efficiency for sulfamethoxazole, most of the unmetabolized sulfamethoxazole enters the environment through excreta. Sulfamethoxazole has a long environmental half-life (10 - 30 days) and high water solubility (869.5 mg / L), resulting in its widespread detection in various water bodies such as sewage, surface water, and groundwater. Especially in the aquaculture industry, the large-scale use of sulfonamide antibiotics makes aquaculture wastewater the main route for them to enter the environment. Therefore, it is urgent to develop technologies for efficient removal of sulfonamide antibiotics, and currently, the treatment technologies for sulfonamide antibiotics in aquaculture wastewater face three major technical bottlenecks.

[0003] First of all, traditional wastewater treatment technologies have fundamental efficiency defects. The removal rate of sulfonamide antibiotics in aquaculture wastewater by the activated sludge method is relatively low (24% - 36%), resulting in their continuous discharge into natural water bodies. Moreover, the high concentrations of organic matter and ammonia nitrogen in aquaculture wastewater further compete for reaction sites, leading to the failure of the biodegradation pathway. More seriously, sulfamethoxazole and its metabolic intermediates may induce the spread of antibiotic resistance genes (ARGs), forming secondary ecological risks.

[0004] In contrast, peracetic acid (PAA)-based advanced oxidation processes have received wide attention because they can completely mineralize pollutants or convert them into low-toxic products by generating free radicals. However, the peracetic acid (PAA) advanced oxidation system is limited by insufficient environmental adaptability, and its practical application faces non-negligible stability obstacles. Under the typical alkaline conditions of aquaculture wastewater, the half-life of PAA is less than 2 hours, and more than 80% of the oxidant is wasted due to spontaneous decomposition. Although existing studies have tried to improve the stability of the PAA system by adding various complexing agents, these small-molecule complexing agents are not only difficult to degrade but also form more stable complexes with heavy metals, further exacerbating environmental risks. Therefore, finding an economical and efficient complexing agent to improve the degradation effect of PAA while avoiding the secondary ecological risks it brings has become an urgent problem to be solved.

[0005] Finally, it is difficult for existing catalytic materials to balance activity and sustainability. As the main by-product of sewage treatment, excess sludge is regarded as an ideal material for preparing biochar due to its rich organic matter and porous structure. However, the catalytic active sites of raw sludge biochar (SBC) are limited, and appropriate modification is required to improve its performance. Nano-manganese dioxide (MnO2) is regarded as an ideal PAA activator due to its excellent electron transfer ability, but free nanoparticles tend to agglomerate severely. Although loading MnO2 on SBC can partially alleviate the above problems, the biochar / MnO2 composite prepared by traditional high-temperature pyrolysis has a single pore structure and lacks effective metal anchoring sites on the surface. In addition, powdered catalysts are difficult to recover in dynamic water flow, and existing immobilization technologies (such as silica gel embedding) will cause a significant decrease in flux due to the blockage of the carrier pore diameter, unable to meet the large-flow demand for aquaculture wastewater treatment.

[0006] Existing improvement attempts have failed to systematically solve the above problems. Therefore, there is an urgent need to develop a low-cost and green synthesis method for sludge biochar / MnO2 composites, introduce an environmentally friendly complexing agent to form a stable composite oxidation system with PAA, further enhance the ability of the MnO2 biochar composite / PAA technology to remove sulfonamide antibiotics in aquaculture wastewater, and improve its anti-interference and recycling ability in natural water bodies, so as to develop a technology capable of efficiently and sustainably removing sulfonamide antibiotics in aquaculture wastewater, realizing waste treatment with waste and promoting the green and sustainable development of aquaculture wastewater treatment. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a composite material, preparation method and application for the treatment of sulfonamide antibiotics.

[0008] The technical solution adopted by the present invention to solve its technical problems is:

[0009] A preparation method of a composite material for the treatment of sulfonamide antibiotics, comprising the following steps:

[0010] S1. Prepare sludge biochar SBC;

[0011] S2. Immerse SBC in acid, and perform microwave-assisted acid treatment through a microwave chemical reactor to obtain functionalized sludge biochar OSBC;

[0012] S3. Wet-mill the functionalized sludge biochar and a pore regulator in anhydrous acetone, mix the ball-milled product with a manganese source, a crystal plane director, a dispersant and a solvent evenly, and perform one-pot hydrothermal synthesis to obtain super-dense polycrystalline structure MnO2-coated porous structure functionalized sludge biochar MnO2@OSBC;

[0013] S4. React protocatechuic acid (PCA) with ethylenediamine (EDA) under the catalysis of carbodiimide / succinimide, i.e., EDC / NHS. Purify by centrifugal precipitation with n-hexane, wash with anhydrous acetone, and then dry in vacuum to obtain amino-functionalized PCA, namely PCA-NH₂.

[0014] S5. React MnO₂@OSBC with PCA-NH₂ in the carbodiimide / succinimide system, i.e., EDC / NHS. After centrifugal washing, dry in vacuum to obtain PCA-MnO₂@OSBC.

[0015] S6. Cut defatted cotton, ultrasonically clean it with deionized water, and dry it for standby. Disperse PCA-MnO₂@OSBC in polyvinyl alcohol (PVA) solution and ultrapure water respectively to obtain a suspension of PCA-MnO₂@OSBC in PVA solution and a water-based suspension of PCA-MnO₂@OSBC. Immerse defatted cotton in the suspension of PCA-MnO₂@OSBC in PVA solution, add glutaraldehyde dropwise for crosslinking and curing. Immerse the crosslinked defatted cotton in the water-based suspension of PCA-MnO₂@OSBC, freeze-dry it, and then perform heat treatment in an inert gas atmosphere. Finally, obtain a defatted cotton-supported protocatechuic acid-MnO₂ / sludge biochar composite PCA-MnO₂@OSBC / Cotton for the treatment of sulfonamide antibiotic breeding wastewater.

[0016] Furthermore, in S1, the sludge biochar is prepared by pyrolyzing sludge.

[0017] Before pyrolyzing the sludge, it also includes: collecting sludge from the sludge treatment system of the sewage treatment plant using a solid-liquid separation device, washing the sludge with ultrapure water and performing freeze-drying treatment until reaching a constant weight state to remove soluble impurities and excess moisture in it, and obtaining pretreated sludge; wherein, the organic matter content of the sludge is 40 - 90%, the freeze-drying temperature is -60 - 10 °C, and the freeze-drying vacuum degree is 10 - 100 Pa.

[0018] During the pyrolysis process of the sludge: the heating rate is 5 - 20 °C / min; continuously pyrolyze at 400 - 800 °C for 60 - 180 min; the pyrolysis atmosphere is an inert gas; the gas flow rate is 0.05 - 0.4 L / min.

[0019] After pyrolyzing the remaining sludge, it also includes: pickling the pyrolysis product to remove soluble ash in it, then alternately rinsing with ethanol and water until the pH of the filtrate is neutral, freeze-drying to constant weight and then grinding and sieving to obtain sludge biochar; wherein, the acid used in the pickling process is an inorganic acid; the freeze-drying temperature is -60 - 10 °C; the freeze-drying vacuum degree is 10 - 100 Pa; after grinding, sieve through a 50 - 300 mesh sieve.

[0020] Alternatively, in S2, the acid is dilute nitric acid; the ratio of SBC to dilute nitric acid is 1-20:200 g:mL; the mass concentration of the dilute nitric acid is 20%-68%; the microwave treatment time is 0.1-2 h, and the microwave power is 100 W-600 W;

[0021] Alternatively, the functionalized sludge biochar OSBC in S2 is further processed as follows:

[0022] It is alternately rinsed with ethanol and water until the pH of the filtrate is neutral, freeze-dried to constant weight, ground and sieved to obtain sludge biochar; among them, the freeze-drying temperature is -60-10 °C; the freeze-drying vacuum degree is 10-100 Pa; it is sieved through a 50-300 mesh sieve after grinding.

[0023] Furthermore, in S3, the functionalized sludge biochar OSBC and solid sodium chloride particles are placed in a zirconia ball milling tank, anhydrous acetone and zirconia grinding balls are added for wet ball milling, and the solvent is recovered by freeze-drying subsequently; then the ball-milled product is ultrasonically mixed evenly in a solution containing permanganate, sodium citrate, polyethylene glycol, and then transferred to a reaction kettle for hydrothermal synthesis under optimized hydrothermal synthesis conditions, filtered to obtain a solid, washed with ultrapure water until the filtrate is colorless, dried and ground and sieved to obtain super-dense polycrystalline structure MnO2-coated porous structure functionalized sludge biochar MnO2@OSBC;

[0024] Among them, solid sodium chloride is used as a soluble hierarchical pore template agent for hydrothermal synthesis, potassium permanganate is used as a manganese source for the hydrothermal synthesis system, sodium citrate is used as a crystal plane guiding agent for the hydrothermal synthesis system, and polyethylene glycol PEG10000 is used as a dispersant for the hydrothermal synthesis system;

[0025] The mass ratio of solid sodium chloride to sludge biochar is 0.1-0.3:1; the mass ratio of acetone to sludge biochar is 3-5:1; the mass ratio of zirconia grinding balls to sludge biochar is 5-50:1; the ball milling speed is 100-500 rpm; the ball milling time is 30-90 min; the freeze-drying temperature is -60-10 °C; the freeze-drying vacuum degree is 10-100 Pa;

[0026] In step S3, the mass ratio of potassium permanganate to sludge biochar is 0.57-5.66:1; the molar concentration ratio of potassium permanganate to sodium citrate is 1-6:1; water is used in the one-pot hydrothermal synthesis, and the dosage ratio of sludge biochar to water is 1:10-100 g:mL; the mass ratio of the dispersant to sludge biochar is 0.1-10:1.

[0027] Alternatively, in S3, it is mixed evenly by ultrasonic means;

[0028] Alternatively, the mass ratio of the dispersant to the sludge biochar is 0.1-10:1; the ultrasonic time is 10-30 min; the ultrasonic temperature is 20-80°C; the ultrasonic power is 100-300 W;

[0029] Alternatively, the temperature of the hydrothermal reaction in S3 is 110-200 °C, and the time of the hydrothermal reaction is 60 min-360 min;

[0030] Alternatively, the product after the one-pot hydrothermal synthesis in S3 is further treated as follows:

[0031] The product after one-pot hydrothermal synthesis was filtered, washed with water until the filtrate was colorless, freeze-dried to constant weight, ground and sieved to obtain ultra-dense polycrystalline MnO2-coated functionalized sludge biochar; wherein the freeze-drying temperature was -60-10°C; the freeze-drying vacuum was 10-100 Pa, and the product was ground and sieved through a 50-200 mesh sieve.

[0032] Further, in S4, protocatechuol PCA and ethylenediamine EDA are dissolved in phosphate buffer, and EDC / NHS is added to react in the dark. After the reaction, the precipitate is centrifuged with n-hexane, and the precipitate is collected and washed with anhydrous acetone, and then dried in vacuo to obtain aminated PCA, i.e., PCA-NH2.

[0033] In the process of synthesizing aminated PCA: the pH of the phosphate buffer solution is 3-9; the volume of the phosphate buffer solution added to each 1.00 g of protocatechol is 60-200 mL; the molar ratio of PCA to EDA is 1:1-5; the molar ratio of EDC:NHS:PCA is 1-3:1-3:1; the reaction time is 4-24 h; the shaking rate is 100-200 rpm; the reaction conditions are room temperature and protected from light throughout the process;

[0034] Alternatively, the volume ratio of n-hexane to reaction liquid is 2-5:1; the centrifugation condition is 4000-8000 rpm; the centrifugation time is 10-30 min; the freeze-drying temperature is -60-10°C; the freeze-drying vacuum degree is 10-100 Pa;

[0035] Alternatively, in S5, PCA-MnO2@OSBC is subjected to a pre-reaction treatment, including: adding MnO2@OSBC and amino PCA to ultrapure water and thoroughly mixing them by ultrasonication; wherein the ultrasonication time is 10-30 min; the ultrasonication temperature is 20-80°C; the ultrasonication power is 100-300 W; and the volume of ultrapure water added to each 1.00 g of MnO2@OSBC is 60-200 mL;

[0036] Alternatively, in S5, the mass ratio of EDC to PCA-MnO2@OSBC is 1 - 3:1; the molar ratio of EDC to NHS is 1:1; the oscillation rate is 100 - 200 rpm; the concentration of PCA-NH2 solution is 1 - 5 mg / mL; the reaction time is 12 - 48 h; the reaction conditions are at room temperature and protected from light throughout the process;

[0037] After the reaction in the EDC / NHS system, the reaction solution is precipitated and centrifuged with absolute ethanol, the precipitate is collected and washed with absolute ethanol, and PCA-MnO2@OSBC is obtained after vacuum drying; wherein, the volume ratio of absolute ethanol to the reaction solution is 2 - 5:1; the centrifugation conditions are 4000 - 8000 rpm; the centrifugation time is 10 - 30 min; the freeze-drying temperature is -60 - 10 °C; the freeze-drying vacuum degree is 10 - 100 Pa.

[0038] Furthermore, in S6, the size of the cut defatted cotton is 0.5 cm × 0.5 cm to 2 cm × 2 cm; the ultrasonic temperature is 20 - 80 °C; the ultrasonic power is 100 - 300 W; the ultrasonic time is 10 - 30 min; the drying temperature is 50 - 80 °C, preferably 60 °C; the drying time is 6 - 12 h;

[0039] Alternatively, the mass concentration of the polyvinyl alcohol PVA solution is 3 - 7%; the impregnation time is 0.5 - 2 h; the added volume concentration of glutaraldehyde is 1 - 3%; the curing temperature is 50 - 70 °C; the curing time is 1 - 3 h; the concentration of the PCA-MnO2@OSBC suspension is 0.5 - 2 mg / mL; the freeze-drying temperature is -60 - 10 °C, the freeze-drying vacuum degree is 10 - 100 Pa; the heat treatment temperature is 100 - 150 °C, the heat treatment time is 0.5 - 2 h; the inert gas is N2.

[0040] Defatted cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material for treating sulfonamide antibiotic aquaculture wastewater prepared by the preparation method as described above.

[0041] Application of the defatted cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material as described above in efficiently activating peracetic acid to degrade sulfonamide antibiotics in water.

[0042] A method for degrading sulfonamide antibiotics in water using the defatted cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material as described above, comprising the following steps:

[0043] After cutting the defatted cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material, it is added to an aqueous solution containing peracetic acid and sulfonamide antibiotics, and after the degradation process is completed, it is filtered to obtain a solution after removing sulfonamide antibiotics.

[0044] Furthermore, the sulfonamide antibiotics include at least one of sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, and sulfathiazole;

[0045] Alternatively, the concentration of the sulfonamide antibiotic is 1 - 20 μmol / L; the concentration of peracetic acid is 100 - 800 μmol / L;

[0046] Alternatively, the dosage of the cotton ball loaded with protocatechuic acid - MnO2 / sludge biochar composite is 0.1 - 0.8 g / L; the pH of the system is 1 - 14.

[0047] Using the fixed - bed system of the cotton ball loaded with protocatechuic acid - MnO2 / sludge biochar composite as described above, the system includes a packed column, a peristaltic pump, and a premixed solution introduction device. The packed column is filled with the cotton ball loaded with protocatechuic acid - MnO2 / sludge biochar composite; the premixed solution introduction device can hold the PAA solution, and the premixed solution introduction device is connected to the input end of the packed column through a peristaltic pump. The premixed solution introduction device can input the PAA solution into the packed column. The sulfamethoxazole - containing aquaculture wastewater is also connected to the input end of the packed column through another peristaltic pump, and this peristaltic pump inputs the sulfamethoxazole - containing aquaculture wastewater into the packed column.

[0048] The advantages and effects achieved by the present invention are as follows:

[0049] 1. The present invention prepares the super - dense polycrystalline structure MnO2 - coated functionalized sludge biochar (MnO2@OSBC) by a one - pot hydrothermal synthesis method, which can effectively reduce the energy consumption and synthesis cost during the synthesis process. Among them, a microwave chemical reactor is used to perform microwave - assisted dilute nitric acid functionalization treatment on the sludge biochar. Through the selective heating and efficient energy transfer of microwaves, the modification efficiency of oxygen - containing functional groups on the biochar surface is significantly improved, and at the same time, its surface roughness and pore structure are optimized, providing highly active attachment sites for subsequent super - dense polycrystalline MnO2 coating and covalent grafting of aminoprotophenol.

[0050] 2. The cotton ball loaded with protocatechuic acid - MnO2 / sludge biochar composite prepared by the present invention has excellent physical and chemical properties, and can rapidly activate low - concentration peracetic acid to efficiently degrade sulfonamide antibiotics in water. This process not only promotes the resource utilization of surplus sludge, but also realizes the efficient removal of sulfonamide antibiotics in different water bodies, achieving the dual goals of waste resource utilization and environmental remediation.

[0051] 3. The stable physicochemical properties of the super-dense polycrystalline structure MnO₂-coated functionalized sludge biochar prepared by the present invention ensure its effective recovery after catalyzing the degradation of sulfonamide antibiotics by peracetic acid, realizing the recycling of the catalyst; in the presence of various anions and within a wide pH range, this system can achieve good degradation effects, showing good removal effects of sulfonamide antibiotics in various actual water bodies and having strong anti-interference ability.

[0052] 4. Compared with traditional MnO₂ synthesis methods (such as redox method, calcination method, chemical precipitation method, etc.), the one-pot hydrothermal method adopted in the present invention significantly improves the reaction activity and efficiency under high temperature and high pressure conditions, and can prepare MnO₂ with nanoscale, high purity, and excellent crystallinity. By innovatively introducing sodium citrate as a crystal plane guiding agent, the crystal growth direction of MnO₂ is precisely regulated, making it preferentially expose high-activity crystal planes and form a nanosheet / nanowire structure with a specific morphology. The method of the present invention is beneficial to preparing MnO₂ with nanoscale, narrow particle size distribution, high purity, and high crystallinity. After compounding this crystal plane-controllable MnO₂ with functionalized sludge biochar, the catalytic ability of the material can be effectively improved, while the material synthesis cost can be effectively reduced, and the performance and application potential of the product can be improved.

[0053] 5. The present invention adopts a water-soluble NaCl template method and innovatively uses acetone as a wet ball-milling medium. Utilizing the extremely low solubility of NaCl in acetone (0.00004 g / 100g) to form a unique "solvent shielding effect", a hierarchical pore MnO₂@OSBC composite material with a synergistic distribution of macropores, mesopores, and micropores is constructed in one step. Compared with traditional pickling template methods (such as CaCO₃ template), this method not only avoids the environmental risks and the risk of MnO₂ structure damage brought by strong acid post-treatment, but also can precisely regulate the hierarchical pore structure through the template dissolution-crystallization process, significantly improving the mass transfer efficiency; at the same time, this method can completely maintain the coating structure of the MnO₂ active component, significantly improving the material performance. The entire process does not require complex post-treatment, and the template can be removed only by water washing, having the prominent advantages of being green and environmentally friendly and suitable for large-scale production.

[0054] 6. The present invention innovatively immobilizes aminated protocatechuic acid (PCA-NH₂) on the surface of the composite material through a covalent grafting strategy. Compared with the traditional physical adsorption method, the formation of amide bonds (-CO-NH-) significantly improves the stability of the active component. This step-by-step method solves the technical problems of many side reactions and low grafting rate in traditional one-step coupling, significantly increasing the PCA loading amount, and the formation of amide bonds significantly enhances the material stability.

[0055] 7. The degreased cotton carrier composite process designed in the present invention adopts a three-stage loading process of "PVA cross-linking - vacuum adsorption - thermal curing". First, a cross-linked network is constructed on the surface of the degreased cotton through PVA / glutaraldehyde to achieve primary fixation. Then, the active material is deeply penetrated into the internal pores of the fiber by vacuum assistance. Finally, heat treatment in an N2 atmosphere is carried out to enhance the interfacial bonding force. This multi-stage loading strategy realizes the uniform distribution of the active components in the three-dimensional fiber network.

[0056] 8. The present invention innovatively integrates four key technologies of microwave-assisted functionalization, solvent-shielded ball milling, crystal plane-directed hydrothermal synthesis, and covalent grafting to form a complete "green preparation technology system of biochar-based composites". There are significant synergistic effects among the process units: the oxygen-containing functional groups introduced by microwave treatment not only promote the nucleation of MnO2 but also provide sites for PCA grafting; the NaCl template not only regulates the pore structure but also assists in controlling the crystal form of MnO2; the cross-linking of PVA and glutaraldehyde enhances the mechanical properties and stability of the composite material, and at the same time optimizes its adsorption performance.

[0057] 9. The super-dense polycrystalline structure MnO2-coated functionalized sludge biochar MnO2@OSBC prepared in the present invention can efficiently activate low-concentration peracetic acid. The removal rates of sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, and sulfathiazole with a concentration of 10 μmol / L can reach 96.1%, 94.7%, 91.4%, 93.9%, and 90.3% respectively at 15 min.

[0058] 10. Compared with other technologies (such as adsorption and microbial degradation), the peracetic acid activation system of the super-dense polycrystalline structure MnO2-coated functionalized sludge biochar MnO2@OSBC prepared in the present invention can efficiently mineralize sulfonamide antibiotics. The mineralization rates of sulfamethoxazole, sulfamethoxypyridazine, sulfacetamide, sulfadoxine, and sulfathiazole with a concentration of 10 μmol / L can reach 71.6%, 67.9%, 68.1%, 70.9%, and 65.5% respectively at 15 min. Most of the pollutants are converted into non-toxic and harmless CO2 and H2O, realizing the complete removal of sulfonamide antibiotics. At the same time, its high physical and chemical stability enables efficient separation from the aqueous solution after degradation, realizing recycling, thereby reducing the generation of wastewater and environmental pollution, meeting the concept of sustainable development. This technology has the prospects of simple operation, low cost, and large-scale application.

[0059] 11. Compared with conventional advanced oxidation, in the present invention, protocatechuic acid (PCA) is immobilized on the surface of the cotton ball supported protocatechuic acid-MnO2 / sludge biochar composite through a covalent grafting strategy. As a water-soluble phenolic acid component, it widely exists in various plants and traditional Chinese medicines. It not only has antibacterial effects and shows different degrees of antibacterial effects on various bacteria, but also has antioxidant effects. In this system, the immobilization of PCA enhances the physical and chemical stability of the reaction system and improves its anti-interference ability against background components (such as inorganic ions and humic acids) in water bodies with complex components. In addition, the antioxidant property of PCA helps to maintain free radicals in the system, reduce oxidative stress, protect the catalyst from oxidative damage, and thus improve the activity and selectivity of the catalyst. This method is simple to operate, low in cost, remarkable in effect, and will not cause secondary pollution or ecological damage to the water body, showing its application potential in the field of water treatment.

[0060] 12. The cotton ball supported protocatechuic acid-MnO2 / sludge biochar composite prepared in the present invention has relatively stable physical and chemical properties, can achieve efficient separation and recycling with the aqueous solution after degradation, and can achieve good degradation effects in a variety of typical real water bodies.

[0061] 13. The technology of the present invention has the prospects of being simple to operate, low in cost, and capable of large-scale application. The fixed bed system designed based on the binary system (PCA-MnO2@OBRB / Cotton / PAA) can maintain a high degradation efficiency even in a complex aquaculture wastewater environment, showing good anti-interference performance, which is particularly important for actual wastewater treatment. By using a peristaltic pump to transport the premixed solution, the system realizes continuous flow reaction, is simple to operate and easy to control, and is suitable for industrial application.

[0062] 14. The cotton ball supported protocatechuic acid-MnO2 / sludge biochar composite of the present invention can be used in the treatment of sulfonamide antibiotic wastewater. At the same time, a suitable device is selected to further enhance the degradation ability and anti-interference ability of this material, so as to solve the technical problem that the MnO2 biochar composite in the prior art has insufficient removal effect on sulfonamide antibiotics in complex water bodies such as aquaculture wastewater. The synthesis method of the present invention can effectively reduce the energy consumption and synthesis cost in the synthesis process, and at the same time improve the performance and application potential of the product. By utilizing the through-hole structure and surface hydroxyl modification characteristics of the three-dimensional porous cellulose-based carrier, it not only ensures a high recovery rate of the catalyst, but also keeps the hydraulic flux stable.

[0063] 15. During the preparation of the composite material of the present invention, protocatechuic acid (PCA) is first aminylated (PCA-NH2) and then covalently grafted onto the surface of biochar, rather than directly physically adsorbed. PCA itself contains phenolic hydroxyl (-OH) and carboxyl (-COOH), but its carboxyl (-COOH) cannot directly form a stable chemical bond with the functional groups on the surface of biochar. After microwave-assisted acid treatment of the biochar surface, its main functional groups are -COOH / -OH. In the present invention, an amino group (-NH2) is introduced by aminylating PCA, enabling it to form a stable amide bond (-CO-NH-) with the carboxyl group (-COOH) on the surface of biochar. In the prior art, PCA is usually combined with biochar by physical adsorption, and this binding method is relatively loose, easily falling off during subsequent processing or use, resulting in unstable performance of the composite material. However, through aminylation modification in the present invention, PCA can form a stable amide bond (-CO-NH-) with the carboxyl group on the surface of biochar, significantly enhancing the binding strength between PCA and biochar, thereby improving the stability and durability of the composite material.

[0064] 16. In the method of the present invention, a carbodiimide / succinimide (EDC / NHS) catalytic system is used to promote the amination of protocatechuic acid (PCA) and its grafting reaction with biochar. In step S4, the goal is to convert the carboxyl group (-COOH) of PCA into an amino group (-NH2). EDC activates the -COOH of PCA to generate an unstable O-acylisourea intermediate, and NHS then converts it into a stable active ester (PCA-NHS) to avoid side reactions. Subsequently, the active ester reacts with the -NH2 of ethylenediamine (EDA) to generate PCA-NH2. Since the carboxyl group of PCA itself has low reactivity, the direct condensation efficiency with EDA is extremely low, while EDC / NHS can significantly increase the amination rate. In step S5, the goal is to form an amide bond (-CO-NH-) between the -NH2 of PCA-NH2 and the -COOH of biochar. EDC first activates the -COOH of biochar to generate an active intermediate, and NHS stabilizes the intermediate to generate a biochar-NHS active ester. Subsequently, biochar-NHS reacts with the -NH2 of PCA-NH2 to form a covalent amide bond. Due to the large steric hindrance of the -COOH on the biochar surface, the direct reaction with PCA-NH2 has low efficiency, while EDC / NHS can greatly increase the grafting rate. If the amination step is skipped and an attempt is made to directly react the -COOH of PCA with the -OH of biochar, there will be many problems: the reaction efficiency is extremely low, a strong dehydrating agent (such as DCC) is required for the condensation of the phenolic hydroxyl group (-OH) and the carboxyl group (-COOH), and there are many by-products; there is a large steric hindrance, and the benzene ring structure of PCA hinders the effective contact between its -COOH and the surface groups of biochar; there is a pH limitation, PAA activation is usually carried out under acidic conditions (pH 3-5), while the direct condensation reaction requires a neutral / alkaline environment, resulting in poor compatibility. Compared with the prior art, the present invention uses an EDC / NHS catalytic system to achieve efficient and stable chemical bonding, significantly improves the binding efficiency between PCA and biochar, reduces the generation of by-products, and overcomes problems such as steric hindrance and pH limitation. This precise surface modification method not only improves the immobilization effect of PCA on the biochar surface but also effectively improves the surface properties of biochar, further enhancing the performance of the composite material. The preparation process of the present invention is simple to operate, has mild conditions, has good controllability, and can achieve precise regulation of the performance of the composite material. Since a stable chemical bond is formed between PCA and biochar, the composite material has been significantly improved in terms of mechanical properties, thermal stability, and chemical stability, making it have potential application value in a wider range of fields.

[0065] 17. In step S6 of the method of the present invention, a PVA (polyvinyl alcohol) and glutaraldehyde (GA) cross-linking system is used to fix PCA-MnO2@OSBC onto absorbent cotton, and its core principle is based on polymer cross-linking chemistry and material composite reinforcement mechanism. The hydroxyl groups (-OH) of PVA can react with the subsequently added glutaraldehyde (GA) to form a three-dimensional cross-linked network, thereby enhancing the mechanical strength of the composite material. Glutaraldehyde, as a dialdehyde cross-linking agent, its two aldehyde groups (-CHO) respectively undergo acetalization reactions with the hydroxyl groups of PVA and the hydroxyl groups of absorbent cotton fibers to generate stable ether bonds (-C-O-C-). This dual cross-linking effect includes: PVA-PVA cross-linking, that is, GA connects adjacent PVA molecular chains to form a dense network structure, encapsulating PCA-MnO2@OSBC particles therein; and PVA-cotton fiber cross-linking, that is, GA bridges the PVA layer and absorbent cotton cellulose to achieve chemical bonding rather than physical adsorption. In addition, the present invention cures at 60 °C. Heating up can not only accelerate the rate of the acetalization reaction, but also evaporate excess water, promote the shrinkage of the cross-linked network, and further enhance the bonding fastness of the composite material.

[0066] Compared with the prior art, the present invention has significant advantages. Traditional methods usually fix functional materials on substrates through physical adsorption or simple chemical treatment, but such methods have problems such as low bonding strength, poor stability, and easy detachment. The present invention realizes the chemical bonding of PVA and absorbent cotton fibers through a dual cross-linking system of PVA and glutaraldehyde, forms a stable three-dimensional cross-linked network, and significantly improves the mechanical strength and stability of the composite material. In addition, the curing process at 60 °C further optimizes the formation of the cross-linked network, enhances the bonding fastness of the composite material, and enables it to have better performance and a wider application prospect in practical applications.

[0067] 18. In the method of the present invention, through functional enhancement treatment, a significant improvement in the performance of absorbent cotton is achieved. During the growth process of cotton, it synthesizes cellulose through photosynthesis, and the hydroxyl groups (-OH) on the cellulose molecular chain exist as inherent functional groups. After pretreatment, a large number of cellulose hydroxyl groups (-OH) on the surface of absorbent cotton are fully exposed. Subsequently, through the cross-linking action of glutaraldehyde (GA), the originally inert absorbent cotton is transformed into an active interface, and then forms a stable chemical bond with PVA / PCA-MnO2@OBRB. The cross-linked composite material can still maintain its integrity under the impact of water flow, facilitating recycling. Compared with the prior art, the present invention overcomes the problem that it is difficult to recover powdered catalysts in dynamic water flow, and at the same time avoids the defect that the existing immobilization technology (such as silica gel embedding) causes a significant decrease in flux due to the blockage of the carrier pore diameter, thus being unable to meet the large flow demand of aquaculture wastewater treatment. Description of the Drawings

[0068] Figure 1Scanning electron microscope image (SEM) of Example 1 in the present invention; among them, Figure 1 (a) is the scanning electron microscope image of the prepared sludge biochar (SBC), Figure 1 (b) is the scanning electron microscope image of the ultra-dense polycrystalline structure MnO2-coated functionalized sludge biochar (MnO2@OSBC), Figure 1 (c) is the scanning electron microscope image of protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC);

[0069] Figure 2 Adsorption rate diagrams of SBC, functionalized sludge biochar (OSBC), polycrystalline structure MnO2 (MnO2), MnO2@OSBC, protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC), and defatted cotton-loaded protocatechuic acid-MnO2 / sludge biochar composite (PCA-MnO2@OSBC / Cotton) with a dose of 0.4 g / L in the present invention for 10 μmol / L sulfamethoxazole at 0 - 15 min;

[0070] Figure 3 Degradation rate diagrams of SBC, OSBC, MnO2, MnO2@OSBC, PCA-MnO2@OSBC, and PCA-MnO2@OSBC / Cotton with a dose of 0.4 g / L in the present invention for 10 μmol / L sulfamethoxazole at 0 - 15 min when the PAA concentration is 400 μmol / L;

[0071] Figure 4 Removal rate diagrams of the one-component system PCA-MnO2@OSBC / Cotton (20 mg), PAA (concentration in the degradation system is 400 μmol / L), or the binary system PCA-MnO2@OSBC / Cotton (20 mg) + PAA (concentration in the degradation system is 400 μmol / L) for 10 μmol / L sulfamethoxazole at 0 - 15 min of degradation time;

[0072] Figure 5 Diagram of the influence of the PCA-MnO2@OSBC / Cotton / PAA / system in the present invention on the removal rate of 10 μmol / L sulfamethoxazole at 0 - 15 min of degradation time when the PAA concentration is 100 - 800 μmol / L and the dosage of PCA-MnO2@OSBC / Cotton is 0.4 g / L;

[0073] Figure 6In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 μmol / L at the addition amount of PCA-MnO2@OSBC / Cotton of 0.1 - 0.8 g / L, the concentration of PAA of 400 μmol / L, and the degradation time of 0 - 15 min;

[0074] Figure 7 In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 μmol / L at pH of 3 - 11 and the degradation time of 0 - 15 min;

[0075] Figure 8 In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 μmol / L at the humic acid concentration of 0 - 10 mg / L and the degradation time of 0 - 15 min;

[0076] Figure 9 In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 mg / L at the concentrations of Na2CO3 of 0, 1, 5, and 10 mmol / L and the degradation time of 0 - 15 min;

[0077] Figure 10 In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 mg / L at the concentrations of NaHCO3 of 0, 1, 5, and 10 mmol / L and the degradation time of 0 - 15 min;

[0078] Figure 11 In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 mg / L at the concentrations of NaNO3 of 0, 1, 5, and 10 mmol / L and the degradation time of 0 - 15 min;

[0079] Figure 12 In the present invention, it is a graph showing the influence of the PCA-MnO2@OSBC / Cotton / PAA system on the removal rate of sulfamethoxazole with a concentration of 10 mg / L at the concentrations of NaCl of 0, 1, 5, and 10 mmol / L and the degradation time of 0 - 15 min;

[0080] Figure 13This is a graph showing the removal rates of sulfamethoxazole at a concentration of 10 mg / L by the PCA-MnO2@OSBC / Cotton / PAA system in the present invention at Na2SO4 concentrations of 0, 1, 5, and 10 mmol / L and degradation times of 0 - 15 min;

[0081] Figure 14 This is a graph showing the ability of PCA-MnO2@OSBC / Cotton to regenerate and degrade sulfamethoxazole in the present invention;

[0082] Figure 15 This is a graph showing the removal rates of sulfamethoxazole at a concentration of 10 μmol / L by the PCA-MnO2@OSBC / Cotton / PAA system in the present invention in typical natural waters such as Yangtze River water, Lake Thonotosassa water, livestock farming wastewater, effluent sewage, tap water, and drinking water within 0 - 15 min;

[0083] Figure 16 This is a graph showing the removal rates of 10 μmol / L sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, and sulfathiazole by PCA-MnO2@OSBC / Cotton at a dose of 0.4 g / L in the present invention at a PAA concentration of 400 μmol / L and degradation times of 0 - 15 min;

[0084] Figure 17 This is a graph showing the degradation rates and mineralization rates of 10 μmol / L sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, and sulfathiazole by MnO2@OSBC at a dose of 0.4 g / L in the present invention at a PAA concentration of 400 μmol / L and degradation times of 0 - 15 min;

[0085] Figure 18 This is a diagram of a fixed-bed system designed based on the PCA-MnO2@OSBC / Cotton / PAA system in the present invention;

[0086] Figure 19 This is a graph showing the removal rate of sulfamethoxazole in filtered farming wastewater containing 10 μmol / L sulfamethoxazole by the fixed-bed system designed based on the PCA-MnO2@OSBC / Cotton / PAA system in the present invention within 0 - 1440 min of degradation time; Detailed implementation manners

[0087] The present invention will be further described below in conjunction with embodiments. The following embodiments are narrative and not restrictive, and the protection scope of the present invention cannot be limited by the following embodiments.

[0088] All the various experimental operations involved in the specific embodiments are conventional techniques in the art. For the parts not specifically noted in this article, those of ordinary skill in the art can refer to various commonly used reference books, scientific and technological literature, or relevant specifications, manuals, etc. before the filing date of this invention application for implementation.

[0089] A protocatechuic acid-modified polycrystalline manganese dioxide sludge biochar-supported absorbent cotton composite material and its preparation method, comprising the following steps:

[0090] S1. Provide excess sludge (SS) and excess sludge biochar (SBC);

[0091] S2. Immerse SBC in an acid with a certain proportion, and perform microwave-assisted acid treatment in a microwave chemical reactor at a certain temperature to obtain functionalized sludge biochar (OSBC);

[0092] S3. Wet-mill the functionalized sludge biochar and a pore regulator in acetone, mix the ball-milled product evenly with a manganese source, a crystal plane director, a dispersant, and a solvent, and obtain super-dense polycrystalline structure MnO2-coated functionalized sludge biochar (MnO2@OSBC) through a hydrothermal synthesis reaction;

[0093] S4. React protocatechuic acid (PCA) with ethylenediamine (EDA) under the catalysis of carbodiimide / succinimide (EDC / NHS), purify by centrifugal precipitation with n-hexane, wash with anhydrous acetone, and then vacuum dry to obtain amino-functionalized PCA (PCA-NH2);

[0094] S5. React MnO2@OSBC and PCA-NH2 in a certain mass ratio in an EDC / NHS system, purify by centrifugation with absolute ethanol, wash with absolute ethanol, and then vacuum dry to obtain protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC);

[0095] S6. Cut the absorbent cotton, ultrasonically clean it with deionized water, dry it for later use. Disperse PCA-MnO2@OSBC in a polyvinyl alcohol (PVA) solution with a certain concentration and ultrapure water, immerse the absorbent cotton in this PVA solution, add a certain concentration of glutaraldehyde (GA) for crosslinking, cure at a certain temperature, immerse the crosslinked absorbent cotton in a PCA-MnO2@OSBC aqueous suspension, freeze-dry, and then perform heat treatment in an N2 atmosphere to finally obtain an absorbent cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material (PCA-MnO2@OSBC / Cotton).

[0096] In step S1 of the present invention, the sludge biochar is prepared by pyrolyzing the sludge.

[0097] Excess sludge is the main by - product generated during the sewage treatment process in urban sewage treatment plants using the activated sludge method. It is an extremely complex heterogeneous substance composed of organic fragments, inorganic particles, colloids, etc. Due to the wide source of excess sludge and its rich organic matter and porous structure, it is regarded as an ideal material for preparing biochar. Compared with other sludges, the high organic matter characteristic of excess sludge provides a natural advantage for its pyrolytic conversion. These organic components mainly originate from proteins, polysaccharides, and lipid substances remaining from microbial metabolism and are more likely to carbonize to form biochar with a porous structure during high - temperature pyrolysis. In contrast, primary sedimentation sludge contains more fibers and inert inorganic particles, and the pyrolysis products often have a lower porosity and limited adsorption performance. Chemical sludge forms precipitation by relying on the addition of coagulants, and the proportion of its inorganic metal salts (such as aluminum and iron compounds) is too high, which not only reduces the carbon production rate of pyrolysis but also may weaken the functionality of biochar due to the blockage of pores by metal oxides. Industrial sludge, due to its complex source, often carries heavy metals or refractory toxic organic substances, and there is a risk of secondary release of pollutants during pyrolysis, requiring additional stabilization pretreatment, which greatly increases the technical threshold and cost.

[0098] Before pyrolyzing the sludge, it also includes: using a solid - liquid separation device to collect sludge from the sludge treatment system of the sewage treatment plant, washing the sludge with ultrapure water and performing freeze - drying treatment until reaching a constant weight state to remove soluble impurities and excess water in it, obtaining pretreated sludge; among them, the biomass raw material is sludge, and most preferably excess sludge; the organic matter content of the sludge is 40 - 90%, most preferably 60%, the freeze - drying temperature is - 60 - 10°C, most preferably - 45°C; the freeze - drying vacuum degree is 10 - 100 Pa, most preferably 15 Pa.

[0099] During the pyrolysis process of the sludge: the heating rate is 5 - 20°C / min, most preferably 10°C / min; continuously pyrolyze for 60 - 180 min at 400 - 800°C, most preferably continuously pyrolyze for 120 min at 600°C; the pyrolysis atmosphere is an inert gas, most preferably nitrogen; the gas flow rate is 0.05 - 0.4 L / min, most preferably 0.1 L / min.

[0100] After pyrolyzing the sludge, it also includes: pickling the pyrolysis product to remove soluble ash in it, then alternately rinsing with ethanol and water until the pH of the filtrate is neutral, freeze - drying to a constant weight and then grinding and sieving to obtain sludge biochar; among them, the acid used in the pickling process is a common inorganic acid, most preferably hydrochloric acid; the freeze - drying temperature is - 60 - 10°C, most preferably - 45°C; the freeze - drying vacuum degree is 10 - 100 Pa, most preferably 15 Pa; after grinding, sieve through a 50 - 300 - mesh sieve, most preferably 150 - mesh sieve.

[0101] In step S2 of the present invention, the functionalized sludge biochar is obtained by immersing the sludge biochar (SBC) obtained in S1 in an acid in a certain proportion and performing microwave-assisted acid treatment at a certain temperature through a microwave chemical reactor.

[0102] In step S2, the sludge biochar is functionalized by an organic acid or an inorganic acid assisted by a microwave chemical reactor.

[0103] Common inorganic acids (such as sulfuric acid, hydrochloric acid, nitric acid, etc.) usually functionalize the surface of sludge biochar through strong oxidation, oxidizing the carbon atoms of sludge biochar into oxygen-containing functional groups such as carboxyl (-COOH), hydroxyl (-OH), and carbonyl (-C=O), thereby improving surface polarity and hydrophilicity. The oxidation of the acid will cause microporosity or etching on the surface of sludge biochar, increasing its surface roughness, thus providing attachment sites for MnO2 crystals. The strong oxidizing property of inorganic acids can decompose and remove soluble impurities on the surface of sludge biochar, improving the surface cleanliness of the material. Common organic acids (such as oxalic acid, citric acid, acetic acid, etc.) usually functionalize the surface of carbon fiber through milder oxidation. Organic acids introduce carboxyl (-COOH) on the surface of carbon fiber through esterification reaction or partial oxidation. These carboxyl groups can form hydrogen bonds or covalent bonds with the carbon atoms of sludge biochar. However, the oxidation ability of organic acids is relatively weak, with less etching effect on the surface of carbon fiber, and relatively limited attachment sites for MnO2 crystals provided. More preferably, it is dilute nitric acid. Dilute nitric acid (HNO3) is a strong oxidant with a relatively high oxidation potential. Compared with dilute sulfuric acid and dilute hydrochloric acid, dilute nitric acid can react quickly at a lower temperature, generating a large number of oxygen-containing functional groups, and can achieve a more significant surface functionalization effect in a shorter time. Dilute nitric acid treatment can generate micropores and pits on the surface of carbon fiber, significantly increasing the surface roughness, thereby increasing the MnO2 attachment sites on the surface of sludge biochar. In addition, the present invention uses a microwave-assisted dilute nitric acid treatment technology to functionalize and modify sludge biochar. Compared with the traditional acid treatment method, microwave radiation can significantly strengthen the oxidation of dilute nitric acid: on the one hand, the selective heating characteristic of microwave efficiently activates nitric acid molecules, and a large number of oxygen-containing functional groups (-COOH, -OH, etc.) can be quickly generated at a relatively low temperature of 80-120°C, and the functionalization efficiency is greatly improved compared with the conventional method. -COOH serves as a covalent anchoring site, providing the necessary reaction groups for the subsequent EDC / NHS-catalyzed amide bond grafting (PCA-NH2 modification). -OH can pre-organize the orientation of PCA molecules through hydrogen bonds, promoting the effective collision of -NH2 and -COOH; on the other hand, the bulk heating effect of microwave promotes the uniform penetration of the acid solution, forming a more uniform microporous structure and nanoscale roughness on the surface of biochar, providing more and more uniform attachment sites for the subsequent MnO2 crystals. At the same time, the microwave-assisted treatment significantly shortens the reaction time, and the reduction product of nitric acid is only CO2 and H2O, which conforms to the concept of green chemistry, produces fewer by-products, and has little impact on the environment.

[0104] Before the functional treatment of the sludge, it also includes: placing SBC and an acid solution with a certain concentration in a closed microwave reaction tank with a polytetrafluoroethylene inner lining, and ultrasonically mixing them evenly; among them, the ultrasonic time is 10 - 60 min, most preferably 30 min; the ultrasonic temperature is 20 - 80 °C, most preferably 25 °C; the ultrasonic power is 100 - 300 W, most preferably 200 W.

[0105] During the process of functional treatment of the sludge biochar: the acid is a diluted common organic acid or inorganic acid, most preferably dilute nitric acid; the mass ratio of SCB to the volume of dilute nitric acid is (1 - 20 g):200 mL, most preferably 5 g:200 mL; the mass concentration of the dilute nitric acid is 20% - 68%, most preferably 50%; the microwave treatment time is 0.1 - 2 h, most preferably 0.5 h, and the microwave power is 100 W - 600 W, most preferably 300 W.

[0106] After the functional treatment of the sludge, it also includes: alternately rinsing with ethanol and water until the pH of the filtrate is neutral, freeze - drying to constant weight, grinding and sieving to obtain the sludge biochar; among them, the freeze - drying temperature is - 60 - 10 °C, most preferably - 45 °C; the freeze - drying vacuum degree is 10 - 100 Pa, most preferably 15 Pa; after grinding, it is sieved through a 50 - 300 - mesh sieve, most preferably a 150 - mesh sieve.

[0107] In step S3 of the present invention, the functionalized sludge biochar (OSBC) obtained in S2 and solid sodium chloride (NaCl) particles are placed in a zirconia ball - milling tank, dehydrated acetone and zirconia grinding balls are added for wet ball - milling, and the solvent is recovered by freeze - drying subsequently. Then the ball - milled product is ultrasonically mixed evenly in a solution containing permanganate (KMnO4), sodium citrate (Na3C6H5O7), and a dispersant, and then transferred to a reaction kettle for hydrothermal synthesis under optimized hydrothermal synthesis conditions, filtered to obtain a solid, washed with ultrapure water until the filtrate is colorless, dried, ground and sieved to obtain the super - dense polycrystalline structure MnO2 - coated porous - structure functionalized sludge biochar (MnO2@OSBC).

[0108] In step S3, solid sodium chloride serves as a soluble hierarchical pore template agent for hydrothermal synthesis.

[0109] The particle size of solid sodium chloride (100 - 300 nm) directly controls the macroporous structure (150 ± 50 nm) of the final material. By using acetone as the wet ball milling medium and taking advantage of the extremely low solubility of NaCl in acetone (0.00004 g / 100 g), the risk of dissolution is thermodynamically eliminated. Through the action of high-energy mechanical force, NaCl crystals are physically embedded in the pores and surface defects of biochar. At the same time, acetone molecules form an adsorption layer on the surface of NaCl crystals, preventing water molecules from contacting. NaCl can still maintain its complete crystal form, playing a solvent shielding effect to ensure that NaCl crystals are intact and do not dissolve during the ball milling stage. In the hydrothermal reaction, NaCl forms through-pore channels through a dynamic dissolution-recrystallization equilibrium, synergistically with the strong oxidizing property of potassium permanganate, and finally a sludge biochar composite material with both macroporous-mesoporous hierarchical structure and loaded ultra-dense polycrystalline phase MnO2 is obtained. This green process avoids the environmental pollution problems caused by traditional pickling template methods (such as CaCO3 and SiO2 templates need to be treated with HF / HCl) through multiple innovative designs. During the hydrothermal process, the soluble hierarchical pore template agent gradually dissolves and only needs to be washed with warm water after the reaction to be completely removed, without complex post-treatment processes.

[0110] In step S3, an ultra-dense polycrystalline structure MnO2-coated functionalized sludge biochar is synthesized by a one-pot hydrothermal method.

[0111] Compared with traditional MnO2 synthesis methods (such as redox method, calcination method, and chemical precipitation method, etc.), the one-pot hydrothermal method can increase the solubility and activity of chemical reagents under high temperature and high pressure conditions, enabling some reactions that are not easy to occur under normal temperature and pressure to be realized, thus broadening the raw materials and reaction paths for preparing MnO2. This method is conducive to preparing MnO2 with nanoscale size, narrow particle size distribution, high purity, and high crystallinity, which can effectively reduce the energy consumption and synthesis cost during the synthesis process, while improving the performance and application potential of the product. In contrast, the MnO2 prepared by the redox method has poor crystallinity and poor single crystal form degree. This means that the MnO2 prepared by the redox method may not possess ideal physical and chemical properties, affecting its performance in specific applications, and it is impossible to precisely control the morphology and size of MnO2, limiting its use in applications that require specific structural materials. Although the calcination method is simple to operate, there are fewer available manganese salts and the raw materials are single. This limits the possibility of regulating the properties of MnO2 by changing the raw materials. Sintering is likely to occur during the high-temperature calcination process, making it difficult to obtain nanoscale MnO2, and the particle size distribution is wide. This may lead to a reduction in the specific surface area and the number of active sites of the material, affecting its catalytic performance. During the chemical precipitation method, precipitates will be generated. In some cases, due to the different particle sizes and morphologies of the precipitates, it is difficult to determine the physical properties of some precipitates, which may affect subsequent processing or use. At the same time, this process requires a large amount of chemicals, especially some chemicals may be consumed more due to chemical reactions, which requires users to master the dosage well, otherwise it will cause unnecessary waste. Since the chemical precipitation method is a method relying on chemical reactions, for some substances, this technology may not work, and other technologies need to be used for separation and extraction.

[0112] In step S3, potassium permanganate serves as the manganese source in the hydrothermal synthesis system.

[0113] The manganese in potassium permanganate is in the +7 oxidation state, which is the highest oxidation state of manganese and has extremely strong oxidizing ability. This strong oxidizing property enables it to be efficiently reduced during the synthesis of nanoscale MnO2, thus realizing rapid chemical reactions and uniform growth of the MnO2 structure. Other common manganese sources (such as MnCl2, Mn(NO3)2, MnSO4) are usually in lower oxidation states (+2 or +3) and require additional oxidants or more stringent conditions to be oxidized to MnO2, and the reaction process is more complex. The reduction products of potassium permanganate are mainly CO2 and H2O, which are harmless to the environment. Compared with other manganese sources, potassium permanganate does not release harmful gases or produce toxic by-products during the reaction process, meeting the requirements of green chemistry. When using MnCl2, chloride wastewater may be generated, requiring complex wastewater treatment processes. Mn(NO3)2 may release nitrogen oxide gases, and MnSO4 may release sulfur-containing gases, which pose potential hazards to the environment and operators.

[0114] In step S3, sodium citrate is used as a crystal plane director in the hydrothermal synthesis system.

[0115] Sodium citrate is a natural organic compound with good biocompatibility and environmental friendliness. It is mainly derived from the neutralization reaction of citric acid and is a renewable resource, which conforms to the development concept of green chemistry. Compared with traditional reducing agents (such as hydrogen, sodium borohydride, hydrazine hydrate, etc.), sodium citrate does not produce harmful by-products or toxic gases during the reaction, making it safer for the environment and operators. Relevant research shows that the reduction process of sodium citrate can be carried out under relatively mild conditions, reducing energy consumption and potential hazards. The aqueous solution of sodium citrate is weakly alkaline, and the by-products generated after the reaction (such as CO2 and H2O) are harmless to the environment. The use of sodium citrate can reduce the cost of wastewater treatment and reduce environmental pollution. Sodium citrate not only has reducibility but also has multiple chemical functional groups (such as carboxyl and hydroxyl groups). These functional groups can coordinate with manganese ions during the synthesis of crystalline MnO2, thus playing a role in surface regulation and stabilization during the synthesis process, making the MnO2 coated on the surface of sludge biochar more dense. At the same time, by regulating the growth direction and morphology of the MnO2 structure, the types of MnO2 crystals synthesized on the surface of sludge biochar are more diverse, effectively improving its catalytic performance. The reduction ability of sodium citrate is moderate, and it can gradually reduce potassium permanganate under mild conditions, avoiding side reactions or damage to the MnO2 crystal structure caused by overly strong reducing agents. As a cheap and easily available chemical, the market price of sodium citrate is much lower than that of many traditional reducing agents (such as sodium borohydride, hydrazine hydrate, etc.). In addition, the synthesis process of sodium citrate is simple and easy for large-scale production, which gives it significant economic advantages in industrial applications.

[0116] In step S3, polyethylene glycol (PEG10000) is used as a dispersant in the hydrothermal synthesis system.

[0117] As a polymer, polyethylene glycol has good dispersibility and stability. During the ultrasonic treatment process, PEG can effectively disperse biochar particles, preventing their agglomeration and precipitation, thus ensuring sufficient contact and mixing between biochar particles and manganese sources and reducing agents. The addition of PEG can increase the viscosity of the solution, which helps to slow down the rising speed of bubbles generated during the ultrasonic treatment process, enabling the bubbles to contact the biochar particles for a longer time, thereby improving the mixing effect. PEG itself may also interact with the surface of biochar to form a coating layer, changing the surface properties and structure of biochar. This coating layer may help to further improve the catalytic performance of biochar. The molecular chain of PEG can interact with the manganese source to help the manganese source be evenly distributed on the surface of biochar, thus improving the crystallization effect of MnO2. More preferably, it is polyethylene glycol 10000.

[0118] In step S3, NaCl and sludge biochar are combined by wet ball milling with anhydrous acetone.

[0119] The mass ratio of solid NaCl template agent to sludge biochar is (0.1 - 0.3):1, most preferably 0.15:1; the mass ratio of acetone solvent to sludge biochar is (3 - 5):1, most preferably 4:1; the mass ratio of zirconia grinding balls to sludge biochar is (5 - 50):1, most preferably 20:1; the ball milling speed is 100 - 500 rpm, most preferably 300 rpm; the ball milling time is 30 - 90 min, most preferably 60 min; the freeze-drying temperature is -60 - 10 °C, most preferably -45 °C; the freeze-drying vacuum degree is 10 - 100 Pa, most preferably 15 Pa.

[0120] In step S3, the mass ratio of potassium permanganate to sludge biochar is (0.57 - 5.66):1, most preferably 2.83:1; the molar concentration ratio of potassium permanganate to sodium citrate is (1 - 6):1, most preferably 3:1; the dosage ratio of sludge biochar to water is 1 g:(10 - 100) mL, most preferably 1 g:60 mL; the mass ratio of dispersant to sludge biochar is (0.1 - 10):1, further preferably 0.1:1.

[0121] In step S3, it is mixed evenly by ultrasonic means.

[0122] The mass ratio of dispersant to sludge biochar is (0.1 - 10):1, most preferably 0.1:1; the ultrasonic time is 10 - 30 min, most preferably 20 min; the ultrasonic temperature is 20 - 80 °C, most preferably 60 °C; the ultrasonic power is 100 - 300 W, most preferably 200 W.

[0123] In step S3, the temperature of the hydrothermal reaction is 110 - 200 °C, most preferably 130 °C, and the time of the hydrothermal reaction is 60 min - 360 min, most preferably 120 min.

[0124] In step S3, after the hydrothermal reaction, it further includes: filtering the hydrothermal product, washing with water until the filtrate is colorless, freeze-drying to constant weight and then grinding and sieving to obtain super-dense polycrystalline structure MnO2-coated functionalized sludge biochar. Among them, the freeze-drying temperature is -60 - 10 °C, most preferably -45 °C; the freeze-drying vacuum degree is 10 - 100 Pa, most preferably 15 Pa, and it is sieved through a 50 - 200 mesh sieve after grinding, most preferably 100 mesh sieve.

[0125] In step S4 of the present invention, protocatechuic acid (PCA) and ethylenediamine (EDA) are dissolved in phosphate buffer solution (PBS) in a certain proportion, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / succinimide (EDC / NHS) is added, followed by shaking reaction in the dark. After the reaction is completed, precipitation and centrifugation are carried out with ethanol, the precipitate is collected and washed with ethanol, and after vacuum drying, amino-functionalized PCA (PCA-NH2) is obtained.

[0126] In the process of synthesizing amino-functionalized PCA (PCA-NH2): the pH of the phosphate buffer solution is 3-9, most preferably 5.5; the volume of the phosphate buffer solution added per 1.00 g of protocatechuic acid is 60-200 mL, most preferably 100 mL; the molar ratio of PCA to EDA is 1:(1-5), most preferably 1:3; the molar ratio of EDC:NHS:PCA is (1-3):(1-3):1, most preferably 2:2:1; the reaction time is 4-24 h, most preferably 12 h; the shaking rate is 100-200 rpm, most preferably 150 rpm; the reaction conditions are at room temperature and in the dark throughout the process.

[0127] After the post-treatment of the amino-functionalized PCA, it further includes: precipitation and centrifugation with n-hexane, the precipitate is collected and washed with anhydrous acetone, and after vacuum drying, amino-functionalized PCA is obtained; wherein, the volume ratio of n-hexane to the reaction solution is (2-5):1, most preferably 3:1; the centrifugation conditions are 4000-8000 rpm, most preferably 6000 rpm; the centrifugation time is 10-30 min, most preferably 15 min; the freeze-drying temperature is -60 - 10°C, most preferably -45°C; the freeze-drying vacuum degree is 10-100 Pa, most preferably 15 Pa.

[0128] In step S5 of the present invention, protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC) is obtained by subjecting the super-dense polycrystalline structure MnO2-coated porous structure-functionalized sludge biochar (MnO2@OSBC) obtained in S3 and the amino-functionalized PCA (PCA-NH2) obtained in S4 to a shaking reaction in 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / succinimide (EDC / NHS) in a certain mass ratio in the dark.

[0129] The pre-treatment of protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC) also includes: adding super-dense polycrystalline structure MnO2-coated porous structure functionalized sludge biochar (MnO2@OSBC) and aminated PCA (PCA-NH2) into ultrapure water and mixing them thoroughly by ultrasonic treatment; wherein, the ultrasonic treatment time is 10-30 min, most preferably 20 min; the ultrasonic treatment temperature is 20-80 °C, most preferably 25 °C; the ultrasonic power is 100-300 W, most preferably 200 W; the volume of ultrapure water added to every 1.00 g of MnO2@OSBC is 60-200 mL, most preferably 100 mL.

[0130] In the process of synthesizing protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC): the mass ratio of EDC to PCA-MnO2@OSBC is (1-3):1, most preferably 2:1; the molar ratio of EDC to NHS is 1:1; the oscillation rate is 100-200 rpm, most preferably 150 rpm; the concentration of PCA-NH2 solution is 1-5 mg / mL, most preferably 2.5 mg / mL; the reaction time is 12-48 h, most preferably 24 h; the reaction conditions are at room temperature and protected from light throughout the process.

[0131] The post-treatment of protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC) also includes: after the reaction is completed, the reaction solution is precipitated by centrifugation with absolute ethanol, the precipitate is collected and washed with absolute ethanol, and protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC) is obtained after vacuum drying; wherein, the volume ratio of absolute ethanol to the reaction solution is (2-5):1, most preferably 3:1; the centrifugation conditions are 4000-8000 rpm, most preferably 6000 rpm; the centrifugation time is 10-30 min, most preferably 15 min; the freeze-drying temperature is -60-10 °C, most preferably -45 °C; the freeze-drying vacuum degree is 10-100 Pa, most preferably 15 Pa.

[0132] In step S6 of the present invention, the absorbent cotton is cut, ultrasonically cleaned with deionized water, and dried for later use. PCA-MnO2@OSBC is dispersed in a polyvinyl alcohol (PVA) solution with a certain concentration, the absorbent cotton is impregnated, a certain concentration of glutaraldehyde (GA) is added dropwise for crosslinking, and it is cured at a certain temperature. The crosslinked absorbent cotton is immersed in the PCA-MnO2@OSBC suspension, freeze-dried and then heat-treated in an N2 atmosphere to finally obtain the absorbent cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material (PCA-MnO2@OSBC / Cotton).

[0133] The pre-treatment of the reaction of absorbent cotton includes: cutting the absorbent cotton and ultrasonically cleaning it with deionized water, then drying it for standby; wherein, the size of the absorbent cotton is from 0.5 cm×0.5 cm to 2 cm×2 cm, most preferably 1 cm×1 cm; the ultrasonic temperature is 20 - 80°C, most preferably 60°C; the ultrasonic power is 100 - 300 W, most preferably 200 W; the ultrasonic time is 10 - 30 min, most preferably 20 min; the drying temperature is 50 - 80°C, most preferably 60°C; the drying time is 6 - 12 h, most preferably 8 h.

[0134] In the process of synthesizing the absorbent cotton supported protocatechuic acid - MnO2 / sludge biochar composite material (PCA - MnO2@OSBC / Cotton): Disperse PCA - MnO2@OSBC in a polyvinyl alcohol (PVA) solution with a certain concentration, impregnate the absorbent cotton, add a certain concentration of glutaraldehyde (GA) for cross - linking, cure at a certain temperature, immerse the cross - linked absorbent cotton in the PCA - MnO2@OSBC suspension, freeze - dry and then heat - treat it under a N2 atmosphere to finally obtain the absorbent cotton supported protocatechuic acid - MnO2 / sludge biochar composite material (PCA - MnO2@OSBC / Cotton); wherein, the concentration of the polyvinyl alcohol (PVA) solution is 3 - 7% (w / v), most preferably 5%; the volume of the PVA solution is 60 - 200 mL, most preferably 100 mL; the impregnation time is 0.5 - 2 h, most preferably 1 h; the added concentration of glutaraldehyde (GA) is 1 - 3% (v / v), most preferably 2%; the curing temperature is 50 - 70°C, most preferably 60°C; the curing time is 1 - 3 h, most preferably 2 h; the concentration of the PCA - MnO2@OSBC suspension is 0.5 - 2 mg / mL, most preferably 1 mg / mL; the freeze - drying temperature is - 60 - 10°C, most preferably - 45°C; the freeze - drying vacuum degree is 10 - 100 Pa, most preferably 15 Pa; the heat - treatment temperature is 100 - 150°C, most preferably 120°C; the heat - treatment time is 0.5 - 2 h, most preferably 1 h; the heat - treatment atmosphere is an inert gas, most preferably N2.

[0135] The present invention provides an absorbent cotton supported protocatechuic acid - MnO2 / sludge biochar composite material, which is obtained by the preparation method of the absorbent cotton supported protocatechuic acid - MnO2 / sludge biochar composite material provided by the present invention.

[0136] The present invention provides an application of a cotton wool supported protocatechuic acid-MnO2 / sludge biochar composite material. The cotton wool supported protocatechuic acid-MnO2 / sludge biochar composite material is applied to efficiently activate peracetic acid for degrading sulfonamide antibiotics in water. Meanwhile, the present invention provides a fixed bed system designed based on the PCA-MnO2@OSBC / Cotton / PAA system.

[0137] The sulfonamide antibiotics include at least one of sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, sulfathiazole, etc.

[0138] In the degradation system, the concentration of sulfonamide antibiotics is 1-20 μmol / L, and most preferably 10 μmol / L.

[0139] In the degradation system, the concentration of peracetic acid is 100-800 μmol / L, and most preferably 400 μmol / L;

[0140] The dosage of the cotton wool supported protocatechuic acid-MnO2 / sludge biochar composite material is 0.1-0.8 g / L, and most preferably 0.4 g / L; the pH of the system is 1-14, including but not limited to 3, 5, 7, 9, 11, etc., and preferably 1-11.

[0141] In the fixed bed system, the flow rate of the peristaltic pump is 0.1-60 mL / min, and most preferably 10 mL / min; the length of the packed column is 10-100 cm, and most preferably 30 cm; the radius of the packed column is 0.5-10 cm, and most preferably 2 cm.

[0142] The application of the above ultra-dense polycrystalline structure MnO2-coated functionalized sludge biochar includes the following steps:

[0143] The cotton wool supported protocatechuic acid-MnO2 / sludge biochar composite material is cut according to a certain weight and added to an aqueous solution containing peracetic acid and sulfonamide antibiotics. After the degradation process is completed, filtration is carried out to obtain the solution after removing sulfonamide antibiotics.

[0144] The cotton wool supported protocatechuic acid-MnO2 / sludge biochar composite material is used as the packing column filler and placed in the packed column. The filtered aquaculture wastewater containing sulfonamide antibiotics and the peracetic acid solution are respectively introduced into the packed column in a certain proportion through a peristaltic pump, and the liquid flowing out of the packed column is the wastewater after removing sulfonamide antibiotics.

[0145] Example 1

[0146] A preparation method of a cotton wool supported protocatechuic acid-MnO2 / sludge biochar composite material for treating sulfonamide antibiotic wastewater includes the following steps:

[0147] S1. Collect the excess sludge (SS) from the sludge treatment system using a solid-liquid separation device, remove impurities from the sludge, and remove the non-degradable impurities (plastics, metals, stones) therein. Subsequently, rinse it three times with ultrapure water, place it in a freeze-dryer and freeze-dry it to a constant weight (the freeze-drying temperature is -45 °C; the freeze-drying vacuum is 15 Pa), then transfer it to a high-temperature tubular furnace (the N2 flow rate is 0.1 L / min, and the heating rate is 10 °C / min), keep it at 600 °C for 120 min, then immerse the pyrolysis product in HCl (1 mol / L) to remove the soluble ash, and then rinse it alternately with absolute ethanol and ultrapure water until the pH of the filtrate is neutral, and freeze-dry it to a constant weight (the freeze-drying temperature is -45 °C; the freeze-drying vacuum is 15 Pa), grind it and pass it through a 150-mesh sieve (0.106 mm) to obtain the sludge biochar SBC. Among them, the excess sludge comes from the Tangxun Lake Urban Wastewater Treatment Plant in Wuhan, and its elemental content is shown in Table 1;

[0148] Table 1 Relative content of non-oxygen elements in excess sludge

[0149]

[0150] S2. Put SBC (with a mass of 5.0 g) and a 50% HNO3 solution (200 mL) into a closed microwave reaction tank with a polytetrafluoroethylene liner, ultrasonically mix them evenly for 30 min, then transfer them to a microwave chemical reactor, treat them at a power of 300 W for 0.5 h to introduce oxygen-containing functional groups and optimize the pore structure, then rinse it alternately with absolute ethanol and ultrapure water until the pH of the filtrate is neutral, freeze-dry it to a constant weight (the freeze-drying temperature is -45 °C; the freeze-drying vacuum is 15 Pa), grind it and pass it through a 150-mesh sieve to obtain the functionalized sludge biochar OSBC;

[0151] S3. Put OSBC (with a mass of 2.0 g), solid sodium chloride (with a mass of 0.3 g), anhydrous acetone (with a mass of 8 g), and zirconia grinding balls (with a mass of 40 g) into a planetary ball mill equipped with a zirconia ball mill jar for wet ball milling (the ball milling speed is 300 rpm, and the ball milling time is 60 min). After ball milling, recover the solvent and the mixture by freeze-drying (the freeze-drying temperature is -45°C; the freeze-drying vacuum is 15 Pa). Subsequently, transfer the ball-milled product (with a mass of 2 g), potassium permanganate (with a mass of 5.66 g), and polyethylene glycol solution (with a mass of 0.1 g and a concentration of 0.1 mmol / L) into 120 mL of ultrapure water respectively, and ultrasonicate for 30 min to mix evenly to obtain a mixture. Then, add sodium citrate solid (with a final concentration of 0.1 mol / L) (Na3C6H5O7 = 3.097 g) to the solution at a controlled concentration ratio relative to KMnO4 (with a final concentration of 0.3 mol / L) (i.e., 1:3), stir continuously, ultrasonicate for 5 min, and then transfer it to a stainless-steel autoclave with a high-pressure valve for hydrothermal synthesis. Carry out hydrothermal synthesis at 130°C for 120 min. After cooling to room temperature, filter to obtain the solid in the autoclave; wash it with ultrapure water until the filtrate is colorless, and freeze-dry to constant weight (the freeze-drying temperature is -45°C; the freeze-drying vacuum is 15 Pa). Grind the sample and pass it through a 100-mesh sieve (0.15 mm) to obtain super-dense polycrystalline structure MnO2-coated functionalized sludge biochar MnO2@OSBC.

[0152] Correspondingly, transfer potassium permanganate (with a mass of 5.66 g) and polyethylene glycol solution (with a mass of 0.1 g and a concentration of 0.1 mmol / L) into 120 mL of ultrapure water respectively, and ultrasonicate for 30 min to mix evenly to obtain a mixture. Then, add sodium citrate solid (with a final concentration of 0.1 mol / L) (Na3C6H5O7 = 3.097 g) to the solution at a controlled concentration ratio relative to KMnO4 (with a final concentration of 0.3 mol / L) (i.e., 1:3), stir continuously, ultrasonicate for 5 min, and then transfer it to a stainless-steel autoclave with a high-pressure valve for hydrothermal synthesis. Carry out hydrothermal synthesis at 130°C for 120 min. After cooling to room temperature, filter to obtain the solid in the autoclave; wash it with ultrapure water until the filtrate is colorless, and freeze-dry to constant weight (the freeze-drying temperature is -45°C; the freeze-drying vacuum is 15 Pa). Grind the sample and pass it through a 100-mesh sieve (0.15 mm) to obtain polycrystalline structure MnO2 (MnO2);

[0153] S4. Dissolve 1.00 g of protocatechuic acid (PCA) and 1.17 g of ethylenediamine (EDA) (molar ratio of PCA to EDA is 1:3) in 100 mL of phosphate buffer solution (PBS, pH = 5.5), add 2.49 g of carbodiimide (EDC) and 2.49 g of N-hydroxysuccinimide (NHS) (molar ratio of EDC:NHS:PCA is 2:2:1) to catalyze the reaction, and react under shaking in the dark at 25 °C for 12 h. After the reaction is completed, add 300 mL of n-hexane (purity ≥ 98%) for precipitation and centrifugation (6000 rpm, 10 min), collect the precipitate and wash it 3 times with anhydrous acetone, and obtain amino-functionalized PCA (PCA-NH2) after vacuum freeze-drying (freeze-drying temperature is -45 °C; freeze-drying vacuum is 15 Pa);

[0154] S5. Add 1.00 g of ultra-dense polycrystalline structure MnO2-coated porous structure functionalized sludge biochar (MnO2@OSBC) and 0.25 g of amino-functionalized PCA (PCA-NH2) to 100 mL of ultrapure water, and ultrasonicate for 30 min to mix well. Then add 2.00 g of carbodiimide (EDC) and 2.00 g of N-hydroxysuccinimide (NHS) to catalyze the reaction for 24 h, and the reaction conditions are room temperature (25 °C) and shaking in the dark throughout the reaction. After the reaction, add 300 mL of absolute ethanol for precipitation and centrifugation (6000 rpm, 10 min), collect the precipitate and wash it 3 times with absolute ethanol, and obtain protocatechuic acid-MnO2 / sludge biochar (PCA-MnO2@OSBC) after vacuum freeze-drying (freeze-drying temperature is -45 °C; freeze-drying vacuum is 15 Pa);

[0155] S6. Cut the absorbent cotton into pieces with a size of 1 cm×1 cm, then place it in deionized water, and use an ultrasonic cleaner to ultrasonically clean it at 60 °C with a power of 200 W for 20 min. Subsequently, dry the cleaned absorbent cotton at 60 °C for 8 h for standby. Then, disperse PCA-MnO2@OSBC at a concentration of 1 mg / mL in 100 mL of a 5% (w / v) polyvinyl alcohol (PVA) solution and 100 mL of ultrapure water respectively to obtain a suspension of PCA-MnO2@OSBC in the PVA solution and a water-based suspension of PCA-MnO2@OSBC (this step will immerse the PCA-MnO2@OSBC suspension twice. First is the suspension of PCA-MnO2@OSBC in the PVA solution, with the solvent being a 5% (w / v) polyvinyl alcohol (PVA) solution, and then is the water-based suspension of PCA-MnO2@OSBC, with the solvent being ultrapure water). Immerse the pretreated absorbent cotton in the suspension of PCA-MnO2@OSBC in the PVA solution. After soaking for 1 h, dropwise add a 2% (v / v) glutaraldehyde (GA) solution for crosslinking, and cure it at 60 °C for 2 h, then rinse the uncrosslinked PVA with deionized water. Then, immerse the crosslinked absorbent cotton in 100 mL of a 1 mg / mL water-based suspension of PCA-MnO2@OSBC, and then place it in a freeze dryer for freeze-drying and curing (the freeze-drying temperature is -45 °C; the freeze-drying vacuum is 15 Pa). Finally, under a N2 atmosphere, heat-treat the dried absorbent cotton at 120 °C for 1 h to finally obtain an absorbent cotton-supported protocatechuic acid-MnO2 / sludge biochar composite material (PCA-MnO2@OSBC / Cotton).

[0156] Example 2

[0157] This example explores the surface morphologies of sludge biochar (SBC), super-dense polycrystalline structure MnO2-coated porous structure functionalized sludge biochar (MnO2@OSBC), and protocatechuic acid-MnO2 / sludge biochar composite materials, including:

[0158] Scanning electron microscope images clearly show the surface morphologies of the original sludge biochar, super-dense polycrystalline structure MnO2-coated functionalized sludge biochar, and the super-dense polycrystalline structure MnO2-coated functionalized sludge biochar after reaction. From Figure 1As can be seen from (a), the surface of the raw sludge biochar is relatively rough and has fewer pore structures, resulting in a low specific surface area and limited defect structures, which restricts its catalytic efficiency. The excess sludge, as the main by-product of anaerobic digestion, is rich in a large amount of organic matter. The organic matter content in the sludge has a significant impact on the properties of the prepared biochar. Generally, sludge with a high organic matter content can usually prepare biochar with rich surface functional groups, good thermal stability and excellent application performance. In contrast, from Figure 1 As can be seen from (b), the surface of the ultra-dense polycrystalline structure MnO2-coated functionalized sludge biochar is covered by fibrous, reticular and nanoflower-like MnO2 nanostructures. This polycrystalline phase structure not only significantly increases the specific surface area of the material, but also provides more active sites, thus greatly improving the catalytic activity. In addition, the excellent catalytic performance of MnO2 itself further enhances the catalytic efficiency of the material. By controlling the molar ratio of sodium citrate to potassium permanganate, the morphology of the polycrystalline phase MnO2 on the surface of the sludge biochar is regulated, significantly improving the surface roughness and activation ability of the sludge biochar. This dense polycrystalline phase MnO2 morphology formed on the surface of the sludge biochar is beneficial to improving the catalytic ability of the material. In addition, treating the surface of the sludge biochar with dilute nitric acid enhances the hydrophilicity of the surface of the sludge biochar by introducing oxygen-containing functional groups (such as carboxyl -COOH, hydroxyl -OH and carbonyl -C=O), thereby enhancing the interfacial binding strength between it and MnO2. The oxidation treatment produces minute etching or pits on the surface of the sludge biochar, increasing the surface roughness, providing more contact points and anchor points for MnO2, enabling it to better penetrate and adhere to the surface of the sludge biochar, and significantly improving the overall performance of the composite material. From Figure 1 As can be seen from (c), after PCA is covalently grafted onto the surface of the ultra-dense polycrystalline structure MnO2-coated functionalized sludge biochar, the surface morphology of the material does not change significantly, indicating the stability of MnO2 on the sludge biochar substrate, and this stability is crucial for maintaining the long-term catalytic activity of the material.

[0159] Example 3

[0160] This example explores the removal rates of sulfamethoxazole by SBC, OSBC, MnO2, MnO2@OSBC, PCA-MnO2@OSBC and PCA-MnO2@OSBC / Cotton at different PAA contents, including:

[0161] Considering that biochar may have a certain adsorption effect on pollutants, 20 mg of SBC, OSBC, MnO2, MnO2@OSBC, PCA-MnO2@OSBC, and PCA-MnO2@OSBC / Cotton were separately added to sulfamethoxazole (with a concentration of 10 μmol / L in the adsorption or degradation system) without PAA. The adsorption or degradation system was 50 mL of ultrapure water, the solution pH was 7.71 (simulating actual aquaculture wastewater), and it was stirred on a magnetic stirrer at a rotation speed of 500 rpm. Samples were taken at the set time (0 - 15 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography-mass spectrometry, and the removal rate of sulfamethoxazole at different times was calculated.

[0162] From Figure 2It can be seen that the removal rates of sulfamethoxazole in the single-component systems of SBC, OSBC, MnO2, MnO2@OSBC, PCA-MnO2@OSBC, and PCA-MnO2@OSBC / Cotton without PAA are 5.0%, 6.4%, 2.7%, 13.3%, 8.1%, and 18.9% respectively. This indicates that the adsorption capacities of SBC, OSBC, MnO2, and PCA-MnO2@OSBC for sulfamethoxazole are limited. This low adsorption rate may be due to the fact that the electrostatic interactions, pore filling, hydrophobic interactions, hydrogen bonds, and π-π interactions between the functional groups and pore structures on the surfaces of these materials and sulfamethoxazole are not obvious or insufficient to overcome the solubility and stability of sulfamethoxazole, resulting in the difficulty of stably adsorbing sulfamethoxazole molecules onto the material surfaces. In contrast, the adsorption rates of MnO2@OSBC and PCA-MnO2@OSBC / Cotton are increased. The increase in the adsorption rate of MnO2@OSBC can be attributed to solid sodium chloride as a soluble hierarchical pore template agent for hydrothermal synthesis. The particle size of solid sodium chloride (100 - 300 nm) directly regulates the macroporous structure (150 ± 50 nm) of the final material. By using acetone as the wet ball milling medium and taking advantage of the extremely low solubility of NaCl in acetone (0.00004 g / 100g), the dissolution risk is eliminated thermodynamically. Under the action of high-energy mechanical force, NaCl crystals are physically embedded in the pores and surface defects of biochar, and at the same time, acetone molecules form an adsorption layer on the surface of NaCl crystals, preventing water molecules from contacting and keeping NaCl in a complete crystal form, playing a solvent shielding effect to ensure the integrity and insolubility of NaCl crystals during the ball milling stage. The increase in the adsorption rate of PCA-MnO2@OSBC / Cotton benefits from the three-dimensional porous cellulose-based carrier constructed by loading protocatechuic acid-MnO2 / sludge biochar on absorbent cotton in the present invention. Its unique structure and modification treatment provide a large specific surface area and good permeability, reduce the risk of pore blockage, and maintain high throughput and treatment efficiency. This design not only enhances the adsorption capacity of the material for sulfamethoxazole but also ensures the stability and recyclability of the catalyst in dynamic water flow, overcoming the problems of difficult recovery of traditional powdered catalysts and the decline in the flux of immobilization technology.

[0163] Meanwhile, it can also be seen that there is a synergistic effect between OSBC and polycrystalline structure MnO2 in the present invention, which can synergistically improve the relevant properties of the prepared PCA-MnO2@OSBC / Cotton. It can also be seen that there is a synergistic effect between protocatechuic acid and absorbent cotton in the present invention, which can synergistically improve the relevant properties of the prepared PCA-MnO2@OSBC / Cotton.

[0164] From Figure 3It can be seen that when the concentration of peracetic acid (PAA) is 400 μmol / L, the degradation rates of sulfamethoxazole by the SBC / PAA, OSBC / PAA, MnO2 / PAA, MnO2@OSBC / PAA, PCA-MnO2@OSBC / PAA, and PCA-MnO2@OSBC / Cotton / PAA degradation systems are 5.0%, 20.7%, 26.6%, 55.8%, 84.4%, and 96.1% respectively. The degradation rates of sulfamethoxazole by each degradation system are different. Among them, the binary system PCA-MnO2@OSBC / Cotton / PAA has the highest degradation rate and degradation rate for sulfamethoxazole. This result indicates that the activation of PAA by MnO2@OSBC plays a key role in the degradation process of sulfamethoxazole, which may be the interaction between the functional groups on the surface of PCA-MnO2@OSBC / Cotton and PAA, thus promoting the oxidative decomposition of sulfamethoxazole. Therefore, the binary system PCA-MnO2@OSBC / Cotton / PAA has potential application value in the treatment of sulfonamide antibiotic pollutants. However, when protocatechuic acid is not grafted on the material surface, the stability and regeneration ability of MnO2@OSBC / PAA may be poor, and the activation sites lose their activity after activating PAA, which limits its application in the continuous degradation process. As an organic complexing agent, protocatechuic acid can promote the adsorption of manganese-modified biochar on sulfamethoxazole, increase the local concentration of pollutants on the catalyst surface, thereby enhancing the activation effect and degradation efficiency of PAA. At the same time, it can effectively prevent the precipitation of transition metals in non-acidic environments and maintain the dissolved state of metal ions, which is crucial for metal-catalyzed redox reactions. The formed coordination field may affect the redox properties of manganese ions, thereby promoting the activation of PAA and the degradation of sulfamethoxazole. At the same time, the degradation rate and degradation efficiency of the PCA-MnO2@OSBC / Cotton / PAA system are significantly higher than those of MnO2 / PAA. This is because MnO2 alone may easily agglomerate in aqueous solution, reducing the accessibility of active sites, while biochar provides a large number of attachment sites for MnO2, enabling MnO2 to disperse better on the biochar surface. This dispersion helps to increase the contact area between MnO2, PAA, and pollutants (such as sulfamethoxazole), thereby improving the activation efficiency. At the same time, there is a synergistic effect between biochar and MnO2, with a higher specific surface area and more suitable pore structure, showing better performance in terms of stability and regeneration ability, which helps to maintain long-term activation efficiency. The three-dimensional porous cellulose-based structure of absorbent cotton provides rich attachment sites for PCA-MnO2@OSBC, enabling it to disperse evenly on the carrier, preventing the agglomeration of active components, and thus increasing the accessibility of active sites. There is a synergistic effect between absorbent cotton, biochar, and MnO2.Its three-dimensional porous structure not only increases the specific surface area but also provides a more suitable pore structure, which helps with the adsorption and degradation of pollutants and performs better in terms of stability and regeneration ability. The three-dimensional porous structure of absorbent cotton helps the pollutants in water to quickly diffuse to the catalyst surface, increasing the contact chance between sulfamethoxazole and the active sites, thus accelerating the degradation reaction.

[0165] Meanwhile, it can also be seen that there is a synergistic effect between protocatechuic acid and peracetic acid in the present invention, which can synergistically improve the relevant properties of the prepared PCA-MnO2@OSBC / Cotton.

[0166] Example 4

[0167] This example explores the removal rates of sulfamethoxazole at different times in a single-component system and a binary-component system, including:

[0168] In the single-component system, PCA-MnO2@OSBC / Cotton (20 mg), PAA (with a concentration of 400 μmol / L in the degradation system) or in the binary-component system, PCA-MnO2@OSBC / Cotton (20 mg) + PAA (with a concentration of 400 μmol / L in the degradation system) was added with sulfamethoxazole (with a concentration of 10 μmol / L in the degradation system). The degradation system was 50 mL of ultrapure water, the solution pH was 7.71 (simulating actual aquaculture wastewater), and it was stirred on a magnetic stirrer at a rotation speed of 500 rpm. Samples were taken at the set time (0 - 15 min), and the residual concentration of sulfamethoxazole was measured using high-performance liquid chromatography-mass spectrometry to calculate the removal rate of sulfamethoxazole at different times.

[0169] From Figure 4It can be seen that the removal rates of sulfamethoxazole by PCA-MnO2@OSBC / Cotton (20 mg), PAA, and the PCA-MnO2@OSBC / Cotton / PAA system are 18.9%, 2.3%, and 96.1%, respectively. The binary system PCA-MnO2@OSBC / Cotton (20 mg) + PAA (with a concentration of 400 μmol / L in the degradation system) has significantly higher removal rates and removal efficiency for sulfamethoxazole than other systems. The removal rate of sulfamethoxazole can reach 96.1% after 15 minutes of reaction, indicating that PCA-MnO2@OSBC / Cotton can efficiently activate peracetic acid to achieve the efficient degradation of sulfamethoxazole. Specifically, the ultra-dense polycrystalline structure of MnO2 coated on the functionalized sludge biochar provides more active sites and improves the dispersion, which helps to improve the activation efficiency of PAA. The synergistic effect between MnO2 and biochar can enhance the activation ability of PAA, generating more reactive oxygen species such as hydroxyl radicals and sulfate radicals. As a natural polyphenol, PCA can form a complex with MnO2, and this complexation can change the electronic structure of MnO2, thereby enhancing its catalytic activity. At the same time, the degreased cotton matrix, as a three-dimensional porous carrier, can load the PCA-MnO2@OSBC material, enabling it to be evenly distributed in the fiber structure of the degreased cotton. This carrier property allows the degreased cotton to provide stable support for the composite material while maintaining its porous structure, which is beneficial for the adsorption and catalytic performance. Previous studies have shown that after PCA is complexed with metal ions, it can significantly improve the removal effect of the catalytic system on sulfonamide antibiotics in a wider pH range. Coating MnO2 on the biochar can improve the stability and regeneration ability of the material, slowing down the decline in the reaction rate caused by catalyst poisoning. The porous structure of the biochar and the presence of PCA can enhance the adsorption ability of sulfamethoxazole, enabling more sulfamethoxazole molecules to approach the catalyst surface, thereby improving the degradation efficiency. Therefore, the binary system (PCA-MnO2@OSBC / Cotton / PAA) shows great potential and advantages in the treatment of sulfonamide antibiotic pollutants and is expected to provide a new efficient method for environmental pollution control.

[0170] Example 5

[0171] This example explores the effect of peracetic acid concentration on the removal of sulfamethoxazole in the ternary system, including:

[0172] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton was 20 mg, the concentration of sulfamethoxazole was 10 μmol / L, the degradation system was 50 mL of ultrapure water, the solution pH was 7.71 (simulating actual aquaculture wastewater), the peracetic acid concentrations were set at 100, 200, 400, 600, and 800 μmol / L respectively, stirred on a magnetic stirrer at a rotation speed of 500 rpm, sampled at the set time (0 - 15 min), and the residual concentration of sulfamethoxazole was measured by high performance liquid chromatography-mass spectrometry to explore the effect of peracetic acid concentration on the removal of sulfamethoxazole in the ternary system.

[0173] It can be seen from Figure 5 that when the peracetic acid concentrations were set at 100, 200, 400, 600, and 800 μmol / L respectively, the removal rates of sulfamethoxazole by the binary system PCA-MnO2@OSBC / Cotton / PAA were 91.1%, 92.4%, 96.1%, 87.9%, and 92.8% respectively. The removal rate of sulfamethoxazole by this binary system was closely related to the peracetic acid concentration. When the peracetic acid concentration was too low, there was a lack of sufficient oxidant to effectively react with the active sites or functional groups on the surface of PCA-MnO2@OSBC / Cotton. Due to the insufficient PAA concentration, the active sites on the catalyst surface could not be fully utilized, resulting in low degradation efficiency. When the peracetic acid concentration reached 400 μmol / L, the active sites of the PCA-MnO2@OSBC / Cotton catalyst tended to be saturated. At this concentration, the further increase of PAA did not significantly improve the degradation efficiency of sulfamethoxazole, indicating that the maximum utilization rate of the active sites on the catalyst surface had been reached, and the reaction efficiency could not be further improved by increasing the PAA concentration. When the PAA concentration was relatively high, the effect did not increase significantly but decreased slightly. This may be due to the excessive accumulation of reactive oxygen species (ROS) in the solution caused by too high PAA concentration, and these ROS may quench each other, reducing the number of effective ROS available for the degradation of sulfamethoxazole. Considering the removal effect and economy comprehensively, a peracetic acid concentration of 400 μmol / L was selected as the addition dosage of the degradation system.

[0174] Example 6

[0175] This example explored the effect of the dosage of PCA-MnO2@OSBC / Cotton in the binary system on the removal of sulfamethoxazole, including:

[0176] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the concentration of PAA is 400 μmol / L, the concentration of sulfamethoxazole is 10 μmol / L, the degradation system is 50 mL of ultrapure water, the solution pH is 7.71 (simulating actual aquaculture wastewater), the dosages of PCA-MnO2@OSBC / Cotton are set to 0.1, 0.2, 0.4, 0.6 and 0.8 g / L respectively, stirred on a magnetic stirrer at a rotation speed of 500 rpm, sampled at the set time (0 - 15 min), and the residual concentration of sulfamethoxazole was determined by high performance liquid chromatography-mass spectrometry to explore the effect of the dosage of PCA-MnO2@OSBC / Cotton in the binary system on the removal of sulfamethoxazole.

[0177] From Figure 6It can be seen that when the dosages of PCA-MnO2@OSBC / Cotton are set at 0.1, 0.2, 0.4, 0.6, and 0.8 g / L respectively, the removal rates of sulfamethoxazole by the binary system PCA-MnO2@OSBC / Cotton / PAA are 69.5%, 81.1%, 96.1%, 96.4%, and 96.5% respectively. The removal rate of sulfamethoxazole by this binary system increases with the increase in the dosage of PCA-MnO2@OSBC / Cotton. When the dosage of PCA-MnO2@OSBC / Cotton is 0.4 - 0.8 g / L, there is no significant difference in the removal rate of sulfamethoxazole after 15 min of reaction, and a high removal efficiency can be achieved, indicating that within this dosage range, further increasing the dosage has limited effect on the improvement of the removal rate. When the dosage of PCA-MnO2@OSBC / Cotton reaches 0.4 g / L, there are sufficient active sites in the system to fully activate PAA, enabling the oxidation potential of PAA to be maximally exerted, thus achieving the efficient degradation of sulfamethoxazole. However, when the dosage of PCA-MnO2@OSBC / Cotton is further increased to 0.6 and 0.8 g / L, although the total amount of the catalyst increases, the concentration of PAA remains unchanged, which means that the additional PCA-MnO2@OSBC / Cotton fails to provide more effective active sites for the activation of PAA and may instead lead to redundancy of some active sites. In this case, the activation efficiency of PAA and the generation amount of ROS do not increase significantly with the increase in the dosage of PCA-MnO2@OSBC / Cotton, so there is no obvious difference in the removal rate of sulfamethoxazole. This shows that at a dosage of 0.4 g / L, PCA-MnO2@OSBC / Cotton can already form an efficient synergistic effect with PAA, and further increasing the dosage cannot effectively improve the degradation efficiency but will increase unnecessary costs. Considering the removal effect and economy comprehensively, 0.4 g / L is selected as the addition dosage of the degradation system.

[0178] Example 7

[0179] This example explores the influence of the solution pH on the removal ability of sulfamethoxazole in the ternary system, including:

[0180] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton is 20 mg, the concentration of sulfamethoxazole is 10 μmol / L, the degradation system is 50 mL of ultrapure water, the concentration of peracetic acid is 400 μmol / L, the solution pH is set to 3, 5, 7, 9, and 11, stirred on a magnetic stirrer at a rotation speed of 500 rpm, sampled at the set time (0 - 15 min), and the residue and concentration of sulfamethoxazole are measured by high performance liquid chromatography-mass spectrometry to explore the effect of solution pH on the removal ability of sulfamethoxazole in the ternary system.

[0181] It can be seen from Figure 7 that the removal rates of sulfamethoxazole in this ternary system are 92.1%, 94.6%, 95.1%, 95.0%, and 92.4% when the solution pH is set to 3, 5, 7, 9, and 11, respectively, and the removal rates show significant differences due to the change of solution pH. When the solution pH is 7, the removal rate of sulfamethoxazole in this binary system is the highest at 95.1%, and the catalytic activity of PCA-MnO2@OSBC / Cotton may reach the best state under neutral conditions. The manganese ions in MnO2 may exist in the forms of Mn 3+ and Mn 4+ . These two oxidation states of manganese ions contribute to the catalytic reaction and are relatively stable under neutral conditions. In acidic or alkaline environments, ROS may be more likely to undergo side reactions or decomposition, resulting in a decrease in its degradation efficiency. In addition, due to the grafting of PCA on the defatted cotton loaded with protocatechuic acid-MnO2 / sludge biochar composite, the anti-interference ability of this system to pH is significantly improved, and it can maintain a high removal rate in a wide pH range.

[0182] Example 8

[0183] This example explores the effect of HA concentration on the removal ability of sulfamethoxazole in the ternary system, including:

[0184] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton is 20 mg, the concentration of sulfamethoxazole is 10 μmol / L, the concentration of peracetic acid is 400 μmol / L, the degradation system is 50 mL of ultrapure water, the solution pH is 7.71 (simulating actual aquaculture wastewater), the concentrations of humic acid (HA) are set to 0, 1, 5, and 10 mg / L respectively, stirred on a magnetic stirrer at a rotation speed of 500 rpm, sampled at the set time (0 - 15 min), and the residue and concentration of sulfamethoxazole are measured by high performance liquid chromatography-mass spectrometry to explore the effect of HA concentration on the removal ability of sulfamethoxazole in the ternary system.

[0185] It can be seen from Figure 8 that when the concentrations of HA are set to 0, 1, 5, and 10 mg / L respectively, the removal rates of sulfamethoxazole in this binary system are 96.1%, 88.4%, 88.9%, and 88.7% respectively. With the increase in the concentration of HA, the removal rate of the system shows a downward trend. When the concentration of HA is 10 mg / L, the removal rate of sulfamethoxazole after 15 min of reaction is 88.7%, indicating that the increase in the concentration of HA will inhibit the ability of MnO2@OSBC to activate ferrate to degrade sulfamethoxazole. The inhibitory effect of HA may be attributed to the fact that HA molecules can compete with sulfamethoxazole for adsorption sites, reducing the contact opportunity between sulfamethoxazole and the active sites on the catalyst surface. At the same time, HA has the ability to scavenge free radicals and can consume the ROS generated in the system, thereby reducing the reaction opportunity between ROS and sulfamethoxazole. Nevertheless, this system still shows good degradation efficiency under the condition of high HA concentration. This is mainly due to the excellent performance of the defatted cotton-supported protocatechuic acid-MnO2 / sludge biochar composite. The three-dimensional porous structure and abundant active sites provided by this composite enhance the adsorption and degradation ability of the system for pollutants. At the same time, the grafted PCA improves the anti-interference ability of the system, enabling it to maintain good degradation efficiency under complex water quality conditions.

[0186] Example 9

[0187] This example explores the influence of coexisting inorganic ions on the ability of this system to remove sulfamethoxazole, including:

[0188] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton is 20 mg, the concentration of peracetic acid is 400 μmol / L, the concentration of sulfamethoxazole is 10 μmol / L, the degradation system is 50 mL of ultrapure water, the solution pH is 7.71 (simulating actual aquaculture wastewater), when the concentrations of Na2CO3, NaHCO3, NaNO3, NaCl, and Na2SO4 are 0, 1, 5, and 10 mmol / L respectively, stir on a magnetic stirrer at a rotation speed of 500 rpm, take samples at the set time (0 - 15 min), and use high performance liquid chromatography-mass spectrometry to determine the residual concentration of sulfamethoxazole to explore the influence of coexisting inorganic ions on the ability of this system to remove sulfamethoxazole.

[0189] It can be seen from Figures 9 - 13It can be seen that the inhibitory effects of Na2CO3, NaHCO3, NaNO3, and Na2SO4 on the ability of the binary system to degrade sulfamethoxazole increase with the increase of their concentrations. Among them, the inhibitory effect of Na2CO3 is the strongest. When the concentrations of Na2CO3 are 0, 1, 5, and 10 mmol / L, the removal rates of sulfamethoxazole by the binary system are 96.1%, 90.5%, 20.0%, and 17.8% respectively. The inhibitory effect of Na2HCO3 is relatively strong. When the concentrations of Na2HCO3 are 0, 1, 5, and 10 mmol / L, the removal rates of sulfamethoxazole by the binary system are 96.1%, 91.9%, 50.9%, and 26.6% respectively. Na2CO3 and Na2HCO3 have strong coordination abilities and can form stable coordination compounds with metal ions on the surface of MnO2, thus blocking the active sites and inhibiting their catalytic activities. In addition, carbonate and bicarbonate ions undergo hydrolysis reactions in the solution to generate carbonic acid (H2CO3) and carbon dioxide (CO2), thereby affecting the catalytic performance of the system. The inhibitory effects of NaNO3, NaCl, and Na2SO4 on the ability of the ternary system to degrade sulfamethoxazole are relatively small. When the concentrations of NaNO3 are 0, 1, 5, and 10 mmol / L, the removal rates of sulfamethoxazole by the binary system are 96.1%, 88.8%, 88.7%, and 88.4% respectively. Nitrate ions have a high mobility in the solution and can compete for adsorption with the active sites on the catalyst surface, reducing the contact opportunities between sulfamethoxazole and the active sites. In addition, nitrate ions may participate in some redox reactions and consume ROS in the system, thus reducing the degradation efficiency. When the concentrations of NaCl are 0, 1, 5, and 10 mmol / L, the removal rates of sulfamethoxazole by the binary system are 96.1%, 88.8%, 92.3%, and 91.1% respectively. Among them, under low concentration of Cl - conditions, it may inhibit the generation of reactive oxygen species in the system. However, under high concentration of Cl - conditions, Cl - may react with PAA to generate additional reactive chlorine species such as Cl · and Cl2 ·− , and these substances may promote the degradation of sulfamethoxazole, making the degradation rate of the system slightly higher than that under low concentration of Cl -Under the conditions, when the concentrations of Na2SO4 were 0, 1, 5, and 10 mmol / L, the removal rates of sulfamethoxazole in the binary system were 96.1%, 89.2%, 89.1%, and 89.1%, respectively. Sulfate ions formed sulfate precipitates with metal ions on the surface of MnO2, covering the surface of the catalyst and reducing the accessibility of active sites. In addition, sulfate ions may participate in ion exchange reactions in the solution, changing the ionic strength of the solution, thereby affecting the catalytic performance of the system. Despite the potential interference of various anions, the system still exhibits strong anti-anion interference ability. The PCA-MnO2@OSBC / Cotton composite loaded on absorbent cotton provides a three-dimensional porous structure, which not only increases the specific surface area but also enhances the adsorption capacity for pollutants. This structure helps to maintain efficient degradation performance under complex water quality conditions. The synergistic effect between biochar and MnO2 protects the active sites to a certain extent, reducing the direct contact between anions and active sites, thereby reducing the inhibitory effect. A variety of ROS are generated in the system. Even if some ROS are consumed or inhibited by anions, other types of ROS can still continue to participate in the degradation reaction. With its unique structural design and multi-component synergistic effect, the system can still maintain good degradation efficiency in the face of interference from different concentrations of anions, showing strong anti-interference ability. This makes the system have significant advantages in practical applications, especially in the treatment of complex aquaculture wastewater.

[0190] Example 10

[0191] This example measures the regeneration and degradation ability of PCA-MnO2@OSBC / Cotton, including:

[0192] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton was 20 mg, the concentration of peracetic acid was 400 μmol / L, the concentration of sulfamethoxazole was 10 μmol / L, the degradation system was 50 mL of ultrapure water, the solution pH was 7.71 (simulating actual aquaculture wastewater), stirred on a magnetic stirrer at a speed of 500 rpm, sampled at the reaction equilibrium (15 min), and the residual concentration of sulfamethoxazole was measured by high performance liquid chromatography-mass spectrometry. The PCA-MnO2@OSBC / Cotton after the degradation reaction was separated by suction filtration and washed 5-6 times with ultrapure water. The PCA-MnO2@OSBC / Cotton was placed in a freeze dryer and freeze-dried before performing the degradation experiment again. Repeat 5 times to measure the regeneration and degradation ability of MnO2@OSBC.

[0193] By Figure 14It can be seen that PCA-MnO2@OSBC / Cotton has good ability to sustainably degrade sulfamethoxazole in this binary system. When PCA-MnO2@OSBC / Cotton was used from the 1st time to the 5th time, the removal rates of sulfamethoxazole in this binary system were 96.1%, 93.9%, 90.0%, 90.8% and 82.8% respectively. After 5 cycles, the removal rate of sulfamethoxazole in this binary system could still reach 82.8%, indicating that PCA-MnO2@OSBC / Cotton has strong regeneration and degradation ability. The possible reason for the decrease in the removal rate is that after multiple reaction and cleaning processes, the physical structure of PCA-MnO2@OSBC / Cotton may change, such as the collapse of the pore structure or the change of the surface morphology, resulting in a decrease in catalytic activity. During the degradation process, the active substances on the surface of PCA-MnO2@OSBC / Cotton may be gradually consumed, leading to a decrease in its catalytic efficiency. Especially after multiple cycles of use, the regeneration of the active substances may not keep up with the consumption rate, which may affect its adsorption ability and catalytic activity to the substrate. Among them, the chemical properties of absorbent cotton are stable and it is not easy to react with other components in the composite material. This helps to maintain the stability of the composite material and extend its service life.

[0194] Example 11

[0195] In this example, the ability of this system to remove sulfamethoxazole was explored when ultrapure water was replaced by filtered Yangtze River water, Tangxun Lake water, livestock breeding wastewater, outlet sewage, tap water and drinking water, including:

[0196] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton was 20 mg, the concentration of peracetic acid was 400 μmol / L, the concentration of sulfamethoxazole was 10 μmol / L. Ultrapure water was replaced by filtered Yangtze River water, Tangxun Lake water, livestock breeding wastewater, outlet sewage, tap water and drinking water. The total volume of the degradation system was 50 mL. It was stirred on a magnetic stirrer at a speed of 500 rpm. Samples were taken at the reaction equilibrium (15 min), and the residual concentration of sulfamethoxazole was measured by high performance liquid chromatography-mass spectrometry.

[0197] From Figure 15It can be seen that this binary system has a strong degradation ability for sulfamethoxazole in various actual water bodies. The degradation rates of sulfamethoxazole in filtered Yangtze River water, Tangxun Lake water, livestock breeding wastewater, outlet sewage, tap water and drinking water are 86.5%, 90.0%, 89.3%, 84.3%, 85.3% and 89.9% respectively. This binary system shows significant advantages in degrading sulfamethoxazole in various water bodies. Considering the various interfering substances that may exist in actual water bodies, such as organic matter, nutrients, suspended solids, antibiotic residues, and disinfection by-products, this binary system can still resist the interference of these factors and continuously maintain its high catalytic activity and stable catalytic effect. The addition of PCA effectively improves the anti-interference ability of this binary system. As a phenolic acid substance with antioxidant properties, PCA can scavenge free radicals in the system, reduce oxidative stress, thereby protecting the catalyst from oxidative damage and maintaining its activity. At the same time, it has an inhibitory effect on a variety of bacteria. This antibacterial property may help reduce the biodegradation of the catalyst by microorganisms in water, thereby improving the stability and degradation efficiency of the catalyst. In addition, this system is easy to operate, without cumbersome pretreatment steps, and can be directly applied to the degradation treatment of actual water bodies, reducing the operation cost and time cost, and having more advantages in terms of economy and practicality. At the same time, the materials and reagents used in this system are relatively environmentally friendly and will not cause secondary pollution to the water environment, meeting the concept of green chemistry and having more environmental advantages compared with traditional treatment methods that may introduce harmful substances. In summary, this binary system has significant advantages over other methods in degrading sulfamethoxazole in breeding wastewater due to its high efficiency, stability, economy and environmental friendliness, and has broad practical application prospects.

[0198] Example 12

[0199] In this example, when different types of sulfonamide antibiotics are added, the ability of this system to remove various sulfonamide antibiotics is explored, including:

[0200] In the binary system (PCA-MnO2@OSBC / Cotton / PAA), the dosage of PCA-MnO2@OSBC / Cotton is 20 mg, the concentration of peracetic acid is 400 μmol / L, the degradation system is 50 mL of ultrapure water, the solution pH is 7.71 (simulating actual breeding wastewater), the concentrations of sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine and sulfathiazole are 10 μmol / L. Stir on a magnetic stirrer at a speed of 500 rpm, sample at the set time (0 - 15 min), and use high performance liquid chromatography - mass spectrometry to determine the residual concentration of sulfamethoxazole to explore the ability of this system to remove sulfonamide antibiotics.

[0201] From Figure 16It can be seen that the degradation rates of sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, and sulfathiazole by the PCA-MnO2@OSBC / Cotton / PAA system are 96.%, 94.6%, 91.4%, 93.9%, and 90.3%, respectively. This binary system exhibits excellent degradation ability for various sulfonamide antibiotics, fully demonstrating its great application potential and prospects in the field of antibiotic wastewater treatment. In addition, as can be seen from Figure 17 It can be seen that this binary system not only has a high degradation efficiency but also has an extremely high mineralization rate, and can quickly mineralize sulfonamide antibiotics into harmless or low-toxic substances. This high degradation ability and mineralization ability greatly reduce the potential risks of antibiotics to the environment and ecological systems, further highlighting its environmental friendliness in wastewater treatment. Therefore, it can be said that this binary system is very effective for most sulfonamide antibiotics, and its high mineralization rate also ensures the safety of the treated water quality, providing an efficient and environmentally friendly solution for the treatment of wastewater containing various sulfonamide antibiotics.

[0202] Example 13

[0203] This example explores the ability of a fixed-bed system to remove sulfonamide antibiotics from aquaculture wastewater, including:

[0204] A set of fixed-bed system was designed based on the binary system (PCA-MnO2@OSBC / Cotton / PAA). As Figure 18 shown, the system includes a packed column 3, a peristaltic pump, and a solution introduction device 1. The packed column is filled with defatted cotton loaded with protocatechuic acid-MnO2 / sludge biochar composite; the solution introduction device can hold peracetic acid solution, and the solution introduction device is connected to the input end of the packed column through a peristaltic pump 2. The premixed solution introduction device can input the peracetic acid solution into the packed column. The aquaculture wastewater 5 containing sulfamethoxazole is also connected to the input end of the packed column through another peristaltic pump 4, and this peristaltic pump inputs the aquaculture wastewater containing sulfamethoxazole into the packed column;

[0205] Among them, the concentration of the peracetic acid is 100 - 800 μmol / L;

[0206] The flow rate of the peristaltic pump is 0.1 - 60 mL / min.

[0207] Preferably, in the fixed-bed system, the flow rate of the peristaltic pump is 10 mL / min, the length of the packed column is 30 cm, the radius of the packed column is 2 cm, and the mass of the PCA-MnO2@OSBC / Cotton packing is 400 mg. The packing is placed in the packed column, and the filtered aquaculture wastewater containing sulfonamide antibiotics and a solution of peracetic acid are introduced into the packed column through the peristaltic pump at a flow rate ratio of 1:1. The liquid flowing out of the packed column is the aquaculture wastewater after removing sulfonamide antibiotics. Samples are taken at the set time (0 - 1440 min), and the residual concentration of sulfamethoxazole is measured using high-performance liquid chromatography-mass spectrometry to explore the ability of this fixed-bed system to remove sulfonamide antibiotics.

[0208] Figure 18 Figure 4 shows a fluidized-bed system designed based on the PCA-MnO2@OSBC / Cotton / PAA binary system, which aims to efficiently remove sulfonamide antibiotics from sludge. The core of the system is a packed column with a length of 30 cm and a radius of 2 cm, filled with PCA-MnO2@OSBC / Cotton packing. Through a peristaltic pump at a flow rate of 10 mL / min, the filtered wastewater containing sulfonamide antibiotics and the peracetic acid solution are transported to the packed column at a flow rate ratio of 1:1 to achieve the continuous removal of sulfamethoxazole in the aquaculture wastewater. As Figure 19 can be seen, this fixed-bed system has a strong degradation ability for sulfamethoxazole in aquaculture wastewater. During the degradation time from 0 to 1440 min, the system can effectively reduce the content of sulfamethoxazole in the aquaculture wastewater with an initial concentration of 10 μmol / L sulfamethoxazole. The system shows a rapid response to sulfamethoxazole at the initial stage, indicating that the PCA-MnO2@OSBC / Cotton / PAA system has immediate and efficient catalytic activity. During the entire 1440-min experiment, the fixed-bed system maintained a stable degradation efficiency, indicating that this system has good persistence and stability and is suitable for long-term operation. The experimental results show that this system can achieve a high removal rate of sulfamethoxazole, which is attributed to the strong oxidation ability of PCA-MnO2@OSBC / Cotton and the role of PAA in the system. Even in the complex environment of aquaculture wastewater, this system can maintain a high degradation efficiency, showing good anti-interference performance, which is particularly important for actual wastewater treatment. By transporting the premixed solution through a peristaltic pump, this system realizes continuous flow reaction, with simple operation and easy control, and is suitable for industrial application. In summary, Figure 18 the fixed-bed system shown in Figure 4 exhibits excellent performance in degrading sulfamethoxazole, not only with high degradation efficiency, but also with simple operation, environmental friendliness, and good application prospects.

[0209] There are some similar products in the prior art, but the fluidized bed system designed based on the PCA-MnO2@OSBC / Cotton / PAA binary system of the present invention has significant advantages, mainly reflected in aspects such as economy, indirect efficiency, catalyst recovery, and packing characteristics. The following is a comparison between the present invention and common prior art:

[0210] Table 2 Comparison of advantages between the present invention and common prior art

[0211]

[0212] The fluidized bed system of the present invention is superior to the prior art in multiple key indicators and has significant advantages. These advantages not only improve the processing efficiency and economy of the system, but also enhance its feasibility and sustainability in practical applications, making it more in line with the requirements of industrial applications. The detailed advantages of the fluidized bed system designed based on the PCA-MnO2@OSBC / Cotton / PAA binary system of the present invention are as follows:

[0213] Advantages in catalyst recovery: In the prior art, powdered catalysts are directly added to the water body, and it is difficult to effectively recover them from the dynamic water flow, resulting in waste of resources and potential secondary pollution. In the present invention, the catalyst is fixed on a three-dimensional porous cellulose-based carrier. The catalyst is not directly added to the treated water body and is fixed through the physical structure and chemical bonding of the carrier. It can be efficiently recovered by simple physical methods (such as filtration, centrifugation), reducing waste of resources and environmental pollution.

[0214] Advantages in treatment efficiency: Existing immobilization technologies (such as silica gel embedding) have a decrease in flux due to blockage of the carrier pores and cannot meet the large-flow requirements of aquaculture wastewater treatment. The present invention uses defatted cotton to load protocatechuic acid-MnO2 / sludge biochar to construct a three-dimensional porous cellulose-based carrier. Its unique structure and modification treatment provide a large specific surface area and good permeability, reducing the risk of pore blockage, maintaining high flux and treatment efficiency. Experiments show that sulfamethoxazole is efficiently degraded during the 1440-minute experiment.

[0215] Advantages in economy: In the prior art, the catalyst needs to be frequently replenished, resulting in high costs. In the present invention, the catalyst is fixed on the carrier and can be reused, reducing the replacement frequency and usage cost. At the same time, the system is easy to operate and has low energy consumption, further reducing the operating cost and improving the economy.

[0216] Advantages in anti-pollution ability: Using defatted cotton as the three-dimensional porous cellulose-based carrier and loading the catalyst has good anti-pollution performance and can maintain a stable treatment effect in a complex wastewater environment. Its porous structure and chemical modification can adsorb and intercept some pollutants, reducing the impact on the catalyst activity and maintaining the long-term stable operation of the system.

[0217] Advantages in operation complexity: Some of the existing technologies are complex in operation and require professional personnel and equipment. The fluidized bed system of the present invention realizes automatic control through equipment such as peristaltic pumps, is easy to operate and maintain, has low requirements for operators, reduces labor costs, and improves the feasibility of practical applications.

[0218] Advantages in start-up time: The system of the present invention is reasonably designed, and the catalyst fixation and fluidized bed structure are conducive to rapid start-up, shortening the preparation time and improving the operation efficiency, while some of the existing systems have a longer start-up time.

[0219] Advantages in maintenance frequency: The system of the present invention has a stable structure, the carrier and catalyst are wear-resistant and pollution-resistant, the maintenance is simple, the component replacement frequency is low, the downtime and maintenance costs are reduced, and the operation continuity and reliability are improved.

[0220] Advantages in energy consumption: The main energy-consuming equipment of the present invention is the peristaltic pump, which has a low power. When operating, it only needs to provide the power for waste water diuresis, with low energy consumption and low operation cost. Some of the existing technologies may involve complex equipment and high temperature and high pressure conditions, resulting in high energy consumption.

[0221] Advantages in adaptability: Using degreased cotton as a three-dimensional porous cellulose-based carrier and loading the catalyst has good adaptability, can treat different types and concentrations of waste water, and the treatment effect can be further optimized by adjusting the carrier and catalyst formulations and system parameters. The present invention maintains high degradation performance in complex aquaculture waste water, demonstrating good adaptability.

[0222] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments.

Claims

1. A preparation method of a composite material for sulfonamide antibiotic treatment, characterized in that: It includes the following steps: S1. Prepare sludge biochar SBC; S2. Immerse SBC in acid, and perform microwave-assisted acid treatment through a microwave chemical reactor to obtain functionalized sludge biochar OSBC; S3. Wet-mill the functionalized sludge biochar and the pore regulator in anhydrous acetone. Mix the ball-milling product evenly with a manganese source, a crystal plane director, a dispersant, and a solvent, and perform one-pot hydrothermal synthesis to obtain super-dense polycrystalline structure MnO₂-coated porous structure functionalized sludge biochar MnO₂@OSBC; solid sodium chloride serves as a soluble hierarchical pore template agent for hydrothermal synthesis, sodium citrate serves as a crystal plane director for the hydrothermal synthesis system, and polyethylene glycol serves as a dispersant for the hydrothermal synthesis system; S4. React protocatechuic acid PCA with ethylenediamine EDA under the catalysis of carbodiimide / succinimide, i.e., EDC / NHS. Purify by centrifugal precipitation with n-hexane, wash with anhydrous acetone, and then dry in vacuum to obtain amino-functionalized PCA, i.e., PCA-NH₂; S5. React MnO₂@OSBC with PCA-NH₂ in a carbodiimide / succinimide, i.e., EDC / NHS system. Wash by centrifugation and then dry in vacuum to obtain PCA-MnO₂@OSBC; S6. Cut the absorbent cotton, ultrasonically clean it with deionized water, and dry it for later use. Disperse PCA-MnO₂@OSBC in a polyvinyl alcohol PVA solution and ultrapure water respectively to obtain a suspension of PCA-MnO₂@OSBC in the PVA solution and a water-based suspension of PCA-MnO₂@OSBC. Immerse the absorbent cotton in the suspension of PCA-MnO₂@OSBC in the PVA solution, add glutaraldehyde for cross-linking and curing. Immerse the cross-linked absorbent cotton in the water-based suspension of PCA-MnO₂@OSBC, perform freeze-drying, and then perform heat treatment in an inert gas atmosphere to finally obtain an absorbent cotton-supported protocatechuic acid-MnO₂ / sludge biochar composite PCA-MnO₂@OSBC / Cotton for treating sulfonamide antibiotic breeding wastewater.

2. The preparation method according to claim 1, characterized in that: In S1, the sludge biochar is prepared by pyrolyzing sludge; Before pyrolyzing the sludge, it also includes: collecting sludge from the sludge treatment system of a sewage treatment plant using a solid-liquid separation device, washing the sludge with ultrapure water and performing freeze-drying until reaching a constant weight state to remove soluble impurities and excess water in it to obtain pretreated sludge; wherein, the sludge organic matter content is 40 - 90%, the freeze-drying temperature is -60 - 10 °C, and the freeze-drying vacuum degree is 10 - 100 Pa; During the pyrolysis process of the sludge: the heating rate is 5 - 20 °C / min; continuously pyrolyze at 400 - 800 °C for 60 - 180 min; the pyrolysis atmosphere is an inert gas; the gas flow rate is 0.05 - 0.4 L / min; After pyrolyzing the excess sludge, it further includes: pickling the pyrolysis product to remove the soluble ash therein, then alternately rinsing with ethanol and water until the pH of the filtrate is neutral, freeze-drying to constant weight and then grinding and sieving to obtain sludge biochar; wherein, the acid used in the pickling process is an inorganic acid; the freeze-drying temperature is -60 - 10 °C; the freeze-drying vacuum degree is 10 - 100 Pa; after grinding, it is sieved through a 50 - 300 mesh sieve; Alternatively, in S2, the acid is dilute nitric acid; the ratio of SBC to dilute nitric acid in g:mL is 1 - 20:200; the mass concentration of the dilute nitric acid is 20% - 68%; the microwave treatment time is 0.1 - 2 h, and the microwave power is 100 W - 600 W; Alternatively, in S2, the functionalized sludge biochar OSBC is further processed as follows: Rinse alternately with ethanol and water until the pH of the filtrate is neutral, freeze-dry to constant weight and then grind and sieve to obtain sludge biochar; wherein, the freeze-drying temperature is -60 - 10 °C; the freeze-drying vacuum degree is 10 - 100 Pa; after grinding, it is sieved through a 50 - 300 mesh sieve.

3. The preparation method according to claim 1, wherein: In S3, place the functionalized sludge biochar OSBC and solid sodium chloride particles in a zirconia ball milling tank, add anhydrous acetone and zirconia grinding balls for wet ball milling, and subsequently recover the solvent by freeze-drying; then place the ball-milled product in a solution containing permanganate, sodium citrate, and polyethylene glycol, ultrasonically mix evenly, and then transfer it to a reaction kettle for hydrothermal synthesis under optimized hydrothermal synthesis conditions, filter to obtain a solid, wash with ultrapure water until the filtrate is colorless, dry and then grind and sieve to obtain super-dense polycrystalline structure MnO2-coated porous structure functionalized sludge biochar MnO2@OSBC; Wherein, potassium permanganate serves as the manganese source in the hydrothermal synthesis system; The mass ratio of solid sodium chloride to sludge biochar is 0.1 - 0.3:1; the mass ratio of acetone to sludge biochar is 3 - 5:1; the mass ratio of zirconia grinding balls to sludge biochar is 5 - 50:1; the ball milling speed is 100 - 500 rpm; the ball milling time is 30 - 90 min; the freeze-drying temperature is -60 - 10 °C; the freeze-drying vacuum degree is 10 - 100 Pa; In step S3, the mass ratio of potassium permanganate to sludge biochar is 0.57 - 5.66:1; the molar concentration ratio of potassium permanganate to sodium citrate is 1 - 6:1; water is used in the one-pot hydrothermal synthesis, and the dosage ratio of sludge biochar to water in g:mL is 1:10 - 100; the mass ratio of the dispersant to sludge biochar is 0.1 - 10:1; Alternatively, in S3, it is mixed evenly by ultrasonic means; Alternatively, the mass ratio of the dispersant to sludge biochar is 0.1 - 10:1; the ultrasonic time is 10 - 30 min; the ultrasonic temperature is 20 - 80 °C; the ultrasonic power is 100 - 300 W; Alternatively, the temperature of the hydrothermal reaction in S3 is 110 - 200 °C, and the time of the hydrothermal reaction is 60 min - 360 min; Alternatively, the product after one-pot hydrothermal synthesis in S3 is further processed as follows: The product after one-pot hydrothermal synthesis is filtered, washed with water until the filtrate is colorless, freeze-dried to constant weight, ground and sieved to obtain ultra-dense polycrystalline MnO2-coated functionalized sludge biochar; wherein the freeze-drying temperature is -60-10°C; the freeze-drying vacuum degree is 10-100Pa, and the product is ground and sieved through a 50-200 mesh sieve.

4. The preparation method according to claim 1, wherein: In S4, protocatechuic acid PCA and ethylenediamine EDA are dissolved in phosphate buffer, and EDC / NHS is added to react in the dark. After the reaction, the mixture is precipitated by centrifugation with n-hexane, the precipitate is collected and washed with anhydrous acetone, and then dried in vacuum to obtain aminated PCA, i.e., PCA-NH2. In the process of synthesizing aminated PCA: the pH of the phosphate buffer solution is 3-9; the volume of the phosphate buffer solution added to each 1.00 g of protocatechuic acid is 60-200 mL; the molar ratio of PCA to EDA is 1:1-5; the molar ratio of EDC:NHS:PCA is 1-3:1-3:1; the reaction time is 4-24 h; the shaking rate is 100-200 rpm; the reaction conditions are room temperature and protected from light throughout the process; Alternatively, the volume ratio of n-hexane to reaction liquid is 2-5:1; the centrifugation condition is 4000-8000 rpm; the centrifugation time is 10-30 min; the freeze-drying temperature is -60-10°C; the freeze-drying vacuum degree is 10-100 Pa; Alternatively, in S5, PCA-MnO2@OSBC is subjected to a pre-reaction treatment, including: adding MnO2@OSBC and amino PCA to ultrapure water and thoroughly mixing them by ultrasonication; wherein the ultrasonication time is 10-30 min; the ultrasonication temperature is 20-80°C; the ultrasonication power is 100-300 W; and the volume of ultrapure water added to each 1.00 g of MnO2@OSBC is 60-200 mL; Alternatively, the mass ratio of EDC to PCA-MnO2@OSBC in S5 is 1-3:1; the molar ratio of EDC to NHS is 1:1; the shaking rate is 100-200 rpm; the concentration of PCA-NH2 solution is 1-5 mg / mL; the reaction time is 12-48 h; the reaction conditions are room temperature and protected from light throughout the process; After the reaction in the EDC / NHS system, the reaction solution was precipitated and centrifuged with anhydrous ethanol, the precipitate was collected and washed with anhydrous ethanol, and then vacuum dried to obtain PCA-MnO2@OSBC; wherein the volume ratio of anhydrous ethanol: reaction solution was 2-5:1; the centrifugation conditions were 4000-8000 rpm; the centrifugation time was 10-30 min; the freeze-drying temperature was -60-10°C; and the freeze-drying vacuum was 10-100 Pa.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In S6, the size of the cotton wool after cutting is 0.5 cm × 0.5 cm to 2 cm × 2 cm; the ultrasonic temperature is 20-80°C; the ultrasonic power is 100-300 W; the ultrasonic time is 10-30 min; the drying temperature is 50-80°C, the drying temperature is 60°C; the drying time is 6-12 h; Alternatively, the mass concentration of the polyvinyl alcohol (PVA) solution is 3 - 7%; the impregnation time is 0.5 - 2 h; the added volume concentration of glutaraldehyde is 1 - 3%; the curing temperature is 50 - 70 °C; the curing time is 1 - 3 h; the concentration of the PCA-MnO2@OSBC suspension is 0.5 - 2 mg / mL; the freeze-drying temperature is -60 - 10 °C, and the freeze-drying vacuum degree is 10 - 100 Pa; the heat treatment temperature is 100 - 150 °C, and the heat treatment time is 0.5 - 2 h; the inert gas is N2.

6. A composite material for treating sulfonamide antibiotics prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the composite material for treating sulfonamide antibiotics according to claim 6 in efficiently activating peracetic acid to degrade sulfonamide antibiotics in water.

8. A method for using the composite material for sulfonamide antibiotic treatment as described in claim 6, characterized in that: Comprising the following steps: After cutting the defatted cotton loaded with protocatechuic acid-MnO2 / sludge biochar composite material, add it to an aqueous solution containing peracetic acid and sulfonamide antibiotics, and filter after the degradation process is completed to obtain the solution after removing sulfonamide antibiotics.

9. The method according to claim 8, wherein: The sulfonamide antibiotics include at least one of sulfamethoxazole, sulfadiazine, sulfacetamide, sulfadoxine, and sulfathiazole; Alternatively, the concentration of the sulfonamide antibiotics is 1 - 20 μmol / L; the concentration of peracetic acid is 100 - 800 μmol / L; Alternatively, the dosage of the defatted cotton loaded with protocatechuic acid-MnO2 / sludge biochar composite material is 0.1 - 0.8 g / L; the system pH is 1 - 14.

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