Method and device for preparing piezoelectric catalytic degradation PFAS nano barium titanate from sludge graded extract

Abstract

The invention relates to a method and a device for preparing piezoelectric catalytic degradation PFAS nano barium titanate from sludge graded extracts, and belongs to the technical field of sludge utilization environments. The method comprises the following steps: uniformly mixing fresh sludge and modified cation resin, and extracting a cation resin extracting solution to obtain the cation resin extracting solution and cation sludge; uniformly mixing the cation mud and the modified anion resin, and extracting an anion resin extracting solution to obtain the anion resin extracting solution and the cation mud; mixing the sludge and alkali for reaction to obtain an alkali extracting solution and extraction residues; mixing barium salt with the cation resin extracting solution to obtain a barium complexing solution, and mixing titanium salt with the anion resin extracting solution to obtain a titanium complexing solution; and mixing the barium complexing solution with the same volume of the alkali extracting solution, then adding the titanium complexing solution with the same molar ratio, heating, drying and calcining to obtain the piezoelectric catalytic degradation PFAS nano barium titanate. According to the method, multi-stage extraction can be carried out according to application property requirements, extraction is sufficient, the comprehensive utilization rate of sludge is high, dispersity is good, the particle size is small, piezoelectric catalysis performance is high, and synthesis cost is low.

Description

Technical Field

[0001] This invention belongs to the field of environmental technology for sludge utilization, and relates to a method and apparatus for the electrocatalytic degradation of PFAS nano-barium titanate using sludge graded extracts. The apparatus is a sludge resin extractor used for resin extraction of sludge. Background Technology

[0002] In recent years, new pollutants such as perfluorooctanoic acid (PFOA) and other perfluorinated or polyfluorinated compounds (PFAS) have attracted significant attention due to their extremely high stability and very strong toxicity. Current PFAS treatment methods mainly include activated carbon adsorption and advanced oxidation processes (AOPs). However, activated carbon requires regeneration after use, causing secondary pollution. AOPs, which indiscriminately oxidize and decompose organic pollutants, are widely used. However, due to the high stability of PFASs, traditional AOPs consume large amounts of oxidant and produce numerous decomposition byproducts, making them difficult to apply in practice. Piezoelectric catalysis is a relatively new treatment technology that has attracted considerable attention because it consumes no reagents, does not introduce new substances, and can enhance the performance of existing AOPs. Barium titanate, as the best-performing piezoelectric catalyst, has been used for pollutant purification (Tang Lingfang, Li Zhi, Zhu Mingshan. Application and prospect of piezoelectric effect in advanced persulfate oxidation technology [J]. Science Bulletin, 2024, 69(34): 4958-4966.; Zhuang Wei, Yang Jing, Gong Bingrou, et al. Degradation of nitrobenzene in water by piezoelectric ozonolysis of barium titanate [J]. China Environmental Science, 2021, 41(10): 4654-4661. Guo Ruoning. Study on efficiency and mechanism of perfluorooctanoic acid degradation by electron-dominated BaTiO3 / ZVAl mechanochemical method [D]. Chongqing University, 2023.). At present, the main industrial large-scale synthesis methods of barium titanate are hydrothermal method and solid-phase method, but the barium titanate synthesized by these two methods has a large particle size and low piezoelectric catalytic performance, and cannot be used for PFAS degradation. The sol-gel method is the best method for synthesizing nano-titanium ions. However, existing sol-gel synthesis methods require a large amount of complexing agents and dispersants, resulting in excessively high synthesis costs for nano-titanium ions, which prevents their widespread application.

[0003] Excess sludge is organic solid waste discharged during wastewater treatment. Sludge, especially its extracellular polymers, is rich in organic matter with complexing and dispersing capabilities. The inventors previously prepared titanate adsorbents by directly modifying sludge and mixing it with titanium salts and alkaline earth metal salts (a method for preparing porous titanate adsorbents using sludge 2015101341309; a method for preparing porous titanate adsorbents by activating sludge with acetic acid 2015101342138; a method for preparing nano titanate adsorbents by treating sludge with sodium hydroxide 2015101342886). This greatly reduced the preparation cost of titanate adsorbents. However, due to the large number of impurities in the sludge and the destruction of organic functional groups during the treatment process, the resulting titanates have many defects, poor particle size, strong adsorption capacity, but weak catalytic ability and cannot be used for piezoelectric catalytic degradation of PFAS.

[0004] The extracellular polymeric components of sludge contain a large number of macromolecular polymers rich in carboxyl and amino groups, which have excellent complexing and dispersing abilities. These extracellular polymers or intracellular matrix can be extracted for the synthesis of titanates via the sol-gel method. In sludge component separation and extraction technologies, ion exchange resin methods have attracted much attention due to their convenient separation and recovery, mild extraction conditions, and the fact that they do not damage the extracted components, functional groups, or introduce pollutants. Dai Xiaohu et al. have already applied resins to sludge treatment (Geng Hui, Xu Ying, Dai Xiaohu, et al. Application and Prospect of Ion Exchange Resin in Sludge Treatment [J]. China Environmental Science, 2022, 42(11): 5220-5228; 2019114111801 A method for enhancing anaerobic fermentation and acid production of excess sludge using cation exchange resin; 2021111073699 A method for enhancing the biological resource utilization of sludge using acidic ion exchange resin pretreatment; 2022110786208 A method for enhancing hydrogen production through anaerobic fermentation of excess sludge using cation exchange resin; 2023109654255 A process for recovering phosphorus and aluminum salts from sludge using acidic cation exchange resin; 2023109654984 A process for enhancing sludge component separation using acidic cation exchange resin; 2024100483424 An application of cation exchange resin. Methods to improve sludge dewatering performance; Geng Hui, Xu Ying, Zheng Linke, et al. Cation exchange resin pretreatment to improve anaerobic digestion and methanogenesis of sludge [C], Chinese Society for Environmental Sciences et al. Proceedings of the 2022 National Conference on Organic Solid Waste Treatment and Resource Utilization, 2022: 9. However, currently, cation exchange resins are used to exchange calcium and magnesium cations in sludge extracellular polymers (EPS), thereby destroying the stability of the extracellular polymers, destabilizing the sludge flocs, releasing organic anions into the solution, breaking down the sludge flocs, releasing organic matter, and improving the anaerobic fermentation performance of sludge; existing processes do not perform classified extraction, and the extraction amount is low, the extracted components are mixed together, and the properties are singular. Chen Yang et al. (A method for stratification and extraction of activated sludge extracellular polymers, application number 201710315592.X) extracted extracellular polymers between colonies by cation exchange resin and then extracted extracellular polymers between bacteria by ultrasonic method. Optimized conditions enable the rapid and effective extraction of different types and functions of extracellular polymers from activated sludge, providing methodological basis and support for studying the flocculation, sedimentation, and dewatering performance of biological activated sludge. However, this method suffers from insufficient fractional extraction, and the extracts are not utilized in a fractional manner. Furthermore, existing resin extraction technologies and equipment all employ mixing and stirring followed by sieve filtration, resulting in cumbersome operation, low efficiency, long extraction times, and issues such as resin damage and loss due to stirring, making them impractical for real-world applications.

[0005] Dai Xiaohu et al. (2022103750269 A device and method for conditioning sludge using ion exchange resin) used a three-dimensional sieve cage and resin packing material filled in the sieve cage for extraction. The sludge reacts with the ion exchange resin in each resin layer, reducing the content of multivalent metal ions in the sludge. This achieves thorough mixing and reaction between the sludge and the ion exchange resin, solving the problem of separating the ion exchange resin from the sludge and increasing the feasibility of practical engineering applications. However, this method easily causes the deposition of sludge solids in the resin cage, affecting long-term stable operation. Summary of the Invention

[0006] To synthesize a high-performance nano-barium titanate piezoelectric catalyst capable of degrading PFAS, while simultaneously increasing the added value and comprehensive utilization rate of sludge and reducing the cost of synthesizing nano-barium titanate via the sol-gel method, this invention proposes a method and apparatus for preparing nano-barium titanate for PFAS degradation using sludge graded extraction. Specifically, it involves graded extraction and graded complexation of sludge organic matter, preparation of nano-barium titanate catalyst for PFAS degradation via the sol-gel method, and a high-efficiency, low-loss extraction device for sludge organic matter.

[0007] The present invention discloses a method for preparing PFAS nano-barium titanate using sludge fractionation extract, comprising the following process steps: S1: Pretreatment modification of ion exchange resin (1) Pretreatment of macroporous cation exchange resin to obtain pretreated cation resin; modification of pretreated cation resin to obtain modified cation resin. (2) Pretreatment of macroporous anion exchange resin to obtain pretreated anion resin; modification of pretreated anion resin to obtain modified anion resin; S2: Sludge Organic Matter Extraction (1) Extraction of cation exchange resin extract: Take fresh sludge, sieve it to remove large particles, and adjust the sludge concentration to 8 g / L-50 g / L. Mix the sludge and modified cation exchange resin at a mass ratio of 1:(1-20) with oven-dried sludge and modified cation exchange resin. Heat the mixture to 73-95℃ and keep it at that temperature for 3-6 hours. Measure the COD of the supernatant. Cr The extraction index R is calculated. When R ≥ 0.2, solid-liquid separation is performed, and the resulting liquid and sludge solid are named cation resin extract and cation sludge, respectively. (2) Extraction of anion exchange resin extract: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The dry sludge to modified anion resin ratio was 1:(1-20) by mass. The cationized sludge mixture and modified anion resin were mixed thoroughly, heated to 73-95℃, and kept at this temperature for 3-6 hours. The COD of the centrifuged supernatant was then measured. CrThe extraction index R is calculated. When R ≥ 0.12, solid-liquid separation is performed, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively. (3) Extraction with alkaline extract: According to the mass ratio, mud:alkali = (10-1):1, take alkali and mud, add 2-6 times the mass of mud and water, stir and mix evenly, seal and heat to 80-120℃ and stir for 1-2 hours. When the mass percentage of organic matter in the solid is <10%, separate the solid and liquid, recover the liquid, adjust and control the pH ≤9 to obtain the alkali extract, and the solid is the extraction residue mainly composed of inorganic matter. S3: Preparation of Nano-Barium Titanate Weigh out the barium salt and titanium salt in a molar ratio of 1:1, where the barium:titanium ratio is 1:1. By COD Cr The mass weight in grams and the molar ratio of barium ions were (2-10) g:1 mol. The obtained cation resin extract was taken, and the barium salt was dissolved in the cation resin extract to obtain a barium complex solution. Titanium salts were dispersed in an equal mass of anhydrous ethanol to prepare a titanium alcohol solution, which was then analyzed according to COD. Cr The mass weight in grams and the molar ratio of titanium are (1-8) g:1 mol. The obtained anion resin extract is taken and titanium alcohol solution is added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain titanium complex solution. The barium complex solution is mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, while stirring continuously, the titanium complex solution is added dropwise to the mixed barium complex solution. While stirring continuously, the mixture is heated and evaporated until it forms a gel. The gel is then dried at 105-120℃, ground and pulverized, and calcined at 600-1000℃ for 3-6 hours. After cooling to room temperature in the furnace, nano-barium titanate powder is obtained, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate.

[0008] The piezoelectric catalytic degradation of PFAS nano-barium titanate of the present invention can be used for the piezoelectric catalytic degradation of PFAS in water. For PFAS, especially for typical PFAS, the unit degradation amount of perfluorooctanoic acid (PFOA) reaches 107.4-126.5 mg / g.

[0009] In S1 (1), the macroporous cation exchange resin is selected from macroporous strong acid cation exchange resin, macroporous weak acid cation exchange resin, preferably one or more of D113, D001 and D151 macroporous resin.

[0010] In step (1) of S1, the pretreatment method of the macroporous cation exchange resin according to conventional methods is as follows: the macroporous cation exchange resin is first soaked in 2 times the resin volume of 95% ethanol for 3-4 hours, and then washed with water until there is no alcohol smell; then soaked in 2 times the resin volume of saline for 1-2 hours, the saline is discarded, and the resin is washed with water until the effluent is clear; then the resin is soaked in 2 times the volume of 2-4% NaOH solution for 2-3 hours, the alkali is drained, and the resin is washed with water until it is nearly neutral; then the resin is soaked in 2 times the volume of 5% HCl solution for 6 hours, the acid is drained, and the resin is rinsed with water until the effluent is neutral to obtain the pretreated cation exchange resin.

[0011] In step (1) of S1, the method for modifying the pretreated cation resin is as follows: the pretreated cation resin is placed in a sealed reaction vessel, heated to 40-60℃, vacuumed to a pressure of -0.08MPa, and then ammonia is introduced until the pressure is 0.5-2MPa. The vessel is then subjected to heat preservation, sealing, and pressure maintenance fumigation for 20-24 hours. Excess ammonia is purged with nitrogen at the same temperature, and the vessel is dried at 60-65℃ to obtain the modified cation resin for later use.

[0012] In step (2) of S1, the macroporous anion exchange resin is selected from macroporous strong basic anion exchange resin and macroporous weak basic anion exchange resin, preferably one or more of D201, D301, ACD-16X and D380 macroporous resin.

[0013] In step (2) of S1, the pretreatment step of the macroporous anion exchange resin mainly includes: (a) Soaking and washing: First, soak the macroporous anion exchange resin in saline solution for 1-2 hours, then gradually dilute it with water until it becomes clear. Rinse repeatedly until the drained water is free of yellow or other impurities. Then, repeatedly wash the resin with hot water at 50-60℃ to remove residual impurities and organic matter, obtaining the washed anion exchange resin. Further, the saline solution is a salt solution with a mass percentage concentration of 8%-10%.

[0014] (2) Acid and alkali treatment: Soak the cleaned anion exchange resin in a 5% hydrochloric acid (HCl) solution for 4-8 hours to remove metal ions and other impurities from the cleaned anion exchange resin; after soaking, rinse with water until neutral; then soak in a 2%-4% sodium hydroxide (NaOH) solution for 4-8 hours to activate it; then soak in a 5% hydrochloric acid solution for 4-8 hours, rinse with water until neutral, and obtain pretreated anion exchange resin for use.

[0015] In step (2) of S1, the method for modifying the pretreated anion resin is as follows: the pretreated anion resin is placed in a sealed reaction vessel, heated to 55-65℃, vacuumed to a pressure of -0.08MPa, and then acetic acid vapor is introduced until the pressure is 0.2-1MPa. The vessel is then subjected to heat preservation, sealing, and pressure maintenance fumigation for 20-24 hours. Excess acetic acid gas is purged with nitrogen gas at the same temperature, and the vessel is dried at 60-70℃ to obtain the modified anion resin for later use. In S2, the extraction index R is calculated as follows: Extraction index R = COD value (g / L) / sludge concentration (g / L).

[0016] In S2 (3), the base is either sodium hydroxide or potassium hydroxide.

[0017] The barium salt in S3 is one of barium chloride and barium nitrate, and the titanium salt is one of tetrabutyl titanate and titanium tetrachloride.

[0018] In the method for preparing pressurized electrocatalytic degradation of PFAS nano-barium titanate using sludge graded extract of the present invention, in S2 (1) and (2), the extraction equipment used can be a sludge resin extractor; the sludge resin extractor includes a reaction tank, a self-circulating ion exchange drum is provided in the reaction tank, a clamshell-type mud trap is provided on the side wall of the self-circulating ion exchange drum, and an openable upper filter screen and a lower filter screen are respectively at the upper and lower ends of the self-circulating ion exchange drum; the self-circulating ion exchange drum is filled with resin, and a mud guide skirt is provided on the side wall below the clamshell-type mud trap, and the upper edge of the self-circulating ion exchange drum extends upward to form a dam; the upper filter screen on the upper end face can be opened, and a reinforcing beam is provided in the center, the two ends of the reinforcing beam are tightly connected to the side wall of the self-circulating ion exchange drum, and a center of the reinforcing beam is provided with A rotating shaft extends axially along the rotating drum. A rotation drive motor is installed at the upper end of the rotating shaft, and the lower end of the rotating shaft extends into the drum of the self-circulating ion exchange rotating drum. Flexible disturbance wings are arranged around the inner part of the rotating shaft, allowing the self-circulating ion exchange rotating drum to rotate freely along the rotating shaft. The clamshell sludge trap is arranged along the tangent of the drum wall, with its opening facing the direction of rotation of the drum. A mesh is installed at the inner end of the clamshell sludge trap to prevent resin from flowing out of the clamshell sludge trap, while sludge can enter freely. The sludge guide skirt is located below the clamshell sludge trap on the outer wall of the rotating drum. The sludge guide skirt allows disturbed sludge to flow from the bottom of the drum along the outer wall to the upper part of the reaction tank when the drum rotates, and continuously enter the self-circulating ion exchange rotating drum through the clamshell sludge trap. After contacting and reacting with the ion exchange resin, the sludge flows out through the filter screen at the bottom of the drum, achieving self-circulation.

[0019] The reaction vessel is equipped with a mud inlet pipe with a mud inlet valve at the top, and a funnel-shaped bottom with a discharge pipe with a discharge valve at the bottommost part. A maintenance port is provided on the side wall of the funnel shape.

[0020] Furthermore, a rotation drive motor bracket is provided on the reaction vessel to support the rotation drive motor.

[0021] The present invention provides a method and apparatus for the pressure electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract, which has the following advantages: I. This invention, through a rationally designed process route, utilizes modified cation exchange resins and anion exchange resins to break down sludge to meet the requirements for complexing alkaline earth metal barium and titanium ions. The cation exchange resin adsorbs cations such as calcium and magnesium in the sludge, releasing negatively charged anionic polymers into the solution, which can be used for the complexation and dispersion of alkaline earth metal barium ions. After extraction, anion exchange resin further adsorbs anions such as phosphate in the sludge, releasing positively charged macromolecular organic polymers into the solution for complexation and dispersion with titanium complex ions. Then, the sludge is treated with alkali to decompose alkaline-soluble organic matter such as proteins, lignin, and humic acid, generating amino acid salts, lignin salts, and other complexing components to enhance the complexation and dispersion of various elements in barium titanate, resulting in a more uniform gel. This multi-stage extraction, tailored to specific application requirements, ensures more thorough extraction, higher sludge utilization rate and value. The prepared sol-gel exhibits good dispersibility, yields smaller nano-barium titanate particles with stronger piezoelectric catalytic performance, and lower synthesis costs. Second, based on the sludge concentration and the COD value of the extract, the unique extraction index is simple to calculate and control, making it convenient and accurate to control the degree of extraction, and facilitating quality control in practice. Third, the sludge resin extraction reactor allows for more complete extraction and avoids resin breakage caused by stirring. It is also easier to automate and is more suitable for large-scale production in practice. Attached Figure Description

[0022] Figure 1 A process flow diagram for the pressurized electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract; Figure 2 A schematic diagram of the overall structure of the sludge resin extractor; Figure 3 A schematic diagram of the internal structure of a sludge resin extractor after part of the tank has been cut open. Figure 4 A schematic diagram showing the internal structure of a section of the self-circulating ion exchange rotating cylinder; Figure 5 A schematic diagram of the overall appearance and structure of a self-circulating ion exchange rotary drum; Figure 6 XRD patterns of barium titanate nanoparticles 1-5 prepared for the examples.

[0023] Figure 1-5In the middle section: 1 is the reaction vessel, 11 is the discharge pipe, 111 is the discharge pipe valve, 12 is the maintenance port, 13 is the rotation drive motor bracket, 14 is the mud inlet pipe, 141 is the mud inlet pipe valve, 2 is the self-circulating ion exchange rotary drum, 21 is the clamshell mud trap, 22 is the mud guide skirt, 23 is the cofferdam, 24 is the upper filter screen, 241 is the reinforcing beam, 25 is the lower filter screen, 26 is the rotating shaft, 261 is the flexible disturbance wing, and 27 is the rotation drive motor; Figure 6 In the example: No. 1 is the barium titanate nanoparticle 1 prepared in Example 2, No. 2 is the barium titanate nanoparticle 2 prepared in Example 3, No. 3 is the barium titanate nanoparticle 3 prepared in Example 4, No. 4 is the barium titanate nanoparticle 4 prepared in Example 5, and No. 5 is the barium titanate nanoparticle 5 prepared in Example 6. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments.

[0025] Example 1 This embodiment is a sludge resin extractor, such as... Figures 2-5As shown, the system includes a reaction vessel 1, inside which is a self-circulating ion exchange rotating drum 2. The side wall of the self-circulating ion exchange rotating drum 2 has a clamshell-type mud trap 21, and the upper and lower ends of the rotating drum 2 are respectively openable upper filter screen 24 and lower filter screen 25. The rotating drum is filled with resin. On the side wall, below the clamshell-type mud trap 21, a mud guide skirt 22 is provided. The upper edge of the rotating drum extends upwards, forming a weir 23. The upper filter screen 24 on the upper end is openable, and a reinforcing beam 241 is provided in the center. The two ends of the reinforcing beam 241 are firmly connected to the side wall of the self-circulating ion exchange rotating drum 2. A rotating shaft 26 extending axially along the rotating drum is provided in the center of the reinforcing beam 241, and a rotation drive motor 27 is provided at the upper end of the rotating shaft. The lower end of the rotating shaft extends into the self-circulating ion exchange drum. Flexible disturbance wings 261 are arranged around the inner circumference of the rotating shaft, allowing the self-circulating ion exchange drum to rotate freely along the rotating shaft 26. The clamshell sludge trap 21 is arranged along the tangent of the drum wall, with its opening facing the direction of the drum's rotation. A mesh is installed at the inner end of the clamshell sludge trap 21 to prevent resin from flowing out of the clamshell sludge trap, while sludge can enter freely. The sludge guide skirt is located at the lower part of the clamshell sludge trap 21 on the outer wall of the drum. When the drum rotates, the sludge is disturbed and flows from the bottom of the drum along the outer wall to the upper part of the reaction tank, and continuously enters the self-circulating ion exchange drum through the clamshell sludge trap 21. After contacting and reacting with the ion exchange resin, the sludge flows out through the filter screen at the bottom of the drum, achieving self-circulation. The reaction vessel is equipped with a sludge inlet pipe 14 with a sludge inlet valve 141 at the top. The bottom of the reaction vessel is funnel-shaped, with a discharge pipe 11 with a discharge pipe valve 111 at the very bottom. A maintenance port 12 is provided on the side wall of the funnel-shaped vessel. A rotation drive motor bracket 13 is provided on the reaction vessel to support the rotation drive motor 27. In use, the treated modified resin (anion or cation resin) is first added between the upper filter screen 24 and the lower filter screen 25 of the self-circulating ion exchange drum 2. The discharge pipe valve 111 is closed, and sludge is added into the reaction vessel through the sludge inlet pipe 14. The rotation drive motor 27 is started to begin extraction. After the extraction reaction is complete, the discharge valve 111 is opened, and the broken sludge liquid is discharged from the discharge pipe 11. Solid-liquid separation yields the corresponding resin extract and the corresponding sludge.

[0026] Example 2 This embodiment describes a method for preparing barium titanate nanoparticles by pressure electrocatalytic degradation of PFAS using sludge fractionation extract. The apparatus described in Example 1 is used to extract sludge components and prepare barium titanate nanoparticles. The process flow is as follows: Figure 1 As shown, it includes the following steps: S1: Pretreatment modification of ion exchange resin (1) Preparation of modified cation exchange resin 1: D113 macroporous cation exchange resin was selected. First, it was soaked in 95% ethanol with a volume of 2 times the resin for 3 hours, and then washed with water until there was no alcohol smell. Then, it was soaked in brine with a volume of 2 times the resin for 1 hour, the brine was discarded, and it was washed with water until the effluent was clear. Then, the resin was soaked in 3% NaOH solution with a mass percentage concentration of 2 times the resin for 3 hours. After the alkali was drained, it was washed with water until it was nearly neutral. Then, the resin was soaked in 5% HCl solution with a mass percentage concentration of 2 times the resin for 6 hours. After the acid was drained, it was rinsed with water until the effluent was neutral to obtain the pretreated cation exchange resin. The pretreated cation exchange resin was placed in a closed reaction vessel, heated to 50°C, evacuated to a pressure of -0.08 MPa, and then ammonia was introduced until the pressure was 1 MPa. The vessel was kept at a constant temperature and pressure for 24 hours for fumigation treatment. The excess ammonia was purged with nitrogen at the same temperature, and the vessel was dried at 65°C to obtain modified cation exchange resin 1 for later use. (2) Preparation of modified anion resin 1: Take D201 type macroporous anion exchange resin. First, soak the macroporous anion exchange resin in 10% saline solution for 2 hours. Then, gradually dilute it with water until it becomes clear water. Rinse repeatedly until the discharged water is free of yellow or other impurities. Then, repeatedly wash the resin with 60°C hot water to remove residual impurities and organic matter, and obtain the cleaned anion resin. Then soak the cleaned anion resin in 5% hydrochloric acid (HCl) solution for 6 hours to remove metal ions and other impurities from the cleaned anion resin. After soaking, rinse with water until neutral. Then soak in 3% sodium hydroxide (NaOH) solution for 6 hours to activate it. Then soak in 5% hydrochloric acid solution for 5 hours and rinse with water until neutral to obtain the pretreated anion resin. The pretreated anion resin was placed in a sealed reaction vessel, heated to 60°C, evacuated to a pressure of -0.08 MPa, and then acetic acid vapor was introduced until the pressure reached 1 MPa. The vessel was then subjected to heat-sealed and pressure-maintained fumigation treatment for 24 hours. Excess acetic acid gas was purged with nitrogen gas at the same temperature, and the vessel was dried at 70°C to obtain the modified anion resin for later use. S2: Extraction of organic matter from sludge (1) Extraction of cation exchange resin extract 1: Take fresh sludge, pass it through a 40-mesh sieve to remove large particles, adjust the sludge concentration to 10 g / L, and mix the sludge and modified cation exchange resin at a mass ratio of 1:10 (octane-dried sludge: modified cation exchange resin). Heat the mixture to 80°C and maintain the temperature for 3 hours. Measure the COD of the supernatant. Cr The extraction index R is calculated according to the formula: COD value (g / L) / sludge concentration (g / L). When R ≥ 0.2, the modified cation exchange resin is separated and recovered. The sludge is separated into solid and liquid, and the liquid and sludge solid are named cation exchange resin extract and cation sludge, respectively. (2) Extraction of anion resin extract 1: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The ratio of oven-dry sludge to modified anion resin was 1:10 by mass. The cationized sludge mixture and modified anion resin were mixed thoroughly, heated to 80°C, and kept at this temperature for 4 hours. The COD of the centrifuged supernatant was then measured. Cr The extraction index R is calculated. When R ≥ 0.12, the modified anion resin is separated and recovered. The sludge is separated into solid and liquid components, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively. (3) Extraction with alkaline extract: According to the mass ratio of mud to alkali = 5:1, take sodium hydroxide and mud, add 4 times the mass of mud with water, stir, then mix the sodium hydroxide and mud evenly, seal and heat to 100℃ and stir for 2 hours. When the mass percentage of organic matter in the solid is less than 10%, separate the solid and liquid, recover the liquid, adjust and control the pH value to not exceed 9, and obtain the alkali extract. The solid is the extraction residue mainly composed of inorganic matter. S3: Preparation of nano-barium titanate Weigh out barium chloride and tetrabutyl titanate in a molar ratio of barium to titanium of 1:1. By COD Cr The mass-to-molar ratio of barium ions was 5g:1mol. The obtained cation resin extract was taken, and barium chloride was dissolved in the cation resin extract to obtain a barium complex solution. Tetrabutyl titanate was dispersed in an equal mass of anhydrous ethanol to prepare a titanol solution, and then dissolved according to COD. Cr With a mass-to-titanium molar ratio of 6g:1mol, the obtained anion resin extract was taken, and titanium alcohol solution was added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain a titanium complex solution. The barium complex solution was mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, the titanium complex solution was added dropwise to the mixed barium complex solution while continuously stirring. The mixture was heated and evaporated until it formed a gel. It was then dried at 110°C, ground and pulverized, and calcined at 1000°C for 6 hours. After cooling to room temperature in the furnace, nano-barium titanate powder was obtained, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate 1.

[0027] Example 3 This embodiment describes a method for preparing barium titanate nanoparticles for the piezocatalytic degradation of PFAS using sludge fractionation extract. The apparatus described in Example 1 is used to extract sludge components and prepare barium titanate nanoparticles, including the following steps: S1: Pretreatment modification of ion exchange resin (1) Preparation of modified cation exchange resin 2: D113 macroporous cation exchange resin was selected. It was first soaked in 95% ethanol with a volume of 2 times the resin for 4 h, and then washed with water until there was no alcohol smell. Then it was soaked in brine with a volume of 2 times the resin for 2 h, the brine was discarded, and the resin was washed with water until the effluent was clear. The resin was then soaked in 3% NaOH solution with a mass percentage concentration of 2 times the resin for 3 h, the alkali was drained, and the resin was washed with water until it was nearly neutral. The resin was then soaked in 5% HCl solution with a mass percentage concentration of 2 times the resin for 6 h, the acid was drained, and the resin was rinsed with water until the effluent was neutral to obtain pretreated cation exchange resin. The pretreated cation exchange resin was placed in a closed reaction vessel, heated to 50℃, vacuumed to a pressure of -0.08MPa, and then ammonia was introduced until the pressure was 1MPa. The vessel was kept at a closed pressure for 20 h, and the excess ammonia was purged with nitrogen at the same temperature. The vessel was then dried at 60℃ to obtain modified cation exchange resin 2 for later use. (2) Preparation of modified anion resin 2: Take D301 type macroporous anion exchange resin. First, soak the macroporous anion exchange resin in 9% saline solution for 1 hour. Then, gradually dilute it with water to clear water and rinse repeatedly until the discharged water is free of yellow or other impurities. Then, repeatedly wash the resin with 50°C hot water to remove residual impurities and organic matter, and obtain the cleaned anion resin. Then, soak the cleaned anion resin in 5% hydrochloric acid (HCl) solution for 7 hours to remove metal ions and other impurities in the cleaned anion resin. After soaking, rinse with water until neutral. Then, soak in 3% sodium hydroxide (NaOH) solution for 7 hours to activate it. Then, soak in 5% hydrochloric acid solution for 5 hours and rinse with water until neutral to obtain the pretreated anion resin. The pretreated anion resin was placed in a sealed reaction vessel, heated to 60°C, evacuated to a pressure of -0.08 MPa, and then acetic acid vapor was introduced until the pressure reached 0.5 MPa. The vessel was then subjected to heat-sealed and pressure-maintained fumigation treatment for 24 hours. Excess acetic acid gas was purged with nitrogen gas at the same temperature, and the vessel was dried at 70°C to obtain modified anion resin 2 for later use. S2: Sludge Organic Matter Extraction (1) Extraction of cation exchange resin extract 2: Take fresh sludge, pass it through a 40-mesh sieve to remove large particles, adjust the sludge concentration to 20 g / L, and mix the sludge and modified cation exchange resin at a mass ratio of 1:2 (octane-dried sludge: modified cation exchange resin). Heat the mixture to 85°C and maintain the temperature for 4 hours. Measure the COD of the supernatant. Cr The extraction index R is calculated according to the formula: COD value (g / L) / sludge concentration (g / L). When R ≥ 0.2, the modified cation exchange resin is separated and recovered. The sludge is separated into solid and liquid, and the liquid and sludge solid are named cation exchange resin extract and cation sludge, respectively. (2) Extraction of anion resin extract 2: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The ratio of oven-dry sludge to modified anion resin was 1:10 by mass. The cationized sludge mixture and modified anion resin were mixed thoroughly, heated to 85°C, and kept at this temperature for 4 hours. The COD of the centrifuged supernatant was then measured. Cr The extraction index R is calculated. When R ≥ 0.12, the modified anion resin is separated and recovered. The sludge is separated into solid and liquid components, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively. (3) Extraction with alkaline extract: According to the mass ratio of mud:alkali = 10:1, take sodium hydroxide and mud, add 5 times the mass of mud water and stir to mix the sodium hydroxide and mud evenly, seal and heat to 120℃ and stir for 1 hour. When the mass percentage of organic matter in the solid is less than 10%, separate the solid and liquid, recover the liquid, adjust and control the pH value to not exceed 9, and obtain the alkali extract. The solid is the extraction residue mainly composed of inorganic matter. S3: Preparation of nano-barium titanate Weigh out barium chloride and tetrabutyl titanate in a molar ratio of barium to titanium of 1:1. By COD Cr The mass-to-molar ratio of barium ions was 5g:1mol. The obtained cation resin extract was taken, and barium chloride was dissolved in the cation resin extract to obtain a barium complex solution. Tetrabutyl titanate was dispersed in an equal mass of anhydrous ethanol to prepare a titanol solution, and then dissolved according to COD. Cr With a mass-to-titanium molar ratio of 2g:1mol, the obtained anion resin extract was taken, and titanium alcohol solution was added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain a titanium complex solution. The barium complex solution was mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, the titanium complex solution was added dropwise to the mixed barium complex solution while continuously stirring. The mixture was heated and evaporated until it formed a gel. It was then dried at 110°C, ground and pulverized, and calcined at 800°C for 5 hours. After cooling to room temperature in the furnace, nano-barium titanate powder was obtained, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate 2.

[0028] Example 4 This embodiment describes a method for preparing barium titanate nanoparticles for the piezocatalytic degradation of PFAS using sludge fractionation extract. The apparatus described in Example 1 is used to extract sludge components and prepare barium titanate nanoparticles, including the following steps: S1: Pretreatment modification of ion exchange resin (1) Preparation of modified cation exchange resin 3: Select D001 macroporous cation exchange resin, first soak it in 95% ethanol with 2 times the resin volume for 4 h, and wash it with water until there is no alcohol smell; then soak it in brine with 2 times the resin volume for 1 h, discard the brine, and wash it with water until the effluent is clear; then soak the resin in 3% NaOH solution with 2 times the resin volume for 3 h, drain the alkali, and wash it with water until it is nearly neutral; then soak the resin in 5% HCl solution with 2 times the resin volume for 6 h, drain the acid, and rinse it with water until the effluent is neutral to obtain pretreated cation exchange resin. Place the pretreated cation exchange resin in a closed reaction vessel, heat it to 60℃, evacuate it to a pressure of -0.08MPa, then introduce ammonia gas to a pressure of 2MPa, keep it warm and sealed for 24 h for fumigation treatment, purge excess ammonia gas with nitrogen gas at the same temperature, and dry it at 65℃ to obtain modified cation exchange resin 3 for later use; (2) Preparation of modified anion resin 3: Take D380 type macroporous anion exchange resin. First, soak the macroporous anion exchange resin in 10% saline solution for 1 hour. Then, gradually dilute it with water until it becomes clear water. Rinse repeatedly until the discharged water is free of yellow or other impurities. Then, repeatedly wash the resin with 60°C hot water to remove residual impurities and organic matter, and obtain the cleaned anion resin. Then soak the cleaned anion resin in 5% hydrochloric acid (HCl) solution for 8 hours to remove metal ions and other impurities from the cleaned anion resin. After soaking, rinse with water until neutral. Then soak in 4% sodium hydroxide (NaOH) solution for 8 hours to activate it. Then soak in 5% hydrochloric acid solution for 8 hours and rinse with water until neutral to obtain the pretreated anion resin. The pretreated anion resin was placed in a sealed reaction vessel, heated to 65°C, evacuated to a pressure of -0.08 MPa, and then acetic acid vapor was introduced until the pressure reached 0.2 MPa. The vessel was then subjected to heat-sealed and pressure-maintained fumigation treatment for 20 hours. Excess acetic acid gas was purged with nitrogen gas at the same temperature, and the vessel was dried at 70°C to obtain modified anion resin 3 for later use. S2: Extraction of organic matter from sludge (1) Extraction of cation exchange resin extract 3: Take fresh sludge, pass it through a 40-mesh sieve to remove large particles, adjust the sludge concentration to 8 g / L, and mix the sludge and modified cation exchange resin at a mass ratio of 1:1 (octane-dried sludge:modified cation exchange resin). Heat the mixture to 95°C and maintain the temperature for 3 hours. Measure the COD of the supernatant. Cr The extraction index R is calculated according to the formula: COD value (g / L) / sludge concentration (g / L). When R ≥ 0.2, the modified cation exchange resin is separated and recovered. The sludge is separated into solid and liquid, and the liquid and sludge solid are named cation exchange resin extract and cation sludge, respectively. (2) Extraction of anion resin extract 3: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The ratio of oven-dry sludge to modified anion resin was 1:1 by mass. The cationized sludge mixture and modified anion resin were mixed thoroughly, heated to 73°C, and kept at this temperature for 3 hours. The COD of the centrifuged supernatant was then measured. Cr The extraction index R is calculated. When R ≥ 0.12, the modified anion resin is separated and recovered. The sludge is separated into solid and liquid components, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively. (3) Extraction with alkaline extract: According to the mass ratio of mud:alkali = 10:1, take sodium hydroxide and mud, add 6 times the mass of mud water and stir to mix the sodium hydroxide and mud evenly, seal and heat to 150℃ and stir for 1 hour. When the mass percentage of organic matter in the solid is less than 10%, separate the solid and liquid, recover the liquid, adjust and control the pH value to not exceed 9, and obtain the alkali extract. The solid is the extraction residue mainly composed of inorganic matter. S3: Preparation of nano-barium titanate Weigh out barium nitrate and tetrabutyl titanate in a molar ratio of barium to titanium of 1:1. By COD Cr The mass-to-molar ratio of barium ions was 2g:1mol. The obtained cation resin extract was taken, and barium nitrate was dissolved in the cation resin extract to obtain a barium complex solution. Tetrabutyl titanate was dispersed in an equal mass of anhydrous ethanol to prepare a titanol solution, and then dissolved according to COD. Cr With a mass-to-titanium molar ratio of 1 g:1 mol, the obtained anion resin extract was taken, and titanium alcohol solution was added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain a titanium complex solution. The barium complex solution was mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, the titanium complex solution was added dropwise to the mixed barium complex solution while continuously stirring. The mixture was heated and evaporated until it formed a gel. It was then dried at 105°C, ground and pulverized, calcined at 600°C for 6 hours, and cooled to room temperature in the furnace to obtain nano-barium titanate powder, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate 3.

[0029] Example 5 This embodiment describes a method for preparing barium titanate nanoparticles for the piezocatalytic degradation of PFAS using sludge fractionation extract. The apparatus described in Example 1 is used to extract sludge components and prepare barium titanate nanoparticles, including the following steps: S1: Pretreatment modification of ion exchange resin (1) Preparation of modified cation exchange resin 4: D151 macroporous cation exchange resin was selected. First, it was soaked in 95% ethanol with a volume of 2 times the resin for 3 h, and then washed with water until there was no alcohol smell. Then, it was soaked in brine with a volume of 2 times the resin for 2 h, the brine was discarded, and it was washed with water until the effluent was clear. Then, the resin was soaked in NaOH solution with a mass percentage concentration of 4% for 2 h, the alkali was drained, and it was washed with water until it was nearly neutral. Then, the resin was soaked in HCl solution with a mass percentage concentration of 5% for 6 h, the acid was drained, and it was rinsed with water until the effluent was neutral to obtain pretreated cation exchange resin. The pretreated cation exchange resin was placed in a closed reaction vessel, heated to 40℃, vacuumed to a pressure of -0.08MPa, and then ammonia was introduced until the pressure was 0.5MPa. The vessel was kept at a constant temperature and pressure for 20 h for fumigation treatment. The excess ammonia was purged with nitrogen at the same temperature, and the vessel was dried at 60℃ to obtain modified cation exchange resin 4 for later use. (2) Preparation of modified anion resin 4: Take ACD-16X type macroporous anion exchange resin. First, soak the macroporous anion exchange resin in 8% saline solution for 2 hours. Then, gradually dilute it with water until it becomes clear water. Rinse repeatedly until the discharged water is free of yellow or other impurities. Then, repeatedly wash the resin with 50°C hot water to remove residual impurities and organic matter, and obtain the cleaned anion resin. Then soak the cleaned anion resin in 5% hydrochloric acid (HCl) solution for 4 hours to remove metal ions and other impurities from the cleaned anion resin. After soaking, rinse with water until neutral. Then soak in 2% sodium hydroxide (NaOH) solution for 4 hours to activate it. Then soak in 5% hydrochloric acid solution for 4 hours and rinse with water until neutral to obtain the pretreated anion resin. The pretreated anion resin was placed in a sealed reaction vessel, heated to 55°C, evacuated to a pressure of -0.08 MPa, and then acetic acid vapor was introduced until the pressure reached 1 MPa. The vessel was then subjected to heat-sealed and pressure-maintained fumigation treatment for 24 hours. Excess acetic acid gas was purged with nitrogen gas at the same temperature, and the vessel was dried at 60°C to obtain the modified anion resin for later use. S2: Sludge Organic Matter Extraction (1) Extraction of cation exchange resin extract 4: Take fresh sludge, pass it through a 40-mesh sieve to remove large particles, adjust the sludge concentration to 50 g / L, and mix the sludge and modified cation exchange resin at a mass ratio of 1:20 (octane-dried sludge: modified cation exchange resin). Heat the mixture to 73°C and maintain the temperature for 6 hours. Measure the COD of the supernatant. Cr The extraction index R is calculated according to the formula: COD value (g / L) / sludge concentration (g / L). When R ≥ 0.2, the modified cation exchange resin is separated and recovered. The sludge is separated into solid and liquid, and the liquid and sludge solid are named cation exchange resin extract and cation sludge, respectively. (2) Extraction of anion resin extract 4: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The ratio of oven-dry sludge to modified anion resin was 1:20 by mass. The cationized sludge mixture and modified anion resin were mixed thoroughly, heated to 95°C, and kept in contact for 6 hours. The COD of the centrifuged supernatant was then measured. Cr The extraction index R is calculated. When R ≥ 0.12, the modified anion resin is separated and recovered. The sludge is separated into solid and liquid components, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively. (3) Extraction with alkaline extract: According to the mass ratio of mud to alkali = 1:1, take sodium hydroxide and mud, add twice the mass of mud water and stir to mix the sodium hydroxide and mud evenly, seal and heat at 80℃ and stir for 2 hours. When the mass percentage of organic matter in the solid is less than 10%, separate the solid and liquid, recover the liquid, adjust and control the pH value to not exceed 9, and obtain the alkali extract. The solid is the extraction residue mainly composed of inorganic matter. S3: Preparation of nano-barium titanate Weigh out barium chloride and tetrabutyl titanate in a molar ratio of barium to titanium of 1:1. By COD Cr The mass-to-molar ratio of barium ions was 10 g: 1 mol. The obtained cation resin extract was taken, and barium chloride was dissolved in the cation resin extract to obtain a barium complex solution. Tetrabutyl titanate was dispersed in an equal mass of anhydrous ethanol to prepare a titanol solution, and then dissolved according to COD. Cr With a mass-to-titanium molar ratio of 8g:1mol, the obtained anion resin extract was taken, and titanium alcohol solution was added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain a titanium complex solution. The barium complex solution was mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, the titanium complex solution was added dropwise to the mixed barium complex solution while continuously stirring. The mixture was heated and evaporated until it formed a gel. It was then dried at 120°C, ground and pulverized, and calcined at 1000°C for 3 hours. After cooling to room temperature in the furnace, nano-barium titanate powder was obtained, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate 4.

[0030] Example 6 This embodiment describes a method for preparing barium titanate nanoparticles for the piezocatalytic degradation of PFAS using sludge fractionation extract. The apparatus described in Example 1 is used to extract sludge components and prepare barium titanate nanoparticles, including the following steps: S1: Pretreatment modification of ion exchange resin (1) Preparation of modified cation exchange resin 5: Select D113 macroporous cation exchange resin, first soak it in 95% ethanol with 2 times the resin volume for 3-4 h, and wash it with water until there is no alcohol smell; then soak it in salt water with 2 times the resin volume for 1-2 h, discard the salt water, and wash it with water until the effluent is clear; then soak the resin in NaOH solution with 2-4% mass percentage concentration for 2-3 h, drain the alkali solution, and wash it with water until it is nearly neutral; then soak the resin in HCl solution with 5% mass percentage concentration for 6 h, drain the acid solution, and rinse it with water until the effluent is neutral to obtain the pretreated cation exchange resin. The pretreated cation exchange resin was placed in a sealed reaction vessel, heated to 40-60℃, evacuated to a pressure of -0.08MPa, and then ammonia was introduced until the pressure was 0.5-2MPa. The vessel was then subjected to heat-sealed and pressure-maintaining fumigation treatment for 20-24 hours. Excess ammonia was purged with nitrogen at the same temperature, and the vessel was dried at 60-65℃ to obtain modified cation exchange resin 5 for later use. (2) Preparation of modified anion resin 5: Take D201 type macroporous anion exchange resin. First, soak the macroporous anion exchange resin in 8%-10% saline solution for 1-2 hours. Then, gradually dilute it with water to clear water and rinse repeatedly until the discharged water is free of yellow or other impurities. Then, repeatedly wash the resin with hot water at 50-60℃ to remove residual impurities and organic matter, and obtain the cleaned anion resin. Then, soak the cleaned anion resin in 5% hydrochloric acid (HCl) solution for 4-8 hours to remove metal ions and other impurities in the cleaned anion resin. After soaking, rinse with water until neutral. Then, soak in 2-4% sodium hydroxide (NaOH) solution for 4-8 hours to activate it. Then, soak in 5% hydrochloric acid solution for 4-8 hours and rinse with water until neutral to obtain the pretreated anion resin. The pretreated anion resin was placed in a sealed reaction vessel, heated to 55-65℃, evacuated to a pressure of -0.08MPa, and then acetic acid vapor was introduced until the pressure was 0.2-1MPa. The vessel was then subjected to heat-sealed and pressure-maintaining fumigation treatment for 20-24 hours. Excess acetic acid gas was purged with nitrogen gas at the same temperature, and the vessel was dried at 60-70℃ to obtain the modified anion resin for later use. S2: Sludge Organic Matter Extraction (1) Extraction of cation exchange resin extract 5: Take fresh sludge, pass it through a 40-mesh sieve to remove large particles, and adjust the sludge concentration to 50 g / L-8 g / L. Mix the sludge and modified cation exchange resin at a mass ratio of 1:(1-20). Heat the mixture to 73-95℃ and maintain the temperature for 3-6 hours. Measure the COD of the supernatant. CrThe extraction index R is calculated according to the formula: COD value (g / L) / sludge concentration (g / L). When R ≥ 0.2, the modified cation exchange resin is separated and recovered. The sludge is separated into solid and liquid, and the liquid and sludge solid are named cation exchange resin extract and cation sludge, respectively. (2) Extraction of anion resin extract 5: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The mass ratio of oven-dry sludge to modified anion resin was 1:(1-20). The cationized sludge mixture and modified anion resin were mixed evenly, heated to 73-95℃, and kept at this temperature for 3-6 hours. The COD of the centrifuged supernatant was then measured. Cr The extraction index R is calculated. When R ≥ 0.12, the modified anion resin is separated and recovered. The sludge is separated into solid and liquid components, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively. (3) Extraction with alkaline extract: According to the mass ratio of mud:alkali = (10-1):1, take sodium hydroxide and mud, add 2-6 times the mass of mud water and stir to mix the sodium hydroxide and mud evenly. Seal and heat at 80-150℃ and stir for 1-2 hours. When the mass percentage of organic matter in the solid is less than 10%, separate the solid and liquid, recover the liquid, adjust and control the pH value not to be greater than 9, and obtain the alkali extract. The solid is the extraction residue mainly composed of inorganic matter. S3: Preparation of nano-barium titanate Weigh out barium chloride and tetrabutyl titanate in a molar ratio of barium to titanium of 1:1. By COD Cr The mass weight in grams and the molar ratio of barium ions were (2-10) g:1 mol. The obtained cation resin extract was taken, and barium chloride was dissolved in the cation resin extract to obtain a barium complex solution. Tetrabutyl titanate was dispersed in an equal mass of anhydrous ethanol to prepare a titanol solution, and then dissolved according to COD. Cr The mass weight in grams and the molar ratio of titanium are (1-8) g: 1 mol. The obtained anion resin extract is taken and titanium alcohol solution is added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain titanium complex solution. The barium complex solution was mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, the titanium complex solution was added dropwise to the mixed barium complex solution while stirring continuously. The mixture was heated and evaporated until it formed a gel. The gel was dried at 105-120℃, ground and pulverized, and calcined at 600-1000℃ for 3-6 hours. The calcined gel was cooled to room temperature in the furnace to obtain nano-barium titanate powder, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate 5.

[0031] Comparative Example 1 Same as Example 2, except that: If the extraction is performed using ordinary mixed extraction equipment, the extraction will be insufficient, the COD value of the extract will be low, and the nano-barium titanate will not be able to form a gel, resulting in precipitation and failure to obtain nano-barium titanate.

[0032] Comparative Example 2 Same as Example 2, except that: If cation exchange resin is used in all cases and anion exchange resin is not used, the resulting extract will not form a uniform gel when preparing nano-barium titanate, and solid phase will precipitate during the process. Therefore, nano-barium titanate cannot be obtained by calcination.

[0033] Comparative Example 3 Same as Example 2, except that: If anion exchange resin is used in all cases and cation exchange resin is not used, the resulting extract will not form a uniform gel when preparing nano-barium titanate, and solid phase will precipitate during the process. Therefore, nano-barium titanate cannot be obtained by calcination.

[0034] Comparative Example 4 Same as Example 2, except that: The S2 and S3 processes employ the following steps: S2: Fresh sludge is added to modified anion resin and modified cation resin, heated and mixed and kept at a constant temperature for reaction, and then separated into solid sludge and resin extract. Add alkali solution to the solid, heat and stir, and then separate the solid and liquid again to obtain alkali extract and residue; S3: Mix barium salt and titanium salt with resin extract, heat and evaporate while stirring. The resulting gel is uneven. Dry at 105-120℃, grind and pulverize, calcine at 600-1000℃ for 3-6 hours, and cool to room temperature in the furnace to obtain powder.

[0035] The powder obtained in this comparative example, although containing barium titanate, has a large particle size, high content of impurities such as barium oxide and titanium dioxide, and low piezoelectric catalytic degradation ability of perfluorooctanoic acid.

[0036] Example 7 This embodiment demonstrates the purification performance of PFAS-synthesized water samples. The nano-barium titanate samples 1-5 obtained in the examples were tested using an XRD instrument under the following conditions: Cu Kα radiation, λ = 1.5406 Å. The XRD spectra of the synthesized samples are shown below. Figure 6 According to the spectra, all samples showed characteristic diffraction peaks of tetragonal barium titanate. Based on the Scherrer equation, the particle sizes of barium titanate 1-5 crystals were calculated to be 20.4, 14.8, 22.1, 11.7 and 18.2 nm, respectively.

[0037] The nano-barium titanate 1-5 prepared in the examples was used for the piezoelectric catalytic degradation of a typical PFAS—perfluorooctanoic acid (PFOA)—in simulated water samples. The experimental method involved adding 50 mL of a 2 g / L PFOA synthetic water sample to a 150 mL stoppered conical flask, adding 0.5 g of nano-barium titanate powder, ultrasonicating at 40 kHz and 200 W at room temperature for 60 min, centrifuging at 8000 r / min, collecting the supernatant, and measuring the absorbance of the original solution and the treated supernatant at 208 nm using a UV spectrophotometer. The PFAS content was calculated according to Beer-Lambert's law, and the unit removal amount was calculated according to formula (1). Unit removal amount (mg / g) (1) In the formula: C0 is the initial concentration of PFAS, mg / mL; C1 is the concentration of PFAS after treatment, mg / mL; V is the volume of the water sample, mL; m is the amount of catalyst nano-barium titanate added, g. Simultaneously, blank and commercially available nano-barium titanate powder (tetragonal phase, average particle size 30 nm) were compared and controlled. The results are shown in Table 1. Table 1. Purification performance of synthesized nano-barium titanate against PFOA in water Initial concentration (mg / mL) Post-treatment concentration (mg / mL) PFOA removal rate (%) Unit removal amount (mg / g) blank 2.000 1.978 1.1 —— Nano barium titanate 1 2.000 0.735 63.25 126.5 Nano barium titanate 2 2.000 0.891 55.45 110.9 Nano barium titanate 3 2.000 0.926 53.7 107.4 Nano barium titanate 4 2.000 0.834 58.3 116.6 Nano barium titanate 5 2.000 0.766 61.7 123.4 Commercially available nano barium titanate 2.000 1.583 20.85 41.7 Comparative Example 1 Powder 2.000 1.902 4.9 9.8 Comparative Example 2 Powder 2.000 1.871 6.45 12.9 Comparative Example 3 Powder 2.000 1.896 5.2 10.4 Comparative Example 4 Powder 2.000 1.462 26.9 53.8 *The absorbance of a 2 g / L PFOA simulated water sample was measured using the ultraviolet method, and the PFOA concentration was obtained by substituting it into the regression equation.

[0038] As can be seen, the nano-barium titanate prepared by this invention exhibits significantly higher piezoelectric catalytic degradation performance for PFAS than that synthesized by conventional methods, with a catalytic degradation efficiency of 53.7–63.25%. This invention's method not only deeply utilizes sludge but also replaces the complexing and dispersing agents necessary for the sol-gel method in synthesizing nano-barium titanate with graded sludge extract, thereby significantly reducing the synthesis cost of nano-barium titanate and improving its piezoelectric catalytic degradation performance for PFAS.

Claims

1. A method for preparing piezo-electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract, characterized in that, Fresh sludge and modified cation exchange resin were mixed evenly, and the cation exchange resin extract was extracted to obtain cation exchange resin extract and cation sludge. The cation sludge and modified anion exchange resin were mixed evenly, and the anion exchange resin extract was extracted to obtain anion exchange resin extract and anion sludge. The anion sludge was mixed with alkali to obtain alkali extract and extraction residue. Barium salt and cation exchange resin extract were mixed to obtain barium complex solution. Titanium salt and anion exchange resin extract were mixed to obtain titanium complex solution. The barium complex solution was mixed with an equal volume of alkali extract, and then an equimolar amount of titanium complex solution was added. The mixture was heated, dried, and calcined to obtain piezoelectrically catalytically degraded PFAS nano-barium titanate.

2. The method for preparing piezocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract according to claim 1, characterized in that, The extraction process of the cation exchange resin extract is as follows: Take fresh sludge, sieve it to remove large particles, and adjust the sludge concentration to 8 g / L-50 g / L. Mix the sludge and modified cation exchange resin at a mass ratio of 1:(1-20) with oven-dried sludge and modified cation exchange resin. Heat the mixture to 73-95℃ and keep it at that temperature for 3-6 hours. Measure the COD of the supernatant. Cr The extraction index R is calculated. When R ≥ 0.2, solid-liquid separation is performed, and the resulting liquid and sludge solid are named cation resin extract and cation sludge, respectively.

3. The method for preparing pressure electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract according to claim 1, characterized in that, The extraction process of the anion exchange resin extract is as follows: The obtained cationized sludge was replenished with water to the original volume of fresh sludge, resulting in a cationized sludge mixture. The dry sludge to modified anion resin ratio was 1:(1-20) by mass. The cationized sludge mixture and modified anion resin were mixed thoroughly, heated to 73-95℃, and kept at this temperature for 3-6 hours. The COD of the centrifuged supernatant was then measured. Cr The extraction index R is calculated. When R ≥ 0.12, solid-liquid separation is performed, and the resulting liquid and sludge solid are named anion resin extract and anion sludge, respectively.

4. The method for preparing piezo-electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract according to claim 1, characterized in that, The extraction process of the alkaline extract is as follows: According to the mass ratio of mud to alkali = (10-1):1, take alkali and mud, add 2-6 times the mass of mud with water, stir and mix evenly, seal and heat to 80-120℃ and stir for 1-2 hours. When the mass percentage of organic matter in the solid is <10%, separate the solid and liquid, recover the liquid, adjust and control the pH ≤9 to obtain the alkali extract, and the solid is the extraction residue mainly composed of inorganic matter.

5. The method for preparing pressurized electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract according to claim 1, characterized in that, The preparation process of piezoelectric catalytic degradation of PFAS nano-barium titanate is as follows: Weigh out the barium salt and titanium salt in a molar ratio of 1:1, where the barium:titanium ratio is 1:

1. COD in cation exchange resin extract Cr The mass weight in grams and the molar ratio of barium ions were (2-10) g:1 mol. The obtained cation resin extract was taken, and the barium salt was dissolved in the cation resin extract to obtain a barium complex solution. Titanium salts were dispersed in an equal mass of anhydrous ethanol to prepare a titanium alcohol solution. The COD of the anion exchange resin extract was then analyzed. Cr The mass weight in grams and the molar ratio of titanium are (1-8) g:1 mol. The obtained anion resin extract is taken and titanium alcohol solution is added dropwise to dissolve the anion resin extract under continuous and rapid stirring to obtain titanium complex solution. The barium complex solution was mixed with an equal volume of alkaline extract to obtain a mixed barium complex solution. Then, the titanium complex solution was added dropwise to the mixed barium complex solution while continuously stirring. The mixture was heated and evaporated while continuously stirring until it formed a gel. The gel was then dried, ground and pulverized, calcined, and cooled to room temperature in a furnace to obtain nano-barium titanate powder, which is the piezoelectric catalytic degradation of PFAS nano-barium titanate.

6. The method for preparing pressure electrocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract according to claim 1, characterized in that, The alkali is one of sodium hydroxide and potassium hydroxide; and / or, the barium salt is one of barium chloride and barium nitrate, and the titanium salt is one of tetrabutyl titanate and titanium tetrachloride.

7. The method for preparing piezocatalytic degradation of PFAS nano-barium titanate using sludge fractionation extract according to claim 1, characterized in that, The calcination temperature is 600-1000℃, and the calcination time is 3-6 hours.

8. A piezoelectric catalytic degradation method for PFAS nano-barium titanate, prepared by any one of claims 1-7, is used for the piezoelectric catalytic degradation of PFAS in water, and achieves a unit degradation amount of 107.4-126.5 mg / g for PFAS, especially for perfluorooctanoic acid.

9. A sludge resin extractor, characterized in that, In the method described in any one of claims 1-8, the extraction device is a sludge resin extractor comprising a reaction tank (1), a self-circulating ion exchange drum (2) is provided inside the reaction tank (1), a clam-type mud trapping port (21) is provided on the side wall of the self-circulating ion exchange drum (2), and an openable upper filter screen (24) and a lower filter screen (25) are respectively provided at the upper and lower ends of the self-circulating ion exchange drum (2); the self-circulating ion exchange drum is filled with resin, and a mud-guiding skirt (22) is provided at the lower part of the clam-type mud trapping port (21) on the side wall; the upper edge of the self-circulating ion exchange drum extends upward to form a weir (23); the upper filter screen (24) on the upper end face is openable, and a reinforcing beam (241) is provided in the center; the two ends of the reinforcing beam (241) are tightly connected to the side wall of the self-circulating ion exchange drum (2), and a rotating shaft (26) extending along the axial direction of the drum is provided in the center of the reinforcing beam (241); the upper end of the rotating shaft... A rotating drive motor (27) is installed, with the lower end of the rotating shaft extending into the cylinder of the self-circulating ion exchange rotating drum. Flexible disturbance wings (261) are arranged around the inner part of the rotating shaft, allowing the self-circulating ion exchange rotating drum to rotate freely along the rotating shaft (26). The clamshell sludge trap (21) is arranged along the tangent of the cylinder wall, with the opening facing the direction of rotation of the rotating drum. A net is installed at the inner end of the clamshell sludge trap (21) to prevent resin from flowing out of the clamshell sludge trap, while sludge can enter freely. The sludge guide skirt is set at the lower part of the clamshell sludge trap (21) on the outer wall of the rotating drum. The sludge guide skirt enables the disturbed sludge to flow from the bottom of the drum along the outer wall to the upper part of the reaction tank when the rotating drum rotates, and continuously enter the self-circulating ion exchange rotating drum through the clamshell sludge trap (21). After contacting and reacting with the ion exchange resin, it flows out through the filter screen at the bottom of the drum to achieve self-circulation. The mixture after the exchange cracking and extraction is separated into solid and liquid, and the resin extract and corresponding sludge are recovered.

10. The sludge resin extractor according to claim 9, characterized in that, The reaction vessel (1) is provided with a mud inlet pipe (14) with a mud inlet valve (141) at the top. The bottom of the reaction vessel (1) is funnel-shaped, and a discharge pipe (11) with a discharge pipe valve (111) is provided at the bottom. A maintenance port (12) is provided on the side wall of the funnel shape.

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