Piezoelectric catalyst, preparation method, application of piezoelectric catalyst in sewage treatment and professional application system

Abstract

The invention discloses a piezoelectric catalyst, a preparation method, application of the piezoelectric catalyst in sewage treatment and a professional application system.The Bi4Ti3O12 piezoelectric catalyst loaded with cation Ti vacancies is prepared through Bi (NO3) 3.5 H2O and Ti (OC4H9) 4 and applied to a special sewage treatment system, a light-pressure catalytic circulation system capable of operating cooperatively and independently is constructed, and the piezoelectric catalyst is applied to the sewage treatment system. And all-weather operation capability is realized. The optical unit and the piezoelectric unit of the special system are independent in structure, functional coupling is achieved through H2O2 directional transmission, and the carrier separation and migration process is optimized step by step. And the problems that the catalyst is difficult to recover and the hydrodynamic response is weak are solved. According to the invention, solar energy and water flow mechanical energy are utilized to realize high-efficiency low-carbon treatment from in-situ oxidant generation, instantaneous activation and deep mineralization, and a stable and economic solution is provided for treatment of refractory organic pollutants.

Description

Technical Field

[0001] This invention relates to a piezoelectric catalyst, its preparation method, and its application in wastewater treatment and specialized application systems, particularly to a Bi4Ti3O4 catalyst with cationic Ti vacancies. 12 The piezoelectric catalyst and its preparation method, as well as its application in wastewater pollutants and a dedicated wastewater treatment system utilizing the catalyst, belong to the field of wastewater treatment. Background Technology

[0002] Recalcitrant new pollutants (such as antibiotics and perfluorinated compounds) pose a serious threat to the aquatic environment, and their deep purification is a major challenge. These pollutants are highly toxic, highly stable, and bioaccumulative. Traditional biological methods or conventional advanced oxidation technologies are difficult to achieve efficient decomposition and complete mineralization of them, and generally suffer from problems such as long treatment cycles, high energy consumption, and high risk of secondary pollution. They are particularly unsuitable for the distributed treatment needs of remote areas without stable power grids.

[0003] To address the aforementioned issues, novel advanced oxidation technologies such as photocatalysis and piezoelectric catalysis, which directly utilize environmental energy sources like light or mechanical energy, have demonstrated potential for green governance. However, the coupling of these two technologies, in practical applications moving towards all-weather, self-driven systems, still suffers from inherent limitations: intermittency (photocatalysis relies on light) or inefficiency (piezoelectric catalysis relies on unstable mechanical energy). The simple superposition of the two technologies fails to achieve deep synergy in energy complementarity and carrier migration, resulting in low energy conversion efficiency. Furthermore, the long-term stability of materials under continuous flow and complex water quality conditions, as well as catalyst recovery issues, remain unresolved, hindering the realization of all-weather, self-driven wastewater treatment. Therefore, current technology lacks an all-weather, self-driven solution that can truly adapt to changes in the natural environment, intelligently couple discrete and fluctuating light and mechanical energy, efficiently convert it into continuous catalytic power, and achieve efficient catalyst utilization and stable system operation. Therefore, developing a novel photo-piezoelectric synergistic wastewater treatment device to overcome the aforementioned energy coupling bottlenecks and material system limitations, and achieve low-energy consumption, high-efficiency, and sustainable deep purification of pollutants, has become a critical technical challenge urgently needing to be solved in this field. Summary of the Invention

[0004] Objectives of the Invention: One objective of the present invention is to provide a Bi4Ti3O1 piezoelectric catalyst with cationic Ti vacancies. Another objective of the present invention is to provide a method for preparing the piezoelectric catalyst. A further objective of the present invention is to provide the application of the piezoelectric catalyst in wastewater treatment. A final objective of the present invention is to provide a dedicated system for treating wastewater using the piezoelectric catalyst.

[0005] Technical solution: The present invention describes a Bi4Ti3O4 with cation Ti vacancies. 12The preparation method of piezoelectric catalyst includes the following steps:

[0006] (1) Synthesis of Bi4Ti3O by hydrothermal method 12 ;

[0007] (2) Bi4Ti3O 12 Mix with an aqueous solution of glyoxal, heat to react, wash, and dry to obtain the intermediate product;

[0008] (3) Dissolve the obtained intermediate product and ethanol in water, continue heating the reaction, centrifuge, wash, and dry.

[0009] Furthermore, in step (1), Bi4Ti3O is synthesized by hydrothermal method. 12 Includes the following steps:

[0010] (1) Dissolve Bi(NO3)3·5H2O in H2O to prepare solution A;

[0011] (2) Dissolve Ti(OC4H9)4 and NaOH in H2O to prepare solution B;

[0012] (3) Add solution A dropwise to solution B and stir vigorously to mix, thus obtaining a homogeneous precursor;

[0013] (4) Add sodium oleate and methanol to the precursor, stir, heat to react, centrifuge, wash and dry.

[0014] Furthermore, the mass-to-volume ratio of Bi(NO3)3·5H2O, Ti(OC4H9)4, NaOH, sodium oleate, and methanol is (1.3968-1.7072):(0.738-0.902):(1.728-2.112):(27-33):(1.8-2.2) g / mL / g / mg / mL; in step (3), the heating temperature is 175-185℃, and the heating time is 30-31h. In step (2), the concentration of glyoxal aqueous solution is 30-50%, and Bi4Ti3O 12 The mass-to-volume ratio of glyoxal to aqueous solution is 25:(21-84) g / mL, the heating temperature is 115-125℃, and the heating time is 4.5-5.5h. In step (3), the mass-to-volume ratio of intermediate product to ethanol is 1:(18-22) g / mL, the heating temperature is 105-115℃, and the heating time is 3.5-4.5h.

[0015] The preparation method of the present invention yields Bi4Ti3O with cationic Ti vacancies. 12 Application of piezoelectric catalysts in wastewater treatment.

[0016] This invention also includes a highly efficient and energy-saving light-pressure coupled wastewater treatment system, using Bi4Ti3O4 with cationic Ti vacancies obtained by the preparation method described in this invention. 12 Piezoelectric catalyst.

[0017] Furthermore, the high-efficiency and energy-saving photo-piezoelectric coupling wastewater treatment system includes a water tank, a photocatalytic reactor, and a piezoelectric catalytic reactor. The piezoelectric catalytic reactor simulates a natural river channel, including a reservoir and a biomimetic river zone. The photocatalytic reactor is located within the reservoir, which is connected to the water tank via the biomimetic river zone. The reservoir is higher than the water tank. The water tank is connected to the photocatalytic reactor via a water conveying device. The photocatalytic reactor contains a photocatalyst. The inner walls and bottom of the reservoir, the biomimetic river zone, and the bottom of the water tank are all lined with Bi₄Ti₃O₃ loaded with cation Ti vacancies. 12 The PVDF composite membrane of the piezoelectric catalyst, the water tank, the photocatalytic reactor, the piezoelectric catalytic reactor, the water transfer device, the reservoir and the biomimetic river area are all made of fully transparent material.

[0018] Furthermore, the biomimetic river channel includes three consecutive curved tracks: a first curved track, a second curved track, and a third curved track. Multiple support columns are located at the bottom of these three tracks, which have a certain height difference. These three tracks form a smooth track, connecting the first curved track to the water storage tank and the third curved track to the water trough. The photocatalytic reactor is located inside the water storage tank, with its bottom flush with the tank. A drainage channel with a leak-proof mesh is located on the bottom side of the photocatalytic reactor. The water delivery device includes a lifting pipe and a water pump. The two ends of the lifting pipe are fixedly connected to the bottom of the lifting pipe and the bottom of the photocatalytic reactor, respectively. The side wall of the lifting pipe has a pipe opening. The water pump's suction port is connected to the water tank through a suction hose. The suction hose extends into the water tank. The water pump's outlet extends into the pipe opening through a delivery hose and is then lifted to the top of the pipe. The end of the delivery hose is connected to a connector. The upper end of the connector is equipped with an overflow baffle with dense small holes, allowing water to flow fully between the upper and lower parts of the overflow baffle. The lower end of the connector is fixedly connected to a leak-proof gasket. The outer diameter of the leak-proof gasket is larger than the outer diameter of the lifting pipe. The leak-proof gasket is placed at the bottom of the inner tank of the photocatalytic reactor and connected to the photocatalytic reactor as a whole, preventing water from leaking out of the lifting pipe.

[0019] This invention utilizes Bi(NO3)3·5H2O and Ti(OC4H9)4 to prepare Bi4Ti3O loaded with Ti vacancy cations. 12This invention utilizes piezoelectric catalysts in a dedicated wastewater treatment system to construct a photo-piezocatalytic cycle system that can operate both synergistically and independently, enabling all-weather operation. The dedicated system features independent photoelectric and piezoelectric units, achieving functional coupling through directional H2O2 transfer, and optimizing carrier separation and migration processes stepwise. It also addresses the problems of difficult catalyst recovery and weak hydrodynamic response. This invention leverages solar energy and hydrodynamic mechanical energy, simulating the energy utilization patterns of natural ecosystems, organically combining solar-driven photocatalysis with hydrodynamic mechanical energy-driven piezoelectric effects to achieve highly efficient and low-carbon treatment from "in-situ oxidant generation → instantaneous activation → deep mineralization." It efficiently and energy-savingly degrades pollutants and utilizes a water transfer device to achieve wastewater recycling. This provides a stable and economical solution for the treatment of recalcitrant organic pollutants.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0021] (1) The present invention uses Bi4Ti3O supported with cation Ti vacancies. 12 A PVDF composite membrane for piezoelectric catalysts and hydrogel particles for photocatalysts serve as catalyst supports. The PVDF membrane exhibits excellent flexibility and processability, perfectly conforming to the shape of the biomimetic river channel. The PVDF composite membrane also possesses high sensitivity, capable of detecting minute pressures or vibrations. Bi₄Ti₃O₃ with cationic Ti vacancies is also used. 12 Piezoelectric catalysts possess a unique layered structure, excellent stability, and superior piezoelectric properties, exhibiting high hydrodynamic response and effectively suppressing carrier recombination that may occur during the reaction. Photocatalyst hydrogel particles are self-cleaning and recyclable, replacing traditional easily lost powdered catalysts and minimizing secondary pollution.

[0022] (2) The special system of this invention simulates a natural river channel and uses the vortex-induced shear force generated when water flows through the bends and obstacles to apply mechanical force to the piezoelectric material, causing it to deform and thus achieving pollutant degradation and H2O2 activation. The system makes full use of solar energy and water flow energy, without the need for additional electricity or fossil fuels, and replaces the high-energy-consuming aeration, ultraviolet lamps or high-voltage power supply of traditional processes, achieving low-carbon, low-energy-consumption and low-cost sewage treatment.

[0023] (3) This invention uses an environmentally friendly and energy-efficient photocatalytic reaction to produce H2O2 in situ, replacing the anthraquinone method used in traditional H2O2 production, thereby reducing the risk of resource consumption and pollution during the transportation and addition of chemicals.

[0024] (4) The special system of this invention couples photocatalysis and piezoelectric catalysis, breaking through the limitations of single technology. When there is natural light, light and piezoelectricity work together to achieve continuous and efficient degradation of pollutants; in cloudy or rainy weather, or at night when there is no light, the piezoelectric effect generated by mechanical energy alone can still drive the continuous degradation of pollutants, thereby achieving all-weather, continuous and efficient degradation of pollutants.

[0025] (5) The dedicated system of this invention overcomes the inherent defects of simple light-piezoelectric superposition, realizes energy complementarity and functional coupling, and enables the photocatalytic unit and the piezoelectric catalytic unit to give full play to the advantages of each unit, optimizing the separation and migration of charge carriers during the degradation process. The enhanced efficiency of charge carrier separation and migration allows the subsequent catalytic reaction to continue, thereby improving the overall reaction efficiency.

[0026] (6) The present invention uses a water transfer device to circulate water until the degraded water meets the discharge standards, which greatly improves the degradation rate of pollutants. In actual water body tests, the degradation rate of new pollutants reached more than 90% within 2 hours, and the catalyst showed excellent stability and universality. Attached Figure Description

[0027] Figure 1 This is an overall structural diagram of the all-weather self-driven photo-piezoelectric synergistic wastewater treatment system in Example 3;

[0028] Figure 2 This is a top view of the all-weather self-driven photo-piezoelectric synergistic wastewater treatment system structure in Example 3;

[0029] Figure 3 This is a partial cross-sectional view of the connection between the water delivery device and the photocatalytic reactor in the all-weather self-driven photo-piezoelectric synergistic wastewater treatment system in Example 3;

[0030] Figure 4 This is a partial view of the piezoelectric catalytic reactor in the all-weather self-driven photo-piezoelectric synergistic wastewater treatment system of Example 3;

[0031] Figure 5 for Figure 4 A magnified view of part A in the image;

[0032] The components include: 1. Water tank; 2. Photocatalytic reactor; 3. Piezoelectric catalytic reactor; 4. Water transfer device; 5. Water storage tank; 6. River biomimetic zone; 7. First curved track; 8. Second curved track; 9. Third curved track; 10. Support column; 11. Lifting pipe; 12. Pipe opening; 13. Pumping hose; 14. Water delivery hose; 15. Leak-proof gasket; 16. Connector; 17. Nut; 18. Overflow baffle; 19. Hydrogel particles; 20. PVDF composite membrane; 21. Water pump; 22. Drainage channel.

[0033] Figure 6 Figure 1 shows the performance results of different glyoxal dosages and the piezoelectric catalyst in Example 3 for degrading RhB fuel wastewater;

[0034] Figure 7 The graph shows the performance results of treating RhB fuel wastewater in Example 3 and Comparative Examples 1-4. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0036] Example 1: Bi4Ti3O with cationic Ti vacancies 12 Preparation of piezoelectric catalysts

[0037] (1)Bi4Ti3O 12 Synthesized via a hydrothermal method: Solution A was prepared by dissolving 1.552 g of Bi(NO3)3·5H2O in 16 mL of H2O (350 rpm, 100 mL beaker). Solution B was prepared by dissolving 0.82 mL of Ti(OC4H9)4 and 1.92 g of NaOH in 16 mL of H2O (800 rpm, approximately 30 min, 50 mL reactor). Solution A was then added dropwise to solution B, and the mixture was stirred vigorously for 60 min (700 rpm, 50 mL reactor) to obtain a homogeneous precursor. Subsequently, 30 mg of sodium oleate and 2 mL of methanol were added sequentially, and the mixture was stirred for 60 min (700 rpm, 50 mL reactor). The mixture was heated at 180 °C for 20 h. The product was collected by centrifugation and then washed three times alternately with deionized water and ethanol. After washing, the product was dried in a vacuum drying oven at 60 °C for 10 h. The dried product was then ground to obtain Bi4Ti3O. 12 , denoted as BTO.

[0038] (2) Bi4Ti3O with Ti vacancy of cation 12 Synthesis: 0.25 g Bi4Ti3O was added to 30 mL H2O. 12 Add 0.42 mL of glyoxal aqueous solution (40 wt. % in H2O) and stir for 120 min (700 rpm, 50 mL reactor). Heat at 120 °C for 5 h. Collect the sample by washing five times with deionized water and vacuum drying. Next, dissolve 0.25 g of the above sample and 5 mL of ethanol in 30 mL of H2O and stir vigorously for 60 min (700 rpm, 50 mL reactor). Heat at 110 °C for 4 h. Collect the product by centrifugation, followed by three alternating washes with deionized water and ethanol. After washing, dry in a vacuum drying oven at 60 °C for 10 h. Grind and dry the product to obtain Bi4Ti3O with cationic Ti vacancy sites.12 , denoted as BTO-V Ti .

[0039] Example 2

[0040] The preparation process is the same as in Example 1, except that Bi4Ti3O with cationic Ti vacancies is prepared. 12 At that time, glyoxal volumes of 0.21, 0.42, and 0.84 mL were used, respectively, to obtain the corresponding BTO-V. Ti 1. BTO-V Ti 2 and BTO-V Ti 3. Three types of samples. 25 mg of each of the three samples and BTO were placed in a beaker containing 50 mL of 5 ppm RhB and sonicated for 30 min. The results are as follows: Figure 6 As shown, Bi4Ti3O with Ti cation vacancies 12 The degradation performance of [the substance] is significantly higher than that of the BTO precursor. Furthermore, BTO-V prepared using 0.42 mL of glyoxal... Ti 2 exhibits the best degradation performance.

[0041] Example 3

[0042] refer to Figure 1 The present invention discloses an all-weather self-driven photo-piezoelectric synergistic wastewater treatment system, comprising a water tank 1, a photocatalytic reactor 2, and a piezoelectric catalytic reactor 3. The piezoelectric catalytic reactor 3 simulates a natural river channel, including a reservoir 5 and a river-inspired bionic zone 6. The photocatalytic reactor 2 is located within the reservoir 5, which is connected to the water tank 1 via the river-inspired zone 6. The reservoir 5 is higher than the water tank 1. The water tank 1 is connected to the photocatalytic reactor 2 via a water conveying device 4. The photocatalytic reactor 2 contains a photocatalyst. The inner walls and bottom of the reservoir 5, the river-inspired zone 6, and the bottom of the water tank 1 are all covered with a PVDF composite membrane loaded with the piezoelectric catalyst prepared in Example 1. The PVDF composite membrane perfectly conforms to the shape of the aforementioned areas. The water tank 1, photocatalytic reactor 2, piezoelectric catalytic reactor 3, water conveying device 4, reservoir 5, and river-inspired zone 6 are all made of fully transparent materials.

[0043] refer to Figure 2The biomimetic river channel 6 includes three consecutive curved tracks: a first curved track 7, a second curved track 8, and a third curved track 9. Multiple support columns 10 are provided at the bottom of these three consecutive curved tracks to increase stability. The three consecutive curved tracks form a smooth track, and there is a certain height difference between them, allowing the first curved track 7 to connect to the reservoir 5 and the third curved track 9 to the water tank 1. The reservoir 5 is smoothly connected to the upper part of the first curved track 7, preventing water from splashing out of the system. The lowest surface of the third curved track 9 is slightly lower than the upper edge of the water tank 1. The three consecutive curved tracks achieve the height difference between the reservoir 5 and the water tank 1.

[0044] refer to Figures 3-5 The photocatalytic reactor 2 is located inside the water storage tank 5, with its bottom flush with the tank 5. The water delivery device 4 includes: a lift pipe 11, a pipe inlet 12, a pumping hose 13, a delivery hose 14, a leak-proof gasket 15, a connector 16, a nut 17, an overflow baffle 18, and a water pump 21. The two ends of the lift pipe 11 are fixedly connected to the bottom of the water tank 1 and the bottom of the photocatalytic reactor 2, respectively, serving as a support and connection. The lift pipe 11 has a pipe inlet 12 on its side wall. The water pump 21's suction port is connected to the water tank 1 through the pumping hose 13, which extends into the water tank 1. The outlet of the water pump 21 extends into the pipe opening 12 through the water delivery hose 14 and is then lifted to the upper end of the pipe 11. The outer diameter of the water delivery hose 14 is smaller than the inner diameter of the lifting pipe 11. The connector 16 is narrow at both ends and wide in the middle. The lower part of the connector 16 gradually widens along the water flow direction and is fixedly connected to the water delivery hose 14. The lower part of the connector 16 is fixedly connected to the leak-proof gasket 15. At the same time, the outer diameter of the leak-proof gasket 15 is larger than the outer diameter of the lifting pipe 11. The leak-proof gasket 15 is placed at the bottom of the inner tank of the photocatalytic reactor 2 and is connected to the photocatalytic reactor 2 as a whole. Water will not leak out from the lifting pipe 11. The upper part of the connector 16 is tapered along the water flow direction, and the end section with a constant diameter is threaded. The overflow baffle 18 passes through the connector 16 and is fixed to the connector 16 by the threaded connection of the nut 17. The inner diameter of the overflow baffle 18 matches the outer diameter of the connector 16. The outer diameter of the overflow baffle 18 is slightly smaller than the inner diameter of the photocatalytic reactor 2. In addition, the overflow baffle 18 has dense small holes, which allow water to flow fully through the upper and lower parts of the overflow baffle 18. The size of the photocatalyst particles in the photocatalytic reactor 2 is controllable. Between the overflow baffle 18 and the bottom of the photocatalytic reactor 2, the diameter of the small holes of the overflow baffle is smaller than the diameter of the photocatalyst particles, which controls the photocatalyst particles from leaking out of the photocatalytic reactor 2. A drainage channel 22 is arranged on the side and bottom of the photocatalytic reactor 2. The drainage channel 22 is covered with a leak-proof mesh, which effectively prevents the photocatalyst particles from flowing out of the photocatalytic reactor 2 while smoothly draining water.

[0045] Wastewater treatment process:

[0046] refer to Figure 4The water to be treated is placed in the water tank 1. The system is placed under sunlight. The power of the water pump 21 is turned on. The water enters the water pump 21 from the water pump 13, and then enters the water delivery hose 14 through the water pump 21. It flows through the pipe opening 12 of the lifting pipe 11 to the end of the water delivery hose 14. Then it flows through the connector 16 and overflows from its upper end. The water flows down and flows into the photocatalytic reactor 2 through the hole of the overflow baffle 18, making full contact with the photocatalyst and causing the photocatalyst to roll. The sunlight excites the photocatalyst to produce H2O2 through a photocatalytic reaction. Then the water carrying H2O2 flows from the side drainage channel 22 of the photoreactor to the water storage tank 5, where mechanical force excites the piezoelectric reaction. The water then flows into the biomimetic river zone 6. Under the influence of gravitational potential energy, the water, with a certain flow velocity, flows sequentially through the first curved track 7, the second curved track 8, and the third curved track 9, generating vortex-induced shear force. The water then rushes into the water tank 1 at the end of the biomimetic river zone 6, generating mechanical force. Under the action of vortex-induced shear force and mechanical force, the PVDF membrane undergoes a piezoelectric effect to degrade organic pollutants. Simultaneously, the piezoelectric effect activates H2O2 to ∙OH, achieving deep mineralization of pollutants. At night without light or on cloudy or rainy days with weak natural light, the photocatalyst in the photocatalytic reactor 2 hardly undergoes photocatalysis. After overflowing, the water directly enters the storage tank 5, generating mechanical force to stimulate the piezoelectric reaction. Flowing through the first curved track 7, the second curved track 8, and the third curved track 9, under the action of gravitational potential energy and vortex-induced shear force, the piezoelectric reaction is further stimulated, causing the PVDF membrane to generate ∙OH and ∙O2 in situ. - Active oxygen species such as H2O2 degrade pollutants in water through piezoelectricity alone. The treated water is then pumped from the water tank 1 to the upper photocatalytic reactor 2 via pump 21, repeating the process until the degraded water meets discharge standards.

[0047] Example 4

[0048] The all-weather self-driven photo-piezoelectric synergistic wastewater treatment system shown in Example 3 uses a hydrogel-like granular KI-PCN photocatalyst, which is combined with a PVDF film-supported Bi4Ti3O4 containing cationic Ti vacancies. 12 A composite catalytic system was constructed using a PVDF composite membrane formed by a piezoelectric catalyst.

[0049] The preparation of the KI-PCN photocatalyst supported on hydrogel particles was based on previously published papers. The specific process is as follows: First, 2 g of melamine and 6 g of potassium iodide were mixed and ground uniformly. The resulting white powder was pyrolyzed in a nitrogen atmosphere at a programmed temperature of 2.5 °C / min to 550 °C and maintained at this temperature for 6 hours. After cooling, the crude product was washed with deionized water and filtered, and then vacuum dried at 80 °C for 12 hours to obtain the KI-PCN catalyst. Then, 1 g of sodium alginate and 0.1 g of KI-PCN catalyst were dispersed in 50 mL of deionized water and stirred vigorously until completely dissolved to form a homogeneous solution. Finally, this mixed solution was added dropwise to a 0.1 g / mL calcium chloride aqueous solution. Upon contact with calcium ions, the droplets rapidly solidified into spherical gel beads. After repeated washing with deionized water to remove surface residues, the final KI-PCN gel material was obtained.

[0050] PVDF thin film supporting Bi4Ti3O with cationic Ti vacancies 12 The preparation of the piezoelectric catalyst (PVDF-based composite membrane) is detailed below:

[0051] PVDF-based composite membranes (PVDF films loaded with Bi₄Ti₃O₃ containing cationic Ti vacancies) were prepared using a phase inversion method. 12 (Piezoelectric catalyst): First, 2.5 g of PVDF was dissolved in 20 mL of triethyl phosphate, and the mixture was magnetically stirred at 90 °C for 4 hours to ensure complete dissolution of the polymer; then, 0.125 g of BTO-V prepared in Example 1 was added to the solution. Ti The material was magnetically stirred at 90°C for 30 minutes to achieve uniform dispersion. The uniformly mixed casting solution was then poured onto a clean glass plate (20cm × 10cm) (corresponding to the riverbed biomimetic area 6 in this embodiment) and scraped to form a thin liquid film. The glass plate with the liquid film was immediately immersed in a deionized water bath for 12 hours to completely remove residual solvent. After natural drying, a PVDF film supporting Bi4Ti3O4 with cationic Ti vacancies was finally obtained. 12 Piezoelectric catalyst composite membrane, namely PVDF-based composite membrane.

[0052] The system was placed under sunlight, and a 0.5 L solution containing 0.5 ppm RhB dye was circulated from water tank 1 using a water pump. Samples were taken every 10 minutes from the start of the reaction. A comparative experiment was also conducted in the absence of sunlight, and the results are shown in Figure 6.

[0053] Comparative Example 1: Piezoelectric catalytic system in a simulated river biomimetic zone under no light exposure

[0054] In Example 4, the system was kept in the dark. 0.5L of RhB dye containing 5ppm was placed in water tank 1 and circulated. Starting from the start of the reaction, samples were taken every 10 minutes for 70 minutes, simulating a nighttime treatment process. The results are as follows. Figure 7 As shown.

[0055] Comparative Example 2: Traditional beaker reaction system under light irradiation only (without mechanical stirring, simulating pure photocatalytic conditions).

[0056] Add 50 mL of the solution containing 5 ppm RhB to a beaker, add 25 mg of photocatalyst (but no piezoelectric catalyst), and irradiate for 70 minutes. Starting from the start of the reaction, take samples every 10 minutes. The results are as follows: Figure 7 As shown.

[0057] Comparative Example 3: Traditional beaker reaction system with pure piezoelectric effect without light (no light, only mechanical stirring).

[0058] Add 50 mL of the solution containing 5 ppm RhB to a beaker, add 25 mg of piezoelectric catalyst (no photocatalyst added), protect the system from light, and magnetically stir (700 rpm) for 70 minutes. Start timing from the beginning of the reaction, and take samples every 10 minutes. Results are as follows: Figure 7 As shown.

[0059] Comparative Example 4: A conventional beaker reaction system with the combined effects of light and mechanical stirring simulates a photo-piezoelectric catalytic system without a riverbed biomimetic zone (with both light and mechanical stirring).

[0060] Add 50 mL of the solution containing 5 ppm RhB to a beaker, then add 25 mg of photocatalyst and 25 mg of piezoelectric catalyst. Under light irradiation, magnetically stir (700 rpm) for 70 minutes. Starting from the start of the reaction, take samples every 10 minutes. Results are as follows: Figure 7 As shown.

[0061] Depend on Figure 7 As can be seen, in Example 1, the solution changed from pink to colorless after 70 minutes of reaction under sunlight, with an RhB degradation rate as high as 98%, indicating that the system has good degradation performance for pollutants in water and shows good potential for practical application. In Comparative Example 4, the degradation rate of simulated light combined with piezoelectricity was 77%, higher than the 50% effect of the simulated river biomimetic zone without light in Comparative Example 1, indicating that the combination of photocatalysis and piezoelectric catalysis can play a synergistic treatment role. Comparing Example 2 and Comparative Example 4, it is evident that the piezoelectric effect provided by the river biomimetic zone has a better treatment effect. In Comparative Examples 2 and 3, the effects of light alone or piezoelectricity alone were significantly poor, only 29% and 26%, respectively.

[0062] The above results show that, under the synergistic effect of light and piezoelectricity, the system of this invention exhibits the highest RhB degradation efficiency. Compared with traditional photocatalytic or piezoelectric catalytic processes under mechanical stirring, the degradation performance of the system of this invention is significantly improved, further highlighting the effectiveness of its synergistic catalytic mechanism.

[0063] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Bi₄Ti₃O₃ with cation Ti vacancies 12 A method for preparing a piezoelectric catalyst, characterized in that, Includes the following steps: (1) Synthesis of Bi4Ti3O by hydrothermal method 12 ; (2) Bi4Ti3O 12 Mix with an aqueous solution of glyoxal, heat to react, wash, and dry to obtain the intermediate product; (3) Dissolve the obtained intermediate product and ethanol in water, continue heating the reaction, centrifuge, wash, and dry.

2. The preparation method according to claim 1, characterized in that, In step (1), Bi4Ti3O is synthesized by hydrothermal method. 12 Includes the following steps: (1) Dissolve Bi(NO3)3·5H2O in H2O to prepare solution A; (2) Dissolve Ti(OC4H9)4 and NaOH in H2O to prepare solution B; (3) Add solution A dropwise to solution B and stir vigorously to mix, thus obtaining a homogeneous precursor; (4) Add sodium oleate and methanol to the precursor, stir, heat to react, centrifuge, wash and dry.

3. The preparation method according to claim 2, characterized in that, The mass-volume ratio of Bi(NO3)3·5H2O, Ti(OC4H9)4, NaOH, sodium oleate, and methanol is (1.3968-1.7072):(0.738-0.902):(1.728-2.112):(27-33):(1.8-2.2) g / mL / g / mg / mL; in step (3), the heating reaction temperature is 175-185℃, and the heating reaction time is 30-31h.

4. The preparation method according to claim 1, characterized in that, In step (2), the concentration of glyoxal aqueous solution is 30-50%, and Bi4Ti3O 12 The mass-to-volume ratio of glyoxal to aqueous solution is 25:(21-84) g / mL, the heating temperature is 115-125℃, and the heating time is 4.5-5.5h. In step (3), the mass-to-volume ratio of intermediate product to ethanol is 1:(18-22) g / mL, the heating temperature is 105-115℃, and the heating time is 3.5-5h.

5. Bi₄Ti₃O₃ with cationic Ti vacancies obtained by the preparation method of claims 1-4 12 Application of piezoelectric catalysts in wastewater treatment.

6. A high-efficiency and energy-saving photo-pressure coupled wastewater treatment system, characterized in that, Bi₄Ti₃O₃ with cation Ti vacancies obtained using the preparation method according to claims 1-4 12 Piezoelectric catalyst.

7. The high-efficiency and energy-saving photo-pressure coupled sewage treatment system according to claim 6, characterized in that, The system includes a water tank (1), a photocatalytic reactor (2), and a piezoelectric catalytic reactor (3). The piezoelectric catalytic reactor (3) simulates a natural river channel and includes a reservoir (5) and a river channel biomimetic zone (6). The photocatalytic reactor (2) is located inside the reservoir (5), which is connected to the water tank (1) via the river channel biomimetic zone (6). The reservoir (5) is higher than the water tank (1). The water tank (1) is connected to the photocatalytic reactor (2) via a water conveying device (4). The photocatalytic reactor (2) contains a photocatalyst. The inner walls and bottom of the reservoir (5), the river channel biomimetic zone (6), and the bottom of the water tank (1) are all covered with Bi4Ti3O4 loaded with cation Ti vacancies. 12 The PVDF composite membrane of the piezoelectric catalyst, the water tank (1), the photocatalytic reactor (2), the piezoelectric catalytic reactor (3), the water transfer device (4), the water storage tank (5) and the biomimetic river area (6) are all made of fully transparent material.

8. The high-efficiency and energy-saving photo-pressure coupled sewage treatment system according to claim 7, characterized in that, The river bionic area (6) includes three continuous curved tracks: the first curved track (7), the second curved track (8) and the third curved track (9); the bottom of the three continuous curved tracks is provided with multiple support columns (10), and there is a certain height difference between the three curved tracks. The three continuous curved tracks form a smooth track, so that the first curved track (7) is connected to the reservoir (5) and the third curved track (9) is connected to the water tank (1).

9. The high-efficiency and energy-saving photo-pressure coupled sewage treatment system according to claim 7, characterized in that, The photocatalytic reactor (2) is located inside the water storage tank (5), with its bottom flush with the water storage tank (5). A drainage channel (22) is arranged on the bottom side of the photocatalytic reactor (2), and a leak-proof mesh is provided on the drainage channel (22).

10. The high-efficiency and energy-saving photo-pressure coupled sewage treatment system according to claim 7, characterized in that, The water delivery device (4) includes a lifting pipe (11) and a water pump (21). The two ends of the lifting pipe (11) are fixedly connected to the bottom of the water tank (1) and the bottom of the photocatalytic reactor (2), respectively. The side wall of the lifting pipe (11) is provided with a pipe opening (12). The water inlet of the water pump (21) is connected to the water tank (1) through a water pumping hose (13). The water pumping hose (13) extends into the water tank (1). The water outlet of the water pump (21) extends into the pipe opening (12) through a water delivery hose (14) and is then lifted to the upper end of the pipe (11). 4) The end is connected to a connector (16). The upper end of the connector (16) is provided with an overflow baffle (18). The overflow baffle (18) has dense small holes, and the water can flow fully in the upper and lower parts of the overflow baffle (18). The lower end of the connector (16) is fixedly connected to a leak-proof gasket (15). The outer diameter of the leak-proof gasket (15) is larger than the outer diameter of the lifting pipe (11). The leak-proof gasket (15) is placed at the bottom of the inner tank of the photocatalytic reactor (2) and connected to the photocatalytic reactor (2) as a whole. The water will not leak out from the lifting pipe (11).

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