Electrocatalytic ceramsite, sewage treatment reaction device and sewage treatment method

Abstract

The invention relates to electrocatalytic ceramsite, a sewage treatment reaction device and a sewage treatment method, and relates to the technical field of environmental engineering and water treatment. The electrocatalytic ceramsite comprises a porous matrix and a composite coating, wherein the porous matrix is formed by mixing, granulating and sintering sludge and fly ash; the composite coating comprises a SnO2-Sb catalyst layer and a polypyrrole conductive coating which are sequentially formed on the surface of the porous matrix. The sewage treatment device comprises a filler layer, a water distribution system, an ultrasonic generator and an electrode system, the filler layer is filled with the electrocatalytic ceramsite, the electrode system comprises a plurality of groups of anodes and cathodes, the anodes and the cathodes are distributed in a crossed array mode, and the electrocatalytic ceramsite is polarized under the action of the electrode system to form particle electrodes. The device is large in reaction area and high in passivation resistance, and has a good removal effect on organic matters and heavy metals.

Description

Technical Field

[0001] This application relates to the fields of environmental engineering and water treatment technology, and in particular to an electrocatalytic ceramic particle, a wastewater treatment reaction device, and a wastewater treatment method. Background Technology

[0002] In recent years, with the acceleration of industrialization, the composition of industrial wastewater generated by industries such as chemical, electroplating, and pharmaceutical has become increasingly complex. This type of wastewater typically exhibits three high characteristics: high concentrations of recalcitrant organic matter, high concentrations of heavy metal ions (such as Cr6+, Pb2+, Cu2+, etc.), and high salinity. Traditional single-treatment technologies are often insufficient to meet increasingly stringent environmental emission standards for this type of wastewater.

[0003] Currently, electrochemical water treatment technology has attracted much attention due to its environmental friendliness and controllability. For example, existing technology CN1122253A discloses an electrochemical oxidation method that uses a flat titanium-based coated electrode to directly electrolyze and generate reactive oxygen species (ROS) to degrade pollutants. However, this technology based on a two-dimensional flat electrode has significant drawbacks: First, the effective reaction area of ​​two-dimensional electrodes is small (usually ≤10m² / m³), resulting in low spacetime yield. Secondly, in the treatment of high-concentration organic wastewater, intermediate products are easily adsorbed on the electrode surface to form a polymer film, which leads to electrode passivation. This results in current efficiency generally being less than 50%, and frequent acid washing maintenance is required, increasing operating costs.

[0004] Another common technology is the fixed-bed adsorption-catalysis method (e.g., US20180056211A1), which uses activated carbon or zeolite as a support to support a catalyst (e.g., Fe3O4), relying on the addition of H2O2 to initiate a Fenton-like reaction. Although this method can effectively degrade organic matter, it consumes a large amount of reagents (H2O2 dosage is often ≥500 mg / L), resulting in high operating costs and generating a large amount of iron-containing sludge (≥2 kg / m³), causing secondary pollution. More importantly, this method mainly targets the oxidation of organic matter, with extremely limited effectiveness in removing heavy metal ions, making it difficult to achieve the synergistic removal of multiple pollutants.

[0005] In addition, although some technologies have attempted to introduce ultrasonic assistance (such as JP2020506781A) to enhance mass transfer by utilizing the cavitation effect, ultrasonic waves are often only used as an auxiliary means in existing devices, and due to the uneven distribution of the sound field, the cavitation area is severely localized (coverage ≤30%), making it difficult to achieve efficient degradation of pollutants across the entire cross section of the reactor.

[0006] In summary, the current field of industrial wastewater treatment faces technical challenges such as the contradiction between efficiency and energy consumption, competitive inhibition of multiple pollutants (organic oxidation and heavy metal reduction competing for electrons), and short electrode and packing lifespan. There is an urgent need for a highly efficient treatment device that can overcome the limitations of two-dimensional electrode area, possess strong resistance to passivation, and simultaneously achieve organic oxidation and heavy metal reduction. Summary of the Invention

[0007] The purpose of this application is to provide an electrocatalytic ceramic particle, a wastewater treatment reaction device, and a wastewater treatment method, aiming to solve the technical problems existing in the current electrochemical water treatment technology, such as small effective reaction area, easy passivation of electrodes, low mass transfer efficiency, and difficulty in simultaneously and efficiently removing organic matter and heavy metal ions.

[0008] Firstly, the electrocatalytic ceramic particle provided in this application adopts the following technical solution: An electrocatalytic ceramic particle, comprising: The porous matrix is ​​formed by mixing and granulating sludge and fly ash, followed by sintering. The composite coating comprises a SnO2-Sb catalytic layer and a polypyrrole conductive coating sequentially formed on the surface of the porous substrate.

[0009] Furthermore, the method for preparing the porous matrix includes the following steps: Fly ash and treated sludge are mixed to form a primary product, wherein the mass ratio of sludge to fly ash is set to 2 to 4:1. Adding binders and conductive agents to the primary product forms a secondary product; The secondary product is granulated and sintered to form the porous matrix.

[0010] Furthermore, the sintering includes the following steps: The temperature was increased from room temperature to 600℃ at a rate of 5℃ / min and held at that temperature for 1 hour. The temperature was increased from 600℃ to 1050℃ at a rate of 10℃ / min, and held at that temperature for 2 hours. The temperature was cooled to room temperature under nitrogen atmosphere.

[0011] Furthermore, the treatment of the sludge includes the following steps: Soak the sludge in 5% hydrochloric acid for 24 hours and rinse until neutral; The cleaned sludge was dried at 105℃ and passed through a 100-mesh sieve. The screened sludge was ball-milled to a particle size D50≤50μm.

[0012] Furthermore, the SnO2-Sb catalyst layer is loaded by electrodeposition, and the thickness of the SnO2-Sb catalyst layer is 50-200 nm.

[0013] Secondly, the wastewater treatment reaction device provided in this application adopts the following technical solution: A wastewater treatment reaction device, comprising: The reaction tank has a packing layer inside, wherein the packing layer is the electrocatalytic ceramic particles as described in any one of claims 1-5; A multi-stage water distribution system, which is configured as a spiral tube structure and located above the packing layer; An ultrasonic generator is installed inside the reaction tank to generate a cavitation field; An electrode system includes multiple sets of anodes and cathodes, with the multiple sets of anodes and cathodes arranged in a cross-array. The electrocatalytic ceramic particles are polarized under the action of the electrode system to form particle electrodes.

[0014] Furthermore, the anode is a composite electrode with a Ti substrate and a surface coated with Ta2O5 and IrO2; the cathode is an activated carbon felt electrode loaded with nano Fe3O4 particles, the Fe3O4 particles having a particle size of 10-50 nm.

[0015] Furthermore, the helical tube structure includes a helical tube and guide fins disposed thereon, wherein the helical angle of the helical tube is 30–45°, used to induce a generation intensity γ ≥ 15s. -1 The vortex.

[0016] Furthermore, a filter layer is provided at the bottom of the reaction tank, the filter layer including an upper activated carbon adsorption layer and a lower ion exchange resin layer.

[0017] Thirdly, the wastewater treatment method provided in this application adopts the following technical solution: A wastewater treatment method, employing the wastewater treatment reaction apparatus described in the second aspect above, includes the following steps: Wastewater is introduced and enters the reaction tank through a multi-stage water distribution system, where it generates swirling flow and flows through a packing layer formed by electrocatalytic ceramic particles. The wastewater undergoes an oxidation-reduction reaction in the packing layer; An ultrasonic generator applies a cavitation effect to the reaction zone, and the ultrasonic generator switches between low-frequency and high-frequency modes to promote the dissociation of pollutants in wastewater and inhibit electrode passivation. The treated wastewater is discharged from the device after filtration.

[0018] In summary, this application includes at least one of the following beneficial technical effects: 1. An electrocatalytic ceramic particle with both adsorption and electrocatalytic functions was prepared by using a porous matrix made from river and lake silt and fly ash, and loading it with a SnO2-Sb catalytic layer and a PPy conductive layer. Under the action of an electric field, this ceramic particle forms a three-dimensional particle electrode, which can increase the effective reaction area of ​​the reaction system several times, significantly improving the current efficiency (≥80%).

[0019] 2. The integrated spiral water distribution system induces strong swirling flow through the spiral tube structure and guide fins, causing isotropic turbulence when wastewater enters the ceramsite layer, thus increasing the mass transfer coefficient to 1.2 × 10⁻⁶. -4 m / s, effectively overcoming the low mass transfer efficiency of traditional fixed-bed reactors.

[0020] 3. An ultrasonic generator is introduced, employing a dual-frequency switching mode. Low-frequency ultrasound (20kHz) generates high cavitation bubble collapse pressure, effectively stripping scale from the electrode and ceramic particle surface, preventing electrode passivation; high-frequency ultrasound (40kHz) promotes the generation of ·OH free radicals, enhancing oxidation efficiency. The synergistic effect of ultrasound and electrochemistry solves the problem of electrode deactivation caused by high-concentration wastewater.

[0021] 4. The electrode system, combined with the micro-electric field effect of electrocatalytic ceramic particles, achieves the synergistic process of organic matter oxidation and heavy metal reduction, solving the problem of competitive inhibition of multiple pollutants in traditional technologies. The COD removal rate can reach over 95%, and the heavy metal removal rate can reach over 99%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the wastewater treatment reaction device in the embodiments of this application; Figure 2 This is a flowchart illustrating the preparation process of electrocatalytic ceramic particles in the embodiments of this application; Figure 3 This is a flowchart illustrating the preparation process of the Ti / IrO2-Ta2O5 anode in the embodiments of this application; Figure 4 This is a flowchart illustrating the preparation process of the Fe3O4-supported activated carbon felt cathode in the embodiments of this application; 1. Reaction tank; 2. Inlet; 3. Exhaust outlet; 4. Drain outlet; 5. Multi-stage water distribution system; 501. Guide fins; 6. Packing layer; 7. Ultrasonic generator; 8. Electrode system; 801. Anode; 802. Cathode; 9. Intelligent control system; 10. Filter layer; 1001. Activated carbon adsorption layer; 1002. Ion exchange resin layer. Detailed Implementation

[0024] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.

[0025] In the description of this application, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this application and to simplify the description, and are not intended to indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] It should also be further understood that the term “and / or” as used in this application refers to any combination of one or more of the listed items, and all possible combinations thereof.

[0028] This embodiment provides an electrocatalytic ceramic particle that serves as a biomembrane carrier and further as a particle electrode in a three-dimensional electrochemical reaction system. Under the influence of the electric field generated by the main electrodes (anode and cathode), the two ends of the ceramic particle become polarized, with one end carrying a positive charge and the other a negative charge, thereby forming several tiny electrolytic cells.

[0029] Specifically, the electrocatalytic ceramic particles include a porous matrix and a composite coating formed on the surface of the porous matrix.

[0030] First, regarding the porous matrix, river and lake silt and fly ash are used as the main raw materials. This reduces raw material costs while enabling the reuse of solid waste. Furthermore, the microsphere structure in the fly ash and the organic matter in the silt form a porous structure during high-temperature sintering, which is beneficial for improving the specific surface area and adsorption performance of the ceramsite.

[0031] The composition tables of river and lake silt and fly ash can be found in Table 1 and Table 2, respectively.

[0032] Table 1 Table 2 The preparation method of the porous matrix includes the following steps: S1: Raw material pretreatment.

[0033] Sludge Treatment: River and lake sludge is collected and first subjected to acid washing. Specifically, the sludge is soaked in 5% hydrochloric acid for 24 hours. The purpose of acid washing is to remove unstable acid-soluble inorganic salt impurities and some organic impurities from the sludge, preventing them from causing cracking or reduced strength of the ceramsite during subsequent sintering. After acid washing, the sludge is rinsed with pure water until neutral, then dried at 105℃ and passed through a 100-mesh sieve. To ensure sintering density, the sieved sludge is further ball-milled to a particle size D50 ≤ 50 μm.

[0034] Fly ash treatment: The fly ash is magnetically separated to remove iron, and the Fe2O3 content is controlled to be ≤3%. This is because excessive iron content will reduce the insulation resistance of the substrate and affect the polarization effect of the subsequent conductive coating. Subsequently, it is activated by alkali fusion (NaOH: fly ash = 1:2), calcined at 600℃ for 1 hour, and finally ball-milled to a particle size ≤50μm.

[0035] S2: Mixed granulation.

[0036] The treated fly ash is mixed with sludge to form a primary product, wherein the ratio of sludge to fly ash is set to 2 to 4:1.

[0037] If the proportion of sludge is too high, excessive shrinkage during sintering will easily lead to cracking; if the proportion of fly ash is too high, the granulation adhesion will be insufficient. For example, in this embodiment, the mass ratio is selected as 3:1.

[0038] A binder and a conductive agent are added to the primary product to form a secondary product.

[0039] Regarding the binder, one or more of polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), or starch can be selected, for example. In this embodiment, 5 wt% PVA is preferably added. Regarding the conductive agent, one or more of graphite powder, carbon black, or carbon nanotubes can be selected, for example. In this embodiment, 2 wt% graphite powder is preferably added. The purpose of adding the conductive agent is to form a preliminary conductive network within the ceramsite matrix, thereby reducing the matrix resistance.

[0040] The secondary product is granulated and sintered to form the porous matrix.

[0041] For example, a rotary granulator is selected to granulate the secondary product. The rotary granulator is used to form and granulate at a speed of 200 rpm, and the particle size is controlled to be 5-10 mm.

[0042] S3: Segmented sintering.

[0043] The secondary product particles are sintered. In this embodiment, a segmented temperature control program is used: Phase 1: The temperature is increased from room temperature to 600°C at a rate of 5°C / min and held at that temperature for 1 hour. This phase aims to slowly remove the binder (PVA) and residual organic matter from the sludge, creating pores while inhibiting particle bursting.

[0044] The second stage involves raising the temperature from 600℃ to 1050℃ at a rate of 10℃ / min and holding it at that temperature for 2 hours. This stage is the liquid-phase sintering stage, which ceramicizes the secondary product particles to achieve sufficient mechanical strength (compressive strength up to 8MPa).

[0045] The third stage involves cooling to room temperature under nitrogen atmosphere. Nitrogen gas inhibits the oxidation of the internally doped graphite conductive agent by air at high temperatures, thus ensuring the conductivity of the matrix.

[0046] The final porous matrix has a porosity of 60% and a specific surface area of ​​≥300m² / g.

[0047] Secondly, regarding the composite coating. The composite coating consists of a SnO2-Sb catalyst layer and a polypyrrole (PPy) conductive coating sequentially formed on the surface of a porous substrate.

[0048] SnO2-Sb catalyst layer: This layer contains the active sites for electrochemical oxidation reactions. SnO2 has a high oxygen evolution overpotential, meaning that during anodic polarization, the oxygen evolution reaction is inhibited, which favors the generation of highly oxidizing hydroxyl radicals, thus efficiently oxidizing organic pollutants. Doping with Sb is to improve the conductivity and catalytic activity of SnO2.

[0049] The SnO2-Sb catalyst layer was prepared by electrodeposition, specifically including the following steps: Using 0.015 mol / L Na₂SO₄ solution as the supporting electrolyte, SnCl₄·5H₂O, SbCl₃, and citric acid were mixed in a molar ratio of 4:1:2, and the pH was adjusted to 2.5. Electrocatalytic ceramic particles were used as the working electrode, and deposition was performed at 40 °C for 30 min using a constant current mode (20 mA / cm²), followed by annealing at 450 °C for 1 hour to form a rutile phase solid solution. The thickness of this layer was controlled to be 50–200 nm; in this example, it was 100 nm.

[0050] A polypyrrole (PPy) conductive coating is applied to the outermost layer. PPy is a highly conductive polymer material. It can improve the conductivity of the ceramic particle surface, making the electrocatalytic ceramic particles easier to polarize by the main electrode. At the same time, it acts as a protective layer to inhibit the peeling off of the internal SnO2-Sb layer under water erosion and acid / alkali environments.

[0051] The polypyrrole (PPy) conductive coating is prepared by chemical oxidative polymerization, specifically including the following steps: The ceramsite loaded with the catalyst layer was immersed in an ethanol solution containing 0.1 mol / L pyrrole monomer and 0.2 mol / L FeCl3 (oxidant), and reacted for 30 min under ultrasonic (40 kHz) assistance. The final PPy film was approximately 100 nm thick and had a sheet resistance ≤0.5 Ω.

[0052] Example 2: This embodiment provides a wastewater treatment reactor based on the aforementioned electrocatalytic ceramic particles. (Refer to...) Figure 1 The main structure of the device includes a reaction tank 1, a multi-stage water distribution system 5, a packing layer 6, an ultrasonic generator 7, an electrode system 8, an intelligent control system 9, and a filter layer 10.

[0053] Reaction tank 1 is the main site for wastewater treatment and adopts a vertical cylindrical design. Considering that the industrial wastewater being treated may be highly corrosive (such as acid and alkali waste liquids), the main body of reaction tank 1 is made of high-strength polypropylene (PP), and a double-layer anti-corrosion lining is installed on the inner wall.

[0054] For example, the bottom layer of the anti-corrosion lining can be a polytetrafluoroethylene (PTFE) membrane, a polyvinylidene fluoride (PVDF) membrane, or an ethylene-tetrafluoroethylene copolymer (ETFE) membrane. In this embodiment, a 2mm thick PTFE membrane is used as the bottom layer, and the top layer is a 10mm thick PP board, which can withstand an environment with pH 1 to 14.

[0055] The top of the reaction tank 1 is equipped with a water inlet 2 and an exhaust outlet 3. The exhaust outlet 3 is used to discharge trace gases (such as O2, H2, and CO2) generated by the electrochemical reaction. The bottom is equipped with a drain outlet 4. The top is also equipped with a gas-liquid separation zone with a height of approximately 200 mm.

[0056] A multi-stage water distribution system 5 is located above the packing layer 6 to address the "short-circuit" and "dead zone" problems present in traditional fixed-bed reactors, as shown in the reference. Figure 1 The multi-stage water distribution system 5 is configured as a spiral tube structure. The spiral tube structure includes a spiral tube and guide fins disposed thereon.

[0057] This strong swirling flow field not only improves mass transfer efficiency, but also causes the ceramic particles to move slightly within the reaction tank. Combined with the vibration of ultrasound, this further prevents the ceramic particles from sticking together and caking, ensuring the long-term stability of the three-dimensional electrode.

[0058] The spiral tube is made of ABS. The spiral angle is 30–45° to enhance turbulence. The guide fins are 3mm high and tilted at 45°. When wastewater flows through this spiral tube structure, it generates an intensity γ≥15s due to centrifugal force and the induction of the guide fins. - ¹ Strong swirling flow.

[0059] This swirling flow gives the wastewater isotropic turbulent kinetic energy (k=0.15m² / s²) as it enters the underlying ceramsite packing layer, greatly eliminating channeling and increasing the mass transfer coefficient at the liquid-solid interface to 1.2×10⁻⁶. -4 m / s.

[0060] Furthermore, the packing layer 6 fills the middle of the reaction tank 1 and is formed by stacking the electrocatalytic ceramic particles described in Example 1. The filling height is approximately 800 mm. The ceramic particles serve as a three-dimensional particle electrode, filling the space between the anode 801 and the cathode 802.

[0061] The electrode system 8 includes multiple sets of anodes 801 and cathodes 802, which are arranged in a cross-array, with the electrode spacing set to 10-20 mm (15 mm in this embodiment). The electrocatalytic ceramic particles are polarized under the action of the electrode system 8 to form particle electrodes.

[0062] Anode 801: Anode 801 is a composite electrode with a Ti substrate and coated with a Ta2O5 underlayer and an IrO2 catalytic surface layer to improve the oxygen evolution overpotential and resist corrosion. The Ta2O5 as an intermediate layer (approximately 1 μm) significantly improves the adhesion between the catalytic layer and the titanium substrate, extending the electrode life. The IrO2 surface layer (approximately 1 μm, Ir loading 1.5 mg / cm²) provides highly efficient oxidation catalytic activity.

[0063] The preparation method is as follows: the titanium mesh is polished with sandpaper (180 mesh and 320 mesh) and then soaked in NaOH solution (40%, w / w) at 80℃ for 2 hours to remove grease. Subsequently, it is etched in boiling oxalic acid solution (10%, w / w) for 2 hours to remove the oxide film, then washed with pure water, and then stored in 5% oxalic acid solution for use.

[0064] IrCl3 and TaCl5 were dissolved in n-butanol solution at a molar ratio of 7:3, and 0.5% polyethylene glycol (PEG-2000) dispersant was added to form a coating solution. The coating solution was then applied to each side of the titanium mesh. The titanium mesh was then placed in a forced-air drying oven at 120°C for 10 min, and then calcined in a muffle furnace at 450°C for 10 min. (This process was repeated 3 times to increase the coating thickness to 2 μm).

[0065] Cathode 802: Cathode 802 uses an activated carbon felt electrode loaded with nano-Fe3O4 particles to enhance the reduction and removal capacity of heavy metal ions. The Fe3O4 particles have a particle size of 10–50 nm.

[0066] The preparation method is as follows: First, the activated carbon felt is refluxed in 65% nitric acid for 3 hours and washed with water until neutral to activate the carbon fibers in the felt. Then, the activated carbon felt treated above is immersed in a 0.1 mol / L FeSO4 solution, N2 is introduced to remove oxygen, and NH3·H2O is added dropwise until pH=10. Finally, the mixture is hydrothermally reacted at 120℃ for 6 hours to form Fe3O4 particles with a particle size of 50 nm.

[0067] Reference Figure 4 An ultrasonic generator 7 is installed on the inner wall of the reaction tank 1 to generate a cavitation field covering the entire reaction area. The ultrasonic generator 7 of this device has a dual-frequency switching function, which can switch between low-frequency mode (20kHz) and high-frequency mode (40kHz).

[0068] Low-frequency mode (20kHz): generates large cavitation bubbles (≥100μm) with high shock waves and micro-jet pressures (≥50MPa) upon collapse. This mode is mainly used for physical cleaning, i.e., removing passivation layers or scale that may form on the electrode and ceramic particle surface, thus maintaining electrode activity.

[0069] High-frequency mode (40kHz): Generates a large number of small-diameter cavitation bubbles (≤10μm). This mode is mainly used for chemical enhancement. The high-temperature and high-pressure environment generated when cavitation bubbles collapse promotes the cleavage of water molecules, generating OH free radicals and enhancing the oxidative degradation ability of organic matter. In addition, the ultrasonic power density is controlled between 0.5 and 2.0 W / cm³, and the sound field coverage diameter is ≥800mm.

[0070] In addition, the device includes a filter layer 10, located at the bottom of the reaction tank 1, for deep purification of the effluent after electrochemical treatment. The filter layer 10 has a composite bed structure, specifically comprising an upper activated carbon adsorption layer 1001 and a lower ion exchange resin layer 1002, with the following specific parameters: Upper layer: Activated carbon adsorption layer 1001. Coal-based granular activated carbon (particle size 1-3 mm, iodine value ≥1000 mg / g) is used, mainly for adsorbing trace organic intermediates that are not fully mineralized in the adsorption reaction.

[0071] Lower layer: Ion exchange resin layer 1002. A cation exchange resin is used to remove residual heavy metal ions (such as Cr) from wastewater. 3+ Cu 2+ For example, the cation exchange resin can be selected from D001 macroporous strong acid resin, 001x7 gel-type strong acid resin, or D113 weak acid resin. In this embodiment, D001 resin is selected, with an exchange capacity ≥4.2 mmol / g. To prevent caking, the filter layer is also equipped with a backwashing system (not shown in detail in the figure), which performs combined air-water backwashing every 72 hours.

[0072] In addition, the wastewater treatment device is also equipped with an intelligent control system 9, which integrates a pH sensor, an ORP (oxidation-reduction potential) sensor, a conductivity meter, etc.

[0073] For example, the pH sensor can be a glass electrode sensor, an ISFET sensor, or an antimony electrode sensor. The system dynamically adjusts the electrode voltage and ultrasonic power based on real-time monitoring data. For instance, when the influent COD concentration is high, the voltage is automatically increased; when a pH change is detected that is suitable for heavy metal reduction, the cathode 802 potential is adjusted.

[0074] Example 3: This embodiment provides a method for wastewater treatment using the above-described apparatus. The method includes the following steps: S100. Wastewater is introduced and enters the reaction tank 1 through the multi-stage water distribution system 5, generating swirling flow, and flows through the packing layer 6 formed by electrocatalytic ceramic particles.

[0075] The industrial wastewater to be treated (such as wastewater containing phenol and Cr) 6+ The mixed wastewater is introduced through inlet 2. The wastewater flows through the spiral water distribution system. Under the action of the guide fins 501 and the spiral tube, the water flow forms a strong vortex and enters the electrocatalytic ceramic particle packing layer 6 below in a turbulent state.

[0076] At this point, to increase the solution conductivity, 0.1 mol / L Na2SO4 can be added as a supporting electrolyte, depending on the situation.

[0077] S200, causing the wastewater to undergo an oxidation-reduction reaction in the packing layer 6.

[0078] Turn on the electrode system. The anode potential is controlled at 1.8–2.2V (vsSHE), and the cathode potential is controlled at -0.5–-1.2V. At this time, the following reaction occurs: (1) Three-dimensional electrode effect: The electrocatalytic ceramic particles are polarized under the action of the main electric field, and micro-electrolysis occurs on the surface. Its effective reaction area is several times that of the traditional two-dimensional electrode, and the current efficiency is increased to more than 80%.

[0079] (2) Oxidation of organic matter: At the anode and the anodic polarization end of the ceramic particles, organic matter such as phenol directly loses electrons and is oxidized, or is indirectly oxidized to CO2 and H2O by the ·OH free radicals generated on the surface.

[0080] (3) Heavy metal reduction: At the cathode and the cathode polarization end of the ceramic particles, Cr 6+ (Cr2O7²) - The electrons are gained and reduced to less toxic Cr. 3+ Simultaneously, Fe2+ generated on the surface of the cathode Fe3O4 will also reduce Cr through chemical reduction. 6+ Reduction. Reaction formula: Cr₂O₇²⁻ - +14H + +6e - →2Cr3 + +7H2O.

[0081] S300, the ultrasonic generator 7 applies a cavitation effect to the reaction zone, and the ultrasonic generator 7 switches between low-frequency mode and high-frequency mode to promote the dissociation of pollutants in wastewater and inhibit electrode passivation.

[0082] Turn on ultrasonic generator 7. The control strategy is as follows: Frequency switching: In the initial stage, a 40kHz high-frequency mode is used to promote the breaking and dissociation of bonds in macromolecular organic matter using the free radicals generated. In the later stage of the reaction (or periodically), the frequency is switched to a 20kHz low-frequency mode to remove bubbles and precipitates from the electrode and ceramic particle surface using its strong physical impact force, thus preventing passivation.

[0083] Pulsed operation: Pulsed ultrasound (e.g., 10s on / 5s off) is used to avoid excessive accumulation of cavitation bubbles forming a sound barrier. For chlorine-containing wastewater, the intelligent control system limits the voltage to ≤3V to suppress chlorine evolution side reactions and prevent excessive oxidation of Cl- to generate toxic ClO. - .

[0084] S400, the treated wastewater is discharged after filtration.

[0085] After electrochemical and ultrasonic treatment, the water flows downwards through filter layer 10. Activated carbon adsorption layer 1001 adsorbs residual small organic molecules. Ion exchange resin layer 1002 retains the generated Cr... 3+ Cu 2+ The treatment removes heavy metal cations to ensure that the heavy metal content in the effluent meets the standards. The final treated water is discharged from the drain outlet.

[0086] Application Examples Application Case 1: The treatment involves chemical wastewater containing phenol (500 mg / L) and Cr. 6+ (50 mg / L).

[0087] Processing conditions: 2 hours of processing, ultrasonic power 150W.

[0088] Treatment results: Phenol degradation rate reached 99.8%, Cr6+ reduction rate reached 99.5%. COD decreased from 2000 mg / L to below 50 mg / L, and current efficiency was 83%.

[0089] Application Case 2: Treating electroplating wastewater containing Cu 2+ (200 mg / L) and CN - (100mg / L).

[0090] Processing conditions: 1.5 hours.

[0091] Processing result: Cu 2+ Removal rate 99.9%, CN - It is completely oxidized into non-toxic carbonate ions, with no secondary pollution.

[0092] Comparative Example 1: The difference between this comparative example and Case 1 is that the wastewater treatment device used omits the electrocatalytic ceramic particles.

[0093] The treatment involves chemical wastewater containing phenol (500 mg / L) and Cr. 6+ (50 mg / L).

[0094] Processing conditions: 2 hours of processing, ultrasonic power 150W.

[0095] Results: Current efficiency was only 54%.

[0096] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. An electrocatalytic ceramic particle, characterized in that, include: The porous matrix is ​​formed by mixing and granulating sludge and fly ash, followed by sintering. The composite coating comprises a SnO2-Sb catalytic layer and a polypyrrole conductive coating sequentially formed on the surface of the porous substrate.

2. The electrocatalytic ceramic particles according to claim 1, characterized in that, The method for preparing the porous matrix includes the following steps: The treated fly ash and sludge are mixed to form a primary product, wherein the ratio of sludge to fly ash is set to 2 to 4:

1. Adding binders and conductive agents to the primary product forms a secondary product; The secondary product is granulated and sintered to form the porous matrix.

3. The electrocatalytic ceramic particles according to claim 2, characterized in that, The sintering process includes the following steps: The temperature was increased from room temperature to 600℃ at a rate of 5℃ / min and held at that temperature for 1 hour. The temperature was increased from 600℃ to 1050℃ at a rate of 10℃ / min, and held at that temperature for 2 hours. The temperature is cooled to room temperature under nitrogen atmosphere.

4. The electrocatalytic ceramic particle according to claim 2, characterized in that, The treatment of the sludge includes the following steps: Soak the sludge in 5% hydrochloric acid for 24 hours and rinse until neutral; The cleaned sludge was dried at 105℃ and passed through a 100-mesh sieve. The screened sludge was ball-milled to a particle size D≤50μm.

5. The electrocatalytic ceramic particles according to claim 1, characterized in that, The SnO2-Sb catalyst layer is loaded onto the surface of the porous substrate by electrodeposition, and the thickness of the SnO2-Sb catalyst layer is 50-200 nm.

6. A wastewater treatment reaction device, characterized in that, include: The reaction tank has a packing layer inside, wherein the packing layer is the electrocatalytic ceramic particles as described in any one of claims 1-5; A multi-stage water distribution system, which is configured as a spiral tube structure and located above the packing layer; An ultrasonic generator is installed inside the reaction tank to generate a cavitation field; An electrode system includes multiple sets of anodes and cathodes, with the multiple sets of anodes and cathodes arranged in a cross-array. The electrocatalytic ceramic particles are polarized under the action of the electrode system to form particle electrodes.

7. The apparatus according to claim 6, characterized in that, The anode is a composite electrode with a Ti substrate and a surface coated with Ta2O5 and IrO2; the cathode is an activated carbon felt electrode loaded with nano Fe3O4 particles, the Fe3O4 particles having a particle size of 10-50 nm.

8. The apparatus according to claim 6, characterized in that, The spiral tube structure includes a spiral tube and guide fins disposed thereon. The spiral angle of the spiral tube is 30-45°, used to induce a generation intensity γ≥15s. -1 The vortex.

9. The apparatus according to claim 6, characterized in that, The bottom of the reaction tank is also provided with a filter layer, which includes an upper activated carbon adsorption layer and a lower ion exchange resin layer.

10. A wastewater treatment method, characterized in that, The wastewater treatment method using the wastewater treatment apparatus according to any one of claims 6-9 includes the following steps: Wastewater is introduced and enters the reaction tank through a multi-stage water distribution system, where it generates swirling flow and flows through a packing layer formed by electrocatalytic ceramic particles. The wastewater undergoes an oxidation-reduction reaction in the packing layer; An ultrasonic generator applies a cavitation effect to the reaction zone, and the ultrasonic generator switches between low-frequency and high-frequency modes to promote the dissociation of pollutants in wastewater and inhibit electrode passivation. The treated wastewater is discharged from the device after filtration.

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