A three-dimensional electrochemical water treatment device

Abstract

This invention relates to the field of wastewater treatment, and more particularly to a three-dimensional electrochemical water treatment device, comprising a hollow cathode tank and an anode column disposed within the cathode tank; a third electrode is filled between the cathode tank and the anode column; and the cathode tank is provided with several through holes. This invention designs the anode and cathode as a column and tank structure, fills the space between them with the third electrode, and uses a cathode tank with distributed through holes, which increases the contact area between the third electrode and the anode and cathode, thereby achieving higher water treatment efficiency and facilitating the combined use of multiple units to improve wastewater treatment effects.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and more particularly to a three-dimensional electrochemical water treatment device. Background Technology

[0002] Electrochemical technology, with its high efficiency, environmental friendliness, and versatility, has made significant progress in industrial wastewater treatment, particularly in removing recalcitrant organic pollutants. Two-dimensional electrochemical methods (two-dimensional electrolysis) were early electrochemical water treatment methods, with only two electrodes (anode and cathode) in the reactor. These methods suffer from drawbacks such as short electrode material lifespan and low current efficiency, limiting their industrial application. Traditional two-dimensional electrochemical reactors also suffer from small reaction area, long mass transfer distance, and low current efficiency.

[0003] Three-dimensional electrochemical technology (three-dimensional electrolysis) is built upon two-dimensional electrochemical methods. Except for the third electrode, they share many similarities in electrode materials and processing techniques. The third electrode, also known as a particulate electrode or bed electrode, is currently primarily composed of granular or fragmented materials filled between the two anode and cathode electrodes. Under the influence of voltage, the particulate electrode within the reactor is polarized into charged particles. One end of these charged particles can be considered the anode, and the other end the cathode, essentially functioning as a miniature electrolytic cell.

[0004] Patent CN201320599154.8 discloses a device for treating phenol wastewater using a third electrode, comprising a reactor body with an anode plate and a cathode plate, wherein a regularly shaped third electrode is sandwiched between the anode plate and the cathode plate. This device has the following problems: the contact area between the third electrode and the anode and cathode plates is small, resulting in low water treatment efficiency; during use, wastewater needs to be pumped into the device from the outside, so when multiple units are used in combination, wastewater needs to be sequentially introduced into each unit, which is inconvenient. Summary of the Invention

[0005] To address the technical problems of low water treatment efficiency and inconvenience in multiple-unit operation of existing three-dimensional electrolysis devices, this invention provides a three-dimensional electrochemical water treatment device. This device can increase the contact area between the third electrode and the anode and cathode, thereby achieving higher water treatment efficiency, and it is also convenient for multiple units to be used in combination to improve wastewater treatment effects.

[0006] The specific technical solution of this invention is as follows:

[0007] A three-dimensional electrochemical water treatment device includes a hollow cathode tank and an anode column disposed inside the cathode tank; a third electrode is filled between the cathode tank and the anode column; and the cathode tank is provided with several through holes.

[0008] This invention designs the anode and cathode as a column and a barrel structure, and fills the space between them with a third electrode. This increases the contact area between the third electrode and the anode and cathode, promotes electron transfer, and enhances the electric field effect, thereby improving the water treatment efficiency of the device.

[0009] In conjunction with a special anode and cathode structure, this invention employs a cathode tank with distributed through holes. During use, the device is immersed in a wastewater tank, and flowing wastewater automatically enters the device, triggering an electrochemical reaction and achieving wastewater degradation. This method offers the following advantages: the entire device is movable and can be suspended and fixed in the wastewater tank using a support frame, making it more flexible than traditional fixed devices (fixed electrodes and containers, with wastewater pumped into the device from the outside); furthermore, when multiple sets are needed to improve wastewater treatment efficiency, it is not necessary to sequentially flow wastewater into each set of devices; simply combine multiple devices into an electrode group and immerse them together in the same wastewater tank, making it more convenient to use.

[0010] Preferably, the top of the cathode barrel is provided with a cover plate; above the cover plate are provided an anode connection potential for connecting the anode column to the positive terminal of the power supply, and a cathode connection potential for connecting the cathode barrel to the negative terminal of the power supply.

[0011] Preferably, the third electrode comprises porous ceramic.

[0012] Preferably, the method for preparing the porous ceramic includes the following steps:

[0013] (1) Add ceramic raw materials, including silica powder and alumina powder, to the dispersant solution, and add monomers, crosslinking agents and surfactants and foaming agents. After stirring and foaming, add an initiator to carry out a polymerization reaction to obtain a slurry.

[0014] (2) The slurry is injected into the mold, solidified and shaped, and then dried and sintered after demolding to obtain porous ceramics.

[0015] In existing technologies, porous ceramic raw materials used as the third electrode often contain clay, which causes significant shrinkage during sintering, making it difficult to form a regular pore structure. The porous ceramic of this invention, however, is made of silicon dioxide and alumina and does not contain clay, thus reducing shrinkage during sintering and facilitating control of the pore shape.

[0016] Building upon this, this application employs a special preparation process to obtain a porous structure with suitable size (micrometer scale) and regular shape (circular), connected to the external environment. The regular shape facilitates interconnection between pores, thereby improving the water permeability of the porous ceramic and allowing organic matter to freely enter and exit the porous ceramic with the water flow during the electrochemical reaction. Simultaneously, the regular shape and suitable size ensure sufficient pore space, thus endowing the porous ceramic with a large specific surface area and enhancing the system's electroadsorption capacity during the electrochemical reaction. Through these methods, the efficiency of electrochemical degradation of organic matter can be improved.

[0017] Preferably, in step (1), the dispersant comprises ammonium citrate and polyvinyl alcohol in a mass ratio of 1.5 to 2.5:1.

[0018] Further, in step (1), the mass of the dispersant is 3.25 to 3.75 wt% of the total mass of silica powder and alumina powder.

[0019] When the amount of dispersant is too small, the ceramic powder cannot be well dispersed in water, and partial adhesion occurs between the powder particles, thus affecting the regularity of the pore shape. When the amount of dispersant is too large, the dispersant will affect the foaming effect of the surfactant foaming agent and the degree of monomer polymerization reaction, thus also affecting the regularity of the pore shape. Based on this, the present invention controls the amount of dispersant at 0.5-1.0 wt% of the ceramic raw material, which makes the obtained pores closer to regular circles, thereby improving the water permeability of porous ceramics and making them have higher wastewater treatment efficiency when used as a third electrode.

[0020] Preferably, in step (1), the surfactant foaming agent is sodium dodecylbenzene sulfonate; the mass of the surfactant foaming agent is 3-5 wt% of the total mass of silica powder and alumina powder.

[0021] When the amount of surfactant foaming agent is too small, the number of foam particles will be insufficient, resulting in a small specific surface area of ​​the porous ceramic and affecting its wastewater treatment efficiency when used as a third electrode. Conversely, when the amount of surfactant foaming agent is too large, foaming will fail, making it difficult to form a regular pore structure, which will also significantly reduce the wastewater treatment efficiency. Therefore, this invention controls the amount of surfactant foaming agent to 1.5–2.5 wt% of the ceramic raw material, enabling the porous ceramic to have a more ideal pore structure, thereby achieving higher wastewater treatment efficiency.

[0022] Preferably, in step (1), the monomer is N-hydroxymethylacrylamide; the mass of the monomer is 11.5 to 12.5 wt% of the total mass of silica powder and alumina powder.

[0023] Preferably, in step (1), the crosslinking agent is N,N-methylenebisacrylamide; the mass ratio of the monomer to the crosslinking agent is 2.5 to 3.5:1.

[0024] Preferably, in step (1), the ceramic raw material further includes modified glass fiber, which is glass fiber with an azide pore-forming agent bonded to its surface; in step (2), ultraviolet light irradiation is performed to induce pores before sintering.

[0025] In this invention, a two-step pore-forming process is performed, as follows: In step (1), during the preparation of the slurry, a surfactant foaming agent is used to stir and foam the slurry, thus performing the first pore-forming process; In step (2), during ultraviolet irradiation and sintering, an azide pore-forming agent is used to decompose and release gas, thus performing the second pore-forming process. Pores are formed inside the porous ceramic body (where no channels are formed after the first pore-forming process), and the generated gas escapes through the channels formed in the first pore-forming process, forming a connected structure between the channels formed in the first pore-forming process, thereby improving the water permeability of the porous ceramic. When used as the third electrode in a three-dimensional electrochemical water treatment device, it can improve the wastewater treatment efficiency.

[0026] This invention, in conjunction with a two-step pore-forming process, incorporates an azide pore-forming agent onto the surface of glass fibers. This facilitates the transmission of ultraviolet light through the glass fibers into the porous ceramic body (where no pores were formed after the first pore-forming process) during the second pore-forming process. The light then comes into contact with the azide pore-forming agent bonded to the glass fibers, causing the azide pore-forming agent to decompose. In this way, a more effective interconnected structure can be formed between the pores created in the first pore-forming process.

[0027] Furthermore, in the second pore-forming process, the present invention sets the step of pore formation by ultraviolet light irradiation before sintering. At this time, the strength of the porous ceramic blank is relatively low, which is conducive to the formation of channels inside the blank by the gas released during ultraviolet light irradiation, thereby making the channels inside the final porous ceramic have better connectivity.

[0028] Preferably, the modified glass fiber content in the ceramic raw material is 5-9 wt%.

[0029] Preferably, the method for preparing the modified glass fiber includes the following steps: mixing 4-azidoaniline and / or its salt, glass fiber and water, controlling the pH at 4.5 to 7.5, stirring for 4 to 6 hours, separating the product, and obtaining the modified glass fiber.

[0030] At pH 4.5–6.5, the zeta potential of glass fiber is negative, and the amino group in 4-azidoaniline carries a positive charge. Therefore, 4-azidoaniline can be bound to the surface of glass fiber through electrostatic attraction. When combined with the two-step pore-forming process, it is beneficial to improve the connectivity between the internal channels of porous ceramics.

[0031] Further, the mass ratio of the 4-azidoaniline and / or its salt, glass fiber and water is 1.5–2.5:1:80–100.

[0032] Preferably, during the ultraviolet light irradiation process to induce pores, the ultraviolet light intensity is 500–800 μW / cm². 2 The time is 0.5 to 1.5 hours.

[0033] Preferably, in step (2), the sintering process includes the following steps: heating to 1300-1500°C at a rate of 3-8°C / min, and holding at 1300-1500°C for 2.5-3.5 hours.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The anode and cathode are designed as column and barrel structures, the third electrode is filled between them, and a cathode barrel with through holes is used to increase the contact area between the third electrode and the anode and cathode, thereby obtaining higher water treatment efficiency and facilitating the use of multiple sets to improve the wastewater treatment effect.

[0036] (2) In the preparation process of porous ceramics, using silica and alumina as raw materials and in conjunction with special preparation processes, it is possible to obtain a pore structure with a suitable size (micrometer level) and regular shape (circular) that is connected to the outside world, which can improve the specific surface area and water permeability of porous ceramics, thereby improving the wastewater treatment efficiency of the three-dimensional electrochemical water treatment device.

[0037] (3) In the preparation process of porous ceramics, by controlling the amount of dispersant and surfactant foaming agent, it is beneficial to obtain pores with appropriate size and regular shape.

[0038] (4) Adding glass fibers with azide pore-forming agent to ceramic raw materials and using a two-step pore-forming process can improve the connectivity between the internal channels of porous ceramics. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a three-dimensional electrochemical water treatment device of the present invention.

[0040] Figure 2 This is a SEM image of the porous ceramic in Example 1.

[0041] The attached diagram is labeled as follows: 1. Cathode barrel; 2. Anode column; 3. Third electrode; 4. Through hole; 5. Cover plate; 6. Anode connection potential; 7. Cathode connection potential. Detailed Implementation

[0042] The present invention will be further described below with reference to embodiments.

[0043] General Implementation Examples

[0044] A three-dimensional electrochemical water treatment device, such as Figure 1 As shown, the device includes a hollow cathode barrel 1, an anode column 2 disposed inside the cathode barrel 1, a cover plate 5 disposed on the top of the cathode barrel 1, and a third electrode 3 filling the space between the cathode barrel 1 and the anode column 2. The cathode barrel 1 is provided with several through holes 4. Above the cover plate 5, there is an anode connection potential 6 for connecting the anode column 2 to the positive terminal of the power supply, and a cathode connection potential 7 for connecting the cathode barrel 1 to the negative terminal of the power supply.

[0045] The third electrode 3 comprises porous ceramic. The method for preparing the porous ceramic includes the following steps:

[0046] (1) Add ceramic raw materials to the dispersant solution, the ceramic raw materials including silica powder and alumina powder, and add monomers, crosslinking agents and surfactants and foaming agents. After stirring and foaming, add an initiator to carry out a polymerization reaction to obtain a slurry; the dispersant includes ammonium citrate and polyvinyl alcohol in a mass ratio of 1.5 to 2.5:1, and the mass of the dispersant is 3.25 to 3.75 wt% of the total mass of silica powder and alumina powder;

[0047] The surfactant foaming agent is sodium dodecylbenzenesulfonate, and the mass of the surfactant foaming agent is 3-5 wt% of the total mass of silica powder and alumina powder;

[0048] The monomer is N-hydroxymethylacrylamide, and the mass of the monomer is 11.5 to 12.5 wt% of the total mass of silica powder and alumina powder;

[0049] The crosslinking agent is N,N-methylenebisacrylamide, and the mass ratio of the monomer to the crosslinking agent is 2.5 to 3.5:1;

[0050] (2) The slurry is injected into the mold, solidified and shaped, and then dried and sintered after demolding to obtain porous ceramics;

[0051] The specific sintering process includes the following steps: heating to 1300-1500℃ at a rate of 3-8℃ / min, and holding at 1300-1500℃ for 2.5-3.5 hours.

[0052] Optionally, in step (1), the ceramic raw material further includes modified glass fiber, the content of which is 5-9 wt%; in step (2), before sintering, the ceramic raw material is subjected to ultraviolet light irradiation to induce pores, with an ultraviolet light intensity of 500-800 μW / cm. 2The time is 0.5 to 1.5 hours. The modified glass fiber is a glass fiber with an azide porogen bonded to its surface. The preparation method includes the following steps: 4-azidoaniline and / or its salt, glass fiber and water are mixed in a mass ratio of 1.5 to 2.5:1:80 to 100, the pH is controlled at 4.5 to 6.5, and the mixture is stirred for 4 to 6 hours. The product is then separated to obtain the modified glass fiber.

[0053] Example 1

[0054] A three-dimensional electrochemical water treatment device, such as Figure 1 As shown, the device includes a hollow cathode barrel 1, an anode column 2 disposed inside the cathode barrel 1, a cover plate 5 disposed on the top of the cathode barrel 1, and a third electrode 3 filling the space between the cathode barrel 1 and the anode column 2. The cathode barrel 1 has a mesh structure with several through holes 4 distributed thereon. Above the cover plate 5, there is an anode connection potential 6 for connecting the anode column 2 to the positive terminal of the power supply, and a cathode connection potential 7 for connecting the cathode barrel 1 to the negative terminal of the power supply.

[0055] The third electrode 3 is a porous ceramic. The porous ceramic is prepared through the following steps:

[0056] (1) By weight, add 1 part ammonium citrate and 0.5 parts polyvinyl alcohol to 40 parts water, then add 30 parts silica powder and 10 parts alumina powder, then add 5 parts N-hydroxymethylacrylamide, 1.5 parts N,N-methylenebisacrylamide and 2 parts sodium dodecylbenzenesulfonate in sequence. Stir at 600 rpm for 30 min, then add 1 part ammonium persulfate and react at room temperature for 5 min to obtain slurry;

[0057] (2) The slurry is injected into the mold and left to solidify at room temperature for 5 hours. After demolding, it is dried at room temperature for 3 hours, and then heated to 1400℃ at a rate of 5℃ / min. It is kept at 1400℃ for 3 hours to obtain porous ceramic.

[0058] The microstructure of the porous ceramic prepared in this embodiment is shown in the figure. Figure 2 .from Figure 2 It can be seen that the pores of this porous ceramic are close to regular circles.

[0059] Example 2

[0060] The only difference between this embodiment and Embodiment 1 is that the porous ceramic is prepared through the following steps:

[0061] (1) By weight, add 0.9 parts ammonium citrate and 0.4 parts polyvinyl alcohol to 40 parts water, then add 30 parts silica powder and 10 parts alumina powder, and then add 4.6 parts N-hydroxymethylacrylamide, 1.5 parts N,N-methylenebisacrylamide and 1.2 parts sodium dodecylbenzenesulfonate in sequence. Stir at 600 rpm for 30 min, then add 1 part ammonium persulfate and react at room temperature for 5 min to obtain slurry;

[0062] (2) The slurry is injected into the mold and left to solidify at room temperature for 5 hours. After demolding, it is dried at room temperature for 3 hours, and then heated to 1500℃ at a rate of 5℃ / min. It is then kept at 1500℃ for 2.5 hours to obtain porous ceramics.

[0063] Example 3

[0064] The only difference between this embodiment and Embodiment 1 is that the porous ceramic is prepared through the following steps:

[0065] (1) By weight, 2 parts of 4-azidoaniline hydrochloride were added to 80 parts of water and dissolved completely. Then, 1 part of glass fiber was immersed in it, the pH was controlled at 5.5±0.5, and after stirring for 5 hours, it was allowed to stand, the precipitate was separated, washed with water 3 times, and then dried to obtain modified glass fiber.

[0066] (2) By weight, add 1 part ammonium citrate and 0.5 parts polyvinyl alcohol to 40 parts water, then add 27.75 parts silica powder, 9.25 parts alumina powder and 3 parts modified glass fiber, then add 5 parts N-hydroxymethylacrylamide, 1.5 parts N,N-methylenebisacrylamide and 2 parts sodium dodecylbenzenesulfonate in sequence. Stir at 600 rpm for 30 min, then add 1 part ammonium persulfate and react at room temperature for 5 min to obtain slurry;

[0067] (3) Inject the slurry into the mold, let it stand at room temperature for 5 hours to solidify and form, and after demolding, dry it at room temperature for 3 hours to obtain a porous ceramic blank;

[0068] (4) Porosity was induced in the porous ceramic body by ultraviolet irradiation with an ultraviolet light intensity of 750 μW / cm². 2 The temperature was increased to 1400℃ at a rate of 5℃ / min and held at 1400℃ for 3 hours to obtain porous ceramics.

[0069] Example 4

[0070] The only difference between this embodiment and Embodiment 1 is that the porous ceramic is prepared through the following steps:

[0071] (1) By weight, 2.5 parts of 4-azidoaniline hydrochloride were added to 100 parts of water and dissolved completely. Then, 1 part of glass fiber was immersed in it, the pH was controlled at 5.0±0.5, and after stirring for 4 hours, it was allowed to stand, the precipitate was separated, washed with water 3 times, and then dried to obtain modified glass fiber.

[0072] (2) By weight, add 1 part ammonium citrate and 0.5 parts polyvinyl alcohol to 40 parts water, then add 28.5 parts silica powder, 9.5 parts alumina powder and 2 parts modified glass fiber, then add 5 parts N-hydroxymethylacrylamide, 1.5 parts N,N-methylenebisacrylamide and 2 parts sodium dodecylbenzenesulfonate in sequence. Stir at 600 rpm for 30 min, then add 1 part ammonium persulfate and react at room temperature for 5 min to obtain slurry;

[0073] (3) Inject the slurry into the mold, let it stand at room temperature for 5 hours to solidify and form, and after demolding, dry it at room temperature for 3 hours to obtain a porous ceramic blank;

[0074] (4) Porosity was induced in the porous ceramic body by ultraviolet irradiation with an ultraviolet light intensity of 500 μW / cm². 2 The temperature was increased for 1.5 hours; then the temperature was increased to 1400℃ at a rate of 5℃ / min and held at 1400℃ for 3 hours to obtain porous ceramics.

[0075] Example 5

[0076] The only difference between this embodiment and Embodiment 1 is that the porous ceramic is prepared through the following steps:

[0077] (1) By weight, 1.5 parts of 4-azidoaniline hydrochloride were added to 80 parts of water and dissolved completely. Then, 1 part of glass fiber was immersed in it, the pH was controlled at 6.0±0.5, and after stirring for 6 hours, it was allowed to stand, the precipitate was separated, washed with water 3 times, and then dried to obtain modified glass fiber.

[0078] (2) By weight, add 1 part ammonium citrate and 0.5 parts polyvinyl alcohol to 40 parts water, then add 27.3 parts silica powder, 9.1 parts alumina powder and 3.6 parts modified glass fiber, then add 5 parts N-hydroxymethylacrylamide, 1.5 parts N,N-methylenebisacrylamide and 2 parts sodium dodecylbenzenesulfonate in sequence. Stir at 600 rpm for 30 min, then add 1 part ammonium persulfate and react at room temperature for 5 min to obtain slurry;

[0079] (3) Inject the slurry into the mold, let it stand at room temperature for 5 hours to solidify and form, and after demolding, dry it at room temperature for 3 hours to obtain a porous ceramic blank;

[0080] (4) Porosity was induced in the porous ceramic body by ultraviolet irradiation with an ultraviolet light intensity of 800 μW / cm². 2 The temperature was increased for 0.5 hours, and then raised to 1400℃ at a rate of 5℃ / min, and held at 1400℃ for 3 hours to obtain porous ceramics.

[0081] Comparative Example 1

[0082] The only difference between this comparative example and Example 1 is that, in step (1), the amounts of ammonium citrate and polyvinyl alcohol are replaced with 0.5 parts and 0.25 parts, respectively.

[0083] Comparative Example 2

[0084] The only difference between this comparative example and Example 1 is that, in step (1), the amounts of ammonium citrate and polyvinyl alcohol are replaced with 2 parts and 1 part, respectively.

[0085] Comparative Example 3

[0086] The only difference from Example 1 is that in step (1), the amount of sodium dodecylbenzenesulfonate is changed to 4 parts.

[0087] Comparative Example 4

[0088] The only difference between this comparative example and Example 2 is that the porous ceramic is prepared by the following steps:

[0089] (1) By weight, 2 parts of 4-azidoaniline hydrochloride were added to 80 parts of water and dissolved completely. Then, 1 part of silica powder was added and ultrasonically dispersed evenly. The pH was controlled at 5.5±0.5. After stirring for 5 hours, the precipitate was separated by centrifugation, washed with water 3 times, and then dried to obtain modified silica powder.

[0090] (2) By weight, add 1 part ammonium citrate and 0.5 parts polyvinyl alcohol to 40 parts water, then add 27 parts silica powder, 3 parts modified silica powder and 10 parts alumina powder, then add 5 parts N-hydroxymethylacrylamide, 1.5 parts N,N-methylenebisacrylamide and 2 parts sodium dodecylbenzenesulfonate in sequence. Stir at 600 rpm for 30 min, then add 1 part ammonium persulfate and react at room temperature for 5 min to obtain slurry;

[0091] (3) Inject the slurry into the mold, let it stand at room temperature for 5 hours to solidify and form, and after demolding, dry it at room temperature for 3 hours to obtain a porous ceramic blank;

[0092] (4) Porosity was induced in the porous ceramic body by ultraviolet irradiation with an ultraviolet light intensity of 750 μW / cm². 2 The temperature was increased to 1400℃ at a rate of 5℃ / min and held at 1400℃ for 3 hours to obtain porous ceramics.

[0093] Comparative Example 5

[0094] The only difference between this comparative example and Example 2 is that, in step (4), ultraviolet light irradiation is not performed to induce pores.

[0095] Test Case

[0096] The effectiveness of the devices in Examples 1-5 and Comparative Examples 1-5 in treating wastewater was tested as follows: A methanol solution with a COD of 53000 mg / L was introduced into the device, the power supply was connected, and after 3 hours of treatment, the COD value of the wastewater was measured, and the COD removal rate was calculated. The results are shown in Table 1.

[0097] Table 1

[0098]

[0099] As can be seen from Table 1:

[0100] (1) Compared with Example 1, the COD removal rates of Comparative Examples 1 and 2 were significantly lower, indicating that both excessive and insufficient dispersant dosage during the preparation of porous ceramics would result in lower wastewater treatment efficiency of the device. This is because: when the amount of dispersant is too small, the ceramic powder cannot be well dispersed in water, and some adhesion occurs between the powder particles, which in turn affects the regularity of the pore shape; when the amount of dispersant is too large, the dispersant will affect the foaming effect of the surfactant foaming agent and the degree of monomer polymerization reaction, which will also affect the regularity of the pore shape.

[0101] (2) Compared with Example 1, the COD removal rate of Comparative Example 3 was significantly lower, indicating that excessive use of surfactant foaming agent during the preparation of porous ceramics would result in lower wastewater treatment efficiency of the device. This is because when the amount of surfactant foaming agent is too large, foaming will fail, making it difficult to form a regular pore structure, which will also greatly reduce the wastewater treatment efficiency.

[0102] (3) Compared with Example 1, the COD removal rates of Examples 3-5 are significantly higher, indicating that the addition of glass fibers with azide porogen bound to the surface and the adoption of a two-step pore-forming process during the preparation of porous ceramics can improve the wastewater treatment efficiency of the device. This is because: during the second pore-forming process, the gas released by the decomposition of the azide porogen can form pores inside the porous ceramic body (where no pores were formed after the first pore-forming process), and the generated gas escapes through the pores formed in the first pore-forming process, forming a connected structure between the pores formed in the first pore-forming process, thereby improving the water permeability of the porous ceramic. Using it as the third electrode in a three-dimensional electrochemical water treatment device can give the device a higher wastewater treatment efficiency.

[0103] (4) Compared with Comparative Example 4, the COD removal rate of Example 3 is significantly higher, indicating that combining the azide porogen with glass fiber during the preparation of porous ceramics can improve the wastewater treatment efficiency of the device. This is because: in conjunction with the two-stage pore-forming process, combining the azide porogen with the surface of glass fiber is beneficial for ultraviolet light to be conducted through the glass fiber to the interior of the porous ceramic body (where no pores were formed after the first pore-forming) during the second pore-forming process, and to contact the azide porogen combined with the glass fiber, thereby decomposing the azide porogen. In this way, a more interconnected structure can be formed between the pores formed in the first pore-forming process. However, if glass fiber is not added and the azide porogen is combined with silica powder instead, it is not conducive to forming an ultraviolet light transmission channel that connects with the outside world inside the body, and it is not conducive to the contact between the ultraviolet light entering the body and the azide porogen, thus making it difficult to form an interconnected structure during the second pore-forming process.

[0104] (5) Compared with Comparative Example 5, the COD removal rate of Example 3 is higher, indicating that ultraviolet irradiation treatment before sintering can improve the wastewater treatment efficiency of the device during the preparation of porous ceramics. This is because: before sintering, the strength of the porous ceramic blank is low. At this time, ultraviolet irradiation treatment is conducive to the formation of channels inside the blank by the gas released during ultraviolet irradiation, so that the channels inside the final porous ceramic have better connectivity; while if ultraviolet irradiation treatment is not performed, although the azide pore-forming agent also decomposes and releases gas during sintering, the porous ceramic blank has been gradually sintered and has high strength when it decomposes, which is not conducive to the formation of channels.

[0105] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a third electrode for a three-dimensional electrochemical water treatment device, characterized in that the step... include: (1) A ceramic raw material composed of silica powder, alumina powder and modified glass fiber is added to a dispersant solution, and monomers, crosslinking agents and surfactants are added. After stirring and foaming, an initiator is added to carry out a polymerization reaction to obtain a slurry; the modified glass fiber is a glass fiber with an azide pore-forming agent bonded to its surface; the dispersant includes ammonium citrate and polyvinyl alcohol in a mass ratio of 1.5~2.5:1, with a mass of 3.25~3.75wt% of the total mass of silica powder and alumina powder; the surfactant foaming agent is sodium dodecylbenzenesulfonate, with a mass of 3~5wt% of the total mass of silica powder and alumina powder; (2) The slurry is injected into the mold, solidified and molded, and then dried, irradiated with ultraviolet light to form pores and sintered to obtain the third electrode.

2. The preparation method according to claim 1, characterized in that, The three-dimensional electrochemical water treatment device includes a hollow cathode barrel and an anode column disposed inside the cathode barrel; a third electrode is filled between the cathode barrel and the anode column; and the cathode barrel is provided with several through holes.

3. The preparation method according to claim 2, characterized in that, The cathode barrel is equipped with a cover plate on top.

4. The preparation method according to claim 3, characterized in that, The cover plate is provided with an anode connection potential above it for connecting the anode column to the positive terminal of the power supply.

5. The preparation method according to claim 3, characterized in that, Above the cover plate is a cathode connection potential for connecting the cathode barrel to the negative terminal of the power supply.

6. The preparation method according to claim 1, characterized in that, The method for preparing the modified glass fiber includes the following steps: mixing 4-azidoaniline and / or its salt, glass fiber and water, controlling the pH at 4.5~6.5, stirring for 4~6 hours, separating the product, and obtaining the modified glass fiber.

7. The preparation method according to claim 1 or 6, characterized in that, In step (2), the sintering process includes the following steps: heating to 1300-1500℃ at a rate of 3-8℃ / min, and holding at 1300-1500℃ for 2.5-3.5h.

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