Nanometer aeration electrode, preparation method thereof and electrocatalytic ozone reaction device

Abstract

The application discloses a kind of nano aeration electrode, including nano aperture inorganic membrane, one side of the nano aperture inorganic membrane is loaded catalytic layer, the other side of the nano aperture inorganic membrane is loaded hydrophilic modification layer, wherein, the catalytic layer includes Mn-Ce-O modified carbon material.Nano aperture aeration electrode preparation method includes, a, using sol immersion method to the one side of nano aperture inorganic membrane matrix is carried out hydrophilic modification;B, carbon material is dispersed in ultrapure water, obtain carbon solution, then Mn salt solution and Ce salt solution are added to the carbon solution, freeze-drying is calcined in inert atmosphere, obtain Mn-Ce-O modified carbon material;C, the other side of the nano aperture inorganic membrane matrix of the Mn-Ce-O modified carbon material obtained in the step b is loaded, forms catalytic layer, and nano aeration electrode is prepared.The aeration electrode of the application can produce micro-nano bubble, significantly enhance gas mass transfer, reduce the occurrence of side reaction, effectively improve the efficiency of removing water pollutants using electro-catalytic ozone oxidation technology.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a nano-aeration electrode, further relating to a method for preparing the nano-aeration electrode, and particularly relating to an electrocatalytic ozone reaction device. Background Technology

[0002] In recent years, the use of reclaimed urban wastewater to replenish natural water bodies has become an important way to address water scarcity. However, the accumulation of new pollutants in natural water bodies through replenishment can have potential impacts on the ecological environment and human health. Ozone oxidation, as a commonly used process for urban wastewater reclamation, faces problems such as low efficiency and intermediate products being more toxic than the parent product. Electrocatalytic in-situ ozone production of H2O2 converts O3 into the more potent free radical ·OH, which can significantly enhance the removal of recalcitrant new pollutants, effectively control the formation of byproducts, avoid the low utilization rate and safety issues of exogenous H2O2 addition, and is easy to implement by retrofitting existing ozone oxidation systems.

[0003] Currently, in the electrocatalytic ozone oxidation process, the mass transfer of the aeration electrode is limited, which is not conducive to improving the removal rate of pollutants. Therefore, it is necessary to study and improve the aeration electrode. Summary of the Invention

[0004] This invention is based on the inventors' discoveries and understanding of the following facts and problems: Efficient and low-consumption electrochemical oxygen reduction (ORR) to produce H2O2 at the cathode is key to electrocatalytic ozone technology. Electrochemical ORR to produce H2O2 mainly relies on two-electron ORR reactions, but four-electron ORR to produce H2O is also present. OOH* is a key reaction intermediate; it is necessary to enhance the protection of the O-O bond in OOH* while ensuring that oxygen combines with active sites to form OOH*. Therefore, the cathode material must possess both high ORR activity and high selectivity for two-electron ORR. Electrocatalytic ozone has great potential to eliminate new pollutants in water; oxygen and excessive metal co-modification can synergistically regulate the ORR reaction; however, limited O2 mass transfer can lead to side reactions affecting ·OH production. Therefore, it is necessary to improve the mass transfer in the electrocatalytic ozone process to increase the removal rate of pollutants in water by electrocatalytic ozone oxidation technology.

[0005] The present invention aims to at least partially solve one of the technical problems in the related art.

[0006] Therefore, embodiments of the present invention propose a nano-aeration electrode that generates micro-nano bubbles, which can significantly enhance gas mass transfer, reduce the occurrence of side reactions, and effectively improve the efficiency of removing water pollutants using electrocatalytic ozone oxidation technology.

[0007] This invention provides a nano-aeration electrode, comprising a nanoporous inorganic membrane substrate, a catalytic layer loaded on one side of the nanoporous inorganic membrane substrate, and a hydrophilic modification layer loaded on the other side of the nanoporous inorganic membrane substrate, wherein the catalytic layer comprises a Mn-Ce-O modified carbon material.

[0008] The advantages and technical effects of the nano-aeration electrode of this invention are as follows: 1. The nano-aeration electrode of this invention uses a nanoporous inorganic membrane as a substrate, which is resistant to the corrosion of ozone or ozone water; 2. The nano-aeration electrode of this invention has a catalytic layer containing Mn-Ce-O modified carbon material on one side of the inorganic membrane. Ce and the transition metal Mn work together to facilitate the formation and migration of oxygen vacancies on the surface, which can generate active oxygen species, especially hydroxyl radicals, on the surface of the catalytic layer of the nano-aeration electrode, which is beneficial to the degradation of pollutants in water; 3. The nano-aeration electrode of this invention has a hydrophilic modification layer on the other side of the inorganic membrane, which can generate micro- and nano-bubbles, significantly enhance gas mass transfer, and help reduce the occurrence of side reactions in electrocatalytic ozone oxidation. In addition, the hydrophilic modification layer facilitates the escape of micro- and nano-bubbles and prevents the generated micro- and nano-bubbles from rapidly agglomerating into large bubbles; 4. The nano-aeration electrode of this invention integrates micro- and nano-bubble aeration and catalyst coating into one, with a simple structure, and can be used in the electrocatalytic ozone oxidation process. It can effectively remove a variety of organic pollutants in water and improve the reaction efficiency of the system.

[0009] In some embodiments, the molar ratio of Mn to Ce in the catalyst layer is (1-4):1; and / or, the total mass content of Mn and Ce elements in the catalyst layer is 0.5-8%, preferably 1-2%; and / or, the thickness of the catalyst layer is 100-300 micrometers.

[0010] In some embodiments, the nanoporous inorganic membrane includes at least one of a ceramic membrane, a titanium suboxide membrane, or a silicon carbide membrane, and / or the pore size of the nanoporous inorganic membrane is 300-1200 nm, preferably 300-1000 nm.

[0011] In some embodiments, the hydrophilic modified layer is either silicon dioxide or titanium dioxide; and / or, the thickness of the hydrophilic modified layer is 200-1200 nanometers.

[0012] In some embodiments, the nanoporous inorganic membrane substrate is a hollow structure. Preferably, the nanoporous inorganic membrane substrate is a hollow tubular structure with an inner diameter of 1-3 cm, a wall thickness of 2-10 mm, and a length of 5-300 cm.

[0013] This invention also provides a method for preparing a nano-aeration electrode, comprising the following steps:

[0014] a. Hydrophilic modification of one side of a nanoporous inorganic membrane substrate was performed using a sol-gel impregnation method;

[0015] b. Disperse the carbon material in ultrapure water to obtain a carbon solution, then add Mn salt solution and Ce salt solution to the carbon solution, freeze dry and calcine in an inert atmosphere to obtain Mn-Ce-O modified carbon material;

[0016] c. Load the Mn-Ce-O modified carbon material obtained in step b onto the other side of the nanoporous inorganic membrane substrate to form a catalytic layer, thereby obtaining a nano-aeration electrode.

[0017] The advantages and technical effects of the preparation method of the nano-aeration electrode in this invention are as follows: 1. In the method of this invention, Mn-Ce-O modified carbon material is loaded on one side of the nano-inorganic membrane substrate. Ce and transition metal Mn work together to facilitate the formation and migration of oxygen vacancies on the surface, enabling the generation of active oxygen species, especially hydroxyl radicals, on the surface of the catalytic layer of the nano-aeration electrode, which is beneficial to the degradation of pollutants in water; 2. In the method of this invention, a hydrophilic modified layer is loaded on the other side of the inorganic membrane substrate, which facilitates the formation of micro- and nano-bubbles on the surface and allows the bubbles to escape from the membrane surface in a timely manner, rapidly forming micro- and nano-bubbles, significantly enhancing gas mass transfer and improving ozone utilization; 3. The method of this invention is simple to prepare, and the prepared nano-aeration electrode can be used in the electrocatalytic ozone oxidation process, effectively improving the removal rate of various organic pollutants in water.

[0018] In some embodiments, in step a, one side of the nanoporous inorganic membrane substrate is impregnated with hydrophilic silica sol or hydrophilic titanium dioxide sol. The impregnated nanoporous inorganic membrane substrate is dried at 80-120°C for 20-40 min, and then heated to 450-550°C at a heating rate of 2-3°C / min for calcination treatment for 1-3 h.

[0019] In some embodiments, in step b, the carbon material includes at least one of carbon black, carbon nanotubes, graphene, or carbon nitride; and / or, the Mn salt includes at least one of manganese nitrate or manganese acetate, and the Ce salt includes at least one of cerium nitrate or cerium acetate; and / or, the calcination heating rate is 5-10℃ / min, the calcination temperature is 400-600℃, and the calcination time is 1-3h.

[0020] In some embodiments, in step c, the Mn-Ce-O modified carbon material, polyvinylidene fluoride, and N,N-dimethylformamide are mixed and stirred to form a sol-like colloid, which is then coated on the other side of the nano-inorganic membrane substrate.

[0021] This invention also provides an electrocatalytic ozone reaction device, including a nano-aeration electrode according to this invention.

[0022] In the electrocatalytic ozone reactor of this invention, there are simultaneously catalytic ozone oxidation reaction, electrocatalytic reaction, micro-nano bubble enhancement reaction, and their coupled enhancement reaction, which effectively enhances the mass transfer of ozone gas. At the same time, multiple mechanisms within the system trigger ozone chain reactions to generate more active oxide species, especially hydroxyl radicals, which are beneficial to the degradation of pollutants, thus exhibiting excellent wastewater treatment effects. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the nano-aeration electrode according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the electrocatalytic ozone reaction device according to an embodiment of the present invention. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] like Figure 1 As shown, an embodiment of the present invention provides a nano-aeration electrode 1, comprising a nanoporous inorganic membrane substrate 11, a catalyst layer 12 loaded on one side of the nanoporous inorganic membrane substrate 11, and a hydrophilic modification layer 13 loaded on the other side of the nanoporous inorganic membrane substrate 11, wherein the catalyst layer 12 comprises a carbon material modified with Mn-Ce-O.

[0027] The nano-aeration electrode of this invention uses a nanoporous inorganic membrane as a substrate, which is resistant to corrosion from ozone or ozone water. On one side of the inorganic membrane, a catalytic layer containing Mn-Ce-O modified carbon material is provided. The interaction between Ce and the transition metal Mn promotes the formation and migration of oxygen vacancies on the surface, enabling the generation of active oxygen species, especially hydroxyl radicals, on the surface of the catalytic layer, which is beneficial for the degradation of pollutants in water. On the other side of the inorganic membrane, a hydrophilic modification layer is provided, which enables the generation of micro- and nano-bubbles, significantly enhancing gas mass transfer and reducing side reactions in electrocatalytic ozone oxidation. Furthermore, the hydrophilic modification layer facilitates the escape of micro- and nano-bubbles, preventing their rapid aggregation into large bubbles. This nano-aeration electrode integrates micro- and nano-bubble aeration and a catalyst coating, has a simple structure, and can be used in electrocatalytic ozone oxidation processes to effectively remove various organic pollutants from water, improving the system's reaction efficiency.

[0028] In some embodiments, the molar ratio of Mn to Ce in the catalyst layer is (1-4):1, and the total mass content of Mn and Ce is 0.5-8%, preferably 1-2%. In this embodiment of the invention, the preferred molar ratio of Mn to Ce is beneficial for fully utilizing the synergistic effect between Mn and Ce, promoting the generation of strong oxidizing free radicals, thereby improving the removal efficiency of pollutants in water.

[0029] In some embodiments, the thickness of the catalyst layer is 100-300 micrometers. In these embodiments, a preferred catalyst layer thickness is preferred to ensure the catalyst layer functions effectively and enhances the generation of strong oxidizing free radicals. If the catalyst layer is too thick, it increases costs, and the interior of the excessively thick catalyst layer may not function properly; if the catalyst layer is too thin, its function is limited.

[0030] In some embodiments, the nanoporous inorganic membrane includes at least one of a ceramic membrane, a titanium suboxide membrane, or a silicon carbide membrane, and / or the pore size of the nanoporous inorganic membrane is 300-1200 nm, preferably 300-1000 nm.

[0031] In some embodiments, the hydrophilic modified layer comprises either silicon dioxide or titanium dioxide; preferably, the thickness of the hydrophilic modified layer is 200-1200 nm. In this embodiment of the invention, a hydrophilic modified layer is preferred, which can control the contact angle to 50-80°. Using superhydrophilic material would actually hinder bubble escape because the bubbles need to overcome greater liquid film tension before separation. If the hydrophilic modified layer is too thick, it will affect gas transport and rapid passage; if the hydrophilic modified layer is too thin, it will affect bubble formation and rapid escape.

[0032] In some embodiments, the nanoporous inorganic membrane substrate is a hollow structure. Preferably, the nanoporous inorganic membrane substrate is a hollow tubular structure with an inner diameter of 1-3 cm, a wall thickness of 2-10 mm, and a length of 5-300 cm.

[0033] This invention also provides a method for preparing a nano-aeration electrode, comprising the following steps:

[0034] a. Hydrophilic modification of one side of a nanoporous inorganic membrane substrate was performed using a sol-gel impregnation method;

[0035] b. Disperse the carbon material in ultrapure water to obtain a carbon solution, then add Mn salt solution and Ce salt solution to the carbon solution, freeze dry and calcine in an inert atmosphere to obtain Mn-Ce-O modified carbon material;

[0036] c. Load the Mn-Ce-O modified carbon material obtained in step b onto the other side of the nanoporous inorganic membrane substrate to form a catalytic layer, thereby obtaining a nano-aeration electrode.

[0037] It should be noted that steps a and b in the preparation method of this embodiment of the invention do not have an order requirement, but on the nanoporous inorganic membrane substrate, it is necessary to first complete the hydrophilic modification of one side and then load the catalytic layer on the other side.

[0038] In the preparation method of the nano-aeration electrode of this invention, Mn-Ce-O modified carbon material is loaded on one side of the nano-inorganic membrane substrate. The interaction between Ce and the transition metal Mn is beneficial to the formation and migration of oxygen vacancies on the surface, enabling the generation of active oxygen species, especially hydroxyl radicals, on the catalytic layer surface of the nano-aeration electrode, which is beneficial to the degradation of pollutants in water. In the method of this invention, a hydrophilic modification layer is loaded on the other side of the inorganic membrane, which facilitates the formation of micro- and nano-bubbles on the surface and allows the bubbles to escape from the membrane surface in a timely manner, thus rapidly forming micro- and nano-bubbles, significantly enhancing gas mass transfer and improving ozone utilization. The method of this invention is simple to prepare, and the obtained nano-aeration electrode can be used in the electrocatalytic ozone oxidation process, effectively improving the removal rate of various organic pollutants in water.

[0039] In some embodiments, in step a, one side of the nanoporous inorganic membrane substrate is impregnated with a hydrophilic silica sol or a hydrophilic titanium dioxide sol. The impregnated nanoporous inorganic membrane substrate is dried at 80-120°C for 20-40 min, and then calcined at a heating rate of 2-3°C / min to 450-550°C for 1-3 h to complete the hydrophilic modification. The hydrophilic silica sol or hydrophilic titanium dioxide sol can be prepared using existing techniques. For example, the preparation method of hydrophilic titanium dioxide sol includes: first, dissolving tetrabutyl titanate (Ti(OC4H9)4) in anhydrous ethanol, adding diethanolamine (NH(C2H4OH)2), and stirring vigorously on a constant temperature magnetic stirrer at room temperature for 2-3 hours, then adding a mixed solution of H2O and C2H5OH, and continuing to stir for about 10-20 minutes to obtain a uniform, transparent light yellow sol. The prepared sol is then aged at room temperature for 48-72 hours to obtain a uniform and stable hydrophilic titanium dioxide sol.

[0040] In some embodiments, in step b, the carbon material includes at least one of carbon black, carbon nanotubes, graphene, or carbon nitride; the Mn salt includes at least one of manganese nitrate or manganese acetate; the Ce salt includes at least one of cerium nitrate or cerium acetate; the calcination heating rate is 5-10℃ / min, the calcination temperature is 400-600℃, and the calcination time is 1-3h.

[0041] In some embodiments, in step c, the Mn-Ce-O modified carbon material, polyvinylidene fluoride, and N,N-dimethylformamide are mixed and stirred to form a sol-like colloid, which is then coated on the other side of the nano-inorganic membrane substrate.

[0042] like Figure 2 As shown, this embodiment of the invention also provides an electrocatalytic ozone reaction device, including a nano-aeration electrode 1 according to this embodiment. Preferably, the electrocatalytic ozone reaction device includes a nano-aeration electrode 1, a reactor 2, an oxygen source 3, an ozone generator 4, a power supply 7, an auxiliary electrode 8, and a tail gas detection and absorption device, wherein the nano-aeration electrode 1 is connected to the negative terminal of the power supply 7 as a cathode, and the auxiliary electrode 8 is connected to the positive terminal of the power supply 7 as an anode.

[0043] In the electrocatalytic ozone reactor of this invention, there are simultaneously catalytic ozone oxidation reaction, electrocatalytic reaction, micro-nano bubble enhancement reaction, and their coupled enhancement reaction, which effectively enhances the mass transfer of ozone gas. At the same time, multiple mechanisms within the system trigger ozone chain reactions to generate more active oxide species, especially hydroxyl radicals, which are beneficial to the degradation of pollutants, thus exhibiting excellent wastewater treatment effects.

[0044] like Figure 2 As shown, the working process of the electrocatalytic ozone reactor of the present invention is as follows:

[0045] Ozone generator 4 converts dry pure oxygen into ozone-containing gas, which is then pressurized by a gas booster pump and enters the central tube of nano-aeration electrode 1 via ozone concentration meter 5. Under pressure, the ozone is released into the water in the form of micro- and nano-bubbles from the hydrophilic modified side of nano-aeration electrode 1. These micro- and nano-bubbles exhibit high ozone solubility, long ozone retention time, high ozone utilization efficiency, fast ozone mass transfer coefficient, and abundant hydroxyl radical generation, thus enhancing the degradation of organic pollutants in the water. The negative terminal of power supply 7 is connected to nano-aeration electrode 1 as the cathode, and the positive terminal of power supply 7 is connected to auxiliary electrode 8 as the anode. Due to the ozone generation... The ozone-containing gas produced by generator 4 has an oxygen content greater than 80%. An oxygen reduction reaction occurs at the cathode surface to produce H2O2. H2O2 itself can react with organic pollutants in the water, and it also gains electrons to generate hydroxyl radicals, which react with organic pollutants in the water. Under electrocatalysis, hydroxylation occurs on the anode surface, followed by catalytic ozone oxidation upon contact with ozone, producing highly reactive oxygen species to degrade organic pollutants in the water. Simultaneously, catalytic ozone oxidation also occurs on the catalytic layer surface of the cathode, producing highly reactive oxygen species to degrade organic pollutants in the water. Wastewater enters the reaction system from the bottom of reactor 2, and after reacting with ozone, H2O2, and various reactive oxygen species to remove organic pollutants, it flows out from the top of reactor 2. Ozone tail gas is discharged from the top of reactor 2 and, after passing through ozone concentration meter 6, undergoes centralized treatment, such as absorption with potassium iodide solution or treatment with an ozone tail gas destroyer.

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] Example 1

[0048] (1) Dissolve tetrabutyl titanate (Ti(OC4H9)4) in anhydrous ethanol, add diethanolamine (NH(C2H4OH)2), stir vigorously on a constant temperature magnetic stirrer for 2 hours at room temperature, then add a mixed solution of H2O and C2H5OH, and continue stirring for about 20 minutes to obtain a uniform, transparent light yellow sol. Let the prepared sol age at room temperature for 50 hours to obtain a uniform and stable hydrophilic titanium dioxide sol.

[0049] One side of a 500nm pore size sub-titanium oxide membrane substrate was impregnated with the prepared hydrophilic titanium dioxide sol. The nanoporous sub-titanium oxide membrane substrate used was a hollow structure with an inner diameter of 2cm, a wall thickness of 4mm, and a length of 80cm. The impregnated nanoporous sub-titanium oxide membrane substrate was dried at 80℃ for 30min, and then heated to 500℃ at a heating rate of 3℃ / min and calcined for 2h to complete the hydrophilic modification. The thickness of the hydrophilic modified layer was 300nm.

[0050] (2) Disperse carbon black in ultrapure water to obtain a carbon solution. Then add manganese nitrate solution and cerium nitrate solution dropwise to the carbon solution, stir thoroughly, freeze dry with liquid nitrogen, and then place the carbon material in a tube furnace and calcine it at high temperature in an argon atmosphere. The heating rate is controlled at 5℃ / min, the calcination temperature is 500℃, and the calcination time is 2h. Keep argon gas flowing in until the tube furnace cools down to room temperature to obtain Mn-Ce-O modified carbon material. The total mass content of Mn and Ce in the obtained carbon material is 2%, and the molar ratio of Mn and Ce is 4:1.

[0051] (3) The Mn-Ce-O modified carbon material obtained in step (2), polyvinylidene fluoride, and N,N-dimethylformamide are mixed and stirred to form a sol-like colloid, which is then coated on one side of a nanoporous sub-titanium oxide membrane to form a catalytic layer with a thickness of 200 micrometers, thus obtaining a nano-aeration electrode.

[0052] Example 2

[0053] The method is the same as in Example 1, except that the molar ratio of Mn to Ce in the carbon material obtained in step (2) is 1:1.

[0054] Example 3

[0055] The method is the same as in Example 1, except that the molar ratio of Mn to Ce in the carbon material obtained in step (2) is 2:1.

[0056] Example 4

[0057] The method is the same as in Example 1, except that the molar ratio of Mn to Ce in the carbon material obtained in step (2) is 3:1.

[0058] Example 5

[0059] The method is the same as in Example 1, except that the total mass content of Mn and Ce in the carbon material obtained in step (2) is 0.5%.

[0060] Example 6

[0061] The method is the same as in Example 1, except that the total mass content of Mn and Ce in the carbon material obtained in step (2) is 5%.

[0062] Example 7

[0063] The method is the same as in Example 1, except that in step (3), the thickness of the catalyst layer is 100 micrometers.

[0064] Example 8

[0065] The method is the same as in Example 1, except that in step (3), the thickness of the catalyst layer is 300 micrometers.

[0066] Example 9

[0067] The method is the same as in Example 1, except that in step (1), the thickness of the hydrophilic modified layer is 200 nanometers.

[0068] Example 10

[0069] The method is the same as in Example 1, except that in step (1), the thickness of the hydrophilic modified layer is 1200 nanometers.

[0070] Example 11

[0071] The method is the same as in Example 1, except that in step (3), the calcination temperature is 600°C and the calcination time is 1 hour.

[0072] Example 12

[0073] The method is the same as in Example 1, except that in step (3), the calcination temperature is 400°C and the calcination time is 2 hours.

[0074] Example 13

[0075] The method is the same as in Example 1, except that in step (1), the pore size of the titanium suboxide film substrate is 1200 nm.

[0076] Example 14

[0077] The method is the same as in Example 1, except that in step (1), the pore size of the titanium suboxide film substrate is 85 nm.

[0078] Comparative Example 1

[0079] The method is the same as in Example 1, except that in step (3), Cu salt and Fe salt are used to prepare metal-doped carbon materials to obtain Cu-Fe-O modified carbon materials.

[0080] Comparative Example 2

[0081] The method is the same as in Example 1, except that in step (3), manganese nitrate solution is not added, but cerium nitrate solution is used to prepare Ce-O modified carbon material, wherein the Ce content in the carbon material is 2%.

[0082] Comparative Example 3

[0083] The method is the same as in Example 1, except that in step (3), cerium nitrate solution is not added, but only manganese nitrate solution is used to prepare Mn-O modified carbon material, wherein the content of Mn in the carbon material is 2%.

[0084] Comparative Example 4

[0085] The method is the same as in Example 1, except that step (1) is omitted and no hydrophilic modified layer is loaded.

[0086] Comparative Example 5

[0087] The method is the same as in Example 1, except that steps (2) and (3) are omitted and no catalyst layer is loaded.

[0088] Comparative Example 6

[0089] The method is the same as in Example 13, except that in step (1), one side of the 1200nm pore size titanium suboxide film substrate is subjected to superhydrophilic modification treatment. Specifically, the following steps are taken: after stirring tetraethoxysilane, anhydrous ethanol and deionized water in a constant temperature water bath, ammonia water is slowly added dropwise and kept at the temperature for 4 hours to prepare nano-silica sol; the nano-silica sol is prepared into a hybrid mixed solution with hydroxyl acrylic resin aqueous dispersion, PVA solution and glutaraldehyde, and the prepared hybrid mixed solution is used to impregnate one side of the 1200nm pore size titanium suboxide film substrate, and dried in a constant temperature vacuum oven at 120°C for 30 minutes to obtain the superhydrophilic coating.

[0090] Comparative Example 7

[0091] The method is the same as in Example 13, except that in step (1), one side of the 1200nm pore size titanium suboxide film substrate is subjected to hydrophobic treatment. Specifically, tetraethoxysilane and anhydrous ethanol are added to a mixture of ammonia, distilled water and anhydrous ethanol, and reacted at a constant temperature for 90 min to obtain colloidal silica; then ethyltrimethoxysilane and anhydrous ethanol are added to the solution, and stirred continuously at 60°C for 19 h to obtain hydrophobic silica sol; after aging the silica sol at room temperature for 3 days, one side of the 1200nm pore size titanium suboxide film substrate is impregnated with the sol, dried at 110°C for 30 min in a constant temperature vacuum oven, and then annealed at 400°C for 2 h to obtain the hydrophobic coating.

[0092] Comparative Example 8

[0093] The method is the same as in Example 1, except that in step (1), the pore size of the titanium suboxide film substrate is 8200 nm.

[0094] Comparative Example 9

[0095] The method is the same as in Example 14, except that in step (1), one side of the 85nm pore size sub-titanium oxide film substrate is hydrophobically treated, and the hydrophobic treatment method is the same as in Comparative Example 7.

[0096] I. Performance tests were conducted on Examples 1-14 and Comparative Examples 1-9. The test results are shown in Table 1.

[0097] 1. Aeration bubble test

[0098] Test method: High-speed camera was used to take pictures, and then Image Pro Plus 6.0 software was used to measure and analyze the diameter of microbubbles; the test results are shown in Table 1.

[0099] Table 1

[0100]

[0101] As can be seen from Table 1, after aeration, the nano-aeration electrodes prepared in Examples 1-14 produce bubbles with a size of approximately 50 micrometers, forming micro-nano bubbles, which is beneficial for enhancing gas mass transfer.

[0102] II. Application Testing

[0103] 1. The secondary biological treatment effluent of urban sewage contains the following pollutant concentrations: DEET 1530 ng / L, ibuprofen 307.3 ng / L, atenolol 3.8 ng / L, carbamazepine 41.3 ng / L, sulpiride 65.8 ng / L, bezafibrate 28.1 ng / L, and sulfamethoxazole 304.3 ng / L.

[0104] like Figure 2 As shown, wastewater treatment was carried out using the aeration electrodes in Examples 1-14 and Comparative Examples 1-9 in the electrocatalytic ozone reactor, and the results are shown in Table 2.

[0105] Experimental conditions: Ozone dosage was 3.0 mg / min. -1 The reaction time is 20 minutes.

[0106] Table 2

[0107]

[0108]

[0109] 2. Treatment of water used in simulation experiments

[0110] Prepare the wastewater for the experiment: The concentration of DEET in the wastewater is 10 mg / L.

[0111] Experimental conditions: ozone gas flow rate was 60 mL / min, and ozone gas concentration was 50 mg / L.

[0112] like Figure 2 As shown, wastewater treatment experiments were conducted using the aeration electrodes from Examples 1-14 and Comparative Examples 1-9 in the electrocatalytic ozone reactor. The results are shown in Table 3.

[0113] Table 3

[0114]

[0115]

[0116] 3. Treatment of coal coking wastewater: Coal coking wastewater typically contains complex inorganic and organic pollutants, such as phenols, cyanides, thiocyanates, ammonia, polycyclic aromatic hydrocarbons (PAHs), nitrogen-containing polycyclic aromatic hydrocarbons, oxygen- and sulfur-containing heterocyclic compounds, and acyclic compounds. Most of these are recalcitrant, toxic, mutagenic, and carcinogenic. Even after biochemical treatment, coal coking wastewater still contains a large amount of recalcitrant substances. This experiment used biochemically treated coking wastewater with a COD of approximately 120-150 mg / L.

[0117] like Figure 2 As shown, the aeration electrodes in Examples 1-14 and Comparative Examples 1-9 were used in the electrocatalytic ozone reactor to treat coking wastewater, and the results are shown in Table 4.

[0118] Experimental conditions: ozone dosage was 180 mg / L, and reaction time was 90 min.

[0119] Table 4

[0120]

[0121] As can be seen from Tables 1-4, the catalyst layer material in Comparative Example 1 is a Cu-Fe-O modified carbon material. This is likely mainly because the synergistic catalytic effect between Cu and Fe is not as strong as that of the Mn and Ce combination, resulting in a significantly inferior treatment effect compared to the embodiments of the present invention. In the embodiments of the present invention, the Mn-Ce bimetallic synergistic effect has a significant advantage. Firstly, Mn exists on the surface of the catalyst layer. 3+ / Ce 3+ ——Mn 4+ / Ce 4+ ——Mn 3+ / Ce 3+ The cyclic reaction, surface Mn 3+ / Ce 3+ Electron transfer triggers the decomposition of ozone into active oxygen species. Secondly, since cerium dioxide (CeO2) can serve as an effective promoter to enhance the activity of the catalyst used in the catalytic ozone oxidation process, and it has the ability to provide or capture electrons, as well as the functions of storing and releasing oxygen, oxygen vacancies are generated on the catalyst surface during the surface electron transfer process, thereby enhancing the oxygen adsorption capacity of the catalyst surface.

[0122] In Comparative Example 2, the catalyst layer material only includes a single metal, Ce. Because cerium dioxide (CeO2) generally acts as a promoter, it cannot play a catalytic role as an active component, resulting in a significant decrease in treatment efficiency. In Comparative Example 3, although Mn is an active component for ozone catalysis, the lack of Ce as a promoter results in a significantly less effective treatment than the Mn-Ce bimetallic synergistic effect used in the embodiments of this invention.

[0123] In Comparative Example 4, the inorganic membrane substrate was not hydrophilically modified on one side, resulting in microbubbles that were detrimental to ozone mass transfer. In Comparative Example 5, no catalyst layer was loaded, and there was no catalytic activity, resulting in a low amount of oxidizing species and poor performance.

[0124] In Comparative Example 6, applying a superhydrophilic treatment to one side of the inorganic membrane substrate actually hindered bubble escape because the bubbles needed to overcome greater liquid film tension before separation. Consequently, the bubbles were larger in diameter and fewer in number compared to Example 13, which was detrimental to mass transfer. In Comparative Example 7, applying a hydrophobic treatment to one side of the inorganic membrane substrate hindered the timely detachment and escape of bubbles from the membrane surface, resulting in larger bubbles that affected the mass transfer of ozone gas.

[0125] In Comparative Example 8, the pore size of the sub-titanium oxide membrane substrate was too large, making it difficult to generate nanobubbles even with hydrophilic modification, thus affecting the mass transfer effect. In Comparative Example 9, although the aeration bubbles could be controlled between 2-20 μm after hydrophobic treatment of the 85 nm pore size sub-titanium oxide membrane substrate, the hydrophobic surface hindered bubble escape, resulting in a small number of bubbles. Furthermore, the small pore size required a high bubble point pressure, making it neither economical nor efficient.

[0126] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0127] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A nano-aeration electrode, characterized in that, The membrane includes a nanoporous inorganic membrane substrate, a catalytic layer loaded on one side of the nanoporous inorganic membrane substrate, and a hydrophilic modification layer loaded on the other side of the nanoporous inorganic membrane substrate. The nanoporous inorganic membrane substrate has a hollow structure, and the nanoporous inorganic membrane includes at least one of a ceramic membrane, a titanium suboxide membrane, or a silicon carbide membrane. The catalytic layer includes a Mn-Ce-O modified carbon material, and the hydrophilic modification layer is either silicon dioxide or titanium dioxide.

2. The nano-aeration electrode according to claim 1, characterized in that, The molar ratio of Mn to Ce in the catalyst layer is (1~4):1; and / or, the total mass content of Mn and Ce elements in the catalyst layer is 0.5-8%; and / or, the thickness of the catalyst layer is 100-300 micrometers.

3. The nano-aeration electrode according to claim 2, characterized in that, The total mass content of Mn and Ce elements in the catalyst layer is 1-2%.

4. The nano-aeration electrode according to claim 1, characterized in that, The pore size of the nanoporous inorganic membrane is 300-1200 nanometers.

5. The nano-aeration electrode according to claim 4, characterized in that, The pore size of the nanoporous inorganic membrane is 300-1000 nm.

6. The nano-aeration electrode according to claim 1, characterized in that, The thickness of the hydrophilic modified layer is 200-1200 nanometers.

7. The nano-aeration electrode according to claim 1, characterized in that, The nanoporous inorganic membrane substrate has a hollow tubular structure with an inner diameter of 1-3 cm, a wall thickness of 2-10 mm, and a length of 5-300 cm.

8. A method for preparing a nano-aeration electrode according to any one of claims 1-7, characterized in that, Includes the following steps: a. Hydrophilic modification of one side of a nanoporous inorganic membrane substrate was performed using a sol-gel impregnation method; b. Disperse the carbon material in ultrapure water to obtain a carbon solution, then add Mn salt solution and Ce salt solution to the carbon solution, freeze dry and calcine in an inert atmosphere to obtain Mn-Ce-O modified carbon material; c. Load the Mn-Ce-O modified carbon material obtained in step b onto the other side of the nanoporous inorganic membrane substrate to form a catalytic layer, thereby obtaining a nano-aeration electrode.

9. The method for preparing the nano-aeration electrode according to claim 8, characterized in that, In step a, one side of the nanoporous inorganic membrane substrate is impregnated with hydrophilic silica sol or hydrophilic titanium dioxide sol. The impregnated nanoporous inorganic membrane substrate is dried at 80-120℃ for 20-40 min, and then heated to 450-550℃ at a heating rate of 2-3℃ / min for calcination treatment for 1-3 h.

10. The method for preparing the nano-aeration electrode according to claim 8, characterized in that, In step b, the carbon material includes at least one of carbon black, carbon nanotubes, graphene, or carbon nitride. And / or, the Mn salt includes at least one of manganese nitrate or manganese acetate, and the Ce salt includes at least one of cerium nitrate or cerium acetate; And / or, the calcination heating rate is 5-10 ℃ / min, the calcination temperature is 400-600 ℃, and the calcination time is 1-3h.

11. The method for preparing the nano-aeration electrode according to claim 8, characterized in that, In step c, the Mn-Ce-O modified carbon material, polyvinylidene fluoride, and N,N-dimethylformamide are mixed and stirred to form a sol-like colloid, which is then coated on the other side of the nano-inorganic membrane substrate.

12. An electrocatalytic ozone reaction device, characterized in that, The nano-aeration electrode includes any one of claims 1-7 or any one of claims 8-11.

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