A conductive aeration membrane cathode electro-Fenton sewage treatment device based on iron circulation, method and application

Abstract

A conductive aeration membrane cathode electro-Fenton sewage treatment device based on iron circulation, as well as a method and application. The present invention belongs to the technical field of electro-Fenton sewage treatment. The purpose of the present invention is to solve the technical problems of low O2 utilization, poor ferrous iron recycling and regeneration performance, and poor selective degradation effect in the current electro-Fenton complex water treatment technology. The nano-confined conductive gas diffusion membrane of the present invention is composed of a base membrane and an active layer, and the active layer is composed of broken CNTs and internal BN. An aeration membrane assembly is provided in the reaction chamber of the device, and the surface of the assembly adjacent to the anode is composed of the above-mentioned gas diffusion membrane. This design enables oxygen to directly contact the catalytic layer through the gas diffusion membrane and be consumed immediately, achieving 100% utilization of oxygen while avoiding the mass transfer resistance generated by water when oxygen diffuses into the catalytic layer. The nano-confined conductive aeration membrane cathode has a strong ferrous iron recycling and regeneration ability, has a good treatment effect in actual nanofiltration concentrated water, and achieves selective degradation of ECs.

Description

Technical Field

[0001] The present invention belongs to the technical field of electro-Fenton wastewater treatment, and in particular relates to a conductive aeration membrane cathode electro-Fenton wastewater treatment device based on iron circulation, a method and an application thereof. Background Art

[0002] Electro-Fenton is a highly efficient and environmentally friendly electrochemical technology for degrading stubborn organic pollutants. However, the technology still faces the challenge of low H2O2 production efficiency during the oxygen reduction reaction (ORR), which limits its application. While catalyst selectivity and charge transfer efficiency can be improved to a certain extent, ORR efficiency is primarily limited by the oxygen mass transfer rate. In electrolysis systems, aeration is commonly used to supply oxygen by blowing air or O2 toward the cathode using an aeration head or multi-port lance. Due to the low solubility of O2 in water and poor mass transfer efficiency, O2 utilization efficiency is extremely low, limiting the generation of reactive oxygen species (ROS). Therefore, numerous studies have been conducted to improve the oxygen mass transfer efficiency during the ORR process. The use of a gas diffusion electrode (GDE) is a common method for increasing the oxygen mass transfer rate during ORR. Although this improves the mass transfer efficiency, the low solubility of O2 in water leads to significant O2 loss, which in turn limits the generation of free radical reactive oxygen species (ROS). Another important factor is that oxygen in gaseous form needs to overcome the physical resistance of water to effectively reach the cathode and participate in the oxygen reduction reaction, making the effective utilization of oxygen in water more difficult, thereby restricting the generation of ROS.

[0003] The main mechanism of electro-Fenton is the two-electron reduction of oxygen at the cathode to generate H2O2 (O2+2e – +2H + →H2O2), and with the added Fe 2+ The reaction generates OH(H2O2+Fe 2+ +H + → OH+H2O+Fe 3+ ) and then oxidize and remove organic matter. ·OH has strong oxidizing properties, but the process is still easily affected by natural organic matter and environmental factors in the water, which limits its application effect in complex water bodies. 2+ Regeneration is a distinct feature of the electro-Fenton process and a key step in controlling its efficiency. 3+ / Fe 2+ The circulation efficiency is low, which leads to the addition of more iron salts, high operating costs, and the generation of a large amount of iron sludge that requires subsequent disposal.

[0004] In recent years, the application of nanofiltration-based membrane purification technology in wastewater treatment has steadily increased, achieving excellent results in pollutant removal. However, the purification process can result in the separation of removed substances into nanofiltration brine, significantly increasing their concentrations and negatively impacting their subsequent treatment, disposal, and safe discharge. Nanofiltration brine contains a variety of antibiotics, pesticides, and emerging contaminants (ECs). Currently, there are no discharge standards that directly limit the types and concentrations of organic matter in nanofiltration brine. However, the ecological risks posed by the direct discharge of brine containing multiple ECs require full attention. However, existing biological treatment technologies are not ideal for removing ECs from water, primarily due to their high toxicity, low concentration, and difficult-to-degrade structural properties. In summary, current electro-Fenton complex water treatment technologies suffer from low O2 utilization, poor ferrous iron regeneration performance, and poor selective degradation. Therefore, the development of an improved electro-Fenton wastewater treatment device and method is crucial. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problems of low O2 utilization, large mass transfer resistance, poor ferrous iron cycle regeneration performance and poor selective degradation effect in the current electro-Fenton complex water treatment technology, and to provide a conductive aeration membrane cathode electro-Fenton sewage treatment device, method and application based on iron cycle.

[0006] One of the objectives of the present invention is to provide a nanoconfined conductive gas diffusion membrane, which is composed of a base membrane and an active layer on its surface, wherein the active layer is composed of broken CNTs and BN inside the base membrane.

[0007] A second object of the present invention is to provide a method for preparing a nanoconfined conductive gas diffusion membrane, the method being carried out according to the following steps:

[0008] S1: The aqueous dispersion of broken CNTs, H3BO3 ethanol solution and acetone were stirred and mixed, then ultrasonicated, allowed to stand, filtered and vacuum dried;

[0009] S2: calcining under nitrogen atmosphere, cooling to room temperature after calcination, washing, and vacuum drying to obtain BN-in-CNT;

[0010] S3: Fix the BN-in-CNT on the surface of the base membrane by vacuum filtration to obtain a nano-confined conductive gas diffusion membrane.

[0011] It is further defined that the preparation process of the broken CNTs in S1 is as follows: CNTs are added to concentrated HNO3 to form a suspension, which is then ultrasonicated at room temperature, followed by reflux in an oil bath at 403.2±5K, cooled to room temperature, filtered and washed to neutrality, followed by vacuum drying and freeze drying.

[0012] It is further defined that the concentration of the aqueous dispersion of broken CNTs in S1 is 5-15 mg / mL.

[0013] It is further defined that the concentration of the H3BO3 ethanol solution in S1 is 0.05-0.1 g / mL.

[0014] It is further defined that the ratio of broken CNTs to H3BO3 and acetone in S1 is 0.2 g:(1-2) g:(10-30) mL.

[0015] It is further defined that in S1, the mixture is stirred for 0.5-1.5 hours, ultrasonically treated for 3-5 hours, and allowed to stand for 20-24 hours.

[0016] It is further defined that the vacuum drying temperature in S1 is 333-353 K and the drying time is 10-12 h.

[0017] It is further defined that the calcination temperature in S2 is 1273-1473 K, the heating rate is 1-3 K / min, and the time is 1.5-2.5 h.

[0018] It is further defined that in S2, ethanol and deionized water are washed alternately.

[0019] It is further defined that the vacuum drying temperature in S2 is 333-353 K and the drying time is 10-12 h.

[0020] It is further defined that the BN-in-CNT loading in S3 is 1-3 g / cm 2 .

[0021] The third object of the present invention is to provide a conductive aeration membrane cathode electro-Fenton sewage treatment device based on iron circulation, comprising: a reaction chamber; an anode and a cathode arranged in the reaction chamber;

[0022] Magnetic stirrer;

[0023] Gas cylinders;

[0024] and DC power supply;

[0025] The device also includes an aeration membrane assembly arranged in the reaction chamber. The surface of the aeration membrane assembly adjacent to the anode is composed of a cathode, which is the above-mentioned nano-confined conductive gas diffusion membrane.

[0026] Further defined, the anode includes but is not limited to platinum sheet, boron doped diamond electrode (BDD), graphite, coated titanium electrode (DSA).

[0027] It is further defined that the distance between the cathode and anode is 0.5-1.5 cm.

[0028] A fourth object of the present invention is to provide a method for treating sewage using the above-mentioned device, the method comprising the following steps:

[0029] Step 1: Adjust the pH value of the wastewater to acidic and add Fe 2+ catalyst;

[0030] Step 2: Open the oxygen cylinder, and the gas enters the aeration membrane assembly from the gas supply pipeline, penetrates the nano-confined conductive gas diffusion membrane, and at the same time turns on the DC power supply, controls the current density of the cathode, and processes for a certain period of time.

[0031] It is further defined that in step 1, the pH value is adjusted to 2-4.

[0032] Further limit, in step 1, Fe 2+ The dosage of the catalyst is 0.05-0.15 mM.

[0033] It is further defined that the aeration rate in step 2 is 0.5-4 mL / min.

[0034] Further defined, the current density in step 2 is 1-8 mA / cm 2 .

[0035] It is further defined that the processing time in step 2 is 20-120 minutes.

[0036] A fifth object of the present invention is to provide an application of the above method in the selective degradation of sulfamethoxazole (SMX) and 17α-ethinylestradiol (EE2) in nanofiltration concentrated water.

[0037] The principle of the device and method of the present invention for selectively degrading ECs in nanofiltration concentrated water is to use a conductive aeration membrane to allow O2 to enter the system in the form of molecules, thereby improving the utilization rate of O2. At the same time, through the spatial confinement structure of the conductive aeration membrane, O2 is encapsulated inside the CNT to generate ROS in situ, and short-lived free radical species and reactants are encapsulated within the critical diffusion length scale, overcoming the mass transfer limitations of ROS generation and producing a ROS generation process different from the traditional Fenton-like process. 1 The reaction pathway with O2 as the intermediate provides a basis for the selective degradation of ECs in nanofiltration concentrated water. At the same time, BN encapsulated inside CNT promotes the 2+ regeneration cycle to improve the efficiency of ROS generation.

[0038] Compared with the prior art, the present invention has the following significant effects:

[0039] (1) The BN-in-CNT nanoconfined conductive aeration membrane treatment device and method of the present invention have a good treatment effect on SMX. Compared with the conventional membrane aeration electro-Fenton technology, the pollutant removal rate is increased by 2.5-11 times.

[0040] (2) In the device of the present invention, air actively diffuses into the cathode, and oxygen enters the carbon nanotubes through the gas diffusion membrane for threshold catalysis. This not only shortens the distance between oxygen molecules and the active center of the catalyst, avoiding the mass transfer restriction caused by oxygen entering the water body, but also improves the utilization rate of O2 and realizes in-situ efficient generation. 1 O2, the device is in the lower current density range (1-8mA / cm 2 ) Efficient production 1 O2.

[0041] (3) The present invention encapsulates BN inside CNT. In the BN-in-CNT structure, BN confines the iron ions in a small space, thereby Fe 2+ / Fe 3+ The local concentration increases, in addition to this, more importantly, Fe 2+ / Fe 3+ The effective collision frequency with oxygen or peroxide also increases accordingly, thereby greatly improving the circulation efficiency of ferrous iron. The ferrous iron recycling capacity of the BN-in-CNT nano-confined conductive aeration membrane cathode is 1.32-3.25 times higher than that of the conductive aeration membrane cathode with no encapsulated BN and BN attached to the outer surface of CNT.

[0042] (4) In the BN-in-CNT structure, BN makes the electrons more effectively distributed among the reactants, thereby promoting the occurrence of the reaction. Especially under the action of current, this difference in electron distribution will further enhance the Fe 2+ The reduction reaction of CNT with oxygen promotes the generation of active species such as superoxide anions and hydrogen peroxide. In addition, the present invention uses the BN inside the CNT to effectively prevent Fe 3+ Aggregation and formation of precipitates, thereby improving the stability of the iron cycle.

[0043] (5) The sewage treatment device and method of the present invention have good treatment effects in actual nanofiltration concentrated water, and have a high removal rate for electron-rich substances sulfamethoxazole (SMX) and 17α-ethinylestradiol (EE2), while the removal rates of pollutants with electron-withdrawing groups such as benzoic acid (BA), atrazine (ATZ), and carbamazepine (CBZ) are relatively low, thereby achieving selective degradation of ECs. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic structural diagram of the membrane aeration-iron cycle enhanced electro-Fenton sewage treatment device of the present invention;

[0045] Figure 2 HRTEM images of the products in steps (1) and (2) of Example 1 and Comparative Examples 1-2 of the present invention; (a) broken CNTs, (b) purified CNTs, (c) BN-in-CNT, and (d) BN-out-CNT;

[0046] Figure 3 This is the SMX removal rate effect diagram in Application Example 1;

[0047] Figure 4 This is the effect diagram of ferrous iron regeneration in Application Example 1;

[0048] Figure 5 This is the effect diagram of the aeration volume on the SMX removal rate in Application Example 1;

[0049] Figure 6 This is a diagram showing the effect of different ions on SMX removal efficiency in Application Example 1;

[0050] Figure 7 This is the effect diagram of the removal rate of different polluted wastewaters for Application Example 2;

[0051] Figure 8 This is the SMX removal rate effect diagram for actual nanofiltration concentrated water in Application Example 3;

[0052] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0053] 1- anode, 2- cathode, 3- aeration membrane assembly, 4- magnetic stirrer, 5- gas cylinder, 6- DC power supply. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0055] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional in the art and can be obtained commercially by those skilled in the art unless otherwise specified.

[0056] As used in the following examples, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0057] The term "one embodiment" or "embodiment" of the present invention refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it necessarily refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0058] The endpoints of the ranges and any values ​​disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0059] Example 1: Combination Figure 1 The conductive aeration membrane cathode electro-Fenton sewage treatment device based on iron circulation of this embodiment comprises:

[0060] A reaction chamber (made of organic glass, with a volume of 0.27 L) is provided with a platinum anode 1 (4 cm × 5 cm), a cathode 2, and an aeration membrane assembly 3 (with a volume of 0.02 L).

[0061] Magnetic stirrer 4;

[0062] Gas cylinder 5;

[0063] and a DC power supply 6;

[0064] The surface of the aeration membrane assembly 3 adjacent to the platinum anode 1 is composed of a cathode 2, which is a nano-confined conductive gas diffusion membrane ( <d>=4cm), the distance between cathode and anode is 1cm;

[0065] The preparation method of the nano-confined conductive gas diffusion membrane is carried out according to the following steps:

[0066] (1) To prepare broken CNTs, 200 mL of concentrated HNO3 (68 wt%) was added to the untreated CNTs, and the suspension was then sonicated at room temperature for 1 h to better disperse the particles. Subsequently, the suspension was refluxed in an oil bath at 403.2 ± 5 K for 14 h. After cooling to room temperature, the suspension was filtered and washed with deionized water until the pH was neutral. The suspension was then dried in a vacuum drying oven at 333.2 K for 12 h. Finally, the suspension was placed in a freeze dryer for 48 hours of freeze drying (228.2 K). The above treatment of carbon nanotubes removed the end caps of the nanotubes as well as amorphous carbon and metal catalyst residues.

[0067] (2) H3BO3 (1.5 g) was dissolved in 20 mL of 99 wt% ethanol as a BN precursor. 0.2 g of the support (broken CNTs) was ultrasonically dispersed in 20 mL of deionized water for 1 h. Then, 20 mL of the aqueous dispersion of broken CNTs, 20 mL of the ethanolic solution of H3BO3, and 20 mL of acetone were stirred and mixed for 1 h and then ultrasonically treated for 4 h. The capillary force of the CNTs was used to introduce H3BO3 into the CNT channels with the assistance of ultrasonic and stirring treatment. After standing for 24 h, the mixture was filtered and then dried in a vacuum oven at 353.2 K for 12 h. The solid mixture sample was heated to 1273.2 K in nitrogen (heating rate 2 K / min) and maintained in a tube furnace for 2 h. Then, the solid sample was washed alternately with ethanol and deionized water at room temperature, each washed 5 times, and then dried in a vacuum oven at 353.2 K for 8 h (333.2 K). H3BO3 decomposes into BN inside the broken CNT, and the obtained sample is recorded as BN-in-CNT.

[0068] (3) BN-in-CNT was fixed on the surface of PTFE / PP membrane by vacuum filtration to obtain BN-in-CNT nanoconfined conductive gas diffusion membrane. The loading of catalytic material on the membrane was 1.19 mg / cm 2 .

[0069] Comparative Example 1:

[0070] The difference between this comparative example and Example 1 is that:

[0071] Step (1): Preparation of purified CNTs: Untreated CNTs were dispersed in 200 mL of diluted nitric acid solution (38 wt %) and refluxed in an oil bath at 382.2 K for 14 h.

[0072] Omit step (2).

[0073] In step (3), the purified CNTs obtained in step (1) are directly fixed on the surface of the PTFE / PP membrane by vacuum filtration. Other steps and parameters are the same as those in Example 1.

[0074] Comparative Example 2:

[0075] The difference between this comparative example and Example 1 is that:

[0076] Step (1): Preparation of purified CNTs: Untreated CNTs were dispersed in 200 mL of diluted nitric acid solution (38 wt %) and refluxed in an oil bath at 382.2 K for 14 h.

[0077] Step (2) obtains BN-out-CNT.

[0078] In step (3), the BN-out-CNT was fixed on the surface of the PTFE / PP membrane by vacuum filtration. The other steps and parameters were the same as those in Example 1.

[0079] HRTEM images of broken CNTs and purified CNTs are shown in Figure 2. Figure 2 (a)-(b) are shown. HRTEM images of BN-in-CNT and BN-out-CNT are shown Figure 2 As shown in (c) and 2(d), it can be seen that in the BN-in-CNT material, the BN is confined inside the CNT, while in the BN-out-CNT material, the BN is dispersed outside the CNT.

[0080] Application Example 1: The devices of Example 1 and Comparative Examples 1-2 were used to treat a 10 μM sulfamethoxazole (SMX) aqueous solution. The specific treatment steps are as follows:

[0081] Step 1: Adjust the pH value of the wastewater to 3 and add 0.05mM FeSO4·7H2O;

[0082] Step 2: Open the oxygen cylinder and the gas enters the aeration membrane assembly through the gas supply line at an aeration rate of 2.5 mL / min. The gas penetrates the nanoconfined conductive gas diffusion membrane and immediately contacts the catalyst loaded on the membrane and is consumed in the catalytic layer. At the same time, turn on the DC power supply, the electrolyte is 0.05 M sodium sulfate solution, and the current density is 8 mA / cm 2 .

[0083] PTFE was used as the cathode as a blank control, BN-out-CNT and CNTs were used as experimental controls, and the degradation effect of SMX was shown in the figure. Figure 3 As shown in the figure, the current density is 8mA / cm 2 The device has a SMX degradation efficiency of 90% in 10 minutes, and only needs 15 minutes of reaction to achieve complete degradation of SMX.

[0084] The membrane aeration-iron circulation enhanced electro-Fenton selective degradation sewage device of the present invention can greatly promote the regeneration of ferrous iron. In Application Example 1, when sulfamethoxazole (SMX) wastewater is not added, the ferrous iron regeneration capacity is as follows: Figure 4 As shown in the figure, it can be seen that O2 is exposed to a 0.05M sodium sulfate electrolyte solution with a pH value of 3 at a flow rate of 2.5mL / min, and the current density is 8mA / cm 2 When the regeneration capacity of the BN-in-CNT nano-confined conductive aeration membrane of the device of the present invention is improved by 1.32-3.25 times that of the conductive aeration membrane cathode of Example 1 without encapsulated BN and Example 2 with BN attached to the outer surface of CNT.

[0085] In Application Example 1, the effects of treating SMX wastewater under different O2 aeration rates and ion conditions are as follows: Figure 5-6 As shown, in Fe 2 + Under the conditions of 0.05 mM FeSO4·7H2O catalyst dosage and pH 3, the current density of the cathode of BN-in-CNT nanoconfined conductive aeration membrane was controlled to be 8 mA / cm 2 . Figure 5 The results showed that the degradation rate of SMX continued to increase with the increase of aeration rate. The aeration membrane cathode achieved 100% degradation of SMX at an aeration rate of only 2.5 mL / min, demonstrating the high in situ ROS generation efficiency of molecularly encapsulating O2 inside CNTs.

[0086] Figure 6 Display, in PO4 3- (0.05M), Cl-(0.05M), HCO3 - Under the condition of 0.05M, it can achieve an efficient removal rate of more than 80% within 15 minutes. Based on this, it can be inferred that the excellent universal ability of nano-confined electrodes in ionic environments makes it possible to efficiently purify ECs in water bodies with complex conditions.

[0087] Application Example 2: The device of Example 1 and the method described in Application Example 1 are used to treat wastewater containing different types of pollutants. The concentration of sulfamethoxazole (SMX) in the wastewater is 10 μM, the concentration of benzoic acid (BA) is 10 μM, the concentration of atrazine (ATZ) is 10 μM, the concentration of carbamazepine (CBZ) is 10 μM, and the concentration of 17α-ethinylestradiol (EE2) is 10 μM.

[0088] Treatment effects on wastewater with different types of pollutants Figure 7 As shown, in Fe 2+ Under the conditions of 0.05 mM dosage (with FeSO4·7H2O as catalyst) and pH 3, the current density of the cathode of the BN-in-CNT nanoconfined conductive aeration membrane was controlled to be 8 mA / cm 2 Sulfamethoxazole (SMX) and 17α-ethinylestradiol (EE2) were effectively removed under spatial nanoscale conditions; whereas benzoic acid (BA), carbamazepine (CBZ), and atrazine (ATZ) with electron-withdrawing groups were difficult to degrade in the system, indicating that the device has strong selectivity for pollutant removal.

[0089] Application Example 3: The device of Example 1 and the method described in Application Example 1 were used to treat actual nanofiltration concentrated water (physical and chemical parameters are shown in Table 1) to evaluate potential environmental applications. Figure 8 The results show that the BN-in-CNT aerated conductive catalytic membrane can achieve 100% degradation of SMX within 20 minutes. This indicates that the system can still achieve good degradation efficiency in actual complex water environments, highlighting the practicality of the system in water treatment.

[0090] Table 1 Physical and chemical parameters of actual nanofiltration concentrate

[0091]

[0092] In summary, the membrane aeration-iron cycle enhanced electro-Fenton selective wastewater degradation device and method proposed in the present invention can simultaneously achieve efficient ROS generation and ferrous regeneration cycle under low O2 aeration conditions, and has a good treatment effect on the selective degradation of SMX in actual nanofiltration concentrated water environment.

[0093] The foregoing are merely preferred embodiments of the present invention. These embodiments are all different implementations based on the overall concept of the present invention. The scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.< / d>

Claims

1. A nano-confined conductive gas diffusion membrane, characterized in that: The nanoconfined conductive gas diffusion membrane is composed of a base membrane and an active layer on its surface, wherein the active layer is composed of broken CNTs and BN inside the base membrane. The preparation method of the nano-confined conductive gas diffusion membrane: S1: The aqueous dispersion of broken CNTs, the ethanol solution of H3BO3, and acetone were stirred and mixed, then ultrasonically treated, allowed to stand, filtered, and vacuum dried. The preparation process of broken CNTs was as follows: CNTs were added to concentrated HNO3 to form a suspension, then ultrasonically treated at room temperature, and then refluxed in an oil bath at 403.2±5 K. After cooling to room temperature, the suspension was filtered and washed to neutrality, followed by vacuum drying and freeze drying. The concentration of the aqueous dispersion of broken CNTs in S1 was 5-15 mg / mL, the concentration of the ethanol solution of H3BO3 was 0.05-0.1 g / mL, and the ratio of broken CNTs to H3BO3 and acetone was 0.2 g: (1-2) g: (10-30) mL. The suspension was stirred for 0.5-1.5 h, ultrasonicated for 3-5 h, and allowed to stand for 20-24 h. S2: calcining under nitrogen atmosphere, cooling to room temperature after calcination, washing, and vacuum drying to obtain BN-in-CNT; S3: Fix the BN-in-CNT on the surface of the base membrane by vacuum filtration to obtain a nano-confined conductive gas diffusion membrane.

2. The nanoconfined conductive gas diffusion membrane according to claim 1, characterized in that: The calcination temperature in S2 is 1273-1473 K, the heating rate is 1-3 K / min, and the time is 1.5-2.5 h.

3. The nanoconfined conductive gas diffusion membrane according to claim 1, wherein: The BN-in-CNT loading in S3 is 1-3 g / cm 2 .

4. Conductive aeration membrane cathode electro-Fenton wastewater treatment device based on iron circulation, including: A reaction chamber; an anode and a cathode are arranged in the reaction chamber; Magnetic stirrer; Gas cylinders; and DC power supply; It is characterized in that the device also includes an aeration membrane assembly arranged in the reaction chamber, and the surface of the aeration membrane assembly adjacent to the anode is composed of a cathode, and the cathode is the nano-confined conductive gas diffusion membrane according to claim 1.

5. A method for treating sewage using the device according to claim 4, characterized in that: The method: Step 1: Adjust the pH value of the wastewater to acidic and add Fe 2+ catalyst; Step 2: Open the oxygen cylinder, and the gas enters the aeration membrane assembly from the gas supply pipeline, penetrates the nano-confined conductive gas diffusion membrane, and at the same time turns on the DC power supply, controls the current density of the cathode, and processes for a certain period of time.

6. The method according to claim 5, characterized in that In step 1, adjust the pH to 2-4, Fe 2+ The dosage of the catalyst is 0.05-0.15 mM.

7. The method according to claim 5, characterized in that In step 2, the aeration rate is 0.5-4 mL / min and the current density is 1-8 mA / cm 2 , the processing time is 20-120min.

8. Use of the method according to any one of claims 5 to 7 in the selective degradation of SMX and EE2 in nanofiltration concentrate.

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