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

Abstract

The invention discloses a conductive aeration membrane cathode electro-Fenton sewage treatment device and method based on iron circulation and application. The invention belongs to the technical field of electro-Fenton sewage treatment. The invention aims to solve the technical problems of low O2 utilization rate, poor ferrous cyclic regeneration performance and poor selective degradation effect in the current electro-Fenton complex water treatment technology. The nano confinement conductive gas diffusion film is composed of a base film and an active layer, wherein the active layer is composed of fractured CNT and internal BN. An aeration membrane assembly is arranged in the reaction chamber of the device, and the surface, adjacent to the anode, of the assembly is composed of the gas diffusion membrane. By means of the design, oxygen directly makes contact with the catalyst layer through the gas diffusion film and is consumed immediately, and mass transfer resistance generated by water when the oxygen is diffused to the catalyst layer is avoided while 100% utilization of the oxygen is achieved. The nanometer confinement conductive aeration membrane cathode is high in ferrous cyclic regeneration capacity and has a good treatment effect in actual nanofiltration concentrated water, and selective degradation of ECs is achieved.

Description

Technical Field

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

[0002] Electro-Fenton is an efficient and environmentally friendly electrochemical technology that can degrade stubborn organic pollutants. However, this technology still faces the problem of H 2 O 2 The problem of low production efficiency limits the application of EF technology. When the selectivity and charge transfer efficiency of the catalyst are improved to a certain extent, the ORR efficiency is mainly limited by the oxygen mass transfer rate. In the electrolysis system, the commonly used aeration oxygen supply method is to use an aeration head or a multi-port spray gun to inject air or O 2 Blowing toward the cathode. 2 Low solubility in water and poor mass transfer efficiency lead to O 2 The utilization efficiency of reactive oxygen species (ROS) is extremely low, which makes the generation of reactive oxygen species (ROS) still limited. Therefore, many studies have been devoted to improving the oxygen mass transfer efficiency in the ORR process. Among them, the use of gas diffusion electrode (GDE) is a common method to improve the oxygen mass transfer rate in ORR. Although the mass transfer efficiency is improved, due to the O 2 The low solubility in water leads to the 2 The loss of oxygen in water is serious, so the generation of free radical reactive oxygen species (ROS) is still limited. 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 use 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 H 2 O 2 (O 2 +2e – +2H + →H 2 O 2 ) and with the addition of Fe 2+ The reaction generates OH(H 2 O 2 +Fe 2+ +H + → OH+H 2 O+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 more iron salt addition, high operating costs, and the generation of a large amount of iron sludge that requires subsequent disposal.

[0004] In recent years, the application of membrane purification technology with nanofiltration as the core in wastewater treatment has gradually increased, and has achieved good results in pollutant removal. However, during the purification process, the removed substances will be separated into nanofiltration concentrate, resulting in a significant increase in their content level, and causing certain negative impacts on their subsequent treatment and safe discharge. Nanofiltration concentrate contains a variety of antibiotics, pesticides and other emerging pollutants (Emerging Contaminants, ECs), and there is currently a lack of direct emission standards to limit the types and contents of organic matter in nanofiltration concentrate, but the direct discharge of concentrate containing a variety of ECs may cause ecological risks that need to be fully taken seriously. However, the existing biological treatment technology is not ideal in removing ECs from water, which is mainly attributed to the high toxicity, low concentration and difficult-to-degrade structural characteristics of ECs. In summary, the current electro-Fenton complex water treatment technology has the following shortcomings: 2 There are problems such as low utilization rate, poor ferrous iron recycling performance and poor selective degradation effect, so it is necessary to construct an improved electro-Fenton wastewater treatment device and method. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the current electro-Fenton complex water treatment technology. 2 In order to solve the technical problems of low utilization rate, large mass transfer resistance, poor ferrous iron cycle regeneration performance and poor selective degradation effect, a conductive aeration membrane cathode electro-Fenton sewage treatment device, method and application based on iron cycle are provided.

[0006] One of the purposes of the present invention is to provide a nanoconfined conductive gas diffusion membrane, wherein 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.

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

[0008] S1: The aqueous dispersion of broken CNTs, H 3 BO 3The ethanol solution and acetone were stirred and mixed, then ultrasonically treated, 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] Further definition, the preparation process of the broken CNT in S1: CNT was added to concentrated HNO 3 The suspension is formed in the solution, which is then ultrasonically treated 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] Further definition, H in S1 3 BO 3 The concentration of the ethanol solution is 0.05-0.1g / mL.

[0014] Further definition, the broken CNT in S1 and H 3 BO 3 The ratio of acetone is 0.2g:(1-2)g:(10-30)mL.

[0015] It is further defined that S1 is stirred and mixed 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 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 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 are 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, and 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 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 definition, 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 min.

[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 concentrate.

[0037] The principle of the method for selectively degrading ECs in nanofiltration concentrated water by the device and method of the present invention is to use a conductive aeration membrane to make O2 Enter the system in the form of molecules, increasing O 2 At the same time, through the space confinement structure of the conductive aeration membrane, O 2 Encapsulation inside CNT generates ROS in situ, encapsulating short-lived free radical species and reactants within the critical diffusion length scale, overcoming the mass transfer limitation of ROS generation, and producing a ROS generation process different from the traditional Fenton-like process. 1 O 2 The reaction pathway of the reaction intermediates provides a basis for the selective degradation of ECs in nanofiltration concentrated water. At the same time, BN encapsulated inside CNTs 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 nano-confined 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 to the cathode, and oxygen enters the carbon nanotubes for threshold catalysis when passing through the gas diffusion membrane. This not only shortens the distance for oxygen molecules to reach the active center of the catalyst, avoids the mass transfer restriction caused by oxygen entering the water body, but also improves O 2 Utilization rate, achieving efficient in-situ generation 1 O 2 , the device is in the lower current density range (1-8mA / cm 2 ) Efficient production 1 O 2 .

[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, among other things, and 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 efficiently distributed among the reactants, thereby promoting the reaction. Especially under the action of electric 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, thus increasing 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 concentrate, and have high removal rates for electron-rich substances such as sulfamethoxazole (SMX) and 17α-ethinylestradiol (EE2), while the removal rates for pollutants with electron-withdrawing groups such as benzoic acid (BA), atrazine (ATZ), and carbamazepine (CBZ) are low, thereby achieving selective degradation of ECs. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure 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 step (1) and step (2) of Example 1 of the present invention and Comparative Examples 1-2; (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 rate in Application Example 1;

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

[0051] Figure 8 This is the effect diagram of SMX removal rate in 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 solution 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 used 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 materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

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

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

[0058] The endpoints and any values ​​of the ranges disclosed in the 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 endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

[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); a platinum anode 1 (4 cm×5 cm), a cathode 2 and an aeration membrane assembly 3 (with a volume of 0.02 L) are arranged in the reaction chamber;

[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 the 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 HNO was added to the untreated CNTs. 3 (68wt%), and then the suspension was ultrasonically treated at room temperature for 1h to better disperse the particles. Then, it was refluxed in an oil bath at 403.2±5K for 14h. After cooling to room temperature, it was filtered and washed with deionized water until the pH was neutral. It was then dried in a vacuum oven at 333.2K for 12h. Finally, it was placed in a freeze dryer for 48 hours of freeze drying (228.2K). The above treatment of carbon nanotubes removes the end caps of the nanotubes as well as amorphous carbon and metal catalyst residues.

[0067] (2) H 3 BO 3 (1.5 g) was dissolved in 20 mL of 99 wt% ethanol as a BN precursor. 0.2 g of the carrier (broken CNT) was dispersed in 20 mL of deionized water by ultrasonication for 1 h. Then, 20 mL of the broken CNT aqueous dispersion, 20 mL of H 3 BO 3 The ethanol solution was mixed with 20 mL of acetone and stirred for 1 h, and then ultrasonicated for 4 h. The capillary force of CNT was used to transfer H 3 BO 3 Introduced into the CNT channel. After standing for 24 hours, it was filtered and then dried in a vacuum oven at 353.2K for 12 hours. The solid mixture sample was heated to 1273.2K in nitrogen (heating rate 2K / min) and kept in a tube furnace for 2 hours. Then, at room temperature, the solid sample was washed alternately with ethanol and deionized water, each washed 5 times, and then dried in a vacuum oven at 353.2K for 8 hours (333.2K). 3 BO 3 It 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 amount 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 a diluted nitric acid solution (38 wt%) and refluxed for 14 h in an oil bath at 382.2 K.

[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 a diluted nitric acid solution (38 wt%) and refluxed for 14 h in an oil bath at 382.2 K.

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

[0078] In step (3), BN-out-CNT is fixed on the surface of the PTFE / PP membrane by vacuum filtration. Other steps and parameters are 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. The HRTEM images of BN-in-CNT and BN-out-CNT are shown in 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 are used to treat a 10 μM sulfamethoxazole (SMX) aqueous solution. The specific treatment method steps are as follows:

[0081] Step 1: Adjust the pH value of the wastewater to 3 and add 0.05 mM FeSO 4 7H 2 O;

[0082] Step 2: Open the oxygen cylinder, and the gas enters the aeration membrane assembly from the gas supply pipeline. The aeration rate is 2.5 mL / min. The gas penetrates the nano-confined 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] Using PTFE as the cathode as a blank control, BN-out-CNT and CNTs as experimental controls, the degradation effect of SMX is 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 wastewater degradation device of the present invention can greatly promote the regeneration of ferrous iron. When no sulfamethoxazole (SMX) wastewater is added in Application Example 1, the regeneration capacity of ferrous iron is as follows: Figure 4 As shown in the figure, it can be seen that the O was exposed to the 0.05M sodium sulfate electrolyte solution with a pH value of 3 at a flow rate of 2.5mL / min. 2 , current density is 8mA / cm 2 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 BN encapsulation and Example 2 with BN attached to the outer surface of CNT.

[0085] In application example 1, in different O 2 Effects of aeration volume and ion conditions on treating SMX wastewater Figure 5-6 As shown, in Fe 2 + Catalyst FeSO 4 7H 2 When the O dosage was 0.05 mM and the pH was 3, the current density of the cathode of the BN-in-CNT nanoconfined conductive aeration membrane was controlled to be 8 mA / cm 2 . Figure 5 The results show that the degradation rate of SMX continues to increase with the increase of aeration rate. The aeration membrane cathode can achieve 100% degradation of SMX at an aeration rate of only 2.5 mL / min, which proves that the degradation of SMX by O 2 Encapsulated in CNT in molecular form, it has a high in situ ROS generation efficiency.

[0086] Figure 6 Show, in PO 4 3- (0.05M), Cl-(0.05M), HCO 3 - Under the environment of 0.05M, it can achieve more than 80% efficient removal within 15 minutes. 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, wherein 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+ Dosage (FeSO 4 7H 2 O as catalyst) was 0.05 mM and pH was 3. The current density of the cathode of the BN-in-CNT nanoconfined conductive aeration membrane was controlled to be 8 mA / cm 2 Sulfadimethoxazole (SMX) and 17α-ethinylestradiol (EE2) can be effectively removed under spatial nano-sizing conditions; while benzoic acid (BA), carbamazepine (CBZ) and atrazine (ATZ) with electron-withdrawing groups are difficult to degrade in the system, indicating that the device has a strong selectivity for the removal of pollutants.

[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 As shown in the figure, the results show that the BN-in-CNT aerated conductive catalytic membrane can achieve 100% degradation of SMX within 20 minutes. This shows that in the actual complex water environment, the system can still achieve good degradation efficiency, which highlights 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 sewage degradation device and method proposed in the present invention can be used in low O 2 The efficient production of ROS and ferrous iron regeneration cycle can be achieved simultaneously under aeration conditions, which has a good treatment effect on the selective degradation of SMX in actual nanofiltration concentrated water environment.

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

Claims

1. A nano-confined conductive gas diffusion membrane, characterized in that: The nano-confined conductive gas diffusion membrane consists of a base membrane and an active layer on its surface, and the active layer consists of broken CNTs and BN inside the base membrane.

2. The method for preparing the nano-confined conductive gas diffusion membrane according to claim 1, characterized in that: The method: S1: Mix the aqueous dispersion of broken CNTs, the ethanol solution of H3BO3 and acetone, then ultrasonicate them, let them stand, filter them and vacuum dry them; 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.

3. The method according to claim 2, characterized in that Preparation process of broken CNT in S1: CNT is added to concentrated HNO3 to form a suspension, then ultrasonically treated at room temperature, followed by oil bath reflux at 403.2±5K, cooled to room temperature, filtered and washed to neutrality, followed by vacuum drying and freeze drying. The concentration of aqueous dispersion of broken CNT in S1 is 5-15 mg / mL, the concentration of ethanol solution of H3BO3 is 0.05-0.1 g / mL, the ratio of broken CNT to H3BO3 and acetone is 0.2 g: (1-2) g: (10-30) mL, stirred and mixed for 0.5-1.5 h, ultrasonically treated for 3-5 h, and allowed to stand for 20-24 h.

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

5. The method according to claim 2, characterized in that: The BN-in-CNT loading in S3 is 1-3 g / cm 2 .

6. Conductive aeration membrane cathode electro-Fenton wastewater treatment device based on iron circulation, comprising: 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.

7. A method for treating sewage using the device according to claim 6, 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.

8. The method according to claim 7, 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.

9. The method according to claim 7, 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.

10. Use of the method according to any one of claims 7 to 9 in the selective degradation of SMX and EE2 in nanofiltration concentrate.

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