Self-oxygen-supply in-situ H2O2-FeOCl production double-cathode coupled electro-catalysis wastewater treatment method

Abstract

The invention discloses a self-oxygen-supply in-situ H2O2-FeOCl production double-cathode coupled electro-catalysis wastewater treatment method. The method comprises the following steps: carrying out electrolytic treatment on wastewater through a double-cathode electro-catalysis electrolytic bath; a first cathode in the double-cathode electro-catalysis electrolytic bath is a crack gas diffusion electrode and comprises a conductive substrate and a carbon black-PTFE catalyst coated on the conductive substrate; the first anode is an MMO mixed metal electrode or a ruthenium-iridium electrode; the second cathode comprises a conductive substrate and a FeOCl catalyst coated on the conductive substrate; and the second anode is a diamond electrode. According to the invention, the oxygen is generated through the first anode MMO, and the crack gas diffusion electrode is used as the first cathode to generate H2O2, so that the problem of oxygen supply is solved; feOCl / GF composite electrodes are connected in series, wastewater is efficiently treated through electro-Fenton, other auxiliary devices do not need to be matched, products are environmentally friendly and free of secondary pollution, and efficient degradation of antibiotics can be achieved through the system.

Description

Technical Field

[0001] The present invention relates to the field of electrocatalytic wastewater treatment, and particularly to an electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2-FeOCl dual cathodes. Background Art

[0002] Hydrogen peroxide (H2O2) is a zero-emission and highly efficient chemical oxidant, which is widely used in the field of industrial water treatment. Currently, more than 95% of commercial H2O2 is industrially produced by the anthraquinone process. Although the anthraquinone process has mature technology and perfect infrastructure, it still has significant disadvantages, such as high operating costs, dangerous explosion problems, and transportation limitations. In recent years, the production of H2O2 through a two-electron redox reaction [ORR, O2 + 2H + + 2e - → H2O2] has been proven to be a cost-effective alternative to traditional chemical methods, avoiding the need for transportation, storage, and handling of concentrated H2O2.

[0003] The in-situ electrochemical production of H2O2 depends on effective oxygen supply. In an in-situ H2O2 electrochemical system, due to the difference in the number of electron transfers between the anode (four-electron OER process) and the cathode (two-electron ORR process), the oxygen consumed for the production of H2O2 at the cathode is twice that of traditional methods. Although injecting oxygen into water is feasible, this process requires additional installation work of oxygen supply equipment and energy consumption. In addition, in the two-electron ORR process, the rapid electro-wetting induced by high current will destroy the initial gas capture channels of the electrode, resulting in O2 starvation at the electroactive interface, thereby reducing the reaction efficiency of in-situ electrochemical production of H2O2.

[0004] How to apply the in-situ electrochemically generated H2O2 to the field of industrial water treatment involves the electrochemical advanced oxidation process (AO). Those technologies based on the Fenton reaction chemistry, such as electro-Fenton (EF), have been proven to be the most robust technologies. For example, a carbon-based self-breathing cathode for in-situ production of hydrogen peroxide and degradation of organic matter and its preparation method disclosed in Patent CN117721490A. The EF reaction lies in the generation of strongly oxidizing hydroxyl radicals (·OH) through the Fenton reaction between hydrogen peroxide (H2O2) generated at the cathode and externally added Fe 2+ catalyst. However, conventional homogeneous EF methods have disadvantages such as a narrow working pH window (2.8 - 3.5) and the formation of iron sludge. Summary of the Invention

[0005] The present invention is to overcome the above problems existing in the prior art, and provides an electrocatalytic wastewater treatment method coupling self-supplied oxygen in-situ production of H2O2 and FeOCl double cathodes. Oxygen is produced by the first anode MMO, and then the crack gas diffusion electrode is used as the first cathode to produce H2O2, thereby solving the problem of oxygen supply; the FeOCl / GF composite electrode is connected in series, and electro-Fenton is used to efficiently treat wastewater without the need to cooperate with other auxiliary devices. The products are green and environmentally friendly and have no secondary pollution. This system can achieve the efficient degradation of antibiotics.

[0006] To achieve the above object, the present invention adopts the following technical solutions: An electrocatalytic wastewater treatment method coupling self-supplied oxygen in-situ production of H2O2 and FeOCl double cathodes, the steps include: electrolyzing wastewater through a double-cathode electrocatalytic electrolytic cell; the double-cathode electrocatalytic electrolytic cell includes a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a crack gas diffusion electrode, including a conductive matrix and a carbon black-PTFE catalyst coated on the conductive matrix; The first anode is an MMO mixed metal electrode or a ruthenium-iridium electrode; The second cathode includes a conductive matrix and an FeOCl catalyst coated on the conductive matrix; The second anode is a diamond electrode.

[0007] The main reaction formulas in the wastewater degradation process of the present invention are as follows: Near the first cathode: Cathode: O2 + 2H + + 2e - → H2O2 (1); Near the first anode: Anode: 2H2O - 4e - → O2 + H + (2); Near the second anode: Cathode: Fe(III) + ·OH → Fe(IV) + OH - (3); Fe(IV) + ·OH → Fe(V) + OH - (4); Near the second cathode: Anode: Fe 2+ + H2O2 → [Fe(OH)2] 2+ → ·OH + OH - + Fe 3+ (5); Organic pollutants + ·OH → Degradation products (6); Fe 3+ + e - → Fe 2+ (7).

[0008] The present invention produces oxygen through the first anode MMO, and then uses the crack gas diffusion electrode as the first cathode to produce H2O2; the O2 generated by the anodic oxygen evolution (OER) reaction of electrochemically in-situ producing H2O2 is used to supply oxygen to the first cathode to realize in-situ self-oxygen supply for producing hydrogen peroxide. In this process, no additional oxygen supply is required, reducing the work and energy consumption. At the same time, the present invention uses the crack gas diffusion electrode to overcome the electrowetting effect during long-term electrolysis under harsh industrial-related conditions. Even under harsh electrolysis conditions, due to the weakening of the local electric field and liquid infiltration capillary force caused by spatial discontinuity, these micron-scale film defects can counterintuitively maintain strong superhydrophobicity, enabling O2 to freely and rapidly diffuse in these channels.

[0009] The second cathode of the present invention uses FeOCl as a catalyst. Iron oxychloride (FeOCl) is a metal chloride with a two-dimensional layered structure, having high electron mobility and electron delocalization properties. It can not only efficiently activate the production of ·OH, but also electrochemically reduce Fe 3+ to generate Fe 2+ , and also has high pH adaptability.

[0010] Therefore, the present invention constructs a self-oxygen supply in-situ hydrogen peroxide production - FeOCl dual cathode system: the first cathode uses a carbon black (CB)-PTFE / GF crack gas diffusion electrode, and the gas diffusion layer of this electrode can efficiently utilize oxygen, thereby realizing a two-electron reaction and in-situ high-efficiency production of H2O2. The second cathode uses a FeOCl / GF composite electrode, which can not only efficiently activate the production of ·OH, but also electrochemically reduce Fe 3+ to avoid the generation of iron sludge. The dual cathode system of the present invention uses electro-Fenton to efficiently treat wastewater, without the need to cooperate with other auxiliary devices. The products are green and environmentally friendly without secondary pollution, and can achieve high-efficiency degradation of antibiotics.

[0011] Preferably, the conductive substrate in the first cathode and the second cathode is one of carbon paper, carbon fiber paper, carbon cloth, carbon fiber cloth, graphite felt, nickel foam, copper foam, titanium plate, ruthenium-iridium electrode plate, and conductive glass.

[0012] Preferably, in the carbon black-PTFE catalyst, the mass ratio of carbon black to PTFE is 5:2 to 4.

[0013] Preferably, the preparation method of the first cathode is as follows: Mix carbon black with absolute ethanol, and perform ultrasonic oscillation. Then add a PTFE suspension and stir at 60 - 80 °C until it becomes a paste to obtain a coating. Coat the coating on a conductive substrate, and then calcine it at 330 - 400 °C for 150 - 200 min to obtain a cracked gas diffusion electrode. In the present invention, the CB-PTFE active layer is first coated on the surface of the conductive substrate and then annealed, so that a discontinuous film with dense and penetrating microcracks can be obtained, thereby obtaining a cracked gas diffusion electrode. This cracked gas diffusion electrode can overcome the electro-wetting effect during long-term electrolysis under harsh industrial-related conditions.

[0014] Preferably, in the first cathode, the coating amount of the carbon black-PTFE catalyst is 5 - 40 mg / cm 2 .

[0015] Preferably, in the second cathode, the coating amount of the FeOCl catalyst is 5 - 40 mg / cm 2 .

[0016] Preferably, the first cathode and the second cathode have the same area, the first anode and the second anode have the same area, and the area ratio of the cathode to the anode is 1 - 20:1.

[0017] Preferably, the wastewater is antibiotic wastewater.

[0018] Preferably, the current density during electrolytic treatment is 5 - 20 mA / cm 2 .

[0019] Preferably, during electrolytic treatment, the wastewater in the dual-cathode electrocatalytic electrolysis cell undergoes internal circulation. The internal circulation of the device during the reaction can enhance the effective contact time and mass transfer effect between the electrode / electrolyte interface, thereby improving the wastewater degradation effect.

[0020] Therefore, the present invention has the following beneficial effects: (1) All reaction processes are completed in a single reaction device without the need for other auxiliary equipment, and the operation and operation costs are low; (2) The first cathode uses a CB-PTFE / GF cracked gas diffusion electrode, and the gas diffusion layer of this electrode can efficiently utilize oxygen, thereby realizing a two-electron reaction and in-situ high-efficiency production of H2O2; (3) The second cathode uses a FeOCl / GF composite electrode, which can not only efficiently activate and produce ·OH, but also electro-reduce Fe 3+ to avoid the generation of iron sludge and simultaneously realize the recycling of iron ions; (4) The degradation efficiency is high, the removal rate in antibiotic wastewater can reach more than 80%, the reaction product is water, and there are no harmful by-products, which conforms to the clean energy theory; (5) Treating wastewater by the method of the present invention not only achieves efficient zero discharge, but also greatly reduces the corresponding traditional treatment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a test chart of the degradation effect of oxytetracycline at different current densities in Example 1 of the present invention.

[0022] Figure 2 It is a test chart of the degradation effect of levofloxacin at different current densities in Example 2 of the present invention.

[0023] Figure 3 It is a test chart of the degradation effect of sulfamethoxazole at different current densities in Example 3 of the present invention.

[0024] Figure 4 It is a test chart of the degradation effect of oxytetracycline at different pH values in Example 4 of the present invention.

[0025] Figure 5 It is a test chart of the degradation effect of levofloxacin at different pH values in Example 5 of the present invention.

[0026] Figure 6 It is a test chart of the degradation effect of sulfamethoxazole at different pH values in Example 6 of the present invention.

[0027] Figure 7 It is a test chart of the degradation effects of oxytetracycline, levofloxacin, sulfamethoxazole and iron leaching amount in Example 7 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0029] In the present invention, unless otherwise specified, all devices and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in this field.

[0030] In order to further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with specific embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention rather than limiting the claims of the present invention.

[0031] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0032] Second, the so-called "one embodiment" or "embodiment" herein refers to specific features, structures, or characteristics that may be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0033] General embodiment: An electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2-FeOCl dual cathodes, the steps include: electrolyzing wastewater through a dual-cathode electrocatalytic electrolytic cell; the dual-cathode electrocatalytic electrolytic cell includes a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a cracked gas diffusion electrode, including a conductive substrate and a carbon black-PTFE catalyst coated on the conductive substrate; The first anode is an MMO mixed metal electrode or a ruthenium-iridium electrode; The second cathode includes a conductive substrate and an FeOCl catalyst coated on the conductive substrate; The second anode is a diamond electrode.

[0034] As a specific implementation manner, the conductive substrate in the first cathode and the second cathode is one of carbon paper (CP), carbon fiber paper (CFP), carbon cloth, carbon fiber cloth, graphite felt (GF), nickel foam (NF), copper foam (CF), titanium plate, ruthenium-iridium electrode plate, and conductive glass.

[0035] As a specific implementation manner, in the carbon black-PTFE catalyst, the mass ratio of carbon black to PTFE is 5:2 to 4.

[0036] As a specific implementation manner, the preparation method of the first cathode is: mixing carbon black with absolute ethanol, ultrasonic oscillation, then adding a PTFE suspension, stirring to a paste at 60-80 °C to obtain a coating; coating the coating on the conductive substrate, and then calcining at 330-400 °C for 150-200 min to obtain a cracked gas diffusion electrode.

[0037] As a specific implementation manner, in the first cathode, the loading amount of carbon black is 5-40 mg / cm 2 .

[0038] As a specific implementation manner, in the second cathode, the loading amount of FeOCl is 5-40 mg / cm 2 .

[0039] As a specific implementation manner, the areas of the first cathode and the second cathode are the same, the areas of the first anode and the second anode are the same, and the area ratio of the cathode to the anode is 1-20:1.

[0040] As a specific embodiment, the wastewater is antibiotic wastewater.

[0041] As a specific embodiment, the current density during electrolytic treatment is 5 - 20 mA / cm 2 .

[0042] As a specific embodiment, during electrolytic treatment, the wastewater in the dual-cathode electrocatalytic electrolytic cell undergoes internal circulation.

[0043] Example 1: An electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2 - FeOCl with dual cathodes, the steps include: using a constant power supply DH1766A-1 as the power source, and electrolytically treating antibiotic wastewater through a dual-cathode electrocatalytic electrolytic cell.

[0044] The selected antibiotic wastewater is a simulated wastewater with components similar to actual wastewater: a 20 mg / L oxytetracycline solution, and the pH value is 3.

[0045] The dual-cathode electrocatalytic electrolytic cell adopts a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a CB-PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black-PTFE catalyst coated on the conductive matrix; the preparation method is: mixing carbon black with absolute ethanol, ultrasonic oscillation, then adding a PTFE suspension (solid content 5 wt%), stirring at 70 °C until it becomes a paste to obtain a coating, and the mass ratio of carbon black to PTFE is 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB-PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode is 29.1 mg / cm 2 ; The first anode is an MMO mixed metal electrode; The second cathode is an FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and an FeOCl catalyst coated on the conductive matrix; the preparation method is: first dissolving FeCl3·6H2O in absolute ethanol and ultrasonicating for 10 minutes to form a uniform ferric chloride solution; then impregnating the GF in the ferric chloride solution for 1 hour and taking it out for drying, transferring it to a sealed crucible, and calcining at 220 °C for 1 hour; after cooling to room temperature, washing the electrode repeatedly with absolute ethanol and deionized water, and drying in a 50 °C vacuum drying oven for 12 hours; finally, soaking the electrode in a PTFE suspension (solid content 5 wt%) for 30 minutes, and then calcining at 180 °C for 1 hour, finally obtaining a second cathode with a loading amount of FeOCl catalyst of 4.2 mg / cm 2 ; The second anode is a diamond (BDD) electrode; The areas of the first cathode and the second cathode are both 9.62 cm 2 , and the areas of the second anode and the second anode are both 2 cm 2 .

[0046] The oxytetracycline solution was circulated at a constant flow rate of 400 mL / min. Without oxygen in the dual-cathode electrocatalytic electrolytic cell under the condition of changing the current density (current density: 5, 10, 15, 20 mA·cm -2 ), the oxytetracycline content in the solution in the dual-cathode electrocatalytic electrolytic cell was measured every ten minutes. The test results are as Figure 1 shown.

[0047] Example 2: An electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2-FeOCl with dual cathodes, the steps include: using a constant power supply DH1766A-1 as the power supply, and electrolyzing antibiotic wastewater through a dual-cathode electrocatalytic electrolytic cell.

[0048] The antibiotic wastewater selects simulated wastewater similar to the actual wastewater components: 15 mg / L levofloxacin solution, and the pH value is 3.

[0049] The dual-cathode electrocatalytic electrolytic cell adopts a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a CB-PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black-PTFE catalyst coated on the conductive matrix; the preparation method is: mixing carbon black with absolute ethanol, ultrasonic oscillation, and then adding a PTFE suspension (solid content 5%), stirring at 70 °C until it becomes paste-like to obtain a coating, and the mass ratio of carbon black to PTFE is 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB-PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode is 29.1 mg / cm 2 ; The first anode is an MMO mixed metal electrode; The second cathode is a FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and a FeOCl catalyst coated on the conductive matrix; the loading amount of the FeOCl catalyst in the second cathode is 4.2 mg / cm 2 , and the preparation method is the same as that in Example 1; The second anode is a diamond (BDD) electrode; The areas of the first cathode and the second cathode are both 9.62 cm 2, the area of the second anode and the second anode is both 2 cm² 2 .

[0050] The levofloxacin solution was circulated at a constant flow rate of 400 mL / min. Without oxygen in the dual-cathode electrocatalytic electrolytic cell under the condition of changing the current density (current density: 5, 10, 15, 20 mA·cm² -2 ), the content of levofloxacin in the solution in the dual-cathode electrocatalytic electrolytic cell was measured every ten minutes, and the test results are as Figure 2 shown in.

[0051] Example 3: An electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2-FeOCl with dual cathodes, the steps include: using a constant power supply DH1766A-1 as the power supply, and electrolyzing antibiotic wastewater through a dual-cathode electrocatalytic electrolytic cell.

[0052] The antibiotic wastewater selected was simulated wastewater similar to the actual wastewater components: 20 mg / L sulfamethoxazole (Compound Sulfamethoxazole) solution, with a pH value of 3.

[0053] The dual-cathode electrocatalytic electrolytic cell used a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode was a CB-PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black-PTFE catalyst coated on the conductive matrix; the preparation method was: mixing carbon black with absolute ethanol, ultrasonic oscillation, and then adding a PTFE suspension (solid content 5%), stirring to a paste at 70 °C to obtain a coating, and the mass ratio of carbon black to PTFE was 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB-PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode was 29.1 mg / cm² 2 ; The first anode was an MMO mixed metal electrode; The second cathode was an FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and an FeOCl catalyst coated on the conductive matrix; the loading amount of the FeOCl catalyst in the second cathode was 4.2 mg / cm² 2 , and the preparation method was the same as that in Example 1; The second anode was a diamond (BDD) electrode; The area of the first cathode and the second cathode was both 9.62 cm² 2 , the area of the second anode and the second anode was both 2 cm² 2 .

[0054] The sulfamethoxazole solution was circulated at a constant flow rate of 400 mL / min. Without oxygen in the dual-cathode electrocatalytic electrolytic cell, under the condition of changing the current density (current density: 5, 10, 15, 20 mA·cm -2 ), the sulfamethoxazole content in the solution in the dual-cathode electrocatalytic electrolytic cell was measured every ten minutes. The test results are as shown in Figure 3 .

[0055] Example 4: An electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2-FeOCl with dual-cathodes, the steps include: using a constant power supply DH1766A-1 as the power source, and electrolyzing antibiotic wastewater through a dual-cathode electrocatalytic electrolytic cell.

[0056] The antibiotic wastewater selected is simulated wastewater with similar composition to the actual wastewater: 20 mg / L oxytetracycline solution, and the pH values are 2, 3, 4, and 5 respectively.

[0057] The dual-cathode electrocatalytic electrolytic cell uses a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a CB-PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black-PTFE catalyst coated on the conductive matrix; the preparation method is: mixing carbon black with absolute ethanol, ultrasonic oscillation, and then adding a PTFE suspension (solid content 5%), stirring to a paste at 70 °C to obtain a coating, and the mass ratio of carbon black to PTFE is 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB-PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode is 29.1 mg / cm 2 ; The first anode is a MMO mixed metal electrode; The second cathode is a FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and a FeOCl catalyst coated on the conductive matrix; the loading amount of the FeOCl catalyst in the second cathode is 4.2 mg / cm 2 , and the preparation method is the same as that in Example 1; The second anode is a diamond (BDD) electrode; The areas of the first cathode and the second cathode are both 9.62 cm 2 , and the areas of the second anode and the second anode are both 2 cm 2 .

[0058] The oxytetracycline solutions with different pH values were circulated at a constant flow rate of 400 mL / min respectively, at a current density of 10 mA·cm -2Under the condition that no oxygen is introduced into the dual-cathode electrocatalytic electrolytic cell, the oxytetracycline content in the solution of the dual-cathode electrocatalytic electrolytic cell is measured every ten minutes, and the test results are as Figure 4 shown in

[0059] Example 5: An electrocatalytic wastewater treatment method coupling self-supplying oxygen in-situ production of H2O2-FeOCl dual cathodes, the steps include: using a constant power supply DH1766A-1 as the power supply, and electrolyzing antibiotic wastewater through a dual-cathode electrocatalytic electrolytic cell.

[0060] The antibiotic wastewater selects simulated wastewater similar to the actual wastewater components: 15 mg / L levofloxacin solution, and the pH values are 2, 3, 4, and 5 respectively.

[0061] The dual-cathode electrocatalytic electrolytic cell adopts a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a CB-PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black-PTFE catalyst coated on the conductive matrix; the preparation method is: mixing carbon black with absolute ethanol, ultrasonic oscillation, and then adding a PTFE suspension (solid content 5%), stirring to a paste at 70 °C to obtain a coating, and the mass ratio of carbon black to PTFE is 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB-PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode is 29.1 mg / cm 2 ; The first anode is a MMO mixed metal electrode; The second cathode is a FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and a FeOCl catalyst coated on the conductive matrix; the loading amount of the FeOCl catalyst in the second cathode is 4.2 mg / cm 2 , and the preparation method is the same as that in Example 1; The second anode is a diamond (BDD) electrode; The areas of the first cathode and the second cathode are both 9.62 cm 2 , and the areas of the second anode and the second anode are both 2 cm 2 .

[0062] The levofloxacin solutions with different pH values are respectively circulated at a constant flow rate of 400 mL / min. Under the condition of a current density of 10 mA·cm -2 , no oxygen is introduced into the dual-cathode electrocatalytic electrolytic cell, and the levofloxacin content in the solution of the dual-cathode electrocatalytic electrolytic cell is measured every ten minutes, and the test results are as Figure 5as shown in

[0063] Example 6: An electrocatalytic wastewater treatment method coupling self-oxygen supply in-situ production of H2O2-FeOCl double cathodes, the steps include: using a constant power supply DH1766A-1 as the power source, and electrolyzing antibiotic wastewater through a double-cathode electrocatalytic electrolytic cell.

[0064] The antibiotic wastewater selects simulated wastewater similar to the actual wastewater composition: 20 mg / L sulfamethoxazole solution, and the pH values are 2, 3, 4, and 5 respectively.

[0065] The double-cathode electrocatalytic electrolytic cell adopts a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a CB-PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black-PTFE catalyst coated on the conductive matrix; the preparation method is: mixing carbon black with absolute ethanol, ultrasonic oscillation, and then adding a PTFE suspension (solid content 5%), stirring to a paste at 70 °C to obtain a coating, and the mass ratio of carbon black to PTFE is 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB-PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode is 29.1 mg / cm 2 ; The first anode is an MMO mixed metal electrode; The second cathode is a FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and a FeOCl catalyst coated on the conductive matrix; the loading amount of the FeOCl catalyst in the second cathode is 4.2 mg / cm 2 , and the preparation method is the same as that in Example 1; The second anode is a diamond (BDD) electrode; The areas of the first cathode and the second cathode are both 9.62 cm 2 , and the areas of the second anode and the second anode are both 2 cm 2 .

[0066] Circulate the sulfamethoxazole solutions with different pH values at a constant flow rate of 400 mL / min respectively. Under the condition of changing the current density to 10 mA·cm -2 , without passing oxygen in the double-cathode electrocatalytic electrolytic cell, measure the sulfamethoxazole content in the solution in the double-cathode electrocatalytic electrolytic cell every ten minutes, and the test results are as Figure 6 shown in

[0067] Example 7: A method for electrocatalytic wastewater treatment coupling self - supplying oxygen and in - situ production of H2O2 - FeOCl double cathodes, the steps include: using the constant - power supply DH1766A - 1 as the power source, and electrolyzing antibiotic wastewater through a double - cathode electrocatalytic electrolytic cell.

[0068] The antibiotic wastewater selects a simulated wastewater similar to the actual wastewater composition: a mixed solution of 400 mL of 20 mg / L oxytetracycline solution, 400 mL of 15 mg / L levofloxacin solution, and 400 mL of 20 mg / L compound sulfamethoxazole solution, with a pH value of 3.

[0069] The double - cathode electrocatalytic electrolytic cell adopts a columnar electrolytic cell, including a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a CB - PTFE / GF crack gas diffusion electrode, including a conductive matrix graphite felt (GF) and a carbon black - PTFE catalyst coated on the conductive matrix; the preparation method is: mixing carbon black with absolute ethanol, ultrasonic oscillation, then adding a PTFE suspension (solid content 5%), stirring at 70 °C until it becomes a paste to obtain a coating, and the mass ratio of carbon black to PTFE is 5:3; coating the coating on the graphite felt, and then calcining at 350 °C for 180 min to obtain the CB - PTFE / GF crack gas diffusion electrode; the loading amount of carbon black in the first cathode is 29.1 mg / cm 2 ; The first anode is an MMO mixed - metal electrode; The second cathode is a FeOCl / GF composite electrode, including a conductive matrix graphite felt (GF) and a FeOCl catalyst coated on the conductive matrix; the loading amount of the FeOCl catalyst in the second cathode is 4.2 mg / cm 2 , and the preparation method is the same as that in Example 1; The second anode is a diamond (BDD) electrode; The areas of the first cathode and the second cathode are both 9.62 cm 2 , and the areas of the second anode and the second anode are both 2 cm 2 .

[0070] Circulate the mixed solution at a constant flow rate of 400 mL / min, under the condition of a current density of 10 mA·cm -2 , without passing oxygen in the double - cathode electrocatalytic electrolytic cell, measure the antibiotic content and iron leaching amount of the solution in the double - cathode electrocatalytic electrolytic cell every ten minutes, and the test results are as shown in Figure 7 .

[0071] From Figures 1 to 7It can be seen from the test results that by adopting the dual-cathode system in the present invention, the efficient degradation of three types of antibiotics can be achieved, and the removal rate of the three types of antibiotic wastewater can reach more than 80%. In the present invention, oxygen is produced by the first anode MMO, and then the crack gas diffusion electrode is used as the first cathode to produce H2O2, thereby solving the problem of oxygen supply; the FeOCl / GF composite electrode is connected in series, and electro-Fenton is used to efficiently treat wastewater. All reaction processes are completed in a single reaction device without the need to cooperate with other auxiliary devices, and the operation and operation costs are low; moreover, the reaction product is water, without harmful by-products, the product is green and environmentally friendly and has no secondary pollution, which conforms to the theory of clean energy. In addition, the second cathode of the present invention adopts the FeOCl / GF composite electrode, which can not only efficiently activate and produce ·OH, but also electro-reduce Fe 3+ to avoid the generation of iron sludge and realize the recycling of iron ions at the same time, and it also has a high pH adaptability.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. An electrocatalytic wastewater treatment method coupling self-oxygen supply and in-situ H2O2-FeOCl double cathodes, characterized by the steps Including: Electrolyzing wastewater through a dual-cathode electrocatalytic electrolytic cell; The dual-cathode electrocatalytic electrolytic cell includes a first cathode, a first anode, a second cathode, and a second anode arranged alternately; The first cathode is a crack gas diffusion electrode, including a conductive substrate and a carbon black-PTFE catalyst coated on the conductive substrate; The first anode is an MMO mixed metal electrode or a ruthenium-iridium electrode; The second cathode includes a conductive substrate and an FeOCl catalyst coated on the conductive substrate; The second anode is a diamond electrode.

2. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual cathodes coupled according to claim 1, characterized in that, The conductive substrate in the first cathode and the second cathode is one of carbon paper, carbon fiber paper, carbon cloth, carbon fiber cloth, graphite felt, nickel foam, copper foam, titanium plate, ruthenium-iridium electrode plate, and conductive glass.

3. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual-cathode coupling according to claim 1, characterized in that, In the carbon black-PTFE catalyst, the mass ratio of carbon black to PTFE is 5:2 to 4.

4. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual-cathode coupling according to claim 1 or 3, characterized in that, The preparation method of the first cathode is: mixing carbon black with absolute ethanol, ultrasonic oscillation, then adding a PTFE suspension, stirring to a paste at 60 to 80 °C to obtain a coating; coating the coating on the conductive substrate, and then calcining at 330 to 400 °C for 150 to 200 min to obtain a crack gas diffusion electrode.

5. The electrocatalytic wastewater treatment method coupling self-oxygen-supplying in-situ H2O2-FeOCl double cathodes according to claim 1 or 2 or 3, characterized in that, In the first cathode, the loading amount of carbon black is 5 to 40 mg / cm 2 .

6. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual cathode coupling according to claim 1 or 2, characterized in that the second In the cathode, the loading amount of the FeOCl catalyst is 5 to 40 mg / cm 2 .

7. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual cathode coupling according to claim 1, characterized in that, The areas of the first cathode and the second cathode are the same, the areas of the first anode and the second anode are the same, and the area ratio of the cathode to the anode is 1 to 20:

1.

8. The electrocatalytic wastewater treatment method using self-oxygen-supplying in-situ H2O2-FeOCl dual cathodes coupled according to claim 1, characterized in that, The wastewater is antibiotic wastewater.

9. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual cathodes according to claim 1 or 8, characterized in that The current density during electrolytic treatment is 5 - 20 mA / cm 2 .

10. The electrocatalytic wastewater treatment method with self-oxygen-supplying in-situ H2O2-FeOCl dual cathodes coupled according to claim 1, characterized in that, During electrolytic treatment, the wastewater in the dual-cathode electrocatalytic electrolytic cell undergoes internal circulation.

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