A wastewater cod degradation coupling hydrogen production catalyst, a preparation method, a system and a method

Abstract

The present application belongs to the technical field of wastewater treatment, and particularly relates to a wastewater COD degradation coupling hydrogen production catalyst, a preparation method, a system and a method. Compared with the prior art, the present application adopts a COD degradation hydrogen production reactor matched with a wastewater COD degradation coupling hydrogen production catalyst, realizes deep oxidation treatment of high COD water quality, and can realize continuous operation through the constructed wastewater COD degradation coupling hydrogen production system, so that low organic pollutant water quality is obtained. The present application adopts an electrochemical oxidation method for COD degradation, efficiently and accurately degrades COD in water by controlling current, voltage, time and other parameters, completes the conversion of organic pollutants in wastewater, and has the advantages of short process flow, remarkable COD reduction effect, green low carbon, continuous reliability and the like. The by-product hydrogen produced by the wastewater COD degradation has wide application, can be used for fuel cell power generation, realizes green electricity driving of wastewater COD degradation, and realizes long-period green low-carbon operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, and particularly relates to a wastewater COD degradation coupling hydrogen production catalyst, a preparation method, a system and a method. BACKGROUND

[0002] Chemical oxygen demand (COD) is a chemical method for testing the content of pollutants in contaminated water, which can represent the content of pollutants in contaminated water. It is considered as an important and fast parameter for determining the content of organic pollutants in the petroleum, chemical, and wastewater treatment industries, and is often represented by the symbol COD. High COD content in water quality can destroy the original living environment of various organisms in the water body, and also emit irritating odors, which can adversely affect the surrounding residents and the environment. Therefore, the state has introduced the discharge standard of water quality containing COD, and each industry must reduce the COD content in water to meet the discharge requirements according to the corresponding indicators.

[0003] Traditional methods for treating wastewater with high COD content mainly include chemical method and microbial degradation method. The chemical method is to add a strong oxidizing agent to the wastewater to oxidize the wastewater with high COD. Common oxidizing agents include potassium permanganate, ozone, and chlorine. These oxidizing agents can oxidize organic matter into inorganic matter or lower molecular weight organic matter, thereby achieving the purpose of reducing COD. However, it is difficult to control the amount of oxidizing agent added during the treatment process, which can easily cause secondary pollution. The microbial degradation method uses activated sludge containing microorganisms to treat wastewater, which can oxidize organic matter in water to reduce the COD content in wastewater. However, the microorganisms in the microbial degradation method are easily affected by external environmental factors such as temperature and pH, which limits the ability of microorganisms to treat organic matter. In addition, in the process of batchwise reduction of COD, the microbial treatment method requires precise control of various operating parameters, which greatly increases the complexity of actual operation and management.

[0004] Therefore, it is an important problem in the field to provide a wastewater COD degradation coupling hydrogen production system and method to solve the existing COD degradation problem. SUMMARY

[0005] In order to solve the various disadvantages of the existing COD degradation technology, the purpose of the present application is to provide a wastewater COD degradation coupling hydrogen production catalyst, a preparation method, a system and a method, which at least partially solve the problems existing in the prior art. In order to achieve the purpose of the present application, the present application provides the following technical solutions.

[0006] The application provides a catalyst for wastewater COD degradation coupling hydrogen production, which is an impregnated nickel ferrite, a nickel-based metal nanosheet loaded with nickel / iron active components, the thickness of the nanosheet is 2-10 nm, and the loading amount of the nickel / iron active components is 3-5 mg / cm 2 .

[0007] The application further provides a preparation method of the catalyst, which comprises the following steps:

[0008] (1) removing surface impurities and oxides from a nickel-based metal carrier, and drying the carrier at 40-100 DEG C for 12-24 hours;

[0009] (2) preparing an active metal soluble salt solution, impregnating the above nickel-based metal carrier by using a supersaturated impregnation method for 6-12 hours, and then drying the carrier at 40-100 DEG C for 6-24 hours;

[0010] The molar ratio of nickel to iron in the active metal soluble salt solution is (3-5):1.

[0011] In some embodiments, the nickel-based metal carrier in the preparation method is a nickel foam, a nickel mesh, a nickel felt or a nickel powder felt.

[0012] In some embodiments, the method for removing surface impurities and oxides in the preparation method is sequentially immersing in water, acetone and ethanol solutions for 2-4 hours. First, the carrier is immersed in water for 2-4 hours, then immersed in acetone for 2-4 hours to remove oil stains, and finally immersed in ethanol for 2-4 hours to remove residual acetone on the surface.

[0013] In some embodiments, the active metal soluble salt in the preparation method is one or more of nickel nitrate, nickel chloride, iron sulfate and iron nitrate.

[0014] In some embodiments, the dissolving medium of the active metal soluble salt in the preparation method is one or more of water, ethanol and isopropanol.

[0015] Further, the application further provides a wastewater COD degradation coupling hydrogen production system, which comprises a hydrogen production reaction system and a COD degradation reaction system.

[0016] The hydrogen production reaction system comprises a cathode wastewater liquid supplementing device, a cathode wastewater storage device, a cathode centrifugal pump and a COD degradation hydrogen production reactor connected by pipelines; and the COD degradation reaction system comprises an anode wastewater liquid supplementing device, an anode wastewater storage device, an anode centrifugal pump and a COD degradation hydrogen production reactor connected by pipelines.

[0017] The COD degradation hydrogen production reactor of the hydrogen production reaction system and the COD degradation hydrogen production reactor of the COD degradation reaction system are the same device, which is an electrolytic reactor symmetrically placed by metal plates, and the COD degradation hydrogen production catalyst is arranged in the reactor, and a wastewater flow pipeline is arranged at the middle position of the metal plates; and the COD degradation hydrogen production reactor is connected with a direct current power supply.

[0018] In the COD degradation hydrogen production reactor, the wastewater flows into the reactor from both sides by countercurrent through the cathode centrifugal pump and the anode centrifugal pump, and flows from bottom to top. The reactor completes the COD degradation and hydrogen production reaction under the action of the direct current power supply, and the COD of the wastewater at the anode outlet can be reduced by 80%.

[0019] Further, the cathode centrifugal pump and the anode centrifugal pump in the wastewater COD degradation hydrogen production system are acid and alkali resistant and chlorine ion corrosion resistant, which can ensure that the wastewater from the cathode wastewater storage tank and the anode wastewater storage tank is continuously transported to the COD degradation hydrogen production reactor for a long period.

[0020] Further, in some embodiments, the wastewater COD degradation hydrogen production system further comprises a wastewater heating device, a post-reaction wastewater reflux pipeline and / or a produced gas output pipeline.

[0021] In some specific embodiments, the post-reaction wastewater is refluxed from the COD degradation hydrogen production reactor to the cathode wastewater storage device and the anode wastewater storage device through the reflux pipeline.

[0022] In some specific embodiments, the post-reaction gas is refluxed from the COD degradation hydrogen production reactor to the cathode wastewater storage device and the anode wastewater storage device through the reflux pipeline together with the post-reaction wastewater. Further, the produced gas is further treated through the produced gas output pipeline of the cathode wastewater storage device and the anode wastewater storage device.

[0023] In some embodiments, the wastewater COD degradation hydrogen production system further comprises a control system, and all device power supplies are connected with the control system, which can be centrally controlled and monitored in real time.

[0024] Further, the application also provides a wastewater COD degradation hydrogen production method,

[0025] The wastewater in the cathode wastewater replenishment device and the anode wastewater replenishment device flows into the cathode wastewater storage device and the anode wastewater storage device through the pipeline;

[0026] The wastewater in the cathode wastewater storage device and the anode wastewater storage device flows out through the pipeline and enters the cathode centrifugal pump and the anode centrifugal pump respectively, and the wastewater is transported to the COD degradation hydrogen production reactor through the cathode centrifugal pump and the anode centrifugal pump;

[0027] Under the action of the direct current power supply, hydrogen is generated on the cathode side of the COD degradation hydrogen production reactor, and organic matter is oxidized to reduce COD on the anode side;

[0028] The reacted wastewater is recycled back to the cathode wastewater storage tank and the anode wastewater storage tank through a pipeline for recycling.

[0029] Further, in some embodiments, a wastewater heating device is arranged in the cathode wastewater replenishing device and the anode wastewater replenishing device for heating and keeping the temperature of the wastewater; a wastewater heating device is arranged in the cathode wastewater storage device and the anode wastewater storage device for heating and keeping the temperature of the wastewater.

[0030] In some embodiments, the temperature for heating and keeping is 40-90℃.

[0031] In some embodiments, the wastewater COD degradation coupling hydrogen production method further comprises the steps of post-treating the hydrogen generated on the cathode side of the COD degradation hydrogen production reactor and post-treating the gas generated on the anode side of the COD degradation hydrogen production reactor.

[0032] In some specific embodiments, the hydrogen generated on the cathode side is transported to a subsequent gas separation unit for purification treatment to obtain pure hydrogen. In some embodiments, the purity of the purified hydrogen according to the present application can reach 99.99%, which can be directly introduced into a fuel cell for power generation, and the generated electric energy can be used for the COD degradation hydrogen production reactor.

[0033] The electricity used by the direct current power supply according to the present application can come from one or more of industrial electricity and renewable energy power generation.

[0034] In some embodiments, the electricity used by the direct current power supply according to the present application comes from wind power generation or solar power generation.

[0035] In some embodiments, the electricity used by the direct current power supply according to the present application comes from the above-mentioned purified hydrogen used for fuel cell power generation.

[0036] In some specific embodiments, the gas such as carbon dioxide generated on the anode side can be directly discharged from the top of the anode wastewater storage tank. In some specific embodiments, the carbon dioxide or carbon-based components generated on the anode side can be absorbed in water to form carbonate ions.

[0037] In some embodiments, the wastewater in the wastewater COD degradation coupling hydrogen production method according to the present application is selected from one or more of oilfield produced water, chemical industrial wastewater and municipal reclaimed water.

[0038] In some embodiments, the flow rate of the cathode centrifugal pump and the anode centrifugal pump in the wastewater COD degradation coupling hydrogen production method according to the present application is 0.1-2 L / min.

[0039] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0040] (1) The present application uses a COD degradation hydrogen production reactor in combination with a wastewater COD degradation coupled hydrogen production catalyst to achieve deep oxidation treatment of high COD water quality. The wastewater COD degradation coupled hydrogen production system constructed can realize continuous operation, thereby obtaining low organic pollutant water quality.

[0041] (2) The present application innovatively uses an electrochemical oxidation method for COD degradation, without the need to add an oxidizing agent to the water sample, without the introduction of other chemical substances, without secondary pollution; by controlling the current, voltage, time and other parameters, the COD in the water is efficiently and accurately degraded, the conversion of organic pollutants in the wastewater is completed, most of the organic matter can be electrochemically burned into carbon dioxide and water, and a small part of the large molecule refractory organic matter can be degraded into small molecule substances, while also having the functions of air flotation, flocculation, sterilization and the like; compared with the existing microbial degradation process, it has the advantages of short process flow, significant COD reduction effect, green and low carbon, continuous and reliable and the like.

[0042] (3) The by-product hydrogen produced by the wastewater COD degradation has a wide range of uses, and can be used for fuel cell power generation to supply the system, achieving green electricity driving of wastewater COD degradation, realizing long-period green and low-carbon operation, and assisting the realization of the national "double carbon" strategic goal. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0044] Figure 1 The electron microscope image of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0045] The embodiments of the present application will be described in detail below with reference to the drawings. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict; and based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present disclosure.

[0046] It is important to note that the various aspects described throughout this disclosure can be combined in a wide variety of ways. It should be apparent that aspects described herein can be implemented in various forms of hardware, software, or a combination thereof; and that the described aspects can be implemented differently depending on the particular application. By way of non-limiting example, one or more aspects can be implemented using a programmable computer (e.g., a general purpose computer, a special purpose computer, or a networked computer) programmed to perform one or more of the described aspects. For example, one or more aspects can be implemented using a general purpose computer programmed to implement one or more of the described aspects. In this implementation, the general purpose computer can be specifically programmed to perform one or more of the described aspects. In another implementation, a special purpose computer, or a networked computer, can be used to perform at least one of the described aspects. In yet another implementation, one or more aspects can implemented using a computer having other device(s), such as a portable computer, a network router, a switch, or a bridge, programmed to perform one or more of the described aspects. The computer can be programmed to perform one or more of the described aspects using devices other than a computer. Other examples and implementations are within the scope of the disclosure and appended claims. For example, one or more aspects can be implemented using a special purpose computer or a networked computer.

[0047] The system and method for wastewater COD degradation coupled with hydrogen production described in the present application are described as follows: wastewater with high COD content from oilfield produced water, chemical wastewater, municipal reclaimed water, etc. is input into the cathode wastewater supplement device and the anode wastewater supplement device after natural sedimentation and impurity removal for preheating treatment, and the heating temperature is 40-90°C; after reaching the preset temperature, the wastewater in the cathode wastewater supplement device and the anode wastewater supplement device flows into the cathode wastewater storage device and the anode wastewater storage device, respectively, and a heating device is arranged in the wastewater storage device to perform secondary heating and heat preservation on the wastewater; then the wastewater flows out of the cathode wastewater storage device and the anode wastewater storage device and enters the cathode centrifugal pump and the anode centrifugal pump, respectively, and the wastewater is transported to the COD degradation hydrogen production reactor by the pump, and the flow rate of the pump is 0.1-2 L / min; the wastewater is contacted with the special catalyst for COD degradation and reacts under the action of a direct current power source, wherein the COD degradation hydrogen production reactor is made of high-purity corrosion-resistant titanium material, oxidation reaction occurs near the anode metal plate, organic matter oxidation and COD reduction are completed, reduction reaction is completed near the cathode metal plate to produce hydrogen gas; the wastewater after the reaction is entrained with gas and is transported back to the cathode wastewater storage device and the anode wastewater storage device for gas-liquid separation, the hydrogen gas produced on the cathode side is transported from the top of the cathode wastewater storage device to a subsequent gas separation unit for purification treatment to obtain pure hydrogen gas, and the carbon dioxide gas or carbon-based components produced on the anode side can be absorbed in water to form carbonate ions, and finally wastewater with degraded COD is obtained.

[0048] Example 1, catalyst for wastewater COD degradation coupled with hydrogen production

[0049] Nickel-based metal carrier foam (10×10cm) to be treated was immersed in approximately 100ml of water, acetone, and ethanol solutions for 3 hours respectively. After immersion, the foam was transferred to a 70℃ oven for drying for 24 hours. 28.3g of nickel nitrate was dispersed in approximately 300ml of deionized water to obtain green solution A. 10.4g of ferric sulfate was dissolved in 400ml of deionized water to obtain solution B. Solution A was slowly poured into solution B to prepare impregnation solution C. The treated nickel foam was then immersed in solution C for 8 hours. After impregnation, the nickel foam was removed and dried in a 70℃ oven for 24 hours to obtain a nickel-iron oxide catalyst specifically for COD degradation in wastewater. Figure 1 The catalyst shown is in the form of nanosheets with an average thickness of approximately 3.5 nm and a catalyst loading of 3.6 mg / cm³. 2 When the impregnation time in mixed solution C was changed to 6 hours, the average thickness of the nanosheets was approximately 2.9 nm, and the catalyst loading was 2.7 mg / cm³. 2 The impregnation time was changed to 12 hours, at which point the average thickness of the nanosheets was approximately 3.6 nm, and the catalyst loading was 3.4 mg / cm³. 2 .

[0050] Example 2: Catalyst for COD degradation coupled with hydrogen production in wastewater

[0051] Nickel-based metal carrier foam (10×10cm) to be treated was immersed in approximately 100ml of water, acetone, and ethanol solutions for 3 hours respectively. After immersion, the foam was transferred to a 70℃ oven for drying for 24 hours. 36.1g of nickel nitrate was dispersed in approximately 300ml of deionized water to obtain green solution A. 10.4g of ferric sulfate was dissolved in 400ml of deionized water to obtain solution B. Solution A was slowly poured into solution B to prepare impregnation solution C, with a nickel-iron molar ratio of 4:1. The treated nickel foam was then immersed in solution C for 8 hours. After impregnation, the foam was removed and dried in a 70℃ oven for 24 hours to obtain a nickel-iron oxide catalyst specifically for COD degradation in wastewater. The prepared catalyst is in the form of nanosheets with an average thickness of approximately 2.9nm and a catalyst loading of 2.9mg / cm³. 2 The 36.1g of nickel nitrate was replaced with 41.2g of nickel nitrate and dispersed in approximately 300ml of deionized water to create mixed impregnation solution C. At this point, the nickel-iron molar ratio was 5:1. Electron microscopy revealed that the average thickness of the nanosheets was approximately 2.5nm, and the catalyst loading was 2.6mg / cm³. 2 .

[0052] Example 3: Catalyst for COD degradation coupled with hydrogen production in wastewater

[0053] The nickel-based metal support nickel foam (10×10cm) to be treated was subjected to a similar treatment scheme as in Example 1, being immersed in approximately 100ml of water, acetone, and ethanol solutions for 3 hours respectively. After immersion, the nickel foam was transferred to a 70°C oven for drying for 24 hours. 28.3g of nickel nitrate was weighed and dispersed in approximately 300ml of isopropanol to obtain green solution A. 10.4g of ferric sulfate was weighed and dissolved in 400ml of isopropanol to obtain solution B. Solution A was slowly poured into solution B to prepare impregnation solution C. The treated nickel foam was then immersed in solution C for 8 hours. After impregnation, the nickel foam was removed and dried in a 70°C oven for 24 hours. Scanning electron microscopy showed that the prepared catalyst was in the form of thin nanosheets with an average thickness of approximately 1.2nm and a catalyst loading of 1.6mg / cm³. 2 The catalyst loading was low, hindering the growth of the nanosheet structure. However, when the solvent was changed to ethanol, the prepared catalyst exhibited a non-uniform nanosheet structure with an average nanosheet thickness of approximately 0.7 nm and a catalyst loading of 0.6 mg / cm³. 2 The catalyst loading is lower.

[0054] Example 4: Catalyst for COD degradation coupled with hydrogen production in wastewater

[0055] The nickel-based metal carrier nickel mesh (10×10cm) to be treated was subjected to a similar treatment scheme as in Example 1, being immersed in approximately 100ml of water, acetone, and ethanol solutions for 3 hours respectively. After immersion, the nickel mesh was transferred to a 70°C oven for drying for 24 hours. 28.3g of nickel nitrate was weighed and dispersed in approximately 300ml of deionized water to obtain green solution A. 10.4g of ferric sulfate solvent was weighed and dissolved in 400ml of deionized water to obtain solution B. Solution A was slowly poured into solution B to prepare impregnation solution C. The treated nickel foam was then immersed in solution C for 8 hours. After impregnation, the nickel foam was removed and dried in a 70°C oven for 24 hours. At this point, the prepared catalyst had no nanostructure, and the catalyst loading was only 0.3mg / cm². 2 Nanosheet structures are difficult to grow on nickel mesh surfaces. However, when the nickel-based metal support is replaced with rough nickel felt and nickel powder felt, the prepared catalyst begins to possess nanosheet-like structures, with an average nanosheet thickness of approximately 1.1 nm (nickel felt) and 1.3 nm (nickel powder felt), and a catalyst loading of 0.5 mg / cm³. 2 (Nickel felt), 0.6 mg / cm 2 (Nickel powder felt).

[0056] Experimental example:

[0057] The method for degrading COD content in wastewater according to the present application adopts the catalyst described in Example 1, the water quality conditions are referenced, the reaction conditions are referred to Table 1 and Table 2, and the details of wastewater COD degradation coupling hydrogen production experiments are as follows:

[0058] The catalyst prepared in Example 1 is loaded into a COD degradation hydrogen production reactor, the pipeline and circuit are connected, the oilfield produced water is introduced into the device, and the related experiments are carried out according to the relevant experimental operation parameters in Table 2.

[0059] Table 1 Main properties of COD wastewater from different sources

[0060] Oilfield produced water Chemical wastewater Reclaimed municipal wastewater pH value 7.6 1.2 7.3 Oil content (mg / L) 115.2 23.3 15.4 Turbidity (NTU) 350 134 258.7 Suspended solids (mg / L) 1800 1240 1520 COD (mg / L) 16000 12000 1350

[0061] Table 2 Test conditions

[0062]

[0063] The same catalyst preparation method as in Example 1 is used to prepare a wastewater COD degradation catalyst. The prepared catalyst is loaded into a COD degradation hydrogen production reactor, the pipeline and circuit are connected, the chemical wastewater is introduced into the device, and the related experiments are carried out according to the relevant experimental operation parameters in Table 2.

[0064] The same catalyst preparation method as in Example 1 is used to prepare a wastewater COD degradation catalyst. The prepared catalyst is loaded into a COD degradation hydrogen production reactor, the pipeline and circuit are connected, the chemical wastewater is introduced into the device, and the related experiments are carried out according to the relevant experimental operation parameters in Table 2.

[0065] Table 3 Reaction results of wastewater degradation COD treatment device of different sources

[0066] Oilfield produced water Chemical wastewater Reclaimed municipal wastewater pH value 9.6 9.1 9.5 Oil content (mg / L) 8.2 7.3 4.4 Turbidity (NTU) 140 65 106 Suspended solids (mg / L) 254 231 218 COD (mg / L) 2832 2160 270

[0067] As can be seen from Table 3, different sources of high COD content wastewater are treated by the wastewater COD degradation coupling hydrogen production device according to the present application, and the COD degradation rate of the wastewater COD degradation catalyst is more than 80% within 6 hours, and the oil content, turbidity, suspended solids and other indicators in the water are reduced by more than 50%. The portable hydrogen purity analyzer detects that the hydrogen production purity can reach 99.99%, realizing efficient conversion of organic pollutants in wastewater, while producing high-purity hydrogen as a byproduct, meeting the needs of wastewater treatment and high-value product acquisition at the same time.

[0068] The wastewater COD degradation catalysts prepared according to the above method using the wastewater COD degradation coupling hydrogen production device of the application were used to treat wastewater with high COD content from different sources, and the results showed that the COD degradation rate was more than 80% within 6 hours, and the oil content, turbidity, suspended solids and other indicators in the water were reduced by more than 50%. The hydrogen purity analyzer detected that the hydrogen purity could reach 99.99%.

[0069] In the above examples, the reliability of the prepared wastewater COD degradation catalyst and its system in long-period operation was verified, and its universality in treating different water qualities was proved, and it showed excellent COD degradation performance. Therefore, the wastewater COD degradation coupling hydrogen production system and method of the application has the advantages of short process flow, significant COD reduction effect, green and low carbon, continuous and reliable, etc., and can meet the degradation treatment requirements of wastewater COD from different sources, while producing high-purity hydrogen as a byproduct, which can realize the resource utilization of wastewater and help achieve the national "double carbon" strategic goal.

[0070] For those skilled in the art, the specific embodiments are only exemplary descriptions of the application, and it is obvious that the specific implementation of the application is not limited by the above method. Any non-essential improvement or direct application of the concept and technical solution of the application to other occasions without improvement is within the protection scope of the application.

Claims

1. A catalyst for degradation of COD in wastewater coupled with hydrogen production, characterized in that, The nickel-based metal nanosheet is a nickel-based nanosheet loaded with a nickel / iron active component, the thickness of the nanosheet is 2-10 nm, and the loading amount of the nickel / iron active component is 3-5 mg / cm 2 comprising the steps of: (1) Take nickel-based metal carrier to remove surface impurities and oxides, dry at 40-100℃ for 12-24 hours; (2) Configure active metal soluble salt solution, immerse the above nickel-based metal carrier by supersaturated impregnation method for 6-12 hours, and then dry at 40-100℃ for 6-24 hours; The molar ratio of nickel and iron in the active metal soluble salt solution is (3-5):1, and the nickel-based metal carrier is foamed nickel, nickel felt or nickel powder felt.

2. A process for the preparation of the catalyst of claim 1, characterized in that, The steps include: (1) Take nickel-based metal carrier to remove surface impurities and oxides, dry at 40-100℃ for 12-24 hours; (2) Configure active metal soluble salt solution, immerse the above nickel-based metal carrier by supersaturated impregnation method for 6-12 hours, and then dry at 40-100℃ for 6-24 hours; The molar ratio of nickel and iron in the active metal soluble salt solution is (3-5):1, and the nickel-based metal carrier is foamed nickel, nickel felt or nickel powder felt.

3. The preparation method according to claim 2, characterized in that, The method for removing surface impurities and oxides is to immerse in water, acetone and ethanol solution for 2-4 hours; the active metal soluble salt is one or more of nickel nitrate, nickel chloride, iron sulfate and iron nitrate; and the dissolving medium of the active metal soluble salt is one or more of water, ethanol and isopropanol.

4. A wastewater COD degradation coupled hydrogen production system, characterized in that, The system is composed of a hydrogen production reaction system and a COD degradation reaction system; The hydrogen production reaction system includes a cathode wastewater supplement device, a cathode wastewater storage device, a cathode centrifugal pump and a COD degradation hydrogen production reactor connected by pipelines; the COD degradation reaction system includes an anode wastewater supplement device, an anode wastewater storage device, an anode centrifugal pump and a COD degradation hydrogen production reactor connected by pipelines; The COD degradation hydrogen production reactor in the hydrogen production reaction system and the COD degradation hydrogen production reactor in the COD degradation reaction system are the same device, which is an electrolytic reactor symmetrically placed in a metal plate, and the COD degradation hydrogen production reactor is provided with the wastewater COD degradation coupling hydrogen production catalyst of claim 1, and a wastewater flow pipeline is arranged at the middle position of the metal plate; the COD degradation hydrogen production reactor is connected with a direct current power supply.

5. The wastewater COD degradation coupling hydrogen production system according to claim 4, characterized in that, It also includes a wastewater heating device, a post-reaction wastewater reflux pipeline and / or a produced gas output pipeline.

6. A wastewater COD degradation coupling hydrogen production method using the wastewater COD degradation coupling hydrogen production system of claim 4 or 5, characterized in that, The wastewater in the cathode wastewater supplement device and the anode wastewater supplement device flows into the cathode wastewater storage device and the anode wastewater storage device through pipelines; The wastewater in the cathode wastewater storage device and the anode wastewater storage device flows out through pipelines and enters the cathode centrifugal pump and the anode centrifugal pump respectively, and the wastewater is transported to the COD degradation hydrogen production reactor through the cathode centrifugal pump and the anode centrifugal pump respectively; Under the action of the direct current power supply, the cathode side of the COD degradation hydrogen production reactor produces hydrogen production reaction, and the anode side completes organic matter oxidation to reduce COD; The post-reaction wastewater is circulated and transported back to the cathode wastewater storage tank and the anode wastewater storage tank through pipelines for recycling.

7. The method according to claim 6, wherein, The wastewater heating device is arranged in the cathode wastewater supplement device and the anode wastewater supplement device, and is used for heating and heat preservation of the wastewater. 8.The method according to claim 7, wherein, The heating and heat preservation temperature is 40-90 DEG C.

9. The method according to any one of claims 6-8, wherein, The method further comprises a step of post-treatment of hydrogen generated on the cathode side of the COD degradation hydrogen production reactor and a step of post-treatment of gas generated on the anode side of the COD degradation hydrogen production reactor.

10. The method according to any one of claims 6-8, wherein, The wastewater is selected from one or more of oilfield produced water, chemical industrial wastewater and municipal reclaimed water; and the flow rate of the wastewater in the cathode centrifugal pump and the anode centrifugal pump is 0.1-2 L / min.

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