Preparation method of graphite-based composite non-noble metal particle electrode

Abstract

The invention discloses a graphite-based composite non-noble metal particle electrode preparation method, which comprises: (1) stirring a surfactant solution with a certain concentration for 1 h, adding waste graphite powder, carrying out ultrasonic treatment for 20-30 min, standing for 12 h, filtering, washing, and carrying out vacuum drying to obtain modified graphite; (2) a, preparing a non-noble metal salt solution and an alkali solution according to a molar ratio; and b, carrying out ultrasonic treatment on the modified graphite for 4 hours, dropwise adding metal salt and an alkali solution, stirring, controlling the pH value to be 10, aging for 6 hours, cleaning, drying for 24 hours, grinding and screening to obtain composite catalyst powder. And (3) mixing the catalyst powder, Portland slag cement and water glass, granulating into spherical particles, and maintaining to obtain the graphite-based composite non-noble metal particle electrode. The prepared three-dimensional particle electrode can be used for electrolyzing organic industrial wastewater, and is low in cost, wide in application and excellent in performance.

Description

Technical Field

[0001] The present invention relates to a preparation method of a graphite-based composite non-precious metal particle electrode, belonging to the technical field of electrocatalysis. Background Art

[0002] Enterprises in the fields of biopharmaceuticals, pesticides, new chemical materials, coal processing, etc., as well as common industrial agglomeration areas (parks), mostly produce wastewater containing refractory organic industrial wastewater, and it is very difficult to meet the discharge standards by biochemical treatment. Heterocyclic compounds, such as pyridine, methylpyridine, dimethylpyridine, quinoline, etc., are commonly present in pharmaceutical wastewater and coal industrial wastewater. Due to their strong toxicity, complex water quality, high organic nitrogen content, low biodegradability, etc., they are listed as class B carcinogens by the World Health Organization. There is an urgent need for a treatment technology that adapts to the water quality characteristics of heterocyclic compounds and is broad-spectrum, low-selectivity, green, economical and efficient.

[0003] The research on the electrochemical treatment of refractory organic compounds has been reported by a large number of researchers. The special ring structure of heterocyclic compounds makes them stable, while the strong oxidizing substances generated during the electrochemical process can effectively cause the "ring-opening" reaction of heterocyclic compounds. Electro-catalytic oxidation is a new advanced oxidation technology that degrades heterocyclic compounds in wastewater into small organic molecules or directly mineralizes them into CO2 and H2O through direct anodic oxidation or indirect oxidation by generating ·OH. Due to its advantages of no need to add chemicals, no secondary pollution, and easy automation, electro-catalytic oxidation has gradually attracted the attention of scholars.

[0004] Traditional electrode materials have problems such as low current efficiency, poor stability, and high cost in wastewater treatment. These disadvantages have severely restricted the development of particle electrode materials. The development of composite particle electrodes has become the research direction and focus of many scholars. The particle electrodes involved in patent literature are mostly composite particle electrodes, which integrate the advantages of various materials and promote each other to improve performance. At present, the treatment efficiency of the reported composite particle electrodes has been improved on the basis of traditional particle electrodes, but their structures are unstable and the effects are not significant. The present invention combines carbon materials with metal materials, which not only has the adsorption property of carbon materials but also has good electrical conductivity and catalytic activity of metals. A layered metal structure is prepared by low-cost methods such as co-precipitation and hydrothermal method, which has good structural stability. Combining it with waste graphite to treat waste with waste enhances the electrical conductivity, catalytic property and adsorption property of the particle electrode. The particle electrode prepared by this method overcomes the problems of complex process, poor electrical conductivity, high cost, etc. of traditional particle electrodes, and improves the structural stability and catalytic activity compared with other composite particle electrodes, with a wide range of applications and no secondary pollution.

[0005] Three-dimensional electrocatalysis introduces particle electrodes on the basis of two dimensions. The addition of particle electrodes increases the catalytic area, improves the electron transfer efficiency, increases the catalytic loading, and enhances the catalytic activity and stability. Particle electrode materials are composite materials composed of electrode carriers with special structures and electrocatalytic particles. There are mainly two categories of common particle electrode materials: carbonaceous materials and metals. Carbonaceous materials play an important role in the electrochemical treatment of wastewater. From traditional activated carbon and graphite to emerging carbon nanotubes, carbon nanofibers, graphene, and carbon aerogels, each material exhibits unique advantages and application prospects. Metal materials are similar to carbonaceous materials, have good electrical conductivity and catalytic active sites for the oxidation-reduction reactions of pollutants, and can provide some metal ions for electro-Fenton reactions or electro-Fenton-like reactions. They are the most widely used particle electrodes in the three-dimensional electrochemical wastewater treatment process. The metal materials most commonly used as particle electrodes include metal particles, metal oxides, and metal foams.

[0006] Emerging carbon materials have better adsorption, catalysis, and recyclability than traditional carbon materials, but they have problems such as long preparation cycles, complex processes, high material consumption, high costs, and low yields. The alkaline catalyst must be used during the preparation of carbon aerogels, and it is difficult to control the catalyst concentration. Too high or too low will affect the gel output. Metal electrodes have strong electrical conductivity and high catalytic activity, but are limited by application occasions and conditions. The most typical is the iron-containing metal particle electrode, which is mainly used for the wastewater treatment using electro-Fenton reactions. It has certain requirements for the pH of the wastewater during use, and improper use will also produce iron-containing sludge, which is difficult to treat and increases costs. The present invention combines carbon materials and metal materials, which not only have the adsorption of carbon materials but also have good electrical conductivity and catalytic activity of metals. Using low-cost methods such as coprecipitation and hydrothermal method to prepare a layered metal structure, which has good controllability, thermal stability, excellent adsorption and catalytic properties. Combining it with waste graphite to treat waste with waste enhances the electrical conductivity, catalysis, and adsorption of the particle electrode. The particle electrode prepared by this method overcomes the problems of complex processes, poor electrical conductivity, and high costs of traditional particle electrodes, and on this basis improves the adsorption and catalytic activity, has a wide range of uses, and no secondary pollution. Summary of the Invention

[0007] Object of the Invention: By modifying graphite with surfactants, overcoming the hydrophobic characteristics of graphite, and combining graphite with layered non-precious metals, a new method for preparing particle electrodes is provided. The prepared graphite-based non-precious metal particle electrodes have the characteristics of high degradation efficiency, good catalytic activity, low cost, wide applicability, excellent performance, etc., and the preparation method is simple, the materials are easy to obtain, and firing is avoided.

[0008] Technical Solution: The present invention adopts the following technical solutions.

[0009] Preparation method of graphite-based composite non-noble metal particle electrode: Using surfactant-modified graphite as a carrier, non-noble metals are loaded onto the modified graphite in layers by in-situ dropwise precipitation method. After aging, washing, drying, powdering, sieving and other steps, graphite-based non-noble metal powder is obtained. Then, the graphite-based non-noble metal powder, slag Portland cement and water glass are mixed in a certain proportion, and after granulation, sieving and curing, graphite-based non-noble metal particle electrode is obtained. The preparation method specifically includes the following steps: (1) Stir a surfactant solution with a certain concentration for 1 h, then add waste graphite into the surfactant solution and ultrasonicate for 20 - 30 minutes, let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2 - 3 times, and finally vacuum dry it at room temperature to obtain modified graphite; (2) Prepare graphite-based composite non-noble metal catalyst powder by in-situ dropwise precipitation, and the steps are as follows: a. First, configure metal salt solutions by combining non-noble metal salts in pairs according to a certain molar ratio, and secondly, configure an alkali solution; b. Add the modified graphite into deionized water and ultrasonicate for 4 h. Dropwise add the metal salt solution and the alkali solution into the deionized water containing a certain mass of modified graphite, while using a stirrer to stir at a speed of 200 - 250 r / min and control the pH value to be 10. After dropping, stir and age in a 60°C water bath for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times, and dry it in a 60°C oven for 24 h, then powder it and sieve it to obtain graphite-based composite non-noble metal catalyst powder with a certain mesh number; (3) Uniformly mix the graphite-based composite non-noble metal catalyst powder, slag Portland cement and water glass in a certain proportion. Add the mixed powder into a disk granulator in batches for granulation, sieving, to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite non-noble metal particle electrode.

[0010] According to the preparation method of a graphite-based composite non-noble metal particle electrode described in claim 1, it is characterized in that in the step (1), the surfactant is sodium dodecylbenzenesulfonate (SDBS), and the concentration is 0.1 - 5 g / L; the waste graphite is 200 - 500 mesh.

[0011] According to the preparation method of a graphite-based composite non-noble metal particle electrode described in claim 2, it is characterized in that in the step (2), the non-noble metal salts are CuCl2·2H2O, MnCl2·4H2O, ZnCl2, AlCl3·6H2O, FeCl3·6H2O.

[0012] A method for preparing a graphite-based composite non-noble metal particle electrode according to claim 2, characterized in that, in the step (2), the non-noble metal salts are combined in pairs as FeCl3·6H2O and CuCl2·2H2O, FeCl3·6H2O and MnCl2·4H2O, FeCl3·6H2O and ZnCl2 or AlCl3·6H2O and CuCl2·2H2O, AlCl3·6H2O and MnCl2·4H2O, AlCl3·6H2O and ZnCl2.

[0013] A method for preparing a graphite-based composite non-noble metal particle electrode according to claim 3, characterized in that, in the step (2), the non-noble metal salts are combined in pairs to prepare a metal salt solution according to the molar ratio of [M 3+ / ([M 2+ +[M 3+ ) = x (0.2 ≤ x ≤ 0.25), and the total cation concentration is 1 mol / L; the alkali solution is a mixed solution of Na2CO3 and NaOH, where [NaOH] = 2.5 mol / L and [CO3 2- = 2[M 3+ =0.5 mol / L.

[0014] A method for preparing a graphite-based composite non-noble metal particle electrode according to claim 4, characterized in that, in the step (2), the ratio of modified graphite to deionized water is 200 g:500 ml; the graphite-based composite non-noble metal catalyst powder is sieved to 200 mesh.

[0015] A method for preparing a graphite-based composite non-noble metal particle electrode according to claim 4, characterized in that, in the step (3), the ratio of the graphite-based composite non-noble metal catalyst powder, slag Portland cement, and water glass is 6:3.5:0.5; the graphite-based composite non-noble metal particle electrode is sieved to 3 - 5 mm.

[0016] In the above application, the graphite-based composite non-noble metal particle electrode is used as a three-dimensional electrode, the anode uses a ruthenium-titanium electrode (RuO2 / Ti), the cathode uses a carbon felt, sodium chloride is used as the electrolyte, and a graphite-based composite non-noble metal electrocatalytic system is assembled to realize the electrocatalytic degradation of heterocyclic pollutants.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation method is simple and the cost is low: The present invention uses surfactant-modified graphite as a carrier, and adopts an in-situ dropwise precipitation method to layer-load non-noble metals onto the modified graphite, and then mixes it with slag Portland cement and water glass, granulates, forms, and cures to obtain a graphite-based composite non-noble metal particle electrode. There is no need for a calcination process, the method is simple, and the cost is only 1 / 3 of the calcination process; (2) The graphite-based composite non-noble metal particle electrode has good electrical conductivity and low energy consumption: Through electrocatalytic experiment tests, the graphite-based composite non-noble metal particle electrode prepared by the present invention has a particle size of 3-5 mm. At a lower voltage, when the initial concentration of pyridine pollutants is 100 mg / L, after 120 minutes of electrocatalysis, the removal rate of the heterocyclic compound pyridine by this catalytic system is stable above 90%, and the COD removal rate is above 85%, which are respectively increased by 35% and 24% compared with the conventional activated carbon particle electrode, and the energy consumption is decreased by 42%. This proves that the graphite-based non-noble metal particle electrode has high-efficiency removal performance for heterocyclic pollutants at low energy consumption; (3) High catalytic activity: The present invention introduces layered non-noble metals into the particle electrode, which enhances the adsorption and catalysis of the particle electrode, and overcomes the problems of poor loading effect and few catalytic sites when the metal is loaded on the particle electrode by the traditional impregnation method. The presence of non-noble metals increases the catalytic active sites and promotes the generation of •OH, so as to better "break the ring" and degrade heterocyclic pollutants. Moreover, the layered non-noble metal structure can be regulated in various ways, the preparation method is simple, and the materials are easy to obtain.

[0018] In summary, the graphite-based composite non-noble metal particle electrode in the present invention has the characteristics of simple preparation method, low cost, good electrical conductivity, high catalytic activity, wide applicability, excellent performance, etc. The preparation materials are easy to obtain and do not require firing. Under the condition of low energy consumption, it can efficiently remove heterocyclic pollutants. Specific implementation mode

[0019] Example 1 Preparation of graphite-based composite FeCu particle electrode and treatment of pyridine and pyrrole wastewater (1) Stir a surfactant solution (sodium dodecylbenzenesulfonate (SDBS)) with a certain concentration for 1 h, then add waste graphite with a mesh size of 200-500 to the surfactant solution and ultrasonicate for 20-30 minutes. Let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite; (2) In-situ dropwise precipitation is used to prepare graphite-based composite FeCu catalyst powder, and the steps are as follows: a. Prepare a mixed solution of 1 mol / L FeCl3·6H2O and CuCl2·2H2O, and a mixed alkali solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3; b. Weigh 100 g of modified graphite, add the modified graphite to deionized water and ultrasonicate for 4 h. Dropwise add the metal salt solution and the alkali solution into the deionized water containing a certain mass of modified graphite. At the same time, use a stirrer to stir at a speed of 200 - 250 r / min, and control the pH value to be 10. After the addition is completed, stir and age in a water bath at 60°C for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times, dry it in an oven at 60°C for 24 h, then powder it and sieve it to obtain graphite-based composite FeCu catalyst powder with a certain mesh size; (3) Uniformly mix the graphite-based composite FeCu catalyst powder, slag Portland cement, and water glass in a certain proportion. Add the mixed powder to a disk granulator in batches for granulation and sieving to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite FeCu particle electrodes; (4) Use the graphite-based composite FeCu particle electrode as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater, use a ruthenium-titanium electrode (RuO2 / Ti) as the anode, a carbon felt as the cathode, and sodium chloride as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system; When the constant voltage is 5 V, the flow rate is 3 ml / min, the electrolyte concentration is 400 mg / L, and the initial pollutant concentration is 100 mg / L, after 120 min, the removal rate of electrolytic pyridine is maintained at 90.6%, and the COD removal rate reaches 85.4%; the removal rate of electrolytic pyrrole is maintained at 93.2%, and the COD removal rate reaches 87%.

[0020] Example 2 Preparation of Graphite-Based Composite FeMn Particle Electrodes and Treatment of Pyridine and Pyrrole Wastewater (1) Stir a surfactant solution (sodium dodecylbenzenesulfonate (SDBS)) with a certain concentration for 1 h. Then add waste graphite with a mesh size of 200 - 500 to the surfactant solution and ultrasonicate for 20 - 30 minutes. Let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2 - 3 times, and finally dry it under vacuum at room temperature to obtain modified graphite; (2) In-situ dropwise precipitation to prepare graphite-based composite FeMn catalyst powder, and the steps are as follows: a. Prepare a mixed solution of 1 mol / L FeCl3·6H2O and MnCl2·4H2O, and a mixed alkali solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3; b. Weigh 100 g of modified graphite, add the modified graphite to deionized water and ultrasonicate for 4 h. Gradually add the metal salt solution and the alkali solution dropwise to the deionized water containing a certain mass of modified graphite. At the same time, use a stirrer to stir at a speed of 200 - 250 r / min and control the pH value to be 10. After the addition is completed, stir and age in a water bath at 60°C for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times, dry it in an oven at 60°C for 24 h, then powder it and sieve it to obtain graphite-based composite FeMn catalyst powder with a certain mesh size; (3) Uniformly mix the graphite-based composite FeMn catalyst powder, slag Portland cement, and water glass in a certain proportion. Add the mixed powder to a disk granulator in batches for granulation and sieving to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite FeMn particle electrodes; (4) Use the graphite-based composite FeMn particle electrode as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater, use a ruthenium-titanium electrode (RuO2 / Ti) as the anode, a carbon felt as the cathode, and sodium chloride as the electrolyte to assemble a graphite-based composite non-noble metal electrocatalytic system; When the constant voltage is 5 V, the flow rate is 3 ml / min, the electrolyte concentration is 400 mg / L, and the initial pollutant concentration is 100 mg / L, after 120 min, the removal rate of electrolyzed pyridine is maintained at 92.5%, and the COD removal rate reaches 89.3%; the removal rate of electrolyzed pyrrole is maintained at 95.7%, and the COD removal rate reaches 90.2%.

[0021] Example 3 Preparation of Graphite-Based Composite FeZn Particle Electrodes and Treatment of Pyridine and Pyrrole Wastewater (1) Stir a surfactant solution with a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 h, then add waste graphite with a mesh size of 200 - 500 to the surfactant solution and ultrasonicate for 20 - 30 minutes. Let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2 - 3 times, and finally dry it under vacuum at room temperature to obtain modified graphite; (2) Prepare graphite-based composite FeZn catalyst powder by in-situ dropwise precipitation, and the steps are as follows: a. Prepare a mixed solution of 1 mol / L FeCl3·6H2O and ZnCl2, and a mixed alkali solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3; b. Weigh 100 g of modified graphite, add the modified graphite to deionized water and ultrasonicate for 4 h. Dropwise add the metal salt solution and the alkali solution into the deionized water containing a certain mass of modified graphite. At the same time, use a stirrer to stir at a speed of 200 - 250 r / min and control the pH value to be 10. After the addition is completed, stir and age in a water bath at 60 °C for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times, dry it in an oven at 60 °C for 24 h, then powder it and sieve it to obtain graphite-based composite FeZn catalyst powder with a certain mesh number; (3) Uniformly mix the graphite-based composite FeZn catalyst powder, slag Portland cement, and water glass in a certain proportion. Add the mixed powder to a disk granulator in batches for granulation and sieving to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite FeZn particle electrodes; (4) Use the graphite-based composite FeZn particle electrode as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater, the ruthenium-titanium electrode (RuO2 / Ti) as the anode, the carbon felt as the cathode, and sodium chloride as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system; At a constant voltage of 5 V, a flow rate of 3 ml / min, an electrolyte concentration of 400 mg / L, and an initial pollutant concentration of 100 mg / L, after 120 min, the removal rate of electrolytic pyridine is maintained at 90.8%, and the COD removal rate reaches 86.8%; the removal rate of electrolytic pyrrole is maintained at 92.3%, and the COD removal rate reaches 87.6%.

[0022] Example 4 Preparation of Graphite-Based Composite AlCu Particle Electrodes and Treatment of Pyridine and Pyrrole Wastewater (1) Stir a surfactant solution (sodium dodecylbenzenesulfonate (SDBS)) with a certain concentration for 1 h. Then add waste graphite with a mesh size of 200 - 500 to the surfactant solution and ultrasonicate for 20 - 30 minutes. Let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2 - 3 times, and finally dry it under vacuum at room temperature to obtain modified graphite; (2) Prepare graphite-based composite AlCu catalyst powder by in-situ dropwise precipitation. The steps are as follows: a. Prepare a mixed solution of 1 mol / L AlCl3·6H2O and CuCl2·2H2O, and a mixed alkali solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3; b. Weigh 100 g of modified graphite, add the modified graphite into deionized water and ultrasonicate for 4 h. Dropwise add the metal salt solution and the alkali solution into the deionized water containing a certain mass of modified graphite. At the same time, use a stirrer to stir at a speed of 200 - 250 r / min, and control the pH value to be 10. After the dropping is completed, stir and age in a water bath at 60 °C for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times, dry it in an oven at 60 °C for 24 h, then powder it and sieve it to obtain graphite-based composite AlCu catalyst powder with a certain mesh number; (3) Uniformly mix the graphite-based composite AlCu catalyst powder, slag Portland cement, and water glass in a certain proportion. Add the mixed powder into a disk granulator in batches for granulation and screening to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite AlCu particle electrodes; (4) Use the graphite-based composite AlCu particle electrode as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater, use a ruthenium-titanium electrode (RuO2 / Ti) as the anode, a carbon felt as the cathode, and sodium chloride as the electrolyte to assemble a graphite-based composite non-noble metal electrocatalytic system; When the constant voltage is 5 V, the flow rate is 3 ml / min, the electrolyte concentration is 400 mg / L, and the initial pollutant concentration is 100 mg / L, after 120 min, the removal rate of electrolytic pyridine is maintained at 93.6%, and the COD removal rate reaches 86.4%; the removal rate of electrolytic pyrrole is maintained at 95.3%, and the COD removal rate reaches 87.6%.

[0023] Example 5 Preparation of Graphite-Based Composite AlMn Particle Electrodes and Treatment of Pyridine and Pyrrole Wastewater (1) Stir a surfactant solution (sodium dodecylbenzenesulfonate (SDBS)) with a certain concentration for 1 h, then add waste graphite with a mesh size of 200 - 500 to the surfactant solution and ultrasonicate for 20 - 30 minutes. Let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2 - 3 times, and finally dry it under vacuum at room temperature to obtain modified graphite; (2) In-situ dropwise precipitation to prepare graphite-based composite AlMn catalyst powder, and the steps are as follows: a. Prepare a mixed solution of 1 mol / L AlCl3·6H2O and MnCl2·4H2O, and a mixed alkali solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3; b. Weigh 100 g of modified graphite, add the modified graphite to deionized water and ultrasonicate for 4 h. Gradually add the metal salt solution and the alkali solution drop by drop to the deionized water containing a certain mass of modified graphite. At the same time, use a stirrer to stir at a speed of 200 - 250 r / min and control the pH value to be 10. After the addition is complete, stir and age in a water bath at 60 °C for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times, dry it in an oven at 60 °C for 24 h, then powder it and sieve it to obtain graphite-based composite AlMn catalyst powder with a certain mesh number; (3) Uniformly mix the graphite-based composite AlMn catalyst powder, slag Portland cement, and water glass in a certain proportion. Add the mixed powder to a disk granulator in batches for granulation and sieving to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite AlMn particle electrodes; (4) Use the graphite-based composite AlMn particle electrode as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater, the ruthenium-titanium electrode (RuO2 / Ti) as the anode, the carbon felt as the cathode, and sodium chloride as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system; When the constant voltage is 5 V, the flow rate is 3 ml / min, the electrolyte concentration is 400 mg / L, and the initial pollutant concentration is 100 mg / L, after 120 min, the removal rate of electrolytic pyridine is maintained at 92.3%, and the removal rate of COD reaches 89.7%; the removal rate of electrolytic pyrrole is maintained at 93.6%, and the removal rate of COD reaches 90.4%.

[0024] Example 6 Preparation of Graphite-Based Composite AlZn Particle Electrodes and Treatment of Pyridine and Pyrrole Wastewater (1) Stir a surfactant solution with a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 h. Then add waste graphite with a mesh size of 200 - 500 to the surfactant solution and ultrasonicate for 20 - 30 minutes. Let it stand at room temperature for 12 h, filter the obtained filter residue, wash it with deionized water 2 - 3 times, and finally dry it under vacuum at room temperature to obtain modified graphite; (2) Prepare graphite-based composite AlZn catalyst powder by in-situ dropwise precipitation, and the steps are as follows: a. Prepare a mixed solution of 1 mol / L AlCl3·6H2O and ZnCl2, and a mixed alkali solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3; b. Weigh 100 g of modified graphite, add the modified graphite to deionized water and ultrasonicate for 4 h. Gradually add the metal salt solution and the alkali solution drop by drop to the deionized water containing a certain mass of modified graphite. At the same time, use a stirrer to stir at a rotation speed of 200 - 250 r / min and control the pH value to be 10. After the addition is complete, stir and age in a water bath at 60°C for 6 h. Thoroughly wash the obtained precipitate with deionized water 2 - 3 times and dry it in an oven at 60°C for 24 h. Then powder it and sieve it to obtain graphite-based composite AlZn catalyst powder with a certain mesh number; (3) Uniformly mix the graphite-based composite AlZn catalyst powder, slag Portland cement, and water glass in a certain proportion. Add the mixed powder to a disk granulator in batches for granulation and sieving to obtain uniform spherical particles. Then place the prepared spherical particles in a curing box for curing to obtain graphite-based composite AlZn particle electrodes; (4) The graphite-based composite AlZn particle electrode is used as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater. The ruthenium-titanium electrode (RuO2 / Ti) is used as the anode, the carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-noble metal electrocatalytic system; When the constant voltage is 5 V, the flow rate is 3 ml / min, the electrolyte concentration is 400 mg / L, and the initial pollutant concentration is 100 mg / L, after 120 min, the removal rate of electrolytic pyridine is maintained at 91.3%, and the removal rate of COD reaches 86.8%; the removal rate of electrolytic pyridine is maintained at 92.4%, and the removal rate of COD reaches 87.6%. Enter the description paragraph of the invention content.

Claims

1. A method for preparing a graphite-based composite non-precious metal particle electrode comprises the following specific steps: (1) Stirring a surfactant solution of a certain concentration for 1 hour, then adding waste graphite to the surfactant solution and ultrasonicating for 20-30 minutes, leaving it to stand at room temperature for 12 hours, filtering the resulting residue, washing it with deionized water for 2-3 times, and finally drying it under vacuum at room temperature to obtain modified graphite; (2) In-situ dropwise precipitation is used to prepare graphite-based composite non-precious metal catalyst powder, the steps of which are as follows: a. First, non-precious metal salts are combined in pairs according to a certain molar ratio to prepare a metal salt solution, and then an alkaline solution is prepared; b. Add modified graphite to deionized water and ultrasonicate for 4 hours, add metal salt solution and alkali solution dropwise to deionized water containing a certain mass of modified graphite, stir at 200-250r / min with a stirrer, and control the pH value to be 10. After the addition is complete, stir and age in a 60°C water bath for 6 hours, wash the obtained precipitate thoroughly with deionized water for 2-3 times, dry in an oven at 60°C for 24 hours, then grind to powder, and sieve to obtain graphite-based composite non-precious metal catalyst powder of a certain mesh size; (3) The graphite-based composite non-precious metal catalyst powder, slag silicate cement and water glass are uniformly mixed in a certain proportion, and the mixed powder is added to a disc granulator in batches for granulation and sieving to obtain uniform spherical particles, and then the prepared spherical particles are placed in a curing box for curing to obtain a graphite-based composite non-precious metal particle electrode.

2. The method for preparing a graphite-based composite non-precious metal particle electrode according to claim 1, characterized in that: In the step (1), the surfactant is sodium dodecylbenzene sulfonate (SDBS) with a concentration of 0.1-5 g / L; and the waste graphite is 200-500 meshes.

3. The method for preparing a graphite-based composite non-precious metal particle electrode according to claim 2, characterized in that: In the step (2), the non-precious metal salt is CuCl2·2H2O, MnCl2·4H2O, ZnCl2, AlCl3·6H2O, FeCl3·6H2O.

4. The method for preparing a graphite-based composite non-precious metal particle electrode according to claim 2, characterized in that: In the step (2), the non-precious metal salts are combined in pairs to form FeCl3·6H2O and CuCl2·2H2O, FeCl3·6H2O and MnCl2·4H2O, FeCl3·6H2O and ZnCl2 or AlCl3·6H2O and CuCl2·2H2O, AlCl3·6H2O and MnCl2·4H2O, AlCl3·6H2O and ZnCl2.

5. The method for preparing a graphite-based composite non-precious metal particle electrode according to claim 3, characterized in that: In the step (2), the non-precious metal salt is in the range of [M 3+ ] / ( [M 2+ ]+[M 3+ ] ) = x (0.2 ≤ x ≤ 0.25) in molar ratios, and the total cation concentration is 1 mol / L; the alkaline solution is a mixed solution of Na2CO3 and NaOH, where [NaOH] = 2.5 mol / L and [CO3 2- ] = 2[M 3+ ]=0.5mol / L.

6. The method for preparing a graphite-based composite non-precious metal particle electrode according to claim 4, characterized in that: In the step (2), the ratio of modified graphite to deionized water is 200 g:500 ml; and the graphite-based composite non-precious metal catalyst powder is sieved to 200 mesh.

7. The method for preparing a graphite-based composite non-precious metal particle electrode according to claim 4, characterized in that: In the step (3), the ratio of graphite-based composite non-precious metal catalyst powder, slag silicate cement and water glass is 6:3.5:0.5; and the graphite-based composite non-precious metal particle electrode is sieved to 3-5 mm.