A method for preparing a graphite-based composite non-noble metal particle electrode

Abstract

The application discloses a preparation method of a graphite-based composite non-noble metal particle electrode, and steps are as follows: (1) stirring a surfactant solution with a certain concentration for 1 hour, adding waste graphite powder and ultrasonicating for 20-30 minutes, filtering, washing and vacuum drying after standing for 12 hours to obtain modified graphite; (2) a, configuring a non-noble metal salt solution and an alkali solution according to a molar ratio; b, ultrasonicating the modified graphite for 4 hours, dropwise adding the metal salt and the alkali solution, stirring and controlling a pH value to be 10, aging for 6 hours, drying for 24 hours after washing, and grinding and screening to obtain a composite catalyst powder; (3) mixing the catalyst powder, a slag silicate cement and a water glass, granulating into spherical particles and curing to obtain the graphite-based composite non-noble metal particle electrode. The three-dimensional particle electrode prepared by the application can be used for electrolyzing organic industrial wastewater, and has the advantages of low cost, wide applicability and excellent performance.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a graphite-based composite non-noble metal particle electrode and belongs to the technical field of electrocatalysis. BACKGROUND

[0002] Biological medicine, pesticide, chemical new material, coal processing and other enterprises and generally existing industrial agglomeration zones (parks) have wastewater which is mostly difficult-to-degrade organic industrial wastewater, and it is very difficult to reach the standard by using the biochemical method. Heterocyclic compounds, such as pyridine, methylpyridine, dimethylpyridine, quinoline and the like, are commonly present in pharmaceutical wastewater and coal industrial wastewater. They have the characteristics of strong toxicity, complex water quality, high organic nitrogen content and low biodegradability, and are listed as B class carcinogens by the World Health Organization. A treatment technology which is suitable for the water quality characteristics of heterocyclic compounds, has wide spectrum, low selectivity, is green, economical and efficient is urgently needed.

[0003] The research on the electrochemical method for treating difficult-to-degrade organic matters has been reported by a large number of researchers. The special cyclic structure of heterocyclic compounds makes them stable in nature, and the strong oxidizing substances generated in the electrochemical process can effectively cause the heterocyclic compounds to have a 'ring-opening' reaction. The electrocatalytic oxidation method is a new emerging advanced oxidation technology, which can degrade the heterocyclic compounds in wastewater into small molecular organic matters or directly mineralize them into CO2 and H2O through direct oxidation of the anode or indirect oxidation of ·OH. The electrocatalytic oxidation method gradually attracts the attention of scholars due to the advantages of no need to add reagents, no secondary pollution and easy automation.

[0004] Traditional electrode materials have problems of low current efficiency, poor stability and high cost in wastewater treatment. These shortcomings seriously limit 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 the patent documents are mostly composite particle electrodes, which combine the advantages of various materials, promote each other and improve the performance. The treatment efficiency of the currently reported composite particle electrodes has been improved on the basis of traditional particle electrodes, but the structure is unstable and the effect is not significant. The carbon material is combined with the metal material in the application, so that the particle electrode has the adsorption of the carbon material and the good conductivity and catalytic activity of the metal. The layered metal structure is prepared by using a low-cost method such as co-precipitation and hydrothermal method, and has good structural stability. The layered metal structure is combined with waste graphite to treat waste with waste, and the conductivity, catalytic property and adsorption of the particle electrode are enhanced. The particle electrode prepared by the method overcomes the problems of complex process, poor conductivity and high cost of traditional particle electrodes, and has good structural stability and catalytic activity compared with other composite particle electrodes, a wide range of uses and no secondary pollution.

[0005] Three-dimensional electrocatalysis introduces particle electrodes into a two-dimensional process. The addition of particle electrodes increases the catalytic area, improves electron transfer efficiency, increases catalytic loading, and enhances catalytic activity and stability. Particle electrode materials are composite materials composed of electrode supports with special structures and electrocatalytic particles. Common particle electrode materials mainly fall into two categories: carbonaceous materials and metals. Carbonaceous materials play an important role in the electrochemical treatment of wastewater. From traditional activated carbon and graphite to emerging materials such as carbon nanotubes, carbon nanofibers, graphene, and carbon aerogels, each material exhibits unique advantages and application prospects. Metallic materials follow the category of carbonaceous materials, possessing good electrical conductivity and catalytically active sites for pollutant redox reactions. They can also provide some metal ions for electro-Fenton reactions or electro-Fenton-like reactions, making them the most widely used particle electrodes in three-dimensional electrochemical wastewater treatment processes. The most commonly used metallic materials as particle electrodes include metal particles, metal oxides, and metal foams.

[0006] Emerging carbon materials exhibit better adsorption, catalytic, and recyclability than traditional carbon materials, but they suffer from drawbacks such as long preparation cycles, complex processes, high material consumption, high costs, and low yields. The preparation of carbon aerogels requires alkaline catalysts, and the catalyst concentration is difficult to control; too high or too low a concentration will affect gel production. Metal electrodes possess strong conductivity and high catalytic activity, but their application is limited by specific conditions. The most typical example is the iron-containing metal particle electrode, primarily used in wastewater treatment employing electro-Fenton reactions. Its use requires specific wastewater pH levels, and improper application can generate iron-containing sludge, leading to treatment difficulties and increased costs. This invention combines carbon materials with metal materials, possessing both the adsorption properties of carbon and the excellent conductivity and catalytic activity of metals. A layered metal structure is prepared using low-cost methods such as co-precipitation and hydrothermal methods, exhibiting good controllability, thermal stability, and excellent adsorption and catalytic performance. Combining this with waste graphite utilizes waste-to-resource technology to enhance the conductivity, catalytic activity, and adsorption of the particle electrode. The particle electrode prepared by this method overcomes the problems of complex process, poor conductivity and high cost of traditional particle electrodes, and improves adsorption and catalytic activity. It has a wide range of applications and no secondary pollution. Summary of the Invention

[0007] Purpose of the invention: By modifying graphite with surfactants to overcome its hydrophobic properties, a new method for preparing particle electrodes is provided, which combines graphite with layered non-precious metals. The prepared graphite-based non-precious metal particle electrodes have the characteristics of high degradation efficiency, good catalytic activity, low cost, wide applicability, and superior performance. Moreover, the preparation method is simple, the materials are readily available, and the firing process is not required.

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

[0009] A method for preparing a graphite-based composite non-precious metal particle electrode: using surfactant-modified graphite as a carrier, non-precious metals are layered and loaded onto the modified graphite using an in-situ dropwise precipitation method. After aging, cleaning, drying, pulverizing, and sieving, graphite-based non-precious metal powder is obtained. Then, the graphite-based non-precious metal powder, slag silicate cement, and water glass are mixed in a certain proportion, and then granulated, sieved, and cured to obtain the graphite-based non-precious metal particle electrode. The specific preparation method includes the following steps:

[0010] (1) Stir a surfactant solution of a certain concentration for 1 hour, then add waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0011] (2) In-situ dropwise precipitation preparation of graphite-based composite non-precious metal catalyst powder, the steps of which are as follows:

[0012] a. First, combine non-precious metal salts in pairs according to a certain molar ratio to prepare metal salt solutions, and then prepare alkaline solutions.

[0013] b. Add modified graphite to deionized water and sonicate for 4 hours. Add metal salt solution and alkaline solution dropwise to deionized water containing a certain mass of modified graphite. At the same time, stir with a stirrer at a speed of 200-250 r / min and control the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite non-precious metal catalyst powder of a certain mesh size.

[0014] (3) The graphite-based composite non-precious metal catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to a disc granulator in batches for granulation and sieving to obtain uniform spherical particles. The prepared spherical particles are then placed in a curing box for curing to obtain the graphite-based composite non-precious metal particle electrode.

[0015] According to claim 1, the method for preparing a graphite-based composite non-precious metal particle electrode is characterized in that, in step (1), the surfactant is sodium dodecylbenzenesulfonate (SDBS) with a concentration of 0.1~5g / L; and the waste graphite is 200~500 mesh.

[0016] According to claim 2, the method for preparing a graphite-based composite non-noble metal particle electrode is characterized in that, in step (2), the non-noble metal salt is CuCl2·2H2O, MnCl2·4H2O, ZnCl2, AlCl3·6H2O, or FeCl3·6H2O.

[0017] According to claim 2, the method for preparing a graphite-based composite non-precious metal particle electrode is characterized in that, in step (2), the non-precious 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.

[0018] According to claim 3, a method for preparing a graphite-based composite non-noble metal particle electrode is characterized in that, in step (2), the non-noble metal salt is prepared according to [M 3+ ] / ( [M 2+ ]+[M 3+ Metal salt solutions are prepared by combining two metal salts in a molar ratio of [0.2 ≤ x ≤ 0.25], with a total cation concentration of 1 mol / L; the alkaline solution is a mixture of Na₂CO₃ and NaOH, where [NaOH] = 2.5 mol / L and [CO₃] = 2.5 mol / L. 2- ] = 2[M 3+ =0.5mol / L.

[0019] According to claim 4, the method for preparing a graphite-based composite non-precious metal particle electrode is characterized in that, in step (2), the ratio of modified graphite to deionized water is 200g:500ml; and the graphite-based composite non-precious metal catalyst powder is sieved through a 200-mesh sieve.

[0020] According to claim 4, the method for preparing a graphite-based composite non-precious metal particle electrode is characterized in that, in 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 a thickness of 3~5 mm.

[0021] In the above applications, a graphite-based composite non-precious metal particle electrode is used as a three-dimensional electrode, with a ruthenium-titanium electrode (RuO2 / Ti) as the anode, a carbon felt as the cathode, and sodium chloride as the electrolyte. A graphite-based composite non-precious metal electrocatalytic system is assembled to achieve electrocatalytic degradation of heterocyclic pollutants.

[0022] Compared with the prior art, the beneficial effects of this invention are as follows:

[0023] (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 load non-precious metals onto the modified graphite in layers. Then, it is mixed with slag silicate cement and water glass, granulated and cured to obtain graphite-based composite non-precious metal particle electrodes. No calcination process is required. The method is simple and the cost is only 1 / 3 of that of the calcination process.

[0024] (2) Graphite-based composite non-precious metal particle electrode has good conductivity and low energy consumption: After electrocatalytic experiments, the particle size of the graphite-based composite non-precious metal particle electrode prepared in this invention is 3~5mm. Under low voltage, when the initial concentration of pyridine pollutant is 100mg / L, after 120min of electrocatalysis, the removal rate of heterocyclic compound pyridine by this catalytic system is stable at more than 90%, and the COD removal rate is more than 85%, which is 35% and 24% higher than that of conventional activated carbon particle electrode, respectively, and the energy consumption is reduced by 42%. This proves that the graphite-based non-precious metal particle electrode has high efficiency in removing heterocyclic pollutants under low energy consumption.

[0025] (3) High catalytic activity: The present invention introduces layered non-precious metals into the particle electrode to enhance the adsorption and catalytic properties of the particle electrode, overcoming the problems of poor loading effect and few catalytic sites when the particle electrode is loaded with metal by the traditional impregnation method. The presence of non-precious metals increases the catalytic active sites and promotes the generation of •OH, thereby better “breaking the ring” and degrading heterocyclic pollutants. Moreover, the layered non-precious metal structure can be regulated in various ways, the preparation method is simple, and the materials are readily available.

[0026] In summary, the graphite-based composite non-precious metal particle electrode preparation method of this invention is simple, low-cost, has good conductivity, high catalytic activity, wide applicability, and superior performance. Moreover, the preparation materials are readily available and do not require firing. Under low energy consumption conditions, it can efficiently remove heterocyclic pollutants. Detailed Implementation

[0027] Example 1

[0028] Preparation of graphite-based composite FeCu particle electrodes and their application in the treatment of pyridine and pyrrole wastewater.

[0029] (1) Stir a surfactant solution of a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 hour, then add 200-500 mesh waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0030] (2) In-situ dropwise precipitation preparation of graphite-based composite FeCu catalyst powder, the steps of which are as follows:

[0031] a. Prepare a mixed solution of 1 mol / L FeCl3·6H2O and CuCl2·2H2O, and a mixed alkaline solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3;

[0032] b. Weigh 100g of modified graphite, add the modified graphite to deionized water and sonicate for 4 hours. Add the metal salt solution and alkaline solution dropwise to the deionized water containing a certain mass of modified graphite, while stirring with a stirrer at a speed of 200-250r / min and controlling the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite FeCu catalyst powder of a certain mesh size.

[0033] (3) The graphite-based composite FeCu catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to the disc granulator in batches to granulate and sieve to obtain uniform spherical particles. Then the prepared spherical particles are placed in the curing box for curing to obtain the graphite-based composite FeCu particle electrode.

[0034] (4) A graphite-based composite FeCu particle electrode is used as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater. A ruthenium titanium electrode (RuO2 / Ti) is used as the anode, a carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system.

[0035] At a constant voltage of 5V, a flow rate of 3ml / min, an electrolyte concentration of 400mg / L, and an initial pollutant concentration of 100mg / L, after 120min, the removal rate of electrolytic pyridine remained at 90.6%, and the COD removal rate reached 85.4%; the removal rate of electrolytic pyrrole remained at 93.2%, and the COD removal rate reached 87%.

[0036] Example 2

[0037] Preparation of graphite-based composite FeMn particle electrodes and their application in the treatment of pyridine and pyrrole wastewater.

[0038] (1) Stir a surfactant solution of a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 hour, then add 200-500 mesh waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0039] (2) In-situ dropwise precipitation preparation of graphite-based composite FeMn catalyst powder, the steps of which are as follows:

[0040] a. Prepare a mixed solution of 1 mol / L FeCl3·6H2O and MnCl2·4H2O, and a mixed alkaline solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3;

[0041] b. Weigh 100g of modified graphite, add the modified graphite to deionized water and sonicate for 4 hours. Add the metal salt solution and alkaline solution dropwise to the deionized water containing a certain mass of modified graphite, while stirring with a stirrer at a speed of 200-250r / min and controlling the pH value to 10. After the addition is complete, age the mixture in a 60°C water bath for 6 hours. Wash the obtained precipitate thoroughly with deionized water 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite FeMn catalyst powder of a certain mesh size.

[0042] (3) The graphite-based composite FeMn catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to the disc granulator in batches to granulate and sieve to obtain uniform spherical particles. Then the prepared spherical particles are placed in the curing box for curing to obtain the graphite-based composite FeMn particle electrode.

[0043] (4) A graphite-based composite FeMn particle electrode is used as a particle electrode for the electrocatalytic degradation of pyridine simulated wastewater. A ruthenium-titanium electrode (RuO2 / Ti) is used as the anode, a carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system.

[0044] At a constant voltage of 5V, a flow rate of 3ml / min, an electrolyte concentration of 400mg / L, and an initial pollutant concentration of 100mg / L, after 120min, the removal rate of electrolytic pyridine remained at 92.5%, and the COD removal rate reached 89.3%; the removal rate of electrolytic pyrrole remained at 95.7%, and the COD removal rate reached 90.2%.

[0045] Example 3

[0046] Preparation of graphite-based composite FeZn particle electrodes and their application in the treatment of pyridine and pyrrole wastewater.

[0047] (1) Stir a surfactant solution of a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 hour, then add 200-500 mesh waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0048] (2) In-situ dropwise precipitation preparation of graphite-based composite FeZn catalyst powder, the steps of which are as follows:

[0049] a. Prepare a mixed solution of 1 mol / L FeCl3·6H2O and ZnCl2, and a mixed alkaline solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3;

[0050] b. Weigh 100g of modified graphite, add the modified graphite to deionized water and sonicate for 4 hours. Add the metal salt solution and alkaline solution dropwise to the deionized water containing a certain mass of modified graphite, while stirring with a stirrer at a speed of 200-250r / min and controlling the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite FeZn catalyst powder of a certain mesh size.

[0051] (3) The graphite-based composite FeZn catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to a disc granulator in batches to granulate and sieve to obtain uniform spherical particles. Then the prepared spherical particles are placed in a curing box for curing to obtain graphite-based composite FeZn particle electrodes.

[0052] (4) A graphite-based composite FeZn particle electrode is used as a particle electrode for the electrocatalytic degradation of pyridine simulated wastewater. A ruthenium-titanium electrode (RuO2 / Ti) is used as the anode, a carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system.

[0053] At a constant voltage of 5V, a flow rate of 3ml / min, an electrolyte concentration of 400mg / L, and an initial pollutant concentration of 100mg / L, after 120min, the removal rate of electrolytic pyridine remained at 90.8%, and the COD removal rate reached 86.8%; the removal rate of electrolytic pyrrole remained at 92.3%, and the COD removal rate reached 87.6%.

[0054] Example 4

[0055] Preparation of graphite-based composite AlCu particle electrodes and their application in the treatment of pyridine and pyrrole wastewater.

[0056] (1) Stir a surfactant solution of a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 hour, then add 200-500 mesh waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0057] (2) In-situ dropwise precipitation preparation of graphite-based composite AlCu catalyst powder, the steps of which are as follows:

[0058] a. Prepare a mixed solution of 1 mol / L AlCl3·6H2O and CuCl2·2H2O, and a mixed alkaline solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3;

[0059] b. Weigh 100g of modified graphite, add the modified graphite to deionized water and sonicate for 4 hours. Add the metal salt solution and alkaline solution dropwise to the deionized water containing a certain mass of modified graphite, while stirring with a stirrer at a speed of 200-250r / min and controlling the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite AlCu catalyst powder of a certain mesh size.

[0060] (3) The graphite-based composite AlCu catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to a disc granulator in batches to granulate and sieve to obtain uniform spherical particles. Then the prepared spherical particles are placed in a curing box for curing to obtain graphite-based composite AlCu particle electrodes.

[0061] (4) A graphite-based composite AlCu particle electrode is used as the particle electrode for electrocatalytic degradation of pyridine simulated wastewater. A ruthenium titanium electrode (RuO2 / Ti) is used as the anode, a carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system.

[0062] At a constant voltage of 5V, a flow rate of 3ml / min, an electrolyte concentration of 400mg / L, and an initial pollutant concentration of 100mg / L, after 120min, the removal rate of electrolytic pyridine remained at 93.6%, and the COD removal rate reached 86.4%; the removal rate of electrolytic pyrrole remained at 95.3%, and the COD removal rate reached 87.6%.

[0063] Example 5

[0064] Preparation of graphite-based composite AlMn particle electrodes and their application in the treatment of pyridine and pyrrole wastewater.

[0065] (1) Stir a surfactant solution of a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 hour, then add 200-500 mesh waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0066] (2) In-situ dropwise precipitation preparation of graphite-based composite AlMn catalyst powder, the steps of which are as follows:

[0067] a. Prepare a mixed solution of 1 mol / L AlCl3·6H2O and MnCl2·4H2O, and a mixed alkaline solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3;

[0068] b. Weigh 100g of modified graphite, add the modified graphite to deionized water and sonicate for 4 hours. Add the metal salt solution and alkaline solution dropwise to the deionized water containing a certain mass of modified graphite, while stirring with a stirrer at 200-250r / min and controlling the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite AlMn catalyst powder of a certain mesh size.

[0069] (3) The graphite-based composite AlMn catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to a disc granulator in batches to granulate and sieve to obtain uniform spherical particles. Then the prepared spherical particles are placed in a curing box for curing to obtain graphite-based composite AlMn particle electrodes.

[0070] (4) A graphite-based composite AlMn particle electrode is used as a particle electrode for the electrocatalytic degradation of pyridine simulated wastewater. A ruthenium-titanium electrode (RuO2 / Ti) is used as the anode, a carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system.

[0071] At a constant voltage of 5V, a flow rate of 3ml / min, an electrolyte concentration of 400mg / L, and an initial pollutant concentration of 100mg / L, after 120min, the removal rate of electrolytic pyridine remained at 92.3%, and the COD removal rate reached 89.7%; the removal rate of electrolytic pyrrole remained at 93.6%, and the COD removal rate reached 90.4%.

[0072] Example 6

[0073] Preparation of graphite-based composite AlZn particle electrodes and their application in the treatment of pyridine and pyrrole wastewater.

[0074] (1) Stir a surfactant solution of a certain concentration (sodium dodecylbenzenesulfonate (SDBS)) for 1 hour, then add 200-500 mesh waste graphite to the surfactant solution and sonicate for 20-30 minutes. Let it stand at room temperature for 12 hours, filter the residue, wash it with deionized water 2-3 times, and finally vacuum dry it at room temperature to obtain modified graphite.

[0075] (2) In-situ dropwise precipitation preparation of graphite-based composite AlZn catalyst powder, the steps of which are as follows:

[0076] a. Prepare a mixed solution of 1 mol / L AlCl3·6H2O and ZnCl2, and a mixed alkaline solution of 2.5 mol / L NaOH and 0.5 mol / L Na2CO3;

[0077] b. Weigh 100g of modified graphite, add the modified graphite to deionized water and sonicate for 4 hours. Add the metal salt solution and alkaline solution dropwise to the deionized water containing a certain mass of modified graphite, while stirring with a stirrer at a speed of 200-250r / min and controlling the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it to obtain graphite-based composite AlZn catalyst powder of a certain mesh size.

[0078] (3) The graphite-based composite AlZn catalyst powder, slag silicate cement and water glass are mixed evenly in a certain proportion. The mixed powder is added to a disc granulator in batches to granulate and sieve to obtain uniform spherical particles. Then the prepared spherical particles are placed in a curing box for curing to obtain graphite-based composite AlZn particle electrodes.

[0079] (4) A graphite-based composite AlZn particle electrode is used as a particle electrode for the electrocatalytic degradation of pyridine simulated wastewater. A ruthenium-titanium electrode (RuO2 / Ti) is used as the anode, a carbon felt is used as the cathode, and sodium chloride is used as the electrolyte to assemble a graphite-based composite non-precious metal electrocatalytic system.

[0080] At a constant voltage of 5V, a flow rate of 3ml / min, an electrolyte concentration of 400mg / L, and an initial pollutant concentration of 100mg / L, after 120min, the removal rate of electrolytic pyridine remained at 91.3%, and the COD removal rate reached 86.8%; the removal rate of electrolytic pyridine remained at 92.4%, and the COD removal rate reached 87.6%. [Insert description paragraph here.]

Claims

1. A method for preparing a graphite-based composite non-noble metal particle electrode, comprising the following specific steps: (1) Stir a surfactant solution of a certain concentration for 1 hour, then add waste graphite to the surfactant solution and sonicate for 20-30 minutes. After standing at room temperature for 12 hours, filter the residue. Wash the filter residue with deionized water 2-3 times and finally vacuum dry at room temperature to obtain modified graphite. (2) In-situ dropwise precipitation preparation of graphite-based composite non-precious metal catalyst powder, the steps of which are as follows: a. First, prepare a metal salt solution by combining two different non-precious metal salts in a certain molar ratio, and then prepare an alkaline solution. b. Add modified graphite to deionized water and sonicate for 4 hours. Add metal salt solution and alkaline solution dropwise to deionized water containing a certain mass of modified graphite. At the same time, stir with a stirrer at a speed of 200-250 r / min and control the pH value to 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 2-3 times and dry it in a 60°C oven for 24 hours. Then grind it into powder and sieve it 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 mixed evenly in a certain proportion. The mixed powder is added to a disc granulator in batches for granulation and sieving to obtain uniform spherical particles. The prepared spherical particles are then placed in a curing box for curing to obtain the graphite-based composite non-precious metal particle electrode.

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

3. The method for preparing a graphite-based composite non-noble metal particle electrode according to claim 1, characterized in that, In step (2), the non-precious metal salts are CuCl2·2H2O, MnCl2·4H2O, ZnCl2, AlCl3·6H2O, and FeCl3·6H2O.

4. The method for preparing a graphite-based composite non-noble metal particle electrode according to claim 1, characterized in that, In step (2), the two different non-noble metal salt combinations are FeCl3·6H2O and CuCl2·2H2O, FeCl3·6H2O and MnCl2·4H2O, FeCl3·6H2O and ZnCl2, AlCl3·6H2O and CuCl2·2H2O, AlCl3·6H2O and MnCl2·4H2O, or AlCl3·6H2O and ZnCl2.

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

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

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