Activated carbon-based particle electrode and preparation method and application thereof

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly discloses an activated carbon-based particle electrode as well as a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: adding activated carbon into a mixed solution of strong acid and hydrogen peroxide for dipping; adding the pretreated activated carbon into a mixed metal ion aqueous solution for soaking; adding the soaked activated carbon into an alkaline solution, and reacting at the pressure of 0.8-4 MPa and the temperature of 160-250 DEG C; and heating the reacted activated carbon to 60-180 DEG C, preserving heat, and calcining at 200-400 DEG C to obtain the activated carbon-based particle electrode. According to the activated carbon-based particle electrode prepared by the method, the problem of low removal rate of organic matters in the existing high-COD-concentration wastewater can be solved, the cycle service life of the activated carbon-based particle electrode can be remarkably prolonged, and a new thought is provided for preparation of the activated carbon-based particle electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly relates to an activated carbon-based granular electrode, a preparation method thereof, and an application thereof. Background Art

[0002] Industrial wastewater usually contains toxic, harmful, and high-concentration organic compounds, and its chemical oxygen demand (COD) often seriously exceeds the standard. If directly discharged into the environment, it will cause serious harm and threat to the ecological environment and human health. Traditional wastewater treatment methods, such as physicochemical methods and biological methods, are often difficult to efficiently treat organic matter, and there are risks of unstable treatment effects and secondary pollution. Advanced oxidation technologies (AOPs) are oxidation technologies with strong oxidation capabilities, having the advantages of rapid, thorough, efficient reactions, and less pollution.

[0003] Commonly used advanced oxidation technologies are mainly divided into ozone oxidation, electrochemical oxidation, Fenton oxidation, persulfate oxidation, etc. Among them, electrochemical technology, as a green and environmentally friendly technology for wastewater treatment, has experienced a relatively long development time. It can completely convert organic matter into harmless inorganic substances, having the advantages of wide applicability, simple and flexible operation, and less secondary pollution. Traditional electrochemical wastewater treatment technologies cannot be applied industrially on a large scale due to factors such as high power consumption and poor electrode stability. Therefore, based on the development and extension of two-dimensional electrochemical technology, three-dimensional electrochemical technology has emerged. The core of three-dimensional electrochemical technology is granular electrodes. In a traditional electrochemical reactor, conductive particles are filled between the cathode and the anode, just like a third electrode. By adding granular electrodes, the surface area of the electrochemical reaction is increased, the electrical efficiency is improved, the treatment effect is improved, and the treatment cost is reduced. However, when the COD concentration in the wastewater is too high, a passivation layer is easily formed on the surface of the granular electrode due to the adsorption and accumulation of organic matter. At the same time, high-concentration pollutants will also cause a sharp drop in the mass transfer efficiency, and the active sites of the granular electrode will be quickly covered, ultimately reducing the removal rate of organic matter. Therefore, it is of great significance to study a granular electrode for efficiently removing organic matter from wastewater with a high COD concentration. Summary of the Invention

[0004] Aiming at the problem of low organic matter removal rate when the existing granular electrode treats wastewater with high COD concentration, the present invention provides an activated carbon-based granular electrode, a preparation method thereof and an application. The preparation method of the activated carbon-based granular electrode provided by the present invention is as follows: First, the pretreated activated carbon is soaked in an aqueous solution of mixed metal ions, and then the soaked activated carbon is reacted in an alkaline solution under specific temperature and pressure conditions, and finally low-temperature calcination is carried out. This preparation method not only tightly combines the activated carbon and the metal active components in the activated carbon-based granular electrode, but also prepares a nano-scale activated carbon-based granular electrode with a microporous structure on the surface. This method significantly improves the catalytic activity and cyclic service life of the activated carbon-based granular electrode, and provides a new idea for the preparation of the activated carbon-based granular electrode.

[0005] To solve the above technical problems, the technical solution provided by the present invention is as follows: The first aspect of the present invention provides a preparation method of an activated carbon-based granular electrode, comprising the following steps: S1. Add activated carbon into a mixed solution of strong acid and hydrogen peroxide, impregnate to obtain pretreated activated carbon; S2. Add the pretreated activated carbon into an aqueous solution of mixed metal ions for soaking to obtain first-treated activated carbon; the aqueous solution of mixed metal ions is a mixed solution of soluble silver salt, soluble potassium salt, soluble copper salt, soluble cobalt salt, soluble nickel salt and soluble cerium salt; S3. Add the first-treated activated carbon into an alkaline solution, and then react at 0.8 MPa to 4 MPa and 160 °C to 250 °C to obtain second-treated activated carbon; S4. Heat the second-treated activated carbon to 60 °C to 180 °C, keep warm, and then calcine at 200 °C to 400 °C to obtain an activated carbon-based granular electrode.

[0006] At present, the preparation of activated carbon-based granular electrodes mainly uses the calcination method, but this method has three significant defects: First, the particle electrodes prepared by high-temperature calcination have uneven sizes and a small specific surface area; Second, the electrode reaction activity is low, and the active components are easily detached during the cyclic use process, resulting in the dissolution of metal particles; Finally, the electrodes prepared by this method have poor treatment efficiency for wastewater with high COD concentration. These problems will not only cause secondary pollution, but also significantly reduce the removal rate of organic matter in the wastewater. Therefore, it is of great significance to develop a new type of granular electrode that can efficiently treat high-COD wastewater and still maintain excellent organic matter removal performance after cyclic use.

[0007] Compared with the prior art, for the activated carbon-based particle electrode provided by the present invention, in S1, pickling the activated carbon with a mixed solution of strong acid and hydrogen peroxide can remove metal oxides such as iron, calcium, and magnesium in the activated carbon, reduce the dissolution of ineffective metal elements during use, thereby avoiding the pollution of the electrolytic cell and the occurrence of other side reactions; pickling can also dissolve ash such as soluble silicates and sulfates on the surface of the activated carbon, improve the purity and conductivity of the activated carbon as a carbon skeleton, and further improve the removal rate of organic matter in high-COD-concentration wastewater by the particle electrode and the cycle service life of the activated carbon-based particle electrode; in addition, pickling can also clean the surface of the activated carbon, which is beneficial to improving the subsequent loading of metal ions such as silver, potassium, copper, cobalt, nickel, and cerium.

[0008] In S2, soaking the pickled activated carbon in an aqueous solution of metal ions can effectively adsorb metal ions. Among them, silver and cerium can promote the decomposition of water on the surface of the particle electrode to generate hydroxyl radicals, accelerating the electrochemical oxidation and decomposition of refractory organic matter; copper, cobalt, and nickel can enhance the electron transfer efficiency, reduce the activation energy of the oxidation reaction of organic matter, and improve the removal rate of organic matter; in addition, copper, cobalt, and nickel can also further improve the removal rate of organic matter in high-COD-concentration wastewater by the activated carbon-based particle electrode by adsorbing organic matter, and extend the cycle service life of the activated carbon-based particle electrode; potassium can adjust the charge distribution on the surface of the activated carbon, thereby improving the adsorption capacity of the activated carbon-based particle electrode for organic matter, and further improving the removal rate of organic matter in high-COD-concentration wastewater by the activated carbon-based particle electrode.

[0009] In S3, under specific temperature and pressure conditions, silver ions, potassium ions, copper ions, cobalt ions, nickel ions, and cerium ions adsorbed in the activated carbon are anchored in the activated carbon to form stable chemical bonds, avoiding the shedding of active metal components during use, and thus extending the cyclic service life of the activated-carbon-based particle electrode; moreover, the specific temperature and pressure conditions can also control the morphology of metal ions, enabling them to be evenly dispersed in the activated carbon, thereby enhancing the chemical activity of the particle electrode, and further increasing the removal rate of organic matter in wastewater and the cyclic service life of the particle electrode; the solubility of the activated carbon in an alkaline solution is significantly increased. Under specific temperature and pressure conditions, a large number of tiny crystal nuclei are simultaneously generated in the dissolved activated carbon, and the specific reaction conditions can also inhibit the excessive growth of crystal grains, thus forming nano-scale activated-carbon particles; under specific pressure, temperature, and alkaline liquid-phase environment conditions, it can also promote the partial carbonization of organic matter in the activated-carbon particles and the in-situ etching of metal oxides. The combined effect of the two makes the surface of the activated-carbon-based particle electrode have a rich microporous structure, increasing the adsorption sites for organic matter in wastewater on the activated-carbon-based particle electrode, and further increasing the removal rate of organic matter in wastewater with a high COD concentration by the activated-carbon-based particle electrode and extending the cyclic service life of the activated-carbon-based particle electrode; at the same time, the microporous structure on the surface of the activated-carbon-based particle electrode prevents the diffusion of organic matter into the interior of the particle electrode, promoting the diffusion of organic matter in wastewater on the surface of the particle electrode through the concentration gradient, thereby increasing the removal rate of organic matter by the activated-carbon-based particle electrode and extending the cyclic service life of the activated-carbon-based particle electrode; in addition, under specific temperature and pressure conditions, when activated-carbon particles are added to an alkaline solution, a solvation layer and an electric double layer are formed on their surface. These two structures can effectively reduce the van der Waals force between activated-carbon particles, avoiding the phenomenon of sintering and agglomeration of activated-carbon particles due to high-temperature calcination. The specific liquid-phase environment can also ensure that the functional groups in the activated-carbon particles are not damaged, ensuring the chemical activity of the activated carbon, and further increasing the cyclic service life of the activated-carbon-based particle electrode.

[0010] In S4, the present invention keeps the second-treated activated carbon at a specific temperature, which can avoid the phenomenon of damage to the structure of the activated-carbon-based particle electrode caused by direct calcination. Further calcining the activated carbon under specific temperature conditions can enhance the stability of the activated-carbon-based particle electrode, avoid the shedding of active components in the activated-carbon-based particle electrode during use, and significantly increase the cyclic service life of the activated-carbon-based particle electrode and the removal rate of organic matter in wastewater.

[0011] It should be further noted that in S1, the activated carbon is coconut shell activated carbon, and it needs to be washed 2 - 3 times with water before use.

[0012] Preferably, in S1, the particle size of the activated carbon is 1 mm - 4 mm.

[0013] By selecting activated carbon with a specific particle size, it is beneficial to further improve the solubility of activated carbon in alkaline solution, thereby enhancing the removal rate of organic matter in wastewater by the activated carbon-based particle electrode.

[0014] It should be further noted that the activated carbon is activated carbon particles.

[0015] Preferably, in S1, the strong acid is concentrated sulfuric acid solution.

[0016] Preferably, in S1, the mass ratio of the activated carbon, strong acid and hydrogen peroxide is 1:(0.01~0.05):(0.01~0.05).

[0017] By limiting the ratio of the activated carbon, strong acid and hydrogen peroxide, the pickling effect on the activated carbon can be improved, thereby enhancing the removal rate of organic matter in wastewater with a high COD concentration by the prepared activated carbon-based particle electrode, as well as the cycle service life of the activated carbon-based particle electrode.

[0018] Preferably, in S1, the impregnation time is 2h~4h.

[0019] Preferably, in S2, the soluble silver salt is silver nitrate.

[0020] Preferably, in S2, the soluble potassium salt is potassium permanganate.

[0021] Preferably, in S2, the soluble copper salt is copper sulfate.

[0022] Preferably, in S2, the soluble cobalt salt is cobalt sulfate.

[0023] Preferably, in S2, the soluble nickel salt is nickel sulfate.

[0024] Preferably, in S2, the soluble cerium salt is cerium sulfate.

[0025] Preferably, in S2, the mass ratio of the soluble silver salt, soluble potassium salt, soluble copper salt, soluble cobalt salt, soluble nickel salt and soluble cerium salt is (0.9~1):(0.9~1):(2.8~3):(2.8~3):(2.8~3):(2.8~3).

[0026] The present invention defines the proportional relationship of the soluble silver salt, soluble potassium salt, soluble copper salt, soluble cobalt salt, soluble nickel salt and soluble cerium salt, which is beneficial to the synergistic effect among several elements, further improving the removal rate of organic matter in wastewater with a high COD concentration by the activated carbon-based particle electrode, and also increasing the cycle service life of the activated carbon-based particle electrode.

[0027] Preferably, in S2, the concentration of the mixed metal ion aqueous solution is 5g / L~10g / L.

[0028] The preferred concentration is more conducive to the solute being loaded onto the activated carbon particles.

[0029] Preferably, in S2, the mass ratio of the pretreated activated carbon to the solute in the aqueous solution of mixed metal ions is 1:(0.01 - 0.02).

[0030] The present invention defines the mass ratio of the pretreated activated carbon to the solute. The preferred ratio is conducive to the synergistic effect of the metal active components in the solute and the activated carbon, realizing the efficient degradation of organic matter in wastewater with a high COD concentration.

[0031] Preferably, in S2, the soaking time is 6h - 48h.

[0032] Preferably, in S3, the alkaline solution is an aqueous sodium hydroxide solution.

[0033] More preferably, the concentration of the aqueous sodium hydroxide solution is 40g / L - 200g / L.

[0034] Preferably, in S3, the mass ratio of the first treated activated carbon to the alkaline solution is 1:(2 - 5).

[0035] Preferably, in S3, the reaction time is 8h - 16h.

[0036] It should be further noted that in S3, stirring treatment is also required during the reaction, and the rotation speed is 50r / min - 400r / min.

[0037] Preferably, after the reaction in S3, cooling and water washing treatments are also required.

[0038] More preferably, the cooling condition is: cooling at a rate of 1℃ / min - 5℃ / min to 40℃ - 80℃.

[0039] Preferably, the water washing condition is: washing 2 - 3 times.

[0040] Preferably, in S4, the heat preservation time is 8h - 16h.

[0041] The preferred heat preservation time can ensure that the structure of the second treated activated carbon is not damaged.

[0042] Preferably, in S4, the calcination time is 4h - 8h.

[0043] The preferred calcination time can ensure the stability of the activated carbon-based particle electrode, firmly combine the metal active components and the activated carbon particles, and avoid the shedding of the active components in the activated carbon-based particle electrode during use.

[0044] The second aspect of the present invention provides an activated carbon-based granular electrode, which is prepared by the preparation method of the above-mentioned activated carbon-based granular electrode.

[0045] The third aspect of the present invention provides the application of the above-mentioned activated carbon-based granular electrode in wastewater treatment.

[0046] The activated carbon-based granular electrode provided by the present invention can effectively treat wastewater with different COD concentrations. Especially for the treatment of wastewater with high COD concentration, the organic matter removal rate can reach 93.4%. Moreover, the preparation process of the activated carbon-based granular electrode provided by the present invention has low energy consumption and has the characteristics of environmental protection. Description of the Drawings

[0047] Figure 1 It is the SEM image of the activated carbon-based granular electrode prepared in Example 1 of the present invention; Figure 2 It is the SEM image of the activated carbon-based granular electrode prepared in Example 1 of the present invention; Figure 3 It is the SEM image of the activated carbon-based granular electrode prepared in Example 1 of the present invention. Detailed Embodiments

[0048] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and the drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] Example 1 This example provides a preparation method of an activated carbon-based granular electrode, which includes the following steps: S1. Wash the activated carbon particles with a particle size range of 1 mm to 4 mm three times with clear water, and then add the washed activated carbon particles to a mixed solution of concentrated sulfuric acid solution and hydrogen peroxide and impregnate for 2 h to obtain pretreated activated carbon; wherein, the mass ratio of the activated carbon particles, concentrated sulfuric acid solution and hydrogen peroxide is 1:0.05:0.05; S2. Add the pretreated activated carbon to an aqueous metal ion solution with silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate as solutes and soak for 6 h to obtain the first treated activated carbon; wherein, the ratio of silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate is 1:1:3:3:3:3, the concentration of the solute in the aqueous metal ion solution is 5 g / L, and the mass ratio of the pickled activated carbon and the solute is 1:0.01; S3. Add the first treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 40 g / L, then react at 4.0 MPa and 250 °C for 16 h. Stir at a rate of 50 r / min during the reaction. After the reaction, cool down to 40 °C at a rate of 1 °C / min, and wash twice with water to obtain the second treated activated carbon. Among them, the mass ratio of the first treated activated carbon to the aqueous sodium hydroxide solution is 1:2; S4. Keep the second treated activated carbon at 180 °C for 8 h, and then calcine it at 400 °C for 4 h to obtain the activated carbon-based particle electrode as shown in Figures 1-3 Figure.

[0050] Example 2 This example provides a method for preparing an activated carbon-based particle electrode, which includes the following steps: S1. Wash the activated carbon particles with a particle size range of 1 mm to 4 mm twice with clean water, and then add the washed activated carbon particles to a mixed solution of concentrated sulfuric acid solution and hydrogen peroxide for impregnation for 4 h to obtain the pretreated activated carbon. Among them, the mass ratio of the activated carbon particles, concentrated sulfuric acid solution and hydrogen peroxide is 1:0.01:0.01; S2. Add the pretreated activated carbon to an aqueous metal ion solution with silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate as solutes and soak for 48 h to obtain the first treated activated carbon. Among them, the ratio of silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate is 0.9:0.9:2.8:2.8:2.8:2.8, the concentration of the solute in the aqueous metal ion solution is 10 g / L, and the mass ratio of the pickled activated carbon to the solute is 1:0.02; S3. Add the first treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 200 g / L, then react at 0.8 MPa and 160 °C for 8 h. Stir at a rate of 400 r / min during the reaction. After the reaction, cool down to 80 °C at a rate of 5 °C / min, and wash three times with water to obtain the second treated activated carbon. Among them, the mass ratio of the first treated activated carbon to the aqueous sodium hydroxide solution is 1:5; S4. Keep the second treated activated carbon at 60 °C for 16 h, and then calcine it at 200 °C for 8 h to obtain the activated carbon-based particle electrode.

[0051] Example 3 This example provides a method for preparing an activated carbon-based particle electrode, which includes the following steps: S1. Wash the activated carbon particles with a particle size range of 1 mm to 4 mm twice with clean water, and then add the washed activated carbon particles to a mixed solution of concentrated sulfuric acid solution and hydrogen peroxide for impregnation for 3 h to obtain the pretreated activated carbon. Among them, the mass ratio of the activated carbon particles, concentrated sulfuric acid solution and hydrogen peroxide is 1:0.03:0.02; S2. Add the pretreated activated carbon to an aqueous metal ion solution with silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate, and cerium sulfate as solutes and soak for 20 h to obtain the first-treated activated carbon. Among them, the ratio of silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate, and cerium sulfate is 1:1:3:3:3:3, the concentration of the solute in the aqueous metal ion solution is 8 g / L, and the mass ratio of the pickled activated carbon to the solute is 1:0.02; S3. Add the first-treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 100 g / L, then react at 1.55 MPa and 200 °C for 10 h, stir at a rate of 200 r / min during the reaction, cool to 60 °C at a rate of 5 °C / min after the reaction, and wash with water 3 times to obtain the second-treated activated carbon. Among them, the mass ratio of the first-treated activated carbon to the aqueous sodium hydroxide solution is 1:4; S4. Keep the second-treated activated carbon at 100 °C for 10 h, and then calcine at 300 °C for 6 h to obtain the activated carbon-based particle electrode.

[0052] Comparative Example 1 This comparative example provides a method for preparing an activated carbon-based particle electrode. Compared with Example 1, the difference is that in S2, the addition of cerium sulfate is omitted; Other components, preparation methods are the same as those in Example 1.

[0053] Comparative Example 2 This comparative example provides a method for preparing an activated carbon-based particle electrode. Compared with Example 1, the difference is that in S3, add the first-treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 40 g / L, then react at 250 °C for 16 h, stir at a rate of 50 r / min during the reaction, cool to 40 °C at a rate of 1 °C / min after the reaction, and wash with water 2 times to obtain the second-treated activated carbon. Among them, the mass ratio of the first-treated activated carbon to the aqueous sodium hydroxide solution is 1:2; Other components, preparation methods are the same as those in Example 1.

[0054] Comparative Example 3 This comparative example provides a method for preparing an activated carbon-based particle electrode. Compared with Example 1, the difference is that in S3, add the first-treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 40 g / L, then react at 0.2 MPa and 250 °C for 16 h, stir at a rate of 50 r / min during the reaction, cool to 40 °C at a rate of 1 °C / min after the reaction, and wash with water 2 times to obtain the second-treated activated carbon. Among them, the mass ratio of the first-treated activated carbon to the aqueous sodium hydroxide solution is 1:2; Other components, preparation methods are the same as those in Example 1.

[0055] Comparative Example 4 This comparative example provides a method for preparing an activated carbon-based granular electrode. Compared with Example 1, the difference lies in: S3. Add the first treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 40 g / L, and then react at 5 MPa and 250 °C for 16 h. During the reaction process, stir at a rate of 50 r / min. After the reaction, cool down to 40 °C at a rate of 1 °C / min, and wash with water twice to obtain the second treated activated carbon; wherein, the mass ratio of the first treated activated carbon to the aqueous sodium hydroxide solution is 1:2; Other components, as well as the preparation method, are the same as those in Example 1.

[0056] Comparative Example 5 This comparative example provides a method for preparing an activated carbon-based granular electrode. Compared with Example 1, the difference lies in: S3. Add the first treated activated carbon to an aqueous sodium hydroxide solution with a concentration of 40 g / L, and then react at 4.0 MPa and 300 °C for 16 h. During the reaction process, stir at a rate of 50 r / min. After the reaction, cool down to 40 °C at a rate of 1 °C / min, and wash with water twice to obtain the second treated activated carbon; wherein, the mass ratio of the first treated activated carbon to the aqueous sodium hydroxide solution is 1:2; Other components, as well as the preparation method, are the same as those in Example 1.

[0057] Comparative Example 6 This comparative example provides a method for preparing an activated carbon-based granular electrode. Compared with Example 1, the difference lies in: S4. Keep the second treated activated carbon at 180 °C for 8 h, and then calcine at 500 °C for 4 h to obtain the activated carbon-based granular electrode; Other components, as well as the preparation method, are the same as those in Example 1.

[0058] Comparative Example 7 This comparative example provides a method for preparing an activated carbon-based granular electrode. Compared with Example 1, the difference lies in: S4. Calcinate the second treated activated carbon at 400 °C for 4 h to obtain the activated carbon-based granular electrode; Other components, as well as the preparation method, are the same as those in Example 1.

[0059] Comparative Example 8 This comparative example provides a method for preparing an activated carbon-based granular electrode. Compared with Example 1, the difference lies in: Omit step S3, and directly perform the heat preservation and calcination process in S4 on the first treated activated carbon to obtain the activated carbon-based granular electrode; Other components, as well as the preparation method, are the same as those in Example 1.

[0060] Application Example 1: Water sample to be measured: Wastewater with a COD concentration of 20000 mg / L; Take equal amounts of 1.5 L of the water sample to be tested and stir slowly under the same conditions. Adjust the pH value to 3 - 5. Add the activated carbon-based particle electrode catalysts prepared in Examples 1 - 3 and Comparative Examples 1 - 8 to the electro-chemical reaction tank, with the filling amount being 40% - 60% of the plate height. Control the voltage between 3 - 20 V. During the reaction process, aerate to fully mix the wastewater with the activated carbon-based particle electrode. The residence time is 2 h. After the reaction ends, turn off the power supply, cut off the air pump, and take samples for testing. Among them, for the detection of COD equivalent, refer to the standard HJ / T 399 - 2007; COD removal rate (%) = (COD influent - COD effluent) / COD influent × 100%; Among them, COD influent represents the COD concentration of the wastewater before treatment, while COD effluent represents the COD concentration of the wastewater after treatment; Specific detection indexes and detection results of Application Example 1 are shown in Table 1; Application Example 2: Water sample to be tested: wastewater with a COD concentration of 4000 mg / L; Take equal amounts of 1 L of the water sample to be tested and stir slowly under the same conditions. Adjust the pH value to 3 - 5. Add the particle electrode catalysts prepared from the adjusted Examples 1 - 3 and Comparative Examples 1 - 8 to the high-temperature and high-pressure reactor. Heat up to 150°C - 230°C and stir at a rate of 150 r / min for 2 h - 4 h. After the reaction ends, cool down and take samples for testing; among them, for the detection of COD equivalent, refer to the standard HJ / T 399 - 2007; COD removal rate (%) = (COD influent - COD effluent) / COD influent × 100%; Among them, COD influent represents the COD concentration of the wastewater before treatment, while COD effluent represents the COD concentration of the wastewater after treatment; Specific detection indexes and detection results of Application Example 2 are shown in Table 2: Table 1 Test Results

[0061] Table 2 Test Results

[0062] As can be seen from Table 1 and Table 2, when the activated carbon-based particle electrode prepared in the embodiment of the present invention is applied to wastewater treatment, when the method provided in Application Example 2 is used to treat wastewater, the COD removal rate after running for 2 h can reach 93.4%, and the COD removal rate after running for 360 h can still reach 89.6%; when the method provided in Application Example 1 is used to treat wastewater, the COD removal rate after running for 2 h can reach 72.6%, and the COD removal rate after running for 360 h can still reach 70.4%; this also proves that the activated carbon-based particle electrode provided by the present invention can significantly improve the COD removal rate when used in the treatment of high-COD-concentration wastewater, and moreover, the activated carbon-based particle electrode provided by the present invention has excellent cyclic service life, and after continuously running for 360 h, the COD removal rate does not decrease significantly. Compared with the embodiment of the present invention, in the comparative example, due to the change of preparation conditions, the pore size structure of the particle electrode, the morphology of the active metal component, and the bonding ability between the active metal component and the activated carbon will all change. Through experiments, it is proved that for the particle electrode provided in the comparative example of the present invention in wastewater treatment, whether the method provided in Application Example 1 or the method provided in Application Example 2 is adopted, the COD removal rate shows an obvious decreasing trend; and when the particle electrode provided in the comparative example is continuously run for 360 h in wastewater treatment, the COD removal rate also shows an obvious decreasing trend compared with the COD removal rate after running for 2 h.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of an activated carbon-based granular electrode, characterized in that, It includes the following steps: S1. Add activated carbon into a mixed solution of strong acid and hydrogen peroxide, and impregnate to obtain pretreated activated carbon; S2. Add the pretreated activated carbon into an aqueous solution of mixed metal ions for soaking to obtain first-treated activated carbon; the aqueous solution of mixed metal ions is a mixed solution of soluble silver salt, soluble potassium salt, soluble copper salt, soluble cobalt salt, soluble nickel salt and soluble cerium salt; S3. Add the first-treated activated carbon into an alkaline solution, and react at 0.8 MPa to 4 MPa and 160 °C to 250 °C to obtain second-treated activated carbon; S4. Heat the second-treated activated carbon to 60 °C to 180 °C, keep it warm, and then calcine at 200 °C to 400 °C to obtain an activated-carbon-based particle electrode.

2. The preparation method of the activated carbon-based particulate electrode according to claim 1, characterized in that, In S1, the particle size of the activated carbon is 1 mm to 4 mm; and / or In S1, the strong acid is concentrated sulfuric acid solution; and / or In S1, the mass ratio of the activated carbon, strong acid and hydrogen peroxide is 1:(0.01 - 0.05):(0.01 - 0.05); and / or In S1, the impregnation time is 2 h to 4 h.

3. The preparation method of the activated carbon-based particle electrode according to claim 1, characterized in that, In S2, the soluble silver salt is silver nitrate; and / or In S2, the soluble potassium salt is potassium permanganate; and / or In S2, the soluble copper salt is copper sulfate; and / or In S2, the soluble cobalt salt is cobalt sulfate; and / or In S2, the soluble nickel salt is nickel sulfate; and / or In S2, the soluble cerium salt is cerium sulfate.

4. The preparation method of the activated carbon-based granular electrode according to claim 1 or 2, characterized in that, In S2, the mass ratio of the soluble silver salt, soluble potassium salt, soluble copper salt, soluble cobalt salt, soluble nickel salt and soluble cerium salt is (0.9 - 1):(0.9 - 1):(2.8 - 3):(2.8 - 3):(2.8 - 3):(2.8 - 3).

5. The preparation method of the activated carbon-based particulate electrode according to claim 1, characterized in that, In S2, the concentration of the aqueous solution of mixed metal ions is 5 g / L to 10 g / L; and / or In S2, the mass ratio of the pretreated activated carbon to the solute in the aqueous solution of mixed metal ions is 1:(0.01 - 0.02); and / or In S2, the soaking time is 6 h to 48 h.

6. The preparation method of the activated carbon-based granular electrode according to claim 1, wherein In S3, the alkaline solution is an aqueous sodium hydroxide solution.

7. The preparation method of the activated carbon-based granular electrode according to claim 6, wherein, The concentration of the aqueous sodium hydroxide solution is 40 g / L to 200 g / L.

8. The preparation method of the activated carbon-based particulate electrode according to claim 1, wherein, In S3, the mass ratio of the first-treated activated carbon to the alkaline solution is 1:(2 - 5); and / or In S3, the reaction time is 8 h to 16 h; and / or In S4, the heat preservation time is 8 h to 16 h; and / or In S4, the calcination time is 4 h to 8 h.

9. An activated carbon-based granular electrode, characterized in that, Prepared by the preparation method of the activated-carbon-based particle electrode according to any one of claims 1 to 8.

10. Application of the activated-carbon-based particle electrode according to claim 9 in wastewater treatment.

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