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

Abstract

The application belongs to the technical field of wastewater treatment, and particularly discloses an activated carbon-based granular electrode, a preparation method and application thereof. The preparation method comprises the following steps: impregnating activated carbon into a mixed solution of strong acid and hydrogen peroxide; soaking the pretreated activated carbon into a mixed metal ion aqueous solution; adding the soaked activated carbon into an alkaline solution, and reacting at 0.8MPa-4MPa and 160 DEG C-250 DEG C; heating the reacted activated carbon to 60 DEG C-180 DEG C, keeping warm, and calcining at 200 DEG C-400 DEG C to obtain the activated carbon-based granular electrode. The activated carbon-based granular electrode prepared by the application can not only solve the problem of low removal rate of organic matter in the existing high COD concentration wastewater, but also significantly improve the cycle service life of the activated carbon-based granular electrode, and provides a new idea for the preparation of the activated carbon-based granular electrode.

Description

TECHNICAL FIELD

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

[0002] Industrial wastewater usually contains toxic, harmful and high-concentration organic compounds, and the chemical oxygen demand (COD) often seriously exceeds the standard, which will cause serious harm and threat to the ecological environment and human health if directly discharged into the environment. Traditional wastewater treatment methods, such as physical and chemical methods and biological methods, often have difficulty in efficiently treating organic matter, and there is a risk of unstable treatment effect and secondary pollution. Advanced oxidation technology (AOPs) is an oxidation technology with strong oxidation ability, which has the advantages of rapid reaction, thoroughness, high efficiency and small pollution.

[0003] Commonly used advanced oxidation technologies mainly include ozone oxidation, electrochemical oxidation, Fenton oxidation, persulfate oxidation, etc. Among them, electrochemical technology as a green and environmentally friendly technology for wastewater treatment has undergone a long development time, which can completely convert organic matter into harmless inorganic matter, has the advantages of wide applicability, simple and flexible operation, and small secondary pollution. The traditional electrochemical wastewater treatment technology cannot be applied on a large scale due to the influence of high power consumption, poor electrode stability and other factors. Therefore, based on the development of two-dimensional electrochemical technology, three-dimensional electrochemical technology is extended, and the core of three-dimensional electrochemical technology is granular electrode. In the traditional electrochemical reactor, conductive particles are filled between the cathode and the anode, like a third electrode. By adding granular electrodes, the surface area of 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 wastewater is too high, the granular electrode surface is easy to form a passivation layer due to the adsorption and accumulation of organic matter, and high-concentration pollutants will also cause a sharp drop in mass transfer efficiency, and the active sites of the granular electrode are quickly covered, ultimately reducing the removal rate of organic matter. Therefore, it is of great significance to study a kind of granular electrode to efficiently remove organic matter in high-COD-concentration wastewater. SUMMARY

[0004] In view of the problem that the existing particle electrode has low organic matter removal rate when treating wastewater with high COD concentration, the application provides an activated carbon-based particle electrode, a preparation method and application thereof. The preparation method of the activated carbon-based particle electrode provided by the application comprises the following steps: firstly, soaking pretreated activated carbon in a mixed metal ion aqueous solution; then, reacting the soaked activated carbon in an alkaline solution under specific temperature and pressure conditions; and finally, low-temperature calcining. The preparation method not only enables the activated carbon and metal active components in the activated carbon-based particle electrode to be closely combined, but also enables the activated carbon-based particle electrode to have a nano-scale activated carbon electrode with microporous structure on the surface. The method significantly improves the catalytic activity and service life of the activated carbon-based particle electrode in circulation, and provides a new idea for the preparation of the activated carbon-based particle electrode.

[0005] To solve the above technical problems, the technical scheme provided by the application is:

[0006] The first aspect of the application provides a preparation method of an activated carbon-based particle electrode, comprising the following steps:

[0007] S1, adding activated carbon into a mixed solution of strong acid and hydrogen peroxide for impregnation to obtain pretreated activated carbon;

[0008] S2, soaking the pretreated activated carbon in a mixed metal ion aqueous solution to obtain first treated activated carbon; the mixed metal ion aqueous solution is a mixed solution of soluble silver salt, soluble potassium salt, soluble copper salt, soluble cobalt salt, soluble nickel salt and soluble cerium salt;

[0009] S3, adding the first treated activated carbon into an alkaline solution, and then reacting under 0.8 MPa to 4 MPa and 160 DEG C to 250 DEG C to obtain second treated activated carbon;

[0010] S4, heating the second treated activated carbon to 60 DEG C to 180 DEG C, keeping warm, and then calcining under 200 DEG C to 400 DEG C to obtain the activated carbon-based particle electrode.

[0011] At present, the preparation of the activated carbon-based particle electrode mainly adopts a calcining method, but the method has three significant defects: firstly, the particle electrode prepared by high-temperature calcination has uneven size and small specific surface area; secondly, the electrode has low reaction activity, and the active components are easy to fall off during the circulation, leading to metal particle dissolution; finally, the electrode prepared by the method has poor treatment efficiency for wastewater with high COD concentration. These problems not only cause secondary pollution, but also significantly reduce the removal rate of organic matter in wastewater. Therefore, it is of great significance to develop a new type of particle electrode which can efficiently treat high-COD wastewater and still maintain excellent organic matter removal performance after circulation.

[0012] Compared with the prior art, the active carbon-based particle electrode provided by the application can remove metal oxides such as iron, calcium and magnesium in the active carbon by acid washing the active carbon with a mixed solution of strong acid and hydrogen peroxide in S1, reduce the dissolution of invalid metal elements in use, and thus avoid pollution of the electrolytic cell and other side reactions; the acid washing can also dissolve ash such as soluble silicate and sulfate on the surface of the active carbon, improve the purity and conductivity of the active carbon as a carbon skeleton, and thus improve the removal rate of the particle electrode on organic matters in high-COD-concentration wastewater and the recycling service life of the active carbon-based particle electrode; in addition, the acid washing can clean the surface of the active carbon, which is conducive to improving the subsequent loading of metal ions such as silver, potassium, copper, cobalt, nickel and cerium.

[0013] In S2, the active carbon after acid washing is soaked in a metal ion aqueous solution, which can effectively adsorb metal ions, and silver and cerium can promote the decomposition of water on the surface of the particle electrode to generate hydroxyl radicals, accelerate the electrochemical oxidation 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 further improve the removal rate of the active carbon-based particle electrode on organic matter in high-COD-concentration wastewater by adsorbing organic matter, and prolong the recycling service life of the active carbon-based particle electrode; potassium can adjust the charge distribution on the surface of the active carbon, thereby improving the adsorption capacity of the active carbon-based particle electrode on organic matter, and further improving the removal rate of the active carbon-based particle electrode on organic matter in high-COD-concentration wastewater.

[0014] In S3, under specific temperature and pressure conditions, the 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, thereby avoiding the shedding of the active metal components during use and prolonging the cycle service life of the activated carbon-based granular electrode; and the specific temperature and pressure conditions can also control the morphology of the metal ions, so that the metal ions are uniformly dispersed in the activated carbon, thereby improving the chemical activity of the granular electrode and further improving the removal rate of the granular electrode for organic matter in wastewater and the cycle service life; the solubility of the activated carbon in the alkaline solution is significantly improved, a large number of tiny crystal nuclei are generated in the dissolved activated carbon at the same time under specific temperature and pressure conditions, and the specific reaction conditions can also inhibit the excessive growth of the crystal grains, thereby forming nanoscale activated carbon particles; under the specific pressure, temperature and alkaline liquid phase environment conditions, the partial carbonization of the organic matter in the activated carbon particles and the in-situ etching of the metal oxides can also be promoted, and the two work together to make the surface of the activated carbon-based granular electrode have a rich microporous structure, increase the adsorption sites of the activated carbon-based granular electrode for organic matter in wastewater, and further improve the removal rate of the activated carbon-based granular electrode for organic matter in wastewater with high COD concentration and prolong the cycle service life of the activated carbon-based granular electrode; at the same time, the microporous structure of the surface of the activated carbon-based granular electrode avoids the diffusion of the organic matter into the interior of the granular electrode, promotes the diffusion of the organic matter in wastewater on the surface of the granular electrode through the concentration gradient, thereby improving the removal rate of the activated carbon-based granular electrode for the organic matter and prolonging the cycle service life of the activated carbon-based granular electrode; in addition, under specific temperature and pressure conditions, the activated carbon particles added into the alkaline solution will form a solvation layer and a charged double electric layer on the surface, the two structures can effectively reduce the van der Waals force between the activated carbon particles, avoid the sintering and agglomeration of the activated carbon particles due to high-temperature calcination, and the specific liquid phase environment can also ensure that the functional groups in the activated carbon particles are not damaged, ensure the chemical activity of the activated carbon, and further improve the cycle service life of the activated carbon-based granular electrode.

[0015] In S4, the second treated activated carbon is kept at a specific temperature, which can avoid the phenomenon that the structure of the activated carbon-based granular electrode is damaged due to direct calcination, and further calcination of the activated carbon under specific temperature conditions can enhance the stability of the activated carbon-based granular electrode, avoid the shedding of the active components in the activated carbon-based granular electrode during use, and significantly improve the cycle service life of the activated carbon-based granular electrode and the removal rate of the activated carbon-based granular electrode for organic matter in wastewater.

[0016] It should be further pointed out that in S1, the activated carbon is coconut shell activated carbon, which needs to be washed with water for 2-3 times before use.

[0017] Preferably, in S1, the particle size of the activated carbon is 1-4 mm.

[0018] By selecting the activated carbon of a specific particle size, the solubility of the activated carbon in the alkaline solution can be further improved, and thus the removal rate of the activated carbon-based particle electrode on the organic matter in the wastewater can be improved.

[0019] It should be further explained that the activated carbon is activated carbon particles.

[0020] Preferably, in S1, the strong acid is a concentrated sulfuric acid solution.

[0021] Preferably, in S1, the mass ratio of the activated carbon, the strong acid and the hydrogen peroxide is 1: (0.01-0.05): (0.01-0.05).

[0022] By limiting the ratio of the activated carbon, the strong acid and the hydrogen peroxide, the pickling effect on the activated carbon can be improved, and thus the removal rate of the prepared activated carbon-based particle electrode on the organic matter in the wastewater with high COD concentration and the cycle service life of the activated carbon-based particle electrode can be improved.

[0023] Preferably, in S1, the impregnation time is 2h-4h.

[0024] Preferably, in S2, the soluble silver salt is silver nitrate.

[0025] Preferably, in S2, the soluble potassium salt is potassium permanganate.

[0026] Preferably, in S2, the soluble copper salt is copper sulfate.

[0027] Preferably, in S2, the soluble cobalt salt is cobalt sulfate.

[0028] Preferably, in S2, the soluble nickel salt is nickel sulfate.

[0029] Preferably, in S2, the soluble cerium salt is cerium sulfate.

[0030] Preferably, in S2, the mass ratio of the soluble silver salt, the soluble potassium salt, the soluble copper salt, the soluble cobalt salt, the soluble nickel salt and the soluble cerium salt is (0.9-1): (0.9-1): (2.8-3): (2.8-3): (2.8-3): (2.8-3).

[0031] The present application limits the ratio of the soluble silver salt, the soluble potassium salt, the soluble copper salt, the soluble cobalt salt, the soluble nickel salt and the soluble cerium salt, which is beneficial to the synergistic effect between the elements, further improves the removal rate of the activated carbon-based particle electrode on the organic matter in the wastewater with high COD concentration, and also increases the cycle service life of the activated carbon-based particle electrode.

[0032] Preferably, in S2, the concentration of the mixed metal ion aqueous solution is 5g / L-10g / L.

[0033] The preferred concentration is more conducive to the loading of the solute on the activated carbon particles.

[0034] Preferably, in S2, the mass ratio of the pretreated activated carbon and the solute in the aqueous solution of mixed metal ions is 1: (0.01-0.02).

[0035] The present application limits the mass ratio of the pretreated activated carbon and the solute, and the preferred ratio is conducive to the synergistic effect of the metal active components in the solute and the activated carbon, thereby achieving efficient degradation of the organic matter in the wastewater with high COD concentration.

[0036] Preferably, in S2, the soaking time is 6-48 h.

[0037] Preferably, in S3, the alkaline solution is an aqueous sodium hydroxide solution.

[0038] Further preferably, the concentration of the aqueous sodium hydroxide solution is 40-200 g / L.

[0039] Preferably, in S3, the mass ratio of the first treated activated carbon and the alkaline solution is 1: (2-5).

[0040] Preferably, in S3, the reaction time is 8-16 h.

[0041] It should be further explained that, in S3, stirring treatment is also required during the reaction, and the rotation speed is 50-400 r / min.

[0042] Preferably, in S3, cooling and water washing treatment are also required after the reaction.

[0043] Further preferably, the cooling condition is to reduce the temperature to 40-80℃ at a rate of 1-5℃ / min.

[0044] Preferably, the water washing condition is to wash 2-3 times.

[0045] Preferably, in S4, the holding time is 8-16 h.

[0046] The preferred holding time can ensure that the structure of the second treated activated carbon is not damaged.

[0047] Preferably, in S4, the calcination time is 4-8 h.

[0048] The preferred calcination time can ensure the stability of the activated carbon-based particle electrode, so that the metal active components and the activated carbon particles are firmly combined, and the shedding of the active components in the activated carbon-based particle electrode during use is avoided.

[0049] The second aspect of the present application provides an activated carbon-based granular electrode prepared by the preparation method of the activated carbon-based granular electrode.

[0050] The third aspect of the present application provides an application of the activated carbon-based granular electrode in wastewater treatment.

[0051] The activated carbon-based granular electrode provided by the present application can effectively treat wastewater with different COD concentrations, especially high-COD-concentration wastewater, and the organic matter removal rate can reach 93.4%. The preparation process of the activated carbon-based granular electrode provided by the present application has low energy consumption and is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0052] Fig. 1 SEM image of the activated carbon-based granular electrode prepared in Example 1 of the present application;

[0053] Fig. 2 SEM image of the activated carbon-based granular electrode prepared in Example 1 of the present application;

[0054] Fig. 3 SEM image of the activated carbon-based granular electrode prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present application clearer, further detailed description will be given below in combination with examples and drawings. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application.

[0056] Example 1

[0057] The present embodiment provides a preparation method of an activated carbon-based granular electrode, comprising the following steps:

[0058] S1, washing activated carbon particles with a particle size range of 1mm-4mm with clean water for 3 times, then immersing the washed activated carbon particles in a mixed solution of concentrated sulfuric acid and hydrogen peroxide for 2h to obtain pretreated activated carbon; wherein the mass ratio of activated carbon particles, concentrated sulfuric acid solution and hydrogen peroxide is 1:0.05:0.05;

[0059] S2, immersing the pretreated activated carbon in a metal ion aqueous solution with silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate as solutes for 6h to obtain 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 solutes in the metal ion aqueous solution is 5g / L, and the mass ratio of pickling activated carbon and solutes is 1:0.01;

[0060] S3, the first processing activated carbon is added to a sodium hydroxide aqueous solution with a concentration of 40 g / L, and then reacted at 4.0 MPa and 250℃ for 16 h, with stirring at a speed of 50 r / min during the reaction, and then cooled to 40℃ at a rate of 1℃ / min after the reaction, and washed with water twice, to obtain second processing activated carbon; wherein the mass ratio of the first processing activated carbon and the sodium hydroxide aqueous solution is 1:2;

[0061] S4, the second processing activated carbon is kept at 180℃ for 8 h, and then calcined at 400℃ for 4 h, to obtain an activated carbon-based particle electrode as shown in Figs. 1-3

[0062] Example 2

[0063] The embodiment provides a preparation method of an activated carbon-based particle electrode, comprising the following steps:

[0064] S1, activated carbon particles with a particle size range of 1 mm-4 mm are washed with clean water twice, and then the washed activated carbon particles are immersed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide for 4 h, to obtain pretreated activated carbon; wherein the mass ratio of the activated carbon particles, the concentrated sulfuric acid solution and the hydrogen peroxide is 1:0.01:0.01;

[0065] S2, the pretreated activated carbon is immersed in a metal ion aqueous solution with silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate as solutes for 48 h, to obtain first processing activated carbon; wherein 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 solutes in the metal ion aqueous solution is 10 g / L, and the mass ratio of the acid-washed activated carbon and the solutes is 1:0.02;

[0066] S3, the first processing activated carbon is added to a sodium hydroxide aqueous solution with a concentration of 40 g / L, and then reacted at 4.0 MPa and 250℃ for 16 h, with stirring at a speed of 50 r / min during the reaction, and then cooled to 40℃ at a rate of 1℃ / min after the reaction, and washed with water twice, to obtain second processing activated carbon; wherein the mass ratio of the first processing activated carbon and the sodium hydroxide aqueous solution is 1:2;

[0067] S4, the second processing activated carbon is kept at 180℃ for 8 h, and then calcined at 400℃ for 4 h, to obtain an activated carbon-based particle electrode as shown in

[0068] Example 3

[0069] The embodiment provides a preparation method of an activated carbon-based particle electrode, comprising the following steps:

[0070] ​S1, washing activated carbon particles with a particle size range of 1mm-4mm with clean water for 2 times, then immersing the washed activated carbon particles into a mixed solution of concentrated sulfuric acid and hydrogen peroxide for 3h, to obtain pretreated activated carbon; wherein the mass ratio of the activated carbon particles, the concentrated sulfuric acid solution and the hydrogen peroxide is 1:0.03:0.02;

[0071] S2, immersing the pretreated activated carbon into a metal ion aqueous solution with silver nitrate, potassium permanganate, copper sulfate, cobalt sulfate, nickel sulfate and cerium sulfate as solutes for 20h, to obtain 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 solutes in the metal ion aqueous solution is 8g / L, and the mass ratio of the pickling activated carbon and the solutes is 1:0.02;

[0072] S3, immersing the first treated activated carbon into a sodium hydroxide aqueous solution with a concentration of 100g / L, then reacting at 1.55MPa and 200℃ for 10h, stirring at a rate of 200r / min during the reaction, and cooling to 60℃ at a rate of 5℃ / min after the reaction, and washing with water for 3 times, to obtain second treated activated carbon; wherein the mass ratio of the first treated activated carbon and the sodium hydroxide aqueous solution is 1:4;

[0073] S4, incubating the second treated activated carbon at 100℃ for 10h, and then calcining at 300℃ for 6h, to obtain an activated carbon-based particulate electrode.

[0074] Comparative Example 1

[0075] This comparative example provides a preparation method of an activated carbon-based particulate electrode, which is different from Example 1 in that in S2, the addition of cerium sulfate is omitted.

[0076] The other components and the preparation method are the same as those in Example 1.

[0077] Comparative Example 2

[0078] This comparative example provides a preparation method of an activated carbon-based particulate electrode, which is different from Example 1 in that in S3, the first treated activated carbon is immersed into a sodium hydroxide aqueous solution with a concentration of 40g / L, then reacted at 250℃ for 16h, stirred at a rate of 50r / min during the reaction, and cooled to 40℃ at a rate of 1℃ / min after the reaction, and washed with water for 2 times, to obtain second treated activated carbon; wherein the mass ratio of the first treated activated carbon and the sodium hydroxide aqueous solution is 1:2.

[0079] The other components and the preparation method are the same as those in Example 1.

[0080] Comparative Example 3

[0081] The comparative example provides a preparation method of an activated carbon-based granular electrode, which is different from example 1 in that: S3, the first treated activated carbon is added to a sodium hydroxide aqueous solution with a concentration of 40 g / L, then reacted at 0.2 MPa and 250°C for 16 h, the reaction is stirred at a rate of 50 r / min during the reaction, and after the reaction is completed, the temperature is lowered to 40°C at a rate of 1°C / min, and the second treated activated carbon is obtained after being washed with water twice; wherein the mass ratio of the first treated activated carbon to the sodium hydroxide aqueous solution is 1:2.

[0082] The other components and the preparation method are the same as those in example 1.

[0083] Comparative example 4

[0084] The comparative example provides a preparation method of an activated carbon-based granular electrode, which is different from example 1 in that: S3, the first treated activated carbon is added to a sodium hydroxide aqueous solution with a concentration of 40 g / L, then reacted at 5 MPa and 250°C for 16 h, the reaction is stirred at a rate of 50 r / min during the reaction, and after the reaction is completed, the temperature is lowered to 40°C at a rate of 1°C / min, and the second treated activated carbon is obtained after being washed with water twice; wherein the mass ratio of the first treated activated carbon to the sodium hydroxide aqueous solution is 1:2.

[0085] The other components and the preparation method are the same as those in example 1.

[0086] Comparative example 5

[0087] The comparative example provides a preparation method of an activated carbon-based granular electrode, which is different from example 1 in that: S3, the first treated activated carbon is added to a sodium hydroxide aqueous solution with a concentration of 40 g / L, then reacted at 4.0 MPa and 300°C for 16 h, the reaction is stirred at a rate of 50 r / min during the reaction, and after the reaction is completed, the temperature is lowered to 40°C at a rate of 1°C / min, and the second treated activated carbon is obtained after being washed with water twice; wherein the mass ratio of the first treated activated carbon to the sodium hydroxide aqueous solution is 1:2.

[0088] The other components and the preparation method are the same as those in example 1.

[0089] Comparative example 6

[0090] The comparative example provides a preparation method of an activated carbon-based granular electrode, which is different from example 1 in that: S4, the second treated activated carbon is incubated at 180°C for 8 h, and then calcined at 500°C for 4 h to obtain the activated carbon-based granular electrode.

[0091] The other components and the preparation method are the same as those in example 1.

[0092] Comparative example 7

[0093] The comparative example provides a preparation method of an activated carbon-based granular electrode, wherein the difference compared with Example 1 is that S4, the second treated activated carbon is calcined at 400 DEG C for 4h to obtain the activated carbon-based granular electrode.

[0094] Other components and the preparation method are the same as those in Example 1.

[0095] Comparative Example 8

[0096] The comparative example provides a preparation method of an activated carbon-based granular electrode, wherein the difference compared with Example 1 is that S3 is omitted, and the first treated activated carbon is directly subjected to the heat preservation calcination process in S4 to obtain the activated carbon-based granular electrode.

[0097] Other components and the preparation method are the same as those in Example 1.

[0098] Application Example 1: The water sample to be tested is wastewater with a COD concentration of 20000 mg / L;

[0099] An equal amount of 1.5L of the water sample to be tested is slowly stirred under the same conditions, the pH value is adjusted to 3-5, the activated carbon-based granular electrode catalyst prepared in Examples 1-3 and Comparative Examples 1-8 is added to the electrochemical reaction tank, the filling amount is 40%-60% of the height of the electrode plate, the voltage is controlled to be between 3-20V, the wastewater is fully mixed with the activated carbon-based granular electrode by aeration during the reaction process, the residence time is 2h, the power is turned off after the reaction is completed, the aeration pump is turned off, and the sample is detected, wherein the detection of the COD equivalent refers to the standard HJ / T 399-2007;

[0100] The COD removal rate (%) = (COD influent-COD effluent) / COD influent x 100%;

[0101] Wherein, COD influent represents the COD concentration of the wastewater before treatment, and COD effluent represents the COD concentration of the wastewater after treatment.

[0102] The specific detection indexes and detection results of Application Example 1 are shown in Table 1.

[0103] Application Example 2: The water sample to be tested is wastewater with a COD concentration of 4000 mg / L;

[0104] An equal amount of 1L of the water sample to be tested is slowly stirred under the same conditions, the pH value is adjusted to 3-5, the granular electrode catalyst prepared by adjusting Examples 1-3 and Comparative Examples 1-8 is added to the high-temperature and high-pressure reaction kettle, the temperature is raised to 150 DEG C-230 DEG C, the stirring rate is 150 r / min, and the treatment time is 2h-4h, the sample is detected after the reaction is completed and the temperature is cooled; wherein the detection of the COD equivalent refers to the standard HJ / T 399-2007.

[0105] COD removal rate (%) = (COD influent - COD effluent) / COD influent x 100%;

[0106] COD influent represents the COD concentration of the wastewater before treatment, and COD effluent represents the COD concentration of the wastewater after treatment;

[0107] The specific detection indexes and detection results of application example 2 are shown in Table 2:

[0108] Table 1 test results

[0109]

[0110] Table 2 test results

[0111]

[0112] As can be seen from Tables 1 and 2, when the activated carbon-based granular electrode prepared in the embodiments of the present application is applied to wastewater treatment, the COD removal rate after 2h of operation can reach 93.4%, and the COD removal rate after 360h of operation can still reach 89.6% when the wastewater is treated by the method provided in application example 2; the COD removal rate after 2h of operation can reach 72.6%, and the COD removal rate after 360h of operation can still reach 70.4% when the wastewater is treated by the method provided in application example 1; this also proves that the activated carbon-based granular electrode provided in the present application can significantly improve the COD removal rate when used in high-COD-concentration wastewater treatment, and the activated carbon-based granular electrode provided in the present application has excellent cycle service life, and the COD removal rate does not decrease significantly after 360h of continuous operation. Compared with the embodiments of the present application, the pore structure of the granular electrode, the morphology of the active metal component, and the bonding ability of the active metal component and the activated carbon will all change due to the change of the preparation conditions. It has been proved through tests that the COD removal rate of the granular electrode provided in the comparative example of the present application has a significant decreasing trend in wastewater treatment, whether the method provided in application example 1 or the method provided in application example 2 is used; and the COD removal rate after 360h of continuous operation in wastewater treatment is also significantly lower than the COD removal rate after 2h of operation.

[0113] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an activated carbon-based granular electrode, characterized in that: The steps include: S1. Add activated carbon with a particle size of 1 mm to 4 mm to a mixed solution of concentrated sulfuric acid solution and hydrogen peroxide for impregnation to obtain pretreated activated carbon; the mass ratio of the activated carbon, concentrated sulfuric acid solution and hydrogen peroxide is 1:(0.01-0.05):(0.01-0.05); S2. Adding the pretreated activated carbon to a mixed metal ion aqueous solution for soaking to obtain a first treated activated carbon; the mixed metal ion aqueous solution is a mixed solution of a soluble silver salt, a soluble potassium salt, a soluble copper salt, a soluble cobalt salt, a soluble nickel salt and a soluble cerium salt; S3, adding the first treated activated carbon to a sodium hydroxide aqueous solution with a concentration of 40 g / L to 200 g / L, reacting at 0.8 MPa to 4 MPa and 160° C. to 250° C. to obtain a second treated activated carbon; S4. Heating the second treated activated carbon to 60° C. to 180° C., maintaining the temperature, and then calcining the activated carbon at 200° C. to 400° C. to obtain an activated carbon-based granular electrode.

2. The method for preparing an activated carbon-based granular electrode according to claim 1, wherein: In S1, the immersion time is 2 h to 4 h.

3. The method for preparing an activated carbon-based granular electrode according to claim 1, wherein: 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 method for preparing an activated carbon-based granular electrode according to claim 1 or 2, wherein: In S2, the mass ratio of the soluble silver salt, the soluble potassium salt, the soluble copper salt, the soluble cobalt salt, the soluble nickel salt and the soluble cerium salt is (0.9~1):(0.9~1):(2.8~3):(2.8~3):(2.8~3):(2.8~3).

5. The method for preparing an activated carbon-based granular electrode according to claim 1, wherein: In S2, the concentration of the mixed metal ion aqueous solution is 5g / L~10g / L; and / or In S2, the mass ratio of the pretreated activated carbon to the solute in the mixed metal ion aqueous solution is 1:(0.01-0.02); and / or In S2, the soaking time is 6h~48h.

6. The method for preparing an activated carbon-based granular 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 8h~16h; and / or In S4, the insulation time is 8h~16h; and / or In S4, the calcination time is 4h~8h.

7. An activated carbon-based granular electrode, characterized in that: The activated carbon-based particle electrode is prepared by the preparation method of any one of claims 1 to 6.

8. Use of the activated carbon-based granular electrode according to claim 7 in wastewater treatment.

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