Potassium-manganese modified electrode material, and preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-05-19
- Publication Date
- 2026-06-16
Smart Images
Figure CN122212352A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wastewater ecological restoration and constructed wetland technology, specifically relating to a potassium-manganese modified electrode, its preparation method, and its application. Background Technology
[0002] Constructed wetlands (CW), as an ecological wastewater treatment method, primarily function by utilizing the interaction between substrates, plants, and microorganisms to adsorb, filter, precipitate, and redox pollutants in wastewater, thereby purifying it. They have a wide range of applications. Microbial fuel cells (MFCs) are devices that use organic matter in wastewater as a carbon source and microorganisms as catalysts to directly convert the chemical energy of organic matter into electrical energy during wastewater treatment. MFCs utilize the redox potential difference formed along the height of the CW, with an aerobic environment at the top and an anaerobic environment at the bottom, to generate electricity through bio-electricity. Simultaneously, the CW provides additional carbon sources for electrochemically active microorganisms, further increasing power generation. In the CW-MFC coupled system, the interaction between wetland plants, substrate materials, and microorganisms improves pollutant removal efficiency, while the action of electrogenic bacteria reduces greenhouse gas emissions from the CW, thus achieving efficient wastewater treatment and bioenergy generation, demonstrating promising development prospects.
[0003] However, existing literature and patent analysis indicate that this technology still faces several key bottlenecks: First, the long-term operational stability of the system is insufficient. Factors such as the long-term effectiveness of electrode materials, the maintenance of microbial activity, and seasonal changes in plant growth all affect the continuous removal efficiency. Second, the power generation performance needs improvement. Limited by factors such as insufficient dissolved oxygen supply at the cathode, excessively high anode overpotential, and large internal resistance of the system, the energy recovery efficiency is far from meeting the requirements of practical applications. Third, although commonly used carbon-based electrode materials such as graphite rods, carbon brushes, and carbon felts are stable, have high specific surface areas, and are inexpensive, they will experience performance degradation during long-term use. This includes carbon corrosion caused by electrochemical oxidation, changes in surface functional groups and blockage of active sites, as well as mechanical cracking, peeling, and even pulverization caused by volume expansion and contraction. For materials containing binders, there is also fiber shedding due to binder degradation. These aging phenomena collectively cause the electrode performance to continuously decline over time, increasing maintenance costs. Therefore, it is urgent to develop new electrode materials for use in constructed wetland-microbial fuel cell systems to overcome the above-mentioned technical bottlenecks and promote their engineering application and large-scale promotion.
[0004] The commonly used electrode materials in CW-MFC systems are carbon-based materials, such as graphite rods, carbon brushes, and carbon felts. Carbon-based materials are stable, have a high specific surface area, and are inexpensive. However, compared to metallic materials, carbon-based materials increase the system's internal resistance and decrease its conductivity, thus affecting the system's power generation and contaminant removal performance. Appropriate electrode modification can not only enhance bacterial adhesion but also improve direct electron transfer (DET) between cells and the electrode surface, thereby improving the power generation performance and contaminant removal efficiency of MFC. Manganese oxides have a unique structure; the oxidation of high-valence manganese and the reduction of low-valence manganese are beneficial for reducing energy consumption in low-oxygen environments, thus manganese oxides have good stability and environmental compatibility. In addition, manganese oxides exhibit high catalytic activity and can be used to modify carbon-based materials, accelerating the reaction rate and improving denitrification efficiency. To better load manganese oxides onto the carbon felt surface, the introduction of potassium salts can make the distribution of manganese oxides in the carbon material more uniform, due to the corrosive effect of potassium salts during the pyrolysis of carbon materials. High-temperature activation with potassium salts increased the specific surface area of carbon materials, which was then modified by loading manganese oxides onto the carbon felt electrode. Iron-carbon micro-electrolysis packing is an ideal and promising packing material for treating high-concentration organic wastewater due to its high efficiency, low cost, and simple operation, attracting widespread attention in the treatment of recalcitrant organic wastewater. However, research on the dual reinforcement of modified electrodes and iron-carbon packing matrix in constructed wetland-microbial fuel cell systems for wastewater treatment is still rare. Based on this, this invention patent is proposed.
[0005] In the prior art, there are some achievements in the preparation methods of related modified electrode materials. For example, Chinese Patent Application No. CN202210903221-4, published on September 20, 2022, discloses a patent document entitled "A Multi-Cathode Type Artificial Wetland Microbial Fuel Cell Nitrogen and Phosphorus Removal Device". This patent uses diatoms as cathode modified electrodes and places three modified cathode materials in parallel in the air-water interface area under aquatic plants. Under light, algae can use CO2 to produce O2 through photosynthesis. The large amount of oxygen production can improve the power generation efficiency, absorb toxins and organic matter, and improve the nitrogen removal efficiency. However, the dissolved oxygen level of the cathode is closely related to the light conditions. When there is insufficient light at night or on cloudy days, the power generation performance of the system will decrease. Moreover, the biofilm formed by diatoms may hinder ion transport and increase the internal resistance of the system. Chinese Patent Application No. CN202511410404-2, published on December 19, 2025, discloses a patent document entitled "A Method for Efficiently and Simultaneously Removing Nitrogen, Phosphorus, and Low-Concentration Antibiotics from Wastewater." This patent uses an electrodeposition method to load riboflavin onto carbon felt for modification, preparing an electrode material with strong conductivity. However, the high potential selection during material preparation can lead to peroxidation or degradation of riboflavin, which is not conducive to industrial application. Chinese Patent Application No. 202511211239-8, published on November 29, 2025, discloses a patent document entitled "A Manganese Matrix-Enhanced Constructed Wetland System Based on Micro-Electric Field Stimulation and Its Application." This patent enriches functional microbial communities in situ in the anode region and directionally inoculates highly efficient manganese-oxidizing bacteria in the cathode region, enhancing the electrode performance of the system through microbial inoculation. However, the directionally inoculated highly efficient manganese-oxidizing bacteria not only destroy the native microbial community but also have a long start-up period. Summary of the Invention
[0006] To address the problems of low efficiency in removing pollutants from water and the tendency of carbon-based materials to increase internal resistance and decrease conductivity, this invention provides a method for preparing potassium-manganese modified electrode materials and their application in constructed wetland-microbial fuel cell systems. The aim is to improve the electrochemical performance and stability of electrode materials, while also providing a technical reference for improving water quality and restoring aquatic ecosystems.
[0007] To solve the above-mentioned technical problems, the present invention is implemented through the following technical solutions.
[0008] This invention provides a method for preparing a potassium-manganese modified electrode material, specifically including the following steps:
[0009] (1) First, the carbon felt electrode material is rinsed with deionized water to remove impurities and carbon fiber residue, then ultrasonically cleaned, then soaked in anhydrous ethanol and ultrasonically cleaned, and the cleaned carbon felt is dried.
[0010] (2) Prepare a potassium carbonate solution, immerse the carbon felt obtained in step 1 in the potassium carbonate solution, stir at room temperature and then sonicate; place the mixed solution in an oil bath, evaporate the solvent until there is no flowing water, and then dry it in a vacuum drying oven; carbonize the dried carbon felt in a tube furnace under a nitrogen atmosphere at 600~800℃; then wash the carbonized carbon felt material with dilute hydrochloric acid and deionized water until neutral, and put it in an electric blast oven to dry.
[0011] (3) First, prepare a mixed solution of water and ethylene glycol, then add manganese chloride to the mixed solution to dissolve it, and prepare a precursor solution;
[0012] The volume ratio of water to ethylene glycol is 1:3~5;
[0013] The molar ratio of potassium ions in the potassium carbonate solution in step 2 to manganese ions in the manganese chloride solution in step 3 is 1~5:1.
[0014] (4) Add the carbon felt obtained in step 2 to the precursor solution prepared in step 3, pour it into the reaction vessel, place it in the oven, heat it to 150~180℃, react for 24h, and take it out after cooling to room temperature. Wash the carbon felt until the washing solution is neutral and colorless, and then dry it to obtain the potassium manganese modified electrode material.
[0015] Furthermore, the molar ratio of potassium ions in the potassium carbonate solution in step (2) to manganese ions in the manganese chloride solution in step (3) is 3:1.
[0016] Furthermore, the method for preparing a potassium-manganese modified electrode material as described in claim 1 is characterized in that, in step (2), the dried carbon felt is carbonized at 700°C in a tube furnace under a nitrogen atmosphere.
[0017] Furthermore, in the method for preparing a potassium-manganese modified electrode material as described in claim 1, the oven is heated to 160°C in step (4).
[0018] The potassium-manganese modified electrode material obtained by any of the above preparation methods can be used in constructed wetland-microbial fuel cell systems. The cathode material of the constructed wetland-microbial fuel cell system is the aforementioned potassium-manganese modified electrode material.
[0019] This invention also provides an artificial wetland-microbial fuel cell system, which comprises, from top to bottom, a wetland plant layer (2), a biochar cathode layer (4), an iron-carbon particle matrix layer (5), a biochar anode layer (7), a ceramsite matrix layer (8), and a gravel water distribution layer (9); an anode (6) is buried in the biochar anode layer (7), and a potassium-manganese modified cathode (3) is laid above the biochar cathode layer (4). A wire (11) passes through the biochar anode layer (7) and the biochar cathode layer (4) to connect the anode (6) and the potassium-manganese modified cathode (3). An outlet (10) is provided in the gravel water distribution layer (9), and an inlet (1) is provided in the wetland plant layer (2); the anode 6 is made of carbon fiber felt wrapped with stainless steel mesh; the potassium-manganese modified cathode 3 is made of potassium-manganese modified carbon fiber felt wrapped with stainless steel mesh.
[0020] Furthermore, a resistor (12) is provided between the wire (11) connecting the anode (6) and the potassium manganese modified cathode 3.
[0021] Furthermore, the gravel water distribution layer (9) has a particle size of 10-20 mm, the ceramsite matrix layer (8) has a particle size of 3-5 mm, the biochar anode layer (7) has a particle size of 5-8 mm, the iron-carbon particle matrix layer (5) has a particle size of 5-8 mm, and the biochar cathode layer (4) has a particle size of 5-8 mm.
[0022] Furthermore, the aforementioned fuel cell system is a cylindrical device with a diameter of not less than 200 mm and a height of not less than 550 mm.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0024] 1. The modified materials described in this invention are potassium carbonate, manganese chloride, and carbon fiber felt. These raw materials are widely available and inexpensive. The potassium-manganese modified carbon felt material has a simple preparation process, high specific surface area, and strong electrical conductivity, providing a high-performance, low-cost, and environmentally friendly electrode material for constructed wetland-microbial fuel cell systems.
[0025] 2. This invention applies the dual enhancement of modified electrode and iron-carbon micro-electrolysis filler to the constructed wetland-microbial fuel cell system, which plays a synergistic role and realizes the removal of pollutants in sewage while generating electricity. At the same time, it provides a new idea for improving the decontamination performance of constructed wetland-microbial fuel cell system.
[0026] 3. This invention adds a fuel cell to the existing constructed wetland conditions. The anaerobic and aerobic zones inherent in constructed wetlands provide a natural redox gradient for the microbial fuel cell. Furthermore, the constructed wetland-microbial fuel cell does not require an ion exchange membrane, resulting in lower costs and ease of construction and operation. It is environmentally friendly, has a wide range of applications, and can remove an increased variety of pollutants. It also achieves highly efficient wastewater treatment, with COD removal rates reaching 91.58%, TP removal rates reaching 79.39%, TN removal rates reaching 79.15%, and NO3 removal rates reaching [missing data]. - -N removal rate can reach 92.82%, NH4+ removal rate can reach 92.82%. + -N removal rate can reach 77.18%. This invention couples potassium-manganese modified electrode material with constructed wetland-microbial fuel cell system, thus showing good market application prospects. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the structure of the potassium-manganese modified electrode-enhanced constructed wetland-microbial fuel cell wastewater treatment system in Embodiment 4 of the present invention;
[0028] Among them: 1-inlet, 2-wetland plants, 3-potassium manganese modified cathode, 4-biochar cathode layer, 5-iron carbon particle matrix layer, 6-anode, 7-biochar anode layer, 8-ceramsite matrix layer, 9-gravel water distribution layer, 10-outlet, 11-wire, 12-resistor.
[0029] Figure 2 The figures show the pollutant removal effects of the constructed wetland-microbial fuel cell wastewater treatment system in Examples 4, 5, and 6 of this invention, as well as in Comparative Example 2.
[0030] Where: (A) is the removal efficiency of chemical oxygen demand (COD), (B) is the removal efficiency of total phosphorus (TP), (C) is the removal efficiency of total nitrogen (TN), and (D) is the removal efficiency of nitrate (NO3). - -N removal effect, (E) is ammonia nitrogen NH4 + -N removes the effect.
[0031] Figure 3 The voltage test results of the artificially simulated wastewater treatment plant effluent treated by the potassium-manganese modified electrode-enhanced constructed wetland-microbial fuel cell wastewater treatment system in Examples 4, 5 and 6 of this invention are shown. Detailed Implementation
[0032] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention.
[0033] Example 1
[0034] This embodiment provides a method for preparing a potassium-manganese modified electrode material, the method comprising the following steps:
[0035] First, rinse the carbon felt electrode material with deionized water multiple times to remove impurities and carbon fiber residue, then perform ultrasonic cleaning, followed by soaking in anhydrous ethanol and ultrasonic cleaning, and finally dry the cleaned carbon felt in an electric blower oven.
[0036] 2. Prepare a 0.3 mol potassium carbonate solution. Immerse the carbon felt in the potassium carbonate solution, stir at room temperature, and then sonicate. Place the mixed solution in an oil bath to evaporate the solvent until no flowing water remains, and then dry it in a vacuum drying oven. Carbonize the dried carbon felt in a tube furnace at 700°C under a N2 atmosphere. Subsequently, wash the activated carbon felt with dilute hydrochloric acid and deionized water until neutral, and then dry it in an electric blast oven.
[0037] 3. First, prepare a mixed solution of water and ethylene glycol, then add manganese chloride to the mixed solution to dissolve it, with a concentration of 0.1 mol, to prepare a precursor solution. The volume ratio of water to ethylene glycol is 1:3.
[0038] 4. Add the carbon felt from step 2 to the precursor solution prepared in step 3, pour it into a reaction vessel, place it in an oven, heat it to 160°C, react for 24 hours, and after it cools to room temperature, take out the carbon felt and wash it with water and ethanol until the washing solution is neutral and colorless. Then place it in an oven to dry, thereby obtaining a potassium-manganese modified electrode material.
[0039] Example 2
[0040] The difference from Example 1 is that in step 2, the dried carbon felt is carbonized in a tube furnace at 600°C under a N2 atmosphere.
[0041] Example 3
[0042] The difference from Example 1 is that in step 2, the dried carbon felt is carbonized in a tube furnace at 800°C under a N2 atmosphere.
[0043] Comparative Example 1
[0044] The difference from Example 1 is that in step 2, the dried carbon felt is not carbonized at high temperature in a tube furnace under N2 atmosphere, but is directly washed with dilute hydrochloric acid and deionized water until neutral.
[0045] Example 4
[0046] A potassium-manganese modified electrode enhanced constructed wetland-microbial fuel cell system (CW-MFC1) has a container body that is a single-layer cylindrical barrel with an inlet 1 on the top side wall and an outlet 10 at the bottom. The inlet 1 and outlet 10 have a diameter of 20 mm. The inner barrel contains, from top to bottom, a wetland plant layer 2, a biochar cathode layer 4, an iron-carbon particle matrix layer 5, a biochar anode layer 7, a ceramsite matrix layer 8, and a gravel water distribution layer 9. An anode 6 is buried in the biochar anode layer 7, and a modified cathode 3 is laid on top of the biochar cathode layer 4. A wire 11 connects the modified cathode 3 and connects it to the anode 6 via a resistor 12.
[0047] The gravel water distribution layer 9 is composed of gravel with a particle size of 10-20mm and a height of 10cm; the ceramsite matrix layer 8 has a particle size of 3-5mm and a height of 20cm; the biochar anode layer 7 has a particle size of 5-8mm and a height of 8cm; the iron-carbon particle layer 5 has a particle size of 5-8mm and a height of 10cm; the biochar cathode layer 4 has a particle size of 5-8mm and a height of 4cm; and the wetland plant layer 2 above the modified cathode 3 is planted with 4 calamus plants.
[0048] The electrode of the anode 6 is composed of stainless steel mesh and carbon fiber felt, and the electrode of the cathode 3 is composed of stainless steel mesh and potassium manganese modified carbon fiber felt. The connection between the copper wire 11 and the electrodes of the anode 6 and cathode 3 is coated with epoxy resin to avoid direct contact between the interface and the water during operation, thus preventing short circuits. Microorganisms mainly attach to the electrodes of the anode 6 and cathode 3 and the iron-carbon particle matrix layer.
[0049] The outer surface of the device of this invention is covered with black light-blocking cloth for dark treatment to prevent algae growth and affect the processing efficiency of the device.
[0050] Example 5
[0051] The difference from Example 4 is that the intermediate matrix layer 5 between the cathode layer and the anode layer is a ceramic matrix layer, denoted as CW-MFC2.
[0052] Example 6
[0053] The difference from Example 4 is that the cathode is an unmodified carbon felt electrode material, and the intermediate matrix layer 5 between the cathode layer and the anode layer is a ceramic matrix layer, denoted as CW-MFC3.
[0054] Comparative Example 2
[0055] The difference from Example 4 is that the cathode is an unmodified carbon felt electrode material, the intermediate matrix layer 5 between the cathode layer and the anode layer is a ceramic matrix layer, and the system operates in an open circuit, that is, the anode and cathode are not connected through an external circuit, denoted as CW0.
[0056] Application testing:
[0057] Different electrode materials prepared using the methods shown in Examples 1-3 and Comparative Example 1 were used to treat laboratory-simulated NO3-containing samples. - -N wastewater. Different electrode materials prepared in Examples 1-3 and Comparative Example 1 were placed in a 150mL small anaerobic reactor. The amount of electrode material added was one piece with a size of 20×20×5mm. The influent concentrations were COD 80mg / L, TN 40mg / L, and NH4+. + -N 10mg / L, NO3 - -N 30mg / L, hydraulic retention time set to 5d, continuous operation results are shown in Table 1.
[0058] Table 1. Experimental results of the examples and comparative examples.
[0059] COD removal rate % TN removal rate % <![CDATA[NO3 - -N removal rate %]]> <![CDATA[NH4 + -N removal rate %]]> Example 1 85.16 75.81 84.26 66.43 Example 2 78.23 68.15 75.17 60.46 Example 3 70.65 61.62 70.42 55.87 Comparative Example 1 49.63 50.54 55.32 41.42
[0060] It can be seen that Examples 1-3 all showed better removal effects of nitrate nitrogen than Comparative Example 1, indicating that the antioxidant properties and stability of the composite material were significantly improved. Furthermore, the electrode material prepared in Example 1 with a carbonization temperature of 700℃ exhibited good nitrate nitrogen removal performance. This is because a lower activation temperature failed to allow potassium carbonate to fully react on the surface of the carbon fiber felt; it needs to be above 700℃ to participate in the activation reaction. Excessively high activation temperatures would damage the microporous structure of the carbon fiber felt, reducing its specific surface area and thus decreasing its adsorption performance. Therefore, considering all factors, the electrode material with a carbonization temperature of 700℃ from Example 1 was selected.
[0061] The systems of Examples 4, 5, 6, and the comparative example were run under the same conditions to test the removal efficiency and power generation effect of each group for different pollutants. The results are as follows: Figure 2 , Figure 3 As shown.
[0062] The operating conditions are as follows: intermittent flow water intake, hydraulic retention time (HRT) of 5 days; influent concentrations: COD 60 mg / L, TN 20 mg / L, TP 1.5 mg / L, NH4+... + -N 5mg / L, NO3 - -N 15mg / L, run for 60 days, the results of continuous operation are shown in Table 2.
[0063] Table 2. Experimental results of the examples and comparative examples.
[0064] COD removal rate % TP removal rate % TN removal rate % <![CDATA[NO3 - -N removal rate %]]> <![CDATA[NH4 + -N removal rate %]]> Example 4 91.58 79.39 79.15 92.82 77.18 Example 5 88.51 75.53 70.55 86.72 69.52 Example 6 86.39 70.91 61.62 80.85 62.58 Comparative Example 2 74.26 63.34 54.21 75.64 59.07
[0065] Regarding COD and TP removal rates, the three systems in Examples 4, 5, and 6 exhibited similar removal efficiencies, with COD removal rates ranging from 86% to 91% and total phosphorus removal rates ranging from 70% to 79%, both higher than the COD and TP removal rates in the comparative example CW0. This indicates that stable removal of COD and TP can likely be achieved primarily through matrix adsorption and the metabolic activity of conventional microorganisms.
[0066] In terms of TN removal rate, the average removal efficiency of CW-MFC1 group (79.15%) was significantly higher than that of CW-MFC2 group (70.55%), CW-MFC3 group (61.62%), and CW group (54.21%); similarly, in terms of NO3... - Regarding NO3- removal efficiency, the average removal efficiency of CW-MFC1 group (92.82%) was significantly higher than that of CW-MFC2 group (86.72%), CW-MFC3 group (80.85%), and CW group (75.64%). This indicates that the anaerobic environment of the wetland system provided favorable conditions for denitrification, and the micro-electric field formed by the iron-carbon granular micro-electrolysis matrix and the modified cathode and anode further enhanced the activity of denitrifying microorganisms and accelerated NO3- removal. - -N conversion and removal. In NH4 + In terms of NH4+ removal rate, CW-MFC1 showed a significant advantage, with an average removal rate of 77.18%, significantly higher than that of CW-MFC2 (69.52%), CW-MFC3 (62.58%), and CW0 (59.07%). This is closely related to the microbial electrochemical ammonia oxidation process under anaerobic conditions. + -N can participate in the reaction as an electron donor, and the closed-loop operation mode of CW-MFC1 and the potassium-manganese modified carbon felt electrode can promote electron transfer and accelerate the electron transfer rate, thereby improving the removal efficiency of ammonia nitrogen. Therefore, it performs better than the control system in Examples 5 and 6 and the open-loop operation.
[0067] Figure 3 The results of the voltage change process over time show that the device voltage gradually increases and eventually stabilizes. The average voltages of CW-MFC1, CW-MFC2, and CW-MFC3 devices are 140mV, 102mV, and 85mV, respectively.
[0068] In summary, compared with the constructed wetland system CW-MFC2 (which uses a potassium-manganese modified carbon felt electrode but does not add an iron-carbon particle matrix), the system CW-MFC3 (which uses an unmodified carbon felt electrode as the cathode and does not add an iron-carbon particle matrix), and the system CW0 (which operates in an open circuit without wires), the CW-MFC1 system of this invention shows improved removal rates and output voltage for various pollutants. This is due to the complete current pathway formed by micro-electric field stimulation and the manganese cycling microenvironment formed by manganese oxides on the potassium-manganese modified electrode. This not only promotes the growth and metabolism of microorganisms related to pollutant degradation but also improves the electron transfer efficiency and extracellular electron transfer rate between microorganisms through the domestication effect of the redox potential gradient, using the electrode as a medium. This reduces the fluctuation of removal rate during stable operation and improves the electrochemical performance and stability of the system.
Claims
1. A method for preparing a potassium-manganese modified electrode material, characterized in that... Includes the following steps: (1) First, the carbon felt electrode material is rinsed with deionized water to remove impurities and carbon fiber residue, then ultrasonically cleaned, then soaked in anhydrous ethanol and ultrasonically cleaned, and the cleaned carbon felt is dried. (2) Prepare a potassium carbonate solution, immerse the carbon felt obtained in step (1) in the potassium carbonate solution, stir at room temperature and then sonicate; The mixed solution was placed in an oil bath and the solvent was evaporated until there was no flowing water. Then it was dried in a vacuum drying oven. The dried carbon felt was carbonized at 600-800℃ in a tube furnace under a nitrogen atmosphere. The carbonized carbon felt material was then washed with dilute hydrochloric acid and deionized water until neutral and then placed in an electric blast oven to dry. (3) First, prepare a mixed solution of water and ethylene glycol, then add manganese chloride to the mixed solution to dissolve it, and prepare a precursor solution; The volume ratio of water to ethylene glycol is 1:3~5; The molar ratio of potassium ions in the potassium carbonate solution in step (2) to manganese ions in the manganese chloride solution in step (3) is 1~5:1; (4) Add the carbon felt obtained in step (2) to the precursor solution prepared in step (3), pour it into the reaction vessel, place it in the oven, heat it to 150~180℃, react for 24h, take it out after cooling to room temperature, wash the carbon felt until the washing solution is neutral and colorless, and then dry it to obtain the potassium manganese modified electrode material.
2. The method for preparing a potassium-manganese modified electrode material as described in claim 1, characterized in that, The molar ratio of potassium ions in the potassium carbonate solution in step (2) to manganese ions in the manganese chloride solution in step (3) is 3:
1.
3. The method for preparing a potassium-manganese modified electrode material as described in claim 1, characterized in that, In step (2), the dried carbon felt is carbonized at 700°C in a tube furnace under a nitrogen atmosphere.
4. The method for preparing a potassium-manganese modified electrode material as described in claim 1, characterized in that, In step (4), the oven is heated to 160°C.
5. The potassium-manganese modified electrode material obtained by any one of the preparation methods described in claims 1 to 4.
6. The application of the potassium-manganese modified electrode material as described in claim 5 in an artificial wetland-microbial fuel cell system, characterized in that, The cathode material of the constructed wetland-microbial fuel cell system is the potassium-manganese modified electrode material as described in claim 5.
7. The constructed wetland-microbial fuel cell system as described in claim 6, characterized in that, The fuel cell system comprises, from top to bottom, a wetland plant layer (2), a biochar cathode layer (4), an iron-carbon particle matrix layer (5), a biochar anode layer (7), a ceramsite matrix layer (8), and a gravel water distribution layer (9). An anode (6) is buried in the biochar anode layer (7), and a potassium-manganese modified cathode (3) is laid above the biochar cathode layer (4). A wire (11) passes through the biochar anode layer (7) and the biochar cathode layer (4) to connect the anode (6) and the potassium-manganese modified cathode (3). An outlet (10) is provided in the gravel water distribution layer (9), and an inlet (1) is provided in the wetland plant layer (2). The anode (6) is made of carbon fiber felt wrapped with stainless steel mesh; the potassium-manganese modified cathode (3) is made of potassium-manganese modified carbon fiber felt wrapped with stainless steel mesh.
8. The constructed wetland-microbial fuel cell system as described in claim 6, characterized in that, A resistor (12) is installed between the wire (11) connecting the anode (6) and the potassium-manganese modified cathode 3.
9. The constructed wetland-microbial fuel cell wastewater treatment system as described in claim 6, characterized in that, The gravel water distribution layer (9) has a particle size of 10-20 mm, the ceramsite matrix layer (8) has a particle size of 3-5 mm, the biochar anode layer (7) has a particle size of 5-8 mm, the iron-carbon particle matrix layer (5) has a particle size of 5-8 mm, and the biochar cathode layer (4) has a particle size of 5-8 mm.
10. The constructed wetland-microbial fuel cell wastewater treatment system as described in claim 6, characterized in that, The fuel cell system is a cylindrical device with a diameter of not less than 200 mm and a height of not less than 550 mm.