Microbial fuel cell anode material based on biochar as well as preparation method and application of microbial fuel cell anode material
By preparing nano-iron modified porous biochar and coating it onto a carbon brush, the cost and efficiency issues of anode materials for microbial fuel cells were solved, achieving high-efficiency and environmentally friendly microbial fuel cell performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA SHANGJIAO CARBONHUI ENVIRONMENTAL TECH CO LTD
- Filing Date
- 2026-02-28
- Publication Date
- 2026-05-15
AI Technical Summary
Existing microbial fuel cell anode materials cannot simultaneously meet the requirements of low cost, good biocompatibility, and high efficiency, and existing modification methods may lead to blockage of active sites and increased interfacial resistance.
Porous biochar was prepared using biomass powder, and nano-iron and polydopamine were loaded through oxygen-limited heat treatment to form nano-iron modified porous biochar. This biochar was then coated onto a carbon brush to form a high-efficiency anode material for microbial fuel cells.
This has led to the development of a low-cost, biocompatible, and highly efficient microbial fuel cell anode material, which improves power density and voltage and reduces environmental pollution risks.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of anode material technology, and in particular to a biochar-based microbial fuel cell anode material, its preparation method, and its application. Background Technology
[0002] The anode of microbial fuel cells (MFCs) is a critical interface for microbial survival, proliferation, and extracellular electron transport (EET), all of which significantly impact MFC performance. A high-performance MFC anode material needs to simultaneously meet multiple requirements, such as high efficiency, high conductivity, high specific surface area, excellent biocompatibility, high chemical stability, and mechanical strength. However, anode materials that simultaneously meet these requirements suffer from high cost. Although numerous strategies have been developed to address the issues of high cost and low efficiency in anode materials, the fabrication of efficient and economical anodes remains challenging due to limitations in preparation methods and material costs.
[0003] Biochar derived from waste biomass is an environmentally sustainable carbon matrix with high conductivity and good biocompatibility, making it an excellent candidate material for anode modification. Various metal loadings have been used to further improve electron transport and MFC (Metal-Based Fuel Cell) efficiency. Iron-based compounds show broad application prospects due to their participation in electron transport through the iron redox cycle. However, the stable immobilization of iron compounds or biochar usually requires additional adhesion to maintain its sustained effectiveness. This additional adhesion can clog active sites and reduce specific surface area, increase interfacial resistance and reduce conductivity, thereby leading to decreased efficiency of MFC anodes; it also reduces the biocompatibility of MFC anode materials.
[0004] Therefore, how to obtain a low-cost, biocompatible, and highly efficient MFC anode material is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] The purpose of this invention is to provide a biochar-based microbial fuel cell anode material, its preparation method, and its application. The preparation method provided by this invention is simple and easy to control, and can yield a low-cost, biocompatible, and highly efficient microbial fuel cell anode material.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a biochar-based microbial fuel cell anode material, comprising the following steps: Porous biochar is obtained by pyrolysis of biomass powder. The porous biochar was mixed with iron salt and water and then subjected to drying and oxygen-limited heat treatment in sequence to obtain nano-iron modified porous biochar. The nano-iron modified porous biochar and polydopamine solution were mixed to obtain a mixed slurry; the mixed slurry was coated on a carbon brush and dried to obtain a microbial fuel cell anode material.
[0007] Preferably, the pyrolysis treatment method includes: performing a first pyrolysis on biomass powder to obtain pyrolytic biochar; mixing the pyrolytic biochar with a pore-expanding agent and then performing oxygen-limited pyrolysis to obtain porous biochar.
[0008] Preferably, the temperature of the first pyrolysis is 600~900℃; the time of the first pyrolysis is 1~4h.
[0009] Preferably, the mass ratio of the pyrolytic biochar to the pore-expanding agent is 1:(1~3).
[0010] Preferably, the temperature of the oxygen-limited pyrolysis is 700~900℃; the time of the oxygen-limited pyrolysis is 1~4h.
[0011] Preferably, the mass ratio of the porous biochar to the iron salt is 1:(0.08~0.1).
[0012] Preferably, the temperature of the oxygen-limited heat treatment is 700~900℃; the time of the oxygen-limited heat treatment is 1~6h.
[0013] Preferably, the mass ratio of the nano-iron modified porous biochar to the polydopamine in the polydopamine solution is (0.5~1):(1~2).
[0014] The present invention also provides a biochar-based microbial fuel cell anode material prepared by the preparation method described above, comprising a carbon brush and a mixture of nano-iron modified porous biochar and polydopamine coated on the surface of the carbon brush.
[0015] The present invention also provides the application of the biochar-based microbial fuel cell anode material described in the above technical solution in microbial fuel cells.
[0016] This invention provides a method for preparing a biochar-based anode material for microbial fuel cells, comprising the following steps: pyrolyzing biomass powder to obtain porous biochar; mixing the porous biochar with iron salts and water, followed by drying and oxygen-limited heat treatment to obtain nano-iron modified porous biochar; mixing the nano-iron modified porous biochar with a polydopamine solution to obtain a mixed slurry; coating the mixed slurry onto a carbon brush and drying to obtain the microbial fuel cell anode material. This invention uses biomass powder as a raw material to prepare porous biochar, which is low-cost, environmentally sustainable, and possesses high conductivity and good biocompatibility. By using oxygen-limited heat treatment and modifying the porous biochar with iron salts, and loading nano-iron onto the porous biochar, this invention improves the electron transfer efficiency of the nano-iron modified porous biochar, thereby improving the conductivity of the microbial fuel cell anode material and enhancing the efficiency of the microbial fuel cell when the prepared anode material is used. This invention involves coating a mixture of nano-iron-modified porous biochar and a polydopamine solution onto a carbon brush. The polydopamine spontaneously polymerizes and deposits on various organic and inorganic surfaces, providing abundant functional groups and excellent bacterial compatibility, which is beneficial for the formation of a biofilm on the electrode surface. The method provided by this invention uses inexpensive raw materials and has a simple preparation process, resulting in low-cost and high-efficiency anode materials for microbial fuel cells. Results from the examples show that the microbial fuel cell anode material prepared by this invention has good biocompatibility, and when assembled into a microbial fuel cell, it exhibits higher power density and voltage. Attached Figure Description
[0017] Figure 1 The image shows a SEM image of the PDA@CB@Fe / PBC prepared in Example 1 of this invention. Figure 2 The infrared spectra of the anode materials prepared in Example 1 and Comparative Examples 1-3 of this invention are shown below. Figure 3 Comparison of power density and polarization curves during the operation cycle of microbial fuel cells assembled with anode materials prepared in Example 1 and Comparative Examples 1-3 of this invention; Figure 4 The diagram shows the anode and cathode microbial composition of the microbial fuel cells assembled with the anode materials prepared in Example 1 and Comparative Examples 1-3 of this invention. Detailed Implementation
[0018] This invention provides a method for preparing a biochar-based microbial fuel cell anode material, comprising the following steps: Porous biochar is obtained by pyrolysis of biomass powder. The porous biochar was mixed with iron salt and water and then subjected to drying and oxygen-limited heat treatment in sequence to obtain nano-iron modified porous biochar. The nano-iron modified porous biochar and polydopamine solution were mixed to obtain a mixed slurry; the mixed slurry was coated on a carbon brush and dried to obtain a microbial fuel cell anode material.
[0019] This invention involves pyrolyzing biomass powder to obtain porous biochar.
[0020] In this invention, the particle size of the biomass powder is preferably 0-6 mm, more preferably 1-2 mm. Controlling the particle size of the biomass powder within this range is more conducive to preparing porous biochar with a large specific surface area.
[0021] In this invention, the preferred method for preparing the biomass powder includes: sequentially air-drying, crushing, and sieving the biomass to obtain biomass powder.
[0022] This invention does not specifically limit the source of the biomass; any biomass available to those skilled in the art can be used. In embodiments of this invention, the biomass is preferably one or more of biogas residue, rice straw, and corn straw, wherein the biogas residue can be anaerobic digest of kitchen waste.
[0023] This invention does not specifically limit the methods of air-drying, crushing, and sieving. Conventional methods of air-drying, crushing, and sieving can be used to dry the biomass and control the particle size to the desired range. In embodiments of this invention, the sieve aperture size can be 100-200 mesh.
[0024] In this invention, the pyrolysis treatment method preferably includes: performing a first pyrolysis on biomass powder to obtain pyrolytic biochar; mixing the pyrolytic biochar with a pore-expanding agent and then performing oxygen-limited pyrolysis to obtain porous biochar.
[0025] The present invention preferably involves subjecting biomass powder to a first pyrolysis to obtain pyrolytic biochar.
[0026] In this invention, the preferred temperature for the first pyrolysis is 600-900℃; the preferred time for the first pyrolysis is 1-4 hours. As one embodiment of this invention, the temperature for the first pyrolysis can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, or 900℃; the preferred time for the first pyrolysis can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. This invention carbonizes biomass powder through the first pyrolysis. In this invention, the apparatus for the first pyrolysis can be a muffle furnace.
[0027] After obtaining pyrolytic biochar, the present invention preferably mixes the pyrolytic biochar with a pore-expanding agent and then performs oxygen-limited pyrolysis to obtain porous biochar.
[0028] In this invention, the pore-expanding agent preferably includes one or more of potassium hydroxide, potassium bicarbonate, zinc chloride, and phosphoric acid, more preferably potassium hydroxide. This invention enables the activation of biochar through the pore-expanding agent, forming a porous structure.
[0029] In this invention, the preferred mass ratio of the pyrolytic biochar to the pore-expanding agent is 1:(1~3). As one embodiment of this invention, the mass ratio of the pyrolytic biochar to the pore-expanding agent can be 1:1, 1:1.5, 1:2, 1:2.5, or 1:3. By controlling the mass ratio of the pyrolytic biochar to the pore-expanding agent within the above range, this invention enables the porous biochar to possess a rich pore structure and good mechanical properties.
[0030] This invention does not specifically limit the method of mixing the pyrolytic biochar and the pore-expanding agent; as long as they are mixed evenly, it is sufficient. In an embodiment of this invention, the method of mixing the pyrolytic biochar and the pore-expanding agent can be ball milling, and the ball milling time can be 2 hours.
[0031] In this invention, the preferred temperature for oxygen-limited pyrolysis is 700-900℃; the preferred time for oxygen-limited pyrolysis is 1-4 hours. As one embodiment of this invention, the temperature for oxygen-limited pyrolysis can be 700℃, 750℃, 800℃, 850℃, or 900℃; the time for oxygen-limited pyrolysis can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. By performing oxygen-limited pyrolysis at the above-mentioned temperatures and times, this invention enables porous biochar to possess a rich pore structure.
[0032] In this invention, the atmosphere for oxygen-limited pyrolysis is preferably an inert atmosphere, more preferably an inert gas or nitrogen. By conducting oxygen-limited pyrolysis under an inert atmosphere, this invention can prevent excessive biochar loss in the presence of oxygen, thereby increasing the yield of porous biochar.
[0033] After obtaining porous biochar, the present invention mixes the porous biochar with iron salt and water, and then performs drying and oxygen-limited heat treatment in sequence to obtain nano-iron modified porous biochar.
[0034] In this invention, the iron salt preferably includes one or more of ferric chloride, potassium bicarbonate, zinc chloride, and ferric phosphate.
[0035] In this invention, the mass ratio of porous biochar to iron salt is preferably 1:(0.08~0.1), more preferably 1:(0.08~0.09). Controlling the mass ratio of porous biochar to iron salt within the above range is more beneficial for improving electron transport and MFCs efficiency.
[0036] This invention does not have a specific limitation on the amount of water used, as long as it can form an iron salt solution and be mixed evenly with porous biochar. In this invention, since water plays the role of dissolving the iron salt, and the solution needs to be dried after being mixed evenly with the porous biochar, this invention does not require a specific limitation on the amount of water used.
[0037] The present invention does not specifically limit the method of mixing the porous biochar with iron salt and water; any method that dissolves the iron salt in water to form a solution and then mixes it evenly with the porous biochar is acceptable. In an embodiment of the present invention, the method of mixing the porous biochar with iron salt and water can be ultrasound.
[0038] The present invention does not specifically limit the drying method; any conventional drying method that can remove water is acceptable.
[0039] In this invention, the preferred temperature for the oxygen-limited heat treatment is 700-900℃; the preferred time for the oxygen-limited heat treatment is 1-6 hours. As one embodiment of this invention, the temperature for the oxygen-limited heat treatment can be 700℃, 750℃, 800℃, 850℃, or 900℃; the preferred time for the oxygen-limited heat treatment can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours. This invention enables the conversion of iron salts distributed in porous biochar into iron, which is then loaded onto the porous biochar, through oxygen-limited heat treatment.
[0040] In this invention, the atmosphere for the oxygen-limited heat treatment is preferably an inert gas or nitrogen. Performing the oxygen-limited heat treatment in an inert gas or nitrogen atmosphere prevents the loss of porous biochar.
[0041] After obtaining nano-iron modified porous biochar, the present invention mixes the nano-iron modified porous biochar with a polydopamine solution to obtain a mixed slurry.
[0042] In this invention, the preferred mass ratio of the nano-iron modified porous biochar to polydopamine in the polydopamine solution is (0.5~1):(1~2), more preferably (0.6~0.8):(1~1.5).
[0043] In this invention, the preferred method for preparing the polydopamine solution includes: mixing ammonia, ethanol and deionized water to obtain a mixed solution; mixing dopamine hydrochloride with water to obtain an aqueous solution of dopamine hydrochloride; adding the aqueous solution of dopamine hydrochloride to the mixed solution and stirring overnight to obtain the polydopamine solution.
[0044] In this invention, the volume ratio of ammonia, ethanol, and deionized water is preferably (0.2~2):40:90, more preferably (1~2):40:90. In embodiments of this invention, the ammonia can be commercially available concentrated ammonia, and the concentration of the ammonia can be 25%~30%.
[0045] The present invention does not have any particular limitation on the method of mixing the ammonia, ethanol and deionized water, as long as the three are mixed to form a homogeneous solution.
[0046] In this invention, the mass ratio of dopamine hydrochloride to deionized water in the dopamine hydrochloride aqueous solution is preferably (0.1~0.5):10, more preferably (0.1~0.4):10.
[0047] In this invention, the volume ratio of the mixed solution to the mass ratio of the dopamine hydrochloride aqueous solution is preferably (100~150) mL: (5~15) g, more preferably 132 mL: 10.5 g.
[0048] The present invention does not have any particular limitation on the method of mixing the nano-iron modified porous biochar and the polydopamine solution, as long as a uniform slurry can be obtained.
[0049] After obtaining the mixed slurry, the present invention coats the mixed slurry onto a carbon brush, and after drying, obtains the anode material for a microbial fuel cell.
[0050] The present invention does not have any special limitations on the specific model and size of the carbon brush; any carbon brush used in conventional microbial fuel cell anode materials can be used.
[0051] Preferably, the carbon brush is pretreated before the mixed slurry is coated onto it.
[0052] In this invention, the pretreatment method preferably includes: immersing the carbon brush in an isopropanol solution, followed by a first washing, drying, sintering, acid leaching, a second washing, and drying. This invention removes impurities from the surface of the carbon brush through pretreatment.
[0053] In embodiments of the present invention, the volume concentration of the isopropanol solution can be 30%; the isopropanol solution can be an aqueous solution of isopropanol.
[0054] In this invention, the soaking time is preferably 12-24 hours, more preferably 18-24 hours.
[0055] In this invention, the reagent used for the first wash can be deionized water. This invention does not specifically limit the operation method of the first wash, as long as it can effectively remove the isopropanol solution remaining on the carbon brush surface.
[0056] The present invention does not have any special limitations on the drying temperature and time, as long as it can remove the deionized water residue on the carbon brush surface.
[0057] In this invention, the sintering temperature is preferably 350~450℃, more preferably 400~450℃; the sintering time is preferably 1~2h, more preferably 1.5~2h. In this invention, the sintering is preferably carried out in a muffle furnace.
[0058] In this invention, the reagent used for acid leaching is preferably a hydrochloric acid solution, and the concentration of the hydrochloric acid solution is preferably 3-5 mol / L, more preferably 4-5 mol / L; the acid leaching time is preferably 0.5-1 h, more preferably 0.8-1 h. In this invention, the acid leaching is preferably performed under ultrasound.
[0059] In this invention, the reagent for the secondary washing can be deionized water. This invention does not specifically limit the operation method of the secondary washing, as long as it can effectively remove the residual acid leaching reagent from the carbon brush surface.
[0060] The present invention does not have any particular limitation on the drying temperature and time, as long as it can remove the deionized water residue on the carbon brush surface.
[0061] The present invention does not specifically limit the coating method, as long as it can form a uniformly thick mixed slurry layer on the carbon brush. In the present invention, the coating method can be to immerse the carbon brush in the mixed slurry and then remove and dry it.
[0062] In this invention, the impregnation time is preferably 12-24 hours, more preferably 18-24 hours. In this invention, the impregnation is preferably carried out under stirring. This invention enables the mixed slurry to be fully immersed into the carbon brush through impregnation, forming a uniformly distributed mixed slurry layer on the carbon brush surface.
[0063] In this invention, the drying temperature is preferably 60-80°C, more preferably 70-80°C; the drying time is preferably 6-12 hours, more preferably 8-12 hours. In this invention, the drying is preferably carried out in an oven.
[0064] The present invention also provides a biochar-based microbial fuel cell anode material prepared by the preparation method described above, comprising a carbon brush and a mixture of nano-iron modified porous biochar and polydopamine coated on the surface of the carbon brush.
[0065] The present invention does not have a special limitation on the mass ratio of the carbon brush, nano-iron modified porous biochar and polydopamine. The mixed slurry described in the above technical solution is coated on the carbon brush and then dried.
[0066] The present invention also provides the application of the biochar-based microbial fuel cell anode material described in the above technical solution in microbial fuel cells.
[0067] This invention does not impose any special limitations on the method of applying the biochar-based microbial fuel cell anode material in a microbial fuel cell; conventional anode materials can be used.
[0068] This invention utilizes low-cost biomass powder as a raw material to prepare porous biochar, which exhibits high conductivity and good biocompatibility. By loading nano-iron onto the porous biochar, the electron transfer efficiency of the nano-iron-modified porous biochar can be improved, thereby enhancing the conductivity of the anode material for microbial fuel cells and increasing the efficiency of the microbial fuel cell when the prepared anode material is used. This invention also involves coating a carbon brush with a mixture of nano-iron-modified porous biochar and polydopamine solution, providing abundant functional groups and excellent bacterial compatibility, which facilitates the formation of a biofilm on the electrode surface. The method provided by this invention uses low-cost raw materials and has a simple preparation process, resulting in a low-cost, high-efficiency anode material for microbial fuel cells.
[0069] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0070] In this embodiment of the invention, commercially available concentrated ammonia solution is used, with a concentration of 25% to 30%.
[0071] Example 1 A method for preparing a biochar-based microbial fuel cell anode material, comprising the following steps: (1) After drying, the biogas residue is crushed by a pulverizer and passed through a 100-mesh sieve to obtain biogas residue powder (biomass powder); the biogas residue powder is transferred to a crucible and compacted, and subjected to a first pyrolysis at 600℃ for 1 hour to obtain biogas residue biochar; 20g of the biogas residue biochar (pyrolysis biochar) is mixed with 20g of potassium hydroxide, ground in a ball mill for 2 hours, transferred to a crucible and compacted, and subjected to oxygen-limited pyrolysis at 800℃ under a nitrogen atmosphere for 2 hours to obtain porous biogas residue biochar (porous biochar). (2) Mix 20g of porous biochar obtained by the method in step (1) with 1.6g of ferric chloride and 100mL of water, sonicate and dry, and then perform oxygen-limited pyrolysis treatment at 700℃ for 2h in a nitrogen atmosphere to obtain nano-iron modified porous biochar (nano-iron modified porous biochar), denoted as Fe / BC. (3) Mix 2 mL of ammonia, 40 mL of ethanol and 90 mL of deionized water and stir at room temperature for 30 min. Mix 0.5 g of dopamine hydrochloride and 10 mL of deionized water and add them to the above solution. Stir at room temperature overnight to obtain polydopamine solution, which is denoted as PDA solution. The carbon brush was immersed in a 30% isopropanol solution for 24 hours, washed once with deionized water, dried, and sintered in a muffle furnace at 370℃ for 1 hour. Then it was acid-immersed in a 3 mol / L hydrochloric acid solution for 0.5 hours, washed a second time with deionized water, and dried to obtain the pretreated carbon brush. After mixing and stirring the 5g Fe / BC and 50mL PDA solution for 8h, a mixed slurry was obtained. The pretreated carbon brush was then immersed in the mixed slurry and stirred at 120rpm for 12h. After drying, the microbial fuel cell anode material was obtained, denoted as PDA@CB@Fe / PBC.
[0072] The SEM image of the PDA@CB@Fe / PBC prepared in this embodiment is shown below. Figure 1 As shown. From Figure 1 As can be seen, compared with the smooth surface of the carbon brush itself, the carbon brush surface modified with Fe / PBC and bonded with PDA has nanoscale particle deposits, and the carbon brush surface becomes rougher, significantly increasing the porous characteristics that it does not have on its own, which confirms the successful adhesion of PDA to Fe / PBC modified materials.
[0073] Figure 2 The infrared spectra of the anode materials prepared in Example 1 and Comparative Examples 1-3 of this invention are shown below. Figure 2 It can be seen that PDA@CB is at 3276cm -1 1540cm -1 1454cm -1 1375cm -1 1240cm -1 Characteristic peaks are observed at [values], representing the stretching vibrations of the –OH / –NH, C=C, NH, –CH, and C–O–H groups of polydopamine, respectively. After the addition of BC, [value] is 3276 cm⁻¹. -1 The peak at 3276 cm⁻¹ is significantly weakened and shifted towards lower wavenumbers, indicating a reduction in the stretching vibration frequency. In Fe / BC@PDA@CB, introduced as a Fe / BC composite, no significant attenuation of the PDA peak was observed, indicating that Fe / BC effectively preserves the infrared peak characteristics of PDA. Furthermore, the peak at 3276 cm⁻¹... -1The PDA characteristic peak of -NH shifts towards higher wavenumbers in Fe / BC@PDA@CB, indicating that the number of positively charged groups on the modified anode increases. This not only helps reduce electrostatic repulsion between the anode and the negatively charged cell wall of bacteria and accelerates the formation of biofilm on the anode surface, but also promotes the capture of electrons by the positive charge on the electrode surface, thereby improving charge transfer efficiency.
[0074] Example 2 A method for preparing a biochar-based microbial fuel cell anode material, comprising the following steps: (1) After drying, rice straw is crushed by a pulverizer and passed through a 100-mesh sieve to obtain rice straw powder (biomass powder); the rice straw powder is transferred to a crucible and compacted, and subjected to a first pyrolysis at 650°C for 1 hour to obtain rice straw biochar (pyrolytic biochar); 20g of the rice straw biochar is mixed with 20g of potassium hydroxide, ground in a ball mill for 2 hours, transferred to a crucible and compacted, and subjected to oxygen-limited pyrolysis at 800°C for 2 hours to obtain porous rice straw biochar (porous biochar). (2) 20g of porous rice straw biochar obtained by the method in step (1) was mixed with 1.8g of ferric chloride and 100mL of water, ultrasonicated and dried, and then subjected to oxygen-limited pyrolysis treatment at 700℃ for 2h in a nitrogen atmosphere to obtain nano-iron modified porous rice straw biochar (nano-iron modified porous biochar), denoted as Fe / PSBC-1; (3) Mix 2 mL of ammonia, 40 mL of ethanol and 90 mL of deionized water and stir at room temperature for 30 min. Mix 0.5 g of dopamine hydrochloride and 10 mL of deionized water and add them to the above solution. Stir at room temperature overnight to obtain polydopamine solution, which is denoted as PDA solution. The carbon brush was immersed in a 30% isopropanol solution for 6 hours, washed once with deionized water and dried, and then sintered in a muffle furnace at a temperature of 450℃ for 2 hours. After that, it was acid-immersed in a 5 mol / L hydrochloric acid solution for 1 hour, washed a second time with deionized water, and dried to obtain the pretreated carbon brush. After mixing and stirring the 5g Fe / PSBC-1 and 50mL PDA solution for 8h, a mixed slurry was obtained. The pretreated carbon brush was then immersed in the mixed slurry and stirred at 120rpm for 12h. After drying, the microbial fuel cell anode material was obtained, denoted as PDA@CB@Fe / PSBC-1.
[0075] Example 3 A method for preparing a biochar-based microbial fuel cell anode material, comprising the following steps: (1) After drying, the corn stalks are crushed by a pulverizer and passed through a 100-mesh sieve to obtain corn stalk powder (biomass powder); the corn stalk powder is transferred to a crucible and compacted, and subjected to a first pyrolysis at 650°C for 1 hour to obtain corn stalk biochar; 20g of the corn stalk biochar (pyrolysis biochar) is mixed with 20g of potassium hydroxide, ground in a ball mill for 2 hours, transferred to a crucible and compacted, and subjected to oxygen-limited pyrolysis at 800°C for 2 hours to obtain porous corn stalk biochar (porous biochar). (2) 20g of porous corn stalk biochar obtained by the method in step (1) was mixed with 1.8g of ferric chloride and 100mL of water, ultrasonicated and dried, and then subjected to oxygen-limited pyrolysis treatment at 650℃ for 2h in a nitrogen atmosphere to obtain nano-iron modified porous corn stalk biochar (nano-iron modified porous biochar), denoted as Fe / PSBC-2. (3) Mix 2 mL of ammonia, 40 mL of ethanol and 90 mL of deionized water and stir at room temperature for 30 min. Mix 0.5 g of dopamine hydrochloride and 10 mL of deionized water and add them to the above solution. Stir at room temperature overnight to obtain polydopamine solution, which is denoted as PDA solution. The carbon brush was immersed in a 30% isopropanol solution for 6 hours, washed once with deionized water, dried, and sintered in a muffle furnace at a temperature of 450℃ for 2 hours. Then it was acid-immersed in a 5 mol / L hydrochloric acid solution for 0.5 hours, washed a second time with deionized water, and dried to obtain the pretreated carbon brush. After mixing and stirring the 5g Fe / PSBC-2 and 50mL PDA solution for 8h, a mixed slurry was obtained. The pretreated carbon brush was then immersed in the mixed slurry and stirred at 120rpm for 12h. After drying, the microbial fuel cell anode material was obtained, denoted as PDA@CB@Fe / PSBC-2.
[0076] Comparative Example 1 A method for preparing PDA@CB@BC: Porous biochar from sludge and PDA solution are mixed at a mass-to-volume ratio of 4:1 and stirred at room temperature for 8 hours. CB is then immersed in the mixture and stirred at 120 rpm / min for 12 hours. After drying, PDA@CB@BC is obtained.
[0077] Comparative Example 2 A method for preparing PDA@CB@Fe3O4: Fe3O4 and PDA solution are mixed at a mass-to-volume ratio of 4:1 and stirred at room temperature for 8 hours. CB is then immersed in the mixture and stirred at 120 rpm / min for 12 hours. After drying, PDA@CB@Fe3O4 is obtained.
[0078] Comparative Example 3 A method for preparing PDA@CB@Fe3O4@BC: Porous biochar from sludge, Fe3O4, and PDA solution are mixed at a mass-to-volume ratio of 4:4:1 and stirred at room temperature for 8 hours. CB is then immersed in the mixture and stirred at 120 rpm / min for 12 hours. After drying, PDA@CB@Fe3O4@BC is obtained.
[0079] Test case The anode materials prepared in Example 1 and Comparative Examples 1-3 were respectively equipped on microbial fuel cells. The equipment method was as follows: carbon brushes were placed on the MFC anode and connected to the cathode through external lines to form a complete circuit.
[0080] Figure 3 The diagram shows a comparison of the power density and polarization curves of the microbial fuel cells assembled with the anode materials prepared in Example 1 and Comparative Examples 1-3 during their operating cycles.
[0081] exist Figure 3 In the figure, (a) is the MFC power density curve; (b) is the MFC polarization curve; (c) is the Fe leaching rate; and (d) is the COD removal rate. Figure 3 (a) and Figure 3 (b) It is evident that the microbial fuel cell using the PDA@CB@Fe / BC anode produced higher power density and voltage than anodes prepared by other methods, more than twice that of the comparative example (porous biochar modified with unloaded nano-iron). Power density and voltage are very important indicators for microbial fuel cells; higher voltage indicates higher efficiency in extracellular electron transfer at the anode, resulting in greater energy production.
[0082] from Figure 3 As shown in (c), the Fe leaching rate of the microbial fuel cell using the PDA@CB@Fe / BC anode is significantly lower than that of the anode directly loaded with PDA@CB@Fe3O4, indicating a lower potential for secondary environmental pollution and better alignment with environmental sustainability goals. Furthermore, Figure 3 (d) shows that the PDA@CB@Fe / BC exhibits a higher COD removal rate, which is superior to other comparative examples. This indicates that the microbial fuel cell anode PDA@CB@Fe / BC prepared by the method provided in this invention not only has excellent performance in terms of power generation capacity, but also has a strong ability to synergistically treat wastewater, highlighting its potential and prospects for in-depth application in the environmental field.
[0083] Figure 4 The diagrams show the anode and cathode microbial composition of the microbial fuel cells assembled from the anode materials prepared in Examples 1 and Comparative Examples 1-3. Figure 4It can be seen that equipping the anode material PDA@CB@Fe / BC, which has good biocompatibility prepared in this invention, has an impact on the microorganisms on the anode surface and its potential impact on the cathode. The results show that PDA@CB@Fe / BC not only increases the diversity of the microbial community and the proportion of electrogenic bacteria, but also selectively influences the microbial community on the cathode through a distal effect, exhibiting good bioselectivity and compatibility, and is an eco-friendly material.
[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a biochar-based microbial fuel cell anode material, characterized in that, Includes the following steps: Porous biochar is obtained by pyrolysis of biomass powder. The porous biochar was mixed with iron salt and water and then subjected to drying and oxygen-limited heat treatment in sequence to obtain nano-iron modified porous biochar. The nano-iron modified porous biochar and polydopamine solution were mixed to obtain a mixed slurry; the mixed slurry was coated on a carbon brush and dried to obtain a microbial fuel cell anode material.
2. The preparation method according to claim 1, characterized in that, The pyrolysis treatment method includes: performing a first pyrolysis on biomass powder to obtain pyrolytic biochar; mixing the pyrolytic biochar with a pore-expanding agent and then performing oxygen-limited pyrolysis to obtain porous biochar.
3. The preparation method according to claim 2, characterized in that, The temperature of the first pyrolysis is 600~900℃; the time of the first pyrolysis is 1~4h.
4. The preparation method according to claim 2, characterized in that, The mass ratio of the pyrolytic biochar to the pore-expanding agent is 1:(1~3).
5. The preparation method according to claim 2, characterized in that, The oxygen-limited pyrolysis temperature is 700~900℃; the oxygen-limited pyrolysis time is 1~4h.
6. The preparation method according to claim 1, characterized in that, The mass ratio of the porous biochar to the iron salt is 1:(0.08~0.1).
7. The preparation method according to claim 1, characterized in that, The oxygen-limited heat treatment temperature is 700~900℃; the oxygen-limited heat treatment time is 1~6h.
8. The preparation method according to claim 1, characterized in that, The mass ratio of the nano-iron modified porous biochar to polydopamine in the polydopamine solution is (0.5~1):(1~2).
9. The biochar-based microbial fuel cell anode material prepared by the preparation method according to any one of claims 1 to 8, characterized in that, It includes a carbon brush and a mixture of nano-iron modified porous biochar and polydopamine coated on the surface of the carbon brush.
10. The application of the biochar-based microbial fuel cell anode material as described in claim 9 in microbial fuel cells.