Biological fuel cell based on PTFE anion exchange membrane

Abstract

The invention discloses a PTFE anion exchange membrane-based biological fuel cell, which comprises an anode chamber, a cathode chamber, an anion exchange membrane and an external circuit system, the anion exchange membrane is a PTFE membrane grafted with quaternary ammonium groups and is arranged between the anode chamber and the cathode chamber, the anode chamber is internally provided with an anode, an anolyte and anaerobic sludge, the anode is attached with anaerobic electrogenesis microorganisms, and the cathode chamber is provided with an anode and an anode liquid. The anaerobic electrogenesis microorganisms decompose organic matters in the anode chamber and generate H < + >, CO2 and electrons; a cathode, a salt buffer solution and O2 are arranged in the cathode chamber, the cathode is conductively connected with the anode through an external circuit system, and OH <-> in the cathode chamber is transferred into the anode chamber through the anion exchange membrane. The biological fuel cell provided by the invention adopts the PTFE membrane grafted with quaternary ammonium groups as the anion exchange membrane, so that OH <-> in the cathode chamber is transferred into the anode chamber through the anion exchange membrane to maintain pH balance of the anode chamber, reduce ion deposition on the surface of the cathode and reduce charge transfer resistance, thereby obtaining higher power density and coulombic efficiency.

Description

Technical Field

[0001] This invention relates to the field of power generation and wastewater treatment technology, and in particular to a biofuel cell based on a PTFE anion exchange membrane. Background Technology

[0002] A biofuel cell is a device that directly converts chemical energy into electrical energy using biological materials or processes. Its core principle is to convert the chemical energy in organic matter into electrical energy through redox reactions using microorganisms or enzymes as biocatalysts. The main components include the anode (where microorganisms or immobilized enzymes decompose the substrate and release electrons), the cathode (which receives electrons and may require oxygen or an oxidant), the proton exchange membrane (which allows proton migration and blocks electrons), and the external circuitry (which conducts electrons to form an electric current). Biofuel cells have important applications in wastewater treatment, renewable energy production, and other fields, especially excelling in generating electricity from organic waste.

[0003] Existing microbial fuel cell (MFC) technologies typically employ cation exchange membranes (CEMs), such as Nafion 117. Protons can be transferred through the cation exchange membrane to the cathode to undergo redox reactions with oxygen, achieving charge transfer balance within the cell. However, microbial fuel cells using cation exchange membranes (Nafion 117 membranes) have the following drawbacks: 1. Cation crossover and pH imbalance: Cations in the anode (such as Na⁺ and K⁺) migrate unexpectedly to the cathode through the cation exchange membrane, disrupting microbial metabolism, reducing the catalytic efficiency of the cathode, and causing acidification of the anode chamber, thereby causing microbial instability and affecting the performance of the biofuel cell.

[0004] 2. Reduced electrochemical efficiency: Cations (such as Na⁺ and K⁺) in the anode migrate unexpectedly to the cathode through the cation exchange membrane and form ion deposits on the cathode surface. Ion deposits on the cathode surface increase internal resistance and reduce long-term power output.

[0005] 3. High cost and poor scalability: Nafion membranes are expensive (up to hundreds of dollars per square meter), which limits their feasibility in large-scale or commercial applications. Summary of the Invention

[0006] In view of the above problems, this invention overcomes at least one of them by proposing a biofuel cell based on a PTFE anion exchange membrane.

[0007] The technical solution adopted in this invention is as follows: This application provides a biofuel cell based on a PTFE anion exchange membrane, comprising: an anode chamber, a cathode chamber, an anion exchange membrane, and an external circuit system, wherein the anion exchange membrane is disposed between the anode chamber and the cathode chamber. The anion exchange membrane is a PTFE membrane grafted with quaternary ammonium groups; The anode chamber contains an anode, anolyte, and anaerobic sludge. Anaerobic electrogenic microorganisms are attached to the anode, decomposing the organic matter in the anode chamber and producing H₂. ＋ CO2 and electrons; The cathode chamber contains a cathode, an alkaline or neutral salt buffer solution, and O2 diffused into the salt buffer solution. The cathode and the anode are electrically connected via an external circuit system, and electrons from the anode chamber move to the cathode chamber through the external circuit system. O2 gains electrons and reacts with H2O in the salt buffer solution to generate OH-. － OH － It is transferred through the anion exchange membrane to the anode chamber and reacts with the H+ in the anode chamber. ＋ A neutralization reaction occurs, maintaining the pH balance of the anode chamber to prevent acidification, thereby supporting stable growth of anaerobic electrogenic microorganisms and long-term biofilm adhesion.

[0008] The biofuel cell provided in this application uses a PTFE membrane grafted with quaternary ammonium groups as an anion exchange membrane, enabling the OH- in the cathode chamber to... － (Or other anions, such as Cl⁻, HCO₃⁻) are transferred to the anode chamber through the anion exchange membrane to maintain the pH balance of the anode chamber, preventing acidification and providing a stable environment for the growth of anaerobic electrogenic microorganisms and long-term biofilm adhesion. Simultaneously, it reduces ion deposition on the cathode surface, lowers charge transfer resistance, and thus achieves higher power density and coulombic efficiency. Furthermore, compared to the Nafion membranes used in existing technologies, PTFE membranes are lower in cost, have a longer lifespan, and are easier to promote and apply on a large scale.

[0009] In an optional embodiment, the pH value of the cathode chamber is 10-12; The oxygen concentration in the cathode chamber is 20% to 40%. The limiting current of biofuel cells is 2 mA / cm² to 10 mA / cm².

[0010] To maximize the migration efficiency of hydroxide ions (OH⁻), the operating current density of the anion exchange membrane microbial fuel cell (AEM-MFC) should be controlled within its "ohmic control zone" (typically 1 mA / cm² to 5 mA / cm² for laboratory systems). This current density range will naturally maintain the cathode chamber pH within the ideal range of 10–12. In practice, the current density needs to be controlled by adjusting the external resistor or the anode substrate dosage to stabilize the cathode pH within this optimal range. If the pH rises too rapidly (>12.5), it indicates that the system may be approaching its mass transfer limit or that a precipitation reaction is imminent. In this case, measures such as reducing the load and cleaning the cathode should be taken to restore the system to its optimal operating state.

[0011] In an optional embodiment, within the cathode chamber, O2 diffused into the salt buffer also gains electrons and becomes O2. － O2 － It reacts with H2O in the salt buffer to produce H2O2, and H2O2 decomposes to produce H ＋ H ＋ It gains electrons and reacts with O2 to produce H2O, but not with OH-. － A neutralization reaction occurs.

[0012] When the oxygen concentration in the cathode chamber is high, H ＋ It will first gain electrons and react with O2 to produce H2O, without waiting for it to accumulate to a certain concentration before reacting with OH-. － A neutralization reaction occurs, which promotes the reaction of OH groups. － It is transferred to the anode chamber through the anion exchange membrane to maintain the pH balance of the anode chamber.

[0013] During this process, H ＋ With OH － Brief coexistence, and H ＋ No accumulation with OH － The concentration at which the neutralization reaction occurs has already reacted with O2.

[0014] In an optional embodiment, the cathode is a porous three-dimensional electrode structure, which ensures that oxygen can easily diffuse to the active site while retaining an appropriate amount of electrolyte to maintain ion conduction.

[0015] In an optional embodiment, a gas diffuser is further included, disposed below the cathode chamber, for blowing oxygen gas or an oxygen-containing gas into the cathode chamber.

[0016] In an optional embodiment, the cathode is a carbon paper electrode, the surface of which is coated with a cathode catalyst.

[0017] In an optional embodiment, the cathode catalyst is a platinum catalyst.

[0018] Carbon paper electrodes coated with platinum catalysts are used to ensure efficient electron transfer and catalytic activity.

[0019] In an optional embodiment, the anolyte in the anode chamber uses palm oil plant wastewater as a substrate; The salt buffer solution in the cathode chamber is a phosphate buffer solution.

[0020] In an optional embodiment, the method for preparing a PTFE membrane grafted with quaternary ammonium groups includes the following steps: A PTFE membrane is provided, and the PTFE membrane is subjected to plasma treatment to introduce reactive groups on the surface of the PTFE membrane, thereby forming an activated PTFE membrane; The activated PTFE membrane is immersed in a solution containing quaternary ammonium compound precursor monomers, an initiator is added, and the reaction is carried out under a nitrogen atmosphere at 60°C~70°C for 2 hours~24 hours to graft quaternary ammonium groups onto the PTFE membrane. The PTFE membrane after the reaction was rinsed with deionized water and then dried.

[0021] In an optional embodiment, the solution containing the quaternary ammonium compound precursor monomer is an ethanolic solution of [2-(methacryloyloxy)ethyl]trimethylammonium chloride, wherein the concentration of [2-(methacryloyloxy)ethyl]trimethylammonium chloride is 5% to 10%. The initiator is benzoyl peroxide at a concentration of 0.5% to 5% of the active ingredient.

[0022] The quaternary ammonium groups in an ethanol solution of [2-(methacryloyloxy)ethyl]trimethylammonium chloride are covalently bonded to the surface of a PTFE membrane via free radical graft polymerization. This method transforms ordinary PTFE membranes into anion exchange membranes (AEMs). The quaternary ammonium groups endow the membrane with hydroxide ion conductivity, while the original PTFE membrane framework retains its hydrophobicity, low swelling, and mechanical strength. When used as an anion exchange membrane (AEM) in microbial fuel cells (MFCs), it significantly improves the system's pH stability, electrochemical performance, and long-term operational feasibility, while maintaining high mechanical stability and exhibiting low cost.

[0023] In an optional embodiment, when the PTFE membrane is subjected to oxygen plasma treatment, reactive groups of -OH or -COOH are introduced onto the surface of the PTFE membrane, the plasma treatment power is 80W~120W, and the treatment time is 4 minutes~6 minutes.

[0024] In an optional embodiment, the temperature for drying the PTFE membrane is 55°C to 65°C.

[0025] In an optional embodiment, the external circuit system includes an external resistor, wires, and an electrical signal acquisition and recording device. The two ends of the external resistor are connected to the anode and the cathode respectively via wires. The electrical signal acquisition and recording device is connected in parallel across the two ends of the external resistor and is used to record electrical data in real time.

[0026] In an optional embodiment, the electrical signal acquisition recorder includes a multimeter and a computer connected to the multimeter for acquiring and analyzing electrical data such as current and voltage of the external resistor.

[0027] The beneficial effects of this invention are: (1) The biofuel cell provided in this application uses a PTFE membrane grafted with quaternary ammonium groups as an anion exchange membrane, so that the OH in the cathode chamber... － The pH balance of the anode chamber is maintained by transferring ions to it via an anion exchange membrane, preventing anode chamber acidification and providing a stable environment for the growth of anaerobic electrogenic microorganisms and long-term biofilm adhesion. Simultaneously, it reduces ion deposition on the cathode surface, lowers charge transfer resistance, and thus achieves higher power density and coulombic efficiency. Furthermore, compared to the Nafion membrane used in existing technologies, PTFE membranes are lower in cost, have a longer lifespan, and are easier to promote and apply on a large scale.

[0028] (2) The biofuel cell based on PTFE anion exchange membrane provided in this application uses PTFE membrane as the skeleton, which maintains its hydrophobicity, low swelling and mechanical strength. In actual use, it can maintain high mechanical stability and demonstrate long-term operational feasibility, which is convenient for large-scale promotion and use.

[0029] (3) By increasing the oxygen concentration in the cathode chamber, H ＋ It will first gain electrons and react with O2 to produce H2O, without waiting for it to accumulate to a certain concentration before reacting with OH-. － A neutralization reaction occurs, which promotes the reaction of OH groups. － The ion is transferred to the anode chamber through the anion exchange membrane, which helps maintain the pH balance in the anode chamber. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the biofuel cell according to an embodiment of this application; Figure 2 This describes the survival status of anaerobic electricity-generating microorganisms in the anode chamber of the biofuel cell in the embodiments and comparative examples of this application.

[0031] The figures in the diagram are labeled as follows: 1. Anode chamber; 2. Anode; 3. Anaerobic electrogenic microorganism; 4. Cathode chamber; 5. Cathode; 6. Anion exchange membrane; 7. Gas diffuser; 8. External resistor; 9. Multimeter; 10. Computer. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings.

[0033] Example This application provides a biofuel cell based on a PTFE anion exchange membrane, comprising: an anode chamber, a cathode chamber, an anion exchange membrane, and an external circuit system, wherein the anion exchange membrane is disposed between the anode chamber and the cathode chamber. The anion exchange membrane is a PTFE membrane grafted with quaternary ammonium groups; The anode chamber contains an anode, anolyte, and anaerobic sludge. Anaerobic electrogenic microorganisms are attached to the anode, which decompose the organic matter in the anode chamber and produce H₂. ＋ CO2 and electrons; The cathode chamber contains a cathode, an alkaline or neutral salt buffer solution, and O2 diffused into the salt buffer solution. The cathode and anode are electrically connected via an external circuit system, and electrons from the anode chamber move to the cathode chamber through the external circuit system. After gaining electrons, the O2 reacts with H2O in the salt buffer solution to generate OH-. － OH － It is transferred through the anion exchange membrane to the anode chamber and reacts with the H+ in the anode chamber. ＋ A neutralization reaction occurs, maintaining the pH balance of the anode chamber to prevent acidification, thereby supporting stable growth of anaerobic electrogenic microorganisms and long-term biofilm adhesion.

[0034] In one embodiment, the pH value of the cathode chamber is 10-12; The oxygen concentration in the cathode chamber is 20%~40%; The limiting current of biofuel cells is 2 mA / cm² to 10 mA / cm².

[0035] In the cathode chamber, O2 diffused into the salt buffer also gains electrons and becomes O2. － O2 － It reacts with H2O in the salt buffer to produce H2O2, and H2O2 decomposes to produce H ＋ H ＋ It gains electrons and reacts with O2 to produce H2O, but not with OH-. － A neutralization reaction occurs. When the oxygen concentration in the cathode chamber is high, H... ＋ It will first gain electrons and react with O2 to produce H2O, without waiting for it to accumulate to a certain concentration before reacting with OH-. － A neutralization reaction occurs, which promotes the reaction of OH groups. － H+ is transferred to the anode chamber via the anion exchange membrane, maintaining the pH balance within the anode chamber. During this process, H+... ＋ With OH － Brief coexistence, and H ＋ No accumulation with OH －The concentration at which the neutralization reaction occurs has already reacted with O2.

[0036] In one embodiment, the cathode is a porous three-dimensional electrode structure, which ensures that oxygen can easily diffuse to the active site while retaining an appropriate amount of electrolyte to maintain ion conduction.

[0037] In one embodiment, a gas diffuser is also included, disposed below the cathode chamber, for blowing oxygen gas or oxygen-containing gas into the cathode chamber.

[0038] In one embodiment, the cathode is a carbon paper electrode, the surface of which is coated with a cathode catalyst. The cathode catalyst is a platinum catalyst. The carbon paper electrode coated with the platinum catalyst is used to ensure efficient electron transfer and catalytic activity.

[0039] In one embodiment, the anolyte in the anode chamber uses palm oil factory wastewater as a substrate; the salt buffer in the cathode chamber is a phosphate buffer.

[0040] In one embodiment, the method for preparing a biofuel cell based on a PTFE anion exchange membrane provided in this application includes: Preparation of PTFE membranes (anion exchange membranes) grafted with quaternary ammonium groups: We provide commercially available PTFE membranes and perform plasma treatment on them to introduce reactive groups -OH or -COOH onto the surface of the PTFE membrane, forming an activated PTFE membrane. The plasma treatment power is 100W and the treatment time is 5 minutes. The activated PTFE membrane was immersed in a 10% ethanol solution of [2-(methacryloyloxy)ethyl]trimethylammonium chloride, 3% benzoyl peroxide was added as an initiator, and the reaction was carried out at 60°C for 2 hours under a nitrogen atmosphere to graft quaternary ammonium groups onto the PTFE membrane. After rinsing the PTFE membrane with deionized water to remove unreacted monomers, and then drying it at 60°C, a PTFE membrane grafted with quaternary ammonium groups can be obtained, which can be used as a PTFE anion exchange membrane for biofuel cells.

[0041] Preparation of biofuel cells based on PTFE anion exchange membranes (e.g.) Figure 1 (as shown) Two identical dual-chamber MFCs (i.e., anode chamber 1 and cathode chamber 4) were constructed using acrylic blocks. The working volume of both anode chamber 1 and cathode chamber 4 was 250 mL. Anode chamber 1 and cathode chamber 4 were separated by a PTFE membrane grafted with quaternary ammonium groups prepared above. Anode 2 is installed in anode chamber 1. Anaerobic sludge is inoculated into anode 2, and real palm oil factory wastewater (POME) is used as substrate and energy source. A cathode 5 and a gas diffuser 7 are installed inside the cathode chamber 4. The gas diffuser 7 is located below the cathode chamber 4. The cathode chamber 4 is filled with a 50 mmol / L phosphate buffer solution and is continuously aerated through the gas diffuser 7 (oxygen gas or oxygen-containing gas is blown in) to provide oxygen as an electron acceptor. The cathode 5 is a carbon paper electrode, and the surface of the carbon paper electrode is coated with a platinum catalyst to ensure efficient electron transfer and catalytic activity.

[0042] An external circuit is set up between the anode 2 and the cathode 5 by a guide. An external resistor 8 and an electrical signal acquisition and recording instrument (multimeter 9 and computer 10 connected to multimeter 9, used to collect and analyze electrical data such as current and voltage of external resistor 8) are set on the external circuit. The electrical signal acquisition and recording instrument is connected in parallel across the external resistor 8 to form a biofuel cell. The biofuel cell operates in continuous mode under the conditions that the external resistor 8 is 1000Ω and the temperature is maintained at 30±2°C.

[0043] During operation: Anaerobic electrogenic microorganisms 3 are attached to anode 2. These microorganisms decompose the organic matter in anode chamber 1 and produce H2O. ＋ CO2 and electrons; the electrons are transferred to the cathode chamber 4 along the external circuit. The pH value of cathode chamber 4 is 10-12, the oxygen concentration in cathode chamber 4 is 20%-40%, and the limiting current of the biofuel cell is 2 mA / cm²-10 mA / cm². O₂ gains electrons and reacts with H₂O in the salt buffer to generate OH⁻. － OH － The ion is transferred through anion exchange membrane 6 into anode chamber 1, and reacts with H+ in anode chamber 1. ＋ A neutralization reaction occurs, maintaining the pH balance of anode chamber 1 to prevent acidification of anode chamber 1, thereby supporting the stable growth of anaerobic electrogenic microorganisms 3 and long-term biofilm adhesion.

[0044] Inside the cathode chamber 4, O2 diffused into the salt buffer solution also gains electrons and becomes O2. － O2 － It reacts with H2O in the salt buffer to produce H2O2, and H2O2 decomposes to produce H ＋ H ＋ It gains electrons and reacts with O2 to produce H2O, but not with OH-. － A neutralization reaction occurs. When the oxygen concentration in cathode chamber 4 is high, H+... ＋ It will first gain electrons and react with O2 to produce H2O, without waiting for it to accumulate to a certain concentration before reacting with OH-. － A neutralization reaction occurs, which promotes the reaction of OH groups. － The ions are transferred to the anode chamber 1 via the anion exchange membrane 6, maintaining the pH balance of the anode chamber 1. During this process, H+... ＋ With OH － Brief coexistence, and H＋ No accumulation with OH － The concentration at which the neutralization reaction occurs has already reacted with O2.

[0045] Data collection and organization: Voltage output: The voltage across the external resistor is recorded at 30-minute intervals using a digital multimeter 9. Power density is calculated based on the stable voltage output and the projected surface area of ​​the anode.

[0046] Chemical oxygen demand (COD) removal rate: The COD concentration in the anode influent and effluent was measured weekly using a standard Hach COD test kit to determine the treatment efficiency.

[0047] Coulomb efficiency (CE): CE is calculated by comparing the total charge recovered as current with the theoretical charge removed based on COD.

[0048] Electrochemical impedance spectroscopy (EIS): EIS tests were performed in the frequency range of 100 kHz to 10 mHz with both MFCs at their stable operating points to determine the internal resistance and charge transfer resistance.

[0049] The measured data are shown in Table 1 below.

[0050] Comparative example: A biofuel cell based on Nafion 117 cation exchange membrane: The commercially available Nafion 117 cation exchange membrane was pretreated according to the standard procedure: it was boiled for 1 hour in 3% hydrogen peroxide, deionized water, 0.5 Mol / L sulfuric acid solution and deionized water respectively to ensure complete protonation and removal of impurities.

[0051] Two identical bichat MFCs were constructed using acrylic blocks, each with a working volume of 250 mL for the anode and cathode chambers. The reaction chambers were separated by a Nafion 117 cation exchange membrane.

[0052] Anaerobic sludge was inoculated at the anode, using real palm oil mill wastewater (POME) as both substrate and energy source. The cathode chamber was filled with a 50 mMol / L phosphate buffer solution and continuously aerated to provide oxygen as an electron acceptor.

[0053] Both MFC chambers operate in continuous mode under conditions of 1000Ω external resistance and a temperature maintained at 30±2°C.

[0054] Similarly, data was collected and organized for the comparative examples, and the measured data are shown in Table 1 below.

[0055] Table 1

[0056] Data analysis was performed on the PTFE anion exchange membrane-based biofuel cell of the embodiment and the Nafion 117 cation exchange membrane-based biofuel cell of the comparative example: Compared with the comparative example, the battery of the embodiment has higher power density, higher COD removal rate, higher coulombic efficiency, longer stable operation time and lower charge transfer resistance.

[0057] The reason is that the PTFE anion exchange membrane-based biofuel cell in this application embodiment endows the PTFE membrane with anion exchange capacity by grafting quaternary ammonium groups, enabling it to conduct hydroxide ions (OH⁻) to maintain pH balance, avoid acidification of the anode chamber, and ensure the survival environment required by anaerobic electrogenic microorganisms, thereby achieving more stable power generation. At the same time, it retains the inherent hydrophobic framework structure of PTFE, ensuring that the membrane has extremely low water absorption and swelling. This structural stability directly translates into excellent mechanical durability, supporting long-term stable operation for more than 600 hours. In addition, compared with CEM-MFC, AEM-MFC reduces the formation of precipitates at the cathode, and the stable framework provides a reliable path for ion transport. Combined with the conductivity of surface functional groups, it reduces charge transfer resistance and increases power density.

[0058] Please refer to Figure 2 During battery operation, the microorganisms in the anode chamber of the embodiment and the anode chamber of the comparative example were scanned and imaged. In the figure, (A) shows the attachment of microorganisms in the embodiment AEM-MFC on the 10th day of operation, (B) shows the attachment of microorganisms in the comparative example CEM-MFC on the 10th day of operation, (C) shows the attachment of microorganisms in the embodiment AEM-MFC on the 20th day of operation, and (D) shows the attachment of microorganisms in the comparative example CEM-MFC on the 20th day of operation.

[0059] As shown in the figure, after 10 days of operation, the electrode surfaces of both batteries were completely covered by biofilm, indicating that microorganisms uniformly adhered to the electrode surfaces, which is beneficial for electron transfer. By day 20, the AEM electrode surface still maintained a high bacterial density, while the amount of microorganisms on the Nafion 117 (CEM) electrode surface was significantly reduced. Correspondingly, on day 20, the pH value of the anode chamber of the AEM-MFC example was (6.7 ± 0.3), while the pH value of the anode chamber of the CEM-MFC comparison example was (5.2 ± 0.3). The acidic environment inhibits the growth of non-acidophilic bacteria, and compared to the anode chamber of the CEM-MFC example, the AEM-MFC example effectively prevented anode chamber acidification.

[0060] In reality, Nafion 117 cation exchange membranes exhibit limited stability in real wastewater: while Nafion performs well under synthetic laboratory conditions, its mechanical durability, stability, and compatibility with microorganisms significantly decrease in complex real wastewater environments.

[0061] Furthermore, PTFE membranes, or polytetrafluoroethylene membranes, are thin-film materials with excellent chemical and thermal stability. They possess a low coefficient of friction, low water absorption, high mechanical strength, and good heat resistance. PTFE membranes are widely used in filtration (such as air and liquid filtration), membrane materials (such as battery separators), biomedicine (such as tissue engineering scaffolds), and surface coatings (such as waterproof and breathable membranes). Their main advantages include strong chemical inertness and good durability, but limitations in pore size distribution and airflow may exist in certain applications. The cost of PTFE membranes is approximately $50 / m², compared to approximately $500 / m² for Nafion 117 membranes. Therefore, the PTFE anion exchange membrane-based biofuel cell provided in this application offers approximately ten times the cost advantage. Combined with its superior long-term performance, this invention is more practical for large-scale and decentralized wastewater treatment applications.

[0062] The PTFE anion exchange membrane-based biofuel cell provided in this application exhibits superior electrochemical performance, higher efficiency, longer operational stability, better microbial compatibility, greater durability, and lower cost. These advantages make it a more feasible solution for the commercialization and practical application of microbial fuel cells.

[0063] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of the present invention.

Claims

1. A biofuel cell based on a PTFE anion exchange membrane, characterized in that, include: The system includes an anode chamber, a cathode chamber, an anion exchange membrane, and an external circuit system, wherein the anion exchange membrane is disposed between the anode chamber and the cathode chamber. The anion exchange membrane is a PTFE membrane grafted with quaternary ammonium groups; The anode chamber contains an anode, anolyte, and anaerobic sludge. Anaerobic electrogenic microorganisms are attached to the anode, decomposing the organic matter in the anode chamber and producing H₂. ＋ CO2 and electrons; The cathode chamber contains a cathode, an alkaline or neutral salt buffer solution, and O2 diffused into the salt buffer solution. The cathode and the anode are electrically connected via an external circuit system, and electrons from the anode chamber move to the cathode chamber through the external circuit system. O2 gains electrons and reacts with H2O in the salt buffer solution to generate OH-. － OH － It is transferred through the anion exchange membrane to the anode chamber and reacts with the H+ in the anode chamber. ＋ A neutralization reaction occurs, maintaining the pH balance of the anode chamber to prevent acidification, thereby supporting stable growth of anaerobic electrogenic microorganisms and long-term biofilm adhesion.

2. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, The pH value of the cathode chamber is 10~12; The oxygen concentration in the cathode chamber is 20% to 40%. The limiting current of biofuel cells is 2 mA / cm² to 10 mA / cm².

3. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, In the cathode chamber, O2 diffused into the salt buffer also gains electrons and becomes O2. － O2 － It reacts with H2O in the salt buffer to produce H2O2, and H2O2 decomposes to produce H ＋ H ＋ It gains electrons and reacts with O2 to produce H2O, but not with OH-. － A neutralization reaction occurs.

4. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, It also includes a gas diffuser disposed below the cathode chamber, the gas diffuser being used to blow oxygen gas or oxygen-containing gas into the cathode chamber.

5. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, The cathode is a carbon paper electrode, and the surface of the carbon paper electrode is coated with a cathode catalyst.

6. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, The anolyte in the anode chamber uses palm oil plant wastewater as the substrate; The salt buffer solution in the cathode chamber is a phosphate buffer solution.

7. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, The method for preparing PTFE membranes grafted with quaternary ammonium groups includes the following steps: A PTFE membrane is provided, and the PTFE membrane is subjected to plasma treatment to introduce reactive groups on the surface of the PTFE membrane, thereby forming an activated PTFE membrane; The activated PTFE membrane is immersed in a solution containing quaternary ammonium compound precursor monomers, an initiator is added, and the reaction is carried out under a nitrogen atmosphere at 60°C~70°C for 2 hours~24 hours to graft quaternary ammonium groups onto the PTFE membrane. The PTFE membrane after the reaction was rinsed with deionized water and then dried.

8. A biofuel cell based on a PTFE anion exchange membrane as described in claim 7, characterized in that, The solution containing the quaternary ammonium compound precursor monomer is an ethanolic solution of [2-(methacryloyloxy)ethyl]trimethylammonium chloride, with a concentration of 5% to 10%. The initiator is benzoyl peroxide at a concentration of 0.5% to 5% of the active ingredient.

9. A biofuel cell based on a PTFE anion exchange membrane as described in claim 7, characterized in that, When treating PTFE membranes with oxygen plasma, reactive groups such as -OH or -COOH are introduced onto the surface of the PTFE membrane. The plasma treatment power is 80W~120W, and the treatment time is 4 minutes~6 minutes.

10. A biofuel cell based on a PTFE anion exchange membrane as described in claim 1, characterized in that, The external circuit system includes an external resistor, wires, and an electrical signal acquisition and recording device. The two ends of the external resistor are connected to the anode and the cathode respectively through wires. The electrical signal acquisition and recording device is connected in parallel across the two ends of the external resistor and is used to record electrical data in real time.

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