Photocatalysis / microorganism coupled anode microbial fuel cell and application thereof in enhanced degradation of sulfamethoxazole

Abstract

The invention relates to a microbial fuel cell and application thereof, in particular to a photocatalytic / microbial coupled anode microbial fuel cell and application thereof in enhanced degradation of sulfamethoxazole. Aiming at the degradation treatment of typical refractory antibiotics such as sulfamethoxazole, the invention provides a photocatalytic / microbial coupled anode microbial fuel cell which can induce a photo-generated hole generated by a photocatalyst through a biological electric field generated by microbial degradation of pollutants, thereby promoting the separation of photo-generated electron hole pairs of the photocatalyst, and further improving the degradation efficiency of the antibiotics. The problem that photo-generated electron hole pairs of a photocatalyst are easy to compound is solved. Meanwhile, due to the existence of the photocatalyst, the electron transfer between the anode electroactive microorganisms and the anode can be improved through the generation of photo-generated holes, and the extracellular electron transfer of the microorganisms is enhanced. When being used for degrading sulfamethoxazole, the photocatalytic / microbial coupled anode microbial fuel cell disclosed by the invention has an extremely important scientific research value and a wide practical application prospect.

Description

Technical Field

[0001] The invention relates to a microbial fuel cell and application thereof. Background Art

[0002] Due to the widespread use of antibiotics at home and abroad, antibiotic pollution has become a key environmental issue that needs to be addressed urgently in my country and even the world. Antibiotics have been detected in surface water, groundwater, domestic sewage and drinking water in most parts of the world. How to efficiently treat antibiotic wastewater has attracted great attention from many experts and scholars at home and abroad. Sulfamethoxazole (SMX) is a sulfonamide antibiotic that is currently widely used in the world and is widely used in the treatment of bacterial infections. Due to the large-scale use of SMX, its residual condition in the environment has become increasingly severe, its detection rate in the environment has been at a high level, and the cumulative amount has shown a continuous upward trend. According to relevant reports, SMX will remain in the water environment for a long time, posing a serious threat to aquatic life. According to the list of carcinogens published by the World Health Organization's International Agency for Research on Cancer, SMX is included in the list of Class 3 carcinogens. Therefore, how to effectively treat antibiotic wastewater has attracted widespread attention from experts and scholars at home and abroad.

[0003] Microbial fuel cell (MFC) technology has shown certain potential in the treatment of antibiotic wastewater. It uses microorganisms as catalysts to degrade pollutants in wastewater, converts the chemical contained in the wastewater into electrical energy, and realizes the functions of outputting electrical energy and waste resource utilization. At present, MFC technology has good removal efficiency for many common antibiotics such as chlortetracycline, sulfadimethoxine, roxithromycin, ciprofloxacin, etc. Its unique advantage is that the reaction conditions are relatively mild, and it can operate stably under normal temperature and pressure environment, without complex extreme conditions such as high pressure and high temperature. The operation process is simple and easy, and there is no need to invest a lot of extra energy to maintain the reaction process, which greatly reduces the treatment cost and simplifies the complexity of the treatment process. However, MFC technology also has certain defects. Its output power density is at a low level, which seriously limits its treatment efficiency and production capacity in large-scale practical applications. And when using MFC to treat antibiotic wastewater, the concentration of antibiotic wastewater that can be dealt with is relatively limited. Studies have shown that high-concentration antibiotic wastewater has strong biological toxicity. When this type of wastewater enters the MFC system, it will have a significant inhibitory effect on the key microorganisms, which will greatly reduce the degradation and mineralization rate of antibiotics in the MFC system, making it difficult to achieve deep purification and thorough mineralization of high-concentration antibiotic wastewater. Therefore, in order to break through this bottleneck and achieve deep degradation and complete mineralization of antibiotic wastewater, coupling MFC with other technologies has become a research direction with great exploration value. Photocatalytic technology has shown great potential in sustainable energy utilization due to its unique advantage of using inexhaustible and geographically unrestricted sunlight as an energy driving source. It also has good stability, can maintain stable catalytic performance during long-term operation, and the entire reaction process is environmentally friendly. After being exposed to light, the photocatalyst can produce strong oxidizing active substances such as hydroxyl radicals, superoxide radicals and holes. These active species can degrade and mineralize various pollutants in an unselective manner. Unfortunately, photocatalytic technology also has inherent defects. Most photocatalysts have low light energy utilization rates, and a large amount of solar energy cannot be effectively converted and utilized during the reaction process, resulting in energy waste. In addition, photogenerated electron-hole pairs are prone to recombination, which greatly reduces the actual efficiency of the photocatalytic reaction, thus restricting the application effect and promotion scope of photocatalytic technology in large-scale practical projects. Coupling microbial fuel cell technology with photocatalytic technology and integrating the advantages of the two technologies can not only make up for the low power output of the microbial electrochemical system and the easy recombination of electron holes in the photocatalyst, but also achieve efficient degradation and mineralization of pollutants.

[0004] In summary, in the field of antibiotic wastewater treatment, especially for the mineralization treatment of typical difficult-to-degrade antibiotics such as sulfamethoxazole, if we can innovatively couple the clean light energy with the chemical energy contained in the wastewater through the catalytic action of microorganisms, and construct a photocatalytic-microbial coupled anode electrochemical system, that is, use the electrical energy generated by microbial degradation of organic matter to effectively promote the separation of photogenerated electrons and holes in the photocatalyst during the photocatalytic process, thereby overcoming the problem of easy recombination of photogenerated electron-hole pairs and improving the photocatalytic degradation performance of SMX. At the same time, through the input of light energy, the power output and SMX degradation efficiency of MFC can be effectively improved, thereby realizing the efficient degradation and mineralization of SMX, which will be of great significance. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a photocatalytic / microbial coupled anode microbial fuel cell and its application in enhanced degradation of sulfamethoxazole.

[0006] The present invention provides a photocatalytic and microbial coupled anode microbial fuel cell that can couple two major clean energy sources, chemical energy and light energy, in sewage. For the degradation treatment of typical difficult-to-degrade antibiotics such as sulfamethoxazole, the photocatalytic / microbial coupled anode microbial fuel cell can induce the photogenerated holes generated by the photocatalyst through the bioelectric field generated by the microbial degradation of pollutants, thereby promoting the separation of the photocatalyst photogenerated electron-hole pairs, and overcoming the problem that the photocatalyst photogenerated electron-hole pairs are easy to recombine. At the same time, due to the presence of the photocatalyst, the generation of photogenerated holes will improve the electron transfer between the anode electroactive microorganisms and the anode, and enhance the extracellular electron transfer of the microorganisms, making up for the low power density of the MFC technology. Therefore, the photocatalytic / microbial coupled anode microbial fuel cell is used to degrade sulfamethoxazole, achieving the complementary advantages and mutual promotion of the two. It is expected to provide a simple, efficient and practical solution for the deep degradation of sulfamethoxazole, which has extremely important scientific research value and broad practical application prospects.

[0007] The photocatalytic / microbial coupled anode microbial fuel cell in the present invention exhibits unique advantages and plays a key role. It uses monoclinic BiVO with oxygen vacancies 4As a photocatalyst, this oxygen vacancy bismuth vanadate can efficiently degrade pollutants and is a core element for improving the photocatalytic degradation capability of the coupled anode. Graphene is used to modify carbon felt, and its high conductivity improves the electronic conduction and photogenerated carrier transfer efficiency of the carbon felt, reduces resistance to increase power density, and improves hydrophilicity to promote material exchange, which is crucial for enhancing the electrochemical performance and overall reaction efficiency of the anode. Dodecyltrimethoxysilane (DTMS) is used as a hydrophobic agent to reduce the attachment of microorganisms to the surface of the photocatalyst, avoiding the death of microorganisms due to photooxidation and the passivation of the photocatalyst. The design of the anode plays an indispensable role in ensuring the overall electrochemical performance, reaction efficiency, long-term effectiveness, and reliability, ensuring that the entire photocatalytic / microbial coupled anode microbial fuel cell can continue to stably exert its functional advantages in the fields of antibiotic wastewater treatment, thereby enhancing the practicality and competitiveness of the present invention.

[0008] A photocatalytic / microbiologically coupled anode microbial fuel cell, wherein the reactor of the microbial fuel cell consists of two chambers, a cathode chamber and an anode chamber;

[0009] The top of the anode chamber and the cathode chamber are respectively provided with three holes, namely, the anode port, the cathode port, and the sampling and liquid replacement port;

[0010] The anode chamber and the cathode chamber are separated by a cation exchange membrane;

[0011] The anode chamber is filled with anolyte, and the anode is arranged in the anolyte through the anode port;

[0012] A quartz glass tube is embedded in one side of the anode chamber for placing a light source;

[0013] The cathode chamber is filled with cathode liquid, and the cathode is arranged in the cathode chamber through the cathode port;

[0014] The photocatalytic / microbial coupled anode microbial fuel cell is provided with a resistor outside, one end of the two wires is connected to the resistor respectively, and the other end is connected to the anode and the cathode respectively to form a loop;

[0015] The anode is a photocatalytic / microbial coupling anode containing electrogenic bacteria; the photocatalytic / microbial coupling anode containing electrogenic bacteria is composed of graphene-modified carbon felt, BiVO 4 It is composed of a photocatalyst and a DTMS hydrophobic layer.

[0016] A photocatalytic / microbial coupled anode microbial fuel cell is used for enhanced degradation of sulfamethoxazole.

[0017] Principle of the present invention:

[0018] The present invention uses a photocatalytic / microbial coupled anode microbial fuel cell, and adds a solution containing sulfamethoxazole and sodium acetate to the anode chamber of the microbial fuel cell to simulate antibiotic-containing wastewater, thereby starting the entire photocatalytic / microbial coupled anode microbial fuel cell. The anode part uses a photocatalytic / microbial coupled anode; under light conditions, the photocatalyst BiVO 4 It will be excited by light to produce photogenerated electron-hole pairs. At the same time, the microorganisms attached to the surface of the electrode will degrade sulfamethoxazole. During this degradation process, the microorganisms will produce electrons. The electrons generated from the anode (including electrons generated by microbial metabolism and photogenerated electrons) will be conducted toward the carbon brush cathode of the battery through the external circuit to form a complete current loop. The cathode and cathode chambers are separated by a cation exchange membrane. When the anode microorganisms degrade sulfamethoxazole, they will produce protons. These protons can pass through the cation exchange membrane into the cathode chamber and participate in the related reactions occurring at the cathode, thereby maintaining the charge balance within the entire battery system and the continuous reaction.

[0019] The photogenerated holes generated by the photocatalyst in the anode chamber will react with water or hydroxyl ions in the anode chamber to generate free radicals. These free radicals can cooperate with microorganisms to degrade sulfamethoxazole and enhance the degradation effect. At the same time, the bioelectric field generated by microbial degradation of pollutants can induce the photogenerated holes generated by the photocatalyst, thereby promoting the separation of photogenerated electron-hole pairs of the photocatalyst; the generation of photogenerated holes will also improve the electron transfer between the electroactive microorganisms of the anode and the anode, thereby increasing the power output of the MFC cell. In summary, the synergistic effect of photocatalysis and microbial degradation of pollutants will greatly improve the degradation and mineralization rate of pollutants. It has the characteristics of stable process, feasible operation and clean energy. It has shown good application potential in the field of antibiotic wastewater treatment and provides a valuable technical solution for solving the problem of antibiotic wastewater pollution.

[0020] Advantages of the present invention:

[0021] First, the present invention successfully realizes the coupling of two clean energy sources, chemical energy and light energy, contained in sewage through the construction of a photocatalytic / microbial coupled anode microbial fuel cell; on the one hand, the electrons generated by the anode microorganisms promote the BiVO 4 The photocatalyst separates the photogenerated electrons and holes; on the other hand, the generation of photogenerated holes will enhance the extracellular electron transfer of microorganisms;

[0022] 2. The present invention utilizes a photocatalytic / microbial coupled anode microbial fuel cell to degrade sulfamethoxazole under light. Compared with a simple microbial fuel cell, the degradation rate of sulfamethoxazole is significantly improved, and the power density of the microbial fuel cell is significantly improved. The design of the photocatalytic / microbial coupled anode utilizes the synergistic cooperation of the microbial degradation process of pollutants and the photocatalytic process to achieve the efficiency improvement of the coupled anode microbial fuel cell and the efficient degradation of sulfamethoxazole. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the photocatalytic / microbial coupled anode microbial fuel cell of the present invention;

[0024] Figure 2 The power density diagram of the photocatalytic / microbial coupled anode microbial fuel cell, in which 5mg-D / B / rGO / CF-light is Example 1 and 5mg-rGO / CF-dark is Control Example 1;

[0025] Figure 3 This is a performance diagram of the degradation of sulfamethoxazole using a photocatalytic / microbial coupled anode microbial fuel cell. In the figure, D / B / rGO / CF-light is Example 1, and rGO / CF-dark is Control Example 1. DETAILED DESCRIPTION

[0026] Specific implementation method 1: This implementation method is a photocatalytic / microbial coupled anode microbial fuel cell, and the reactor of the microbial fuel cell consists of two chambers: a cathode chamber and an anode chamber;

[0027] The top of the anode chamber and the cathode chamber are respectively provided with three holes, namely, the anode port, the cathode port, and the sampling and liquid replacement port;

[0028] The anode chamber and the cathode chamber are separated by a cation exchange membrane;

[0029] The anode chamber is filled with anolyte, and the anode is arranged in the anolyte through the anode port;

[0030] A quartz glass tube is embedded in one side of the anode chamber for placing a light source;

[0031] The cathode chamber is filled with cathode liquid, and the cathode is arranged in the cathode chamber through the cathode port;

[0032] The photocatalytic / microbial coupled anode microbial fuel cell is provided with a resistor outside, one end of the two wires is connected to the resistor respectively, and the other end is connected to the anode and the cathode respectively to form a loop;

[0033] The anode is a photocatalytic / microbial coupling anode containing electrogenic bacteria; the photocatalytic / microbial coupling anode containing electrogenic bacteria is composed of graphene-modified carbon felt, BiVO 4 It is composed of a photocatalyst and a DTMS hydrophobic layer.

[0034] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the light source is an LED lamp; the cathode is a carbon brush cathode; the preparation method of the anolyte is as follows: 1g of anhydrous sodium acetate, 100mL of phosphate buffer solution and 5mg of sulfamethoxazole are added to deionized water to a constant volume of 1000mL to obtain the anolyte; the preparation method of the catholyte is as follows: potassium ferrocyanide is dissolved in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50mmol / L, which is the catholyte. The other steps are the same as those of specific implementation method 1.

[0035] Specific implementation method three: This implementation method is different from specific implementation method one or two in that: the preparation method of the photocatalytic / microorganism coupling anode is specifically completed according to the following steps:

[0036] 1. Preparation of graphene-modified carbon felt:

[0037] ①, soak the carbon felt block in acetone and anhydrous ethanol for a period of time, then immerse it in anhydrous ethanol for ultrasonic treatment, and then immerse it in deionized water for ultrasonic treatment, take it out and place it in an oven to dry, so as to obtain the cleaned carbon felt;

[0038] ②, coating the graphene oxide dispersion on one surface of the carbon felt, placing it in an oven to dry, and repeating 2 to 4 times to obtain the graphene oxide modified carbon felt;

[0039] ③. In a three-electrode system, the graphene oxide-modified carbon felt is immersed in Na 2 SO 4 In the electrolyte, a constant voltage of -1.2 V is applied to the graphene oxide modified carbon felt for 5 to 10 minutes using a chronoamperometry method of an electrochemical workstation, and then the carbon felt is rinsed with deionized water and dried to obtain a graphene modified carbon felt;

[0040] 2. Preparation of BiVO 4 / Graphene modified carbon felt:

[0041] ①、BiVO 4 , Nafion solution and isopropanol were mixed, then ultrasonicated and magnetically stirred for a period of time to obtain a uniform BiVO 4 Paste;

[0042] ②、BiVO 4The paste is evenly coated on a surface of the graphene-modified carbon felt that does not contain graphene, and then placed in an oven to dry for a period of time to obtain BiVO 4 / graphene modified carbon felt;

[0043] 3. Preparation of Hydrophobically Modified BiVO 4 / Graphene modified carbon felt coupled anode:

[0044] ①, adding dodecyltrimethoxysilane to anhydrous ethanol, and ultrasonicating for a period of time to obtain an ethanol solution of dodecyltrimethoxysilane;

[0045] ② Use a pipette to absorb the ethanol solution of dodecyltrimethoxysilane and apply it on BiVO 4 / Graphene modified carbon felt containing BiVO 4 and then placed in an oven to dry for a period of time to obtain a hydrophobically modified BiVO 4 The photocatalytic / microorganism coupled anode is a photocatalytic / microorganism coupled anode. The other steps are the same as those in the first or second embodiment.

[0046] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: the size of the carbon felt block described in step 1① is 2cm×3cm×0.5cm; in step 1①, the carbon felt block is soaked in acetone and anhydrous ethanol for 20min to 30min respectively, then immersed in anhydrous ethanol for ultrasonic treatment for 30min to 60min, and then immersed in deionized water for ultrasonic treatment for 30min to 60min, and then taken out and placed in an oven at a temperature of 60℃ to 70℃ for 5h to 7h to obtain the cleaned carbon felt. The other steps are the same as those of specific embodiments 1 to 3.

[0047] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: the graphene oxide dispersion described in step 1 ② is a single-layer graphene oxide dispersion with a concentration of 2 mg / mL, the solvent is ethylene glycol, the average radial size of the graphene oxide is 5 μm to 8 μm, and the thickness is 1 nm; the Na 2 SO 4 The concentration of the electrolyte is 0.5 mol / L; the drying temperature in step 1③ is 60°C to 70°C, and the drying time is 3h to 5h. The other steps are the same as those in specific embodiments 1 to 4.

[0048] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that: the BiVO 4, the mass volume ratio of Nafion solution and isopropanol is 240mg:600μL:400μL; the mass fraction of Nafion solution described in step 2① is 5%; the ultrasonic time described in step 2① is 5min~10min; the magnetic stirring time described in step 2① is 20h~24h, and the speed of magnetic stirring is 800r / min. The other steps are the same as those in specific embodiments 1 to 5.

[0049] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that: the BiVO 4 The ratio of the volume of the paste to the surface area of ​​the graphene-modified carbon felt is 1000 μL: (5 cm 2 ~7cm 2 ); the drying temperature in step 2② is 50°C to 70°C, and the drying time is 10h to 12h. The other steps are the same as those in specific embodiments 1 to 6.

[0050] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that the volume ratio of dodecyltrimethoxysilane to anhydrous ethanol in step three ① is (50 μL to 60 μL): 10 mL; the ultrasonic time in step three ① is 40 min to 60 min; the volume of the ethanol solution of dodecyltrimethoxysilane in step three ② is about the same as that of BiVO 4 / The surface area ratio of graphene-modified carbon felt is 5mL:(5cm 2 ~7cm 2 ); the drying temperature in step 3② is 50℃~70℃, and the drying time is 20h~24h. The other steps are the same as those in specific embodiments 1 to 7.

[0051] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: the preparation method of the photocatalytic / microbial coupled anode containing electrogenic bacteria is specifically prepared according to the following steps:

[0052] (1) Prepare anolyte, culture medium solution and catholyte:

[0053] ①, add 1g of anhydrous sodium acetate, 100mL of phosphate buffer solution and 5mg of sulfamethoxazole to deionized water and make the volume to 1000mL to obtain an anolyte;

[0054] The phosphate buffer solution described in step (1) ① is prepared as follows: weigh 3.1 g NH 4 Cl, 1.3 g KCl, 33.2 g NaH 2 PO 4 ·2H 2 O and 103.2g Na2 HPO 4 12H 2 O into a 1L volumetric flask, then pour 500mL of deionized water into the volumetric flask and stir with a magnetic stirrer to make NH 4 Cl, KCl, NaH 2 PO 4 ·2H 2 O and Na 2 HPO 4 12H 2 O was fully dissolved, and then deionized water was added to make the solution to 1 L to obtain a phosphate buffer solution;

[0055] ②, add 500 mL of fresh domestic sewage that has been acclimatized in the anolyte for 2 months into 500 mL of the anolyte to obtain a culture medium solution;

[0056] ③. Dissolve potassium ferrocyanide in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50mmol / L, which is the cathode liquid;

[0057] (2) Training start:

[0058] The culture medium solution is added into the anode chamber of the photocatalytic / microorganism coupled anode microbial fuel cell, the cathode liquid is added into the cathode chamber, the photocatalytic / microorganism coupled anode is immersed in the culture medium solution, the reactor is sealed to maintain an anaerobic state, and an external resistance value of 1000Ω is applied, and an LED light bar composed of 6 LED lamp beads with a power of 1W is inserted into the quartz glass tube of the reactor as a light source, the culture medium solution is replaced every 24 hours, and the photocatalytic / microorganism coupled anode and the carbon brush cathode are respectively connected to the data acquisition system with wires, and the output voltage change of the photocatalytic / microorganism coupled anode microbial fuel cell is monitored by the data acquisition system. When the output voltage of the photocatalytic / microorganism coupled anode microbial fuel cell reaches 0.3V to 0.6V, a photocatalytic / microorganism coupled anode containing electrogenic bacteria is obtained. The other steps are the same as those in the first to eighth embodiments.

[0059] Specific embodiment ten: This embodiment is a photocatalytic / microbial coupled anode microbial fuel cell for enhanced degradation of sulfamethoxazole.

[0060] The following examples are used to verify the beneficial effects of the present invention:

[0061] Embodiment 1: A photocatalytic / microbiologically coupled anode microbial fuel cell (PB-MFC), wherein the reactor of the microbial fuel cell consists of two chambers, a cathode chamber and an anode chamber;

[0062] The top of the anode chamber and the cathode chamber are respectively provided with three holes, namely, the anode port, the cathode port, and the sampling and liquid replacement port;

[0063] The anode chamber and the cathode chamber are separated by a cation exchange membrane;

[0064] The anode chamber is filled with anolyte, and the anode is arranged in the anolyte through the anode port;

[0065] A quartz glass tube is embedded in one side of the anode chamber for placing a light source;

[0066] The cathode chamber is filled with cathode liquid, and the cathode is arranged in the cathode chamber through the cathode port;

[0067] The photocatalytic / microbial coupled anode microbial fuel cell is provided with a resistor outside, one end of the two wires is connected to the resistor respectively, and the other end is connected to the anode and the cathode respectively to form a loop;

[0068] The light source is an LED lamp; the cathode is a carbon brush cathode;

[0069] The preparation method of the anolyte is as follows: 1 g of anhydrous sodium acetate, 100 mL of phosphate buffer solution and 5 mg of sulfamethoxazole are added to deionized water and the volume is fixed to 1000 mL to obtain the anolyte;

[0070] The cathode liquid is prepared as follows: potassium ferrocyanide is dissolved in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50 mmol / L, which is the cathode liquid;

[0071] The anode is a photocatalytic / microbial coupling anode containing electrogenic bacteria, wherein the photocatalytic / microbial coupling anode containing electrogenic bacteria is composed of graphene-modified carbon felt, BiVO 4 The photocatalyst and the DTMS hydrophobic layer are formed, which is specifically completed in the following steps:

[0072] 1. Preparation of graphene-modified carbon felt:

[0073] ①, sequentially soak the carbon felt block (size 2cm×3cm×0.5cm) in acetone (purity 99.5%) and anhydrous ethanol (purity 99.7%) for 30 min, then immerse it in anhydrous ethanol for ultrasonic treatment for 30 min, and then immerse it in deionized water for ultrasonic treatment for 1 h. After taking it out, place the carbon felt in an oven at 60°C for 6 h to obtain the cleaned carbon felt;

[0074] ②, 1 mL of graphene oxide dispersion was applied to one surface of the carbon felt (size 2 cm × 3 cm), and dried in an oven at 60 ° C. After repeating 3 times, the graphene oxide-modified carbon felt was obtained;

[0075] The graphene oxide dispersion described in step 1② is a single-layer graphene oxide dispersion with a concentration of 2 mg / mL, a solvent of ethylene glycol, an average radial size of the graphene oxide of 5 μm to 8 μm, and a thickness of 1 nm;

[0076] ③. In a three-electrode system, the graphene oxide-modified carbon felt was immersed in a 0.5 mol / L Na 2 SO 4 In the electrolyte, a constant voltage of -1.2 V was applied to the graphene oxide modified carbon felt by the chronoamperometry of the electrochemical workstation for 10 min, and then it was thoroughly rinsed with deionized water and dried at 60 ° C for 4 h to obtain graphene modified carbon felt (rGO / CF);

[0077] 2. Preparation of BiVO 4 / Graphene modified carbon felt:

[0078] ①. Preparation of bismuth vanadate photocatalyst:

[0079] 0.192 g of sodium metavanadate and 0.232 g of hexadecyltrimethylammonium bromide were added to 40 mL of water and heated and stirred at 40 °C for 30 min to obtain NaVO 3 and a mixed solution of CTAB;

[0080] Add 0.52g Bi(NO 3 ) 3 ·5H 2 O was added into 20 mL of 17.8 mM nitric acid and stirred for 30 min to obtain a bismuth nitrate solution;

[0081] Add bismuth nitrate solution to NaVO 3 and CTAB, stirring for 60 minutes, and then adjusting the pH value to 6.0 with a 10M sodium hydroxide solution to obtain a mixed solution with a pH value of 6.0; placing the mixed solution with a pH value of 6.0 in a stainless steel reactor, and then placing it in an oven for hydrothermal reaction at a temperature of 105°C and a hydrothermal reaction time of 24 hours to obtain a reaction product; setting the centrifuge speed to 1000 rpm, centrifuging the reaction product for 10 minutes to obtain a precipitate; first washing the precipitate 5 times with anhydrous ethanol, then washing it 5 times with deionized water, and finally drying it in a vacuum drying oven at 60°C for 12 hours to obtain a bismuth vanadate photocatalyst;

[0082] ② 240mg BiVO 4 , 600 μL Nafion solution (DuPont, 5 wt%) and 400 μL isopropanol (purity 99.7%) were mixed, then ultrasonicated for 10 min, and then magnetically stirred for 24 h at a speed of 800 r / min to obtain a uniform BiVO4 Paste;

[0083] ②、BiVO 4 The paste was evenly coated on a surface of the graphene-modified carbon felt without graphene (size 2 cm × 3 cm), and then placed in an oven at 60 ° C for 12 h to obtain BiVO 4 / graphene modified carbon felt (B / rGO / CF);

[0084] 3. Preparation of Hydrophobically Modified BiVO 4 / Graphene modified carbon felt coupled anode:

[0085] ①, add 50 μL of dodecyltrimethoxysilane (DTMS) to 10 mL of anhydrous ethanol, and ultrasonicate for 60 min to obtain an ethanol solution of dodecyltrimethoxysilane;

[0086] ② Use a pipette to absorb 5 mL of dodecyltrimethoxysilane ethanol solution and apply it on the BiVO 4 / Graphene modified carbon felt containing BiVO 4 The surface of the hydrophobic modified BiVO was prepared by drying the surface of the hydrophobic modified BiVO in an oven at 60 °C for 24 h. 4 / graphene-modified carbon felt coupled anode, that is, photocatalytic / microbial coupled anode (D / B / rGO / CF);

[0087] The method for preparing the photocatalytic / microbial coupled anode containing electrogenic bacteria is specifically completed according to the following steps:

[0088] (1) Prepare anolyte, culture medium solution and catholyte:

[0089] ①, add 1g of anhydrous sodium acetate, 100mL of phosphate buffer solution and 5mg of sulfamethoxazole to deionized water and make the volume to 1000mL to obtain an anolyte;

[0090] The phosphate buffer solution described in step (1) ① is prepared as follows: weigh 3.1 g NH 4 Cl, 1.3 g KCl, 33.2 g NaH 2 PO 4 ·2H 2 O and 103.2g Na 2 HPO 4 12H 2 O into a 1L volumetric flask, then pour 500mL of deionized water into the volumetric flask and stir with a magnetic stirrer to make NH 4 Cl, KCl, NaH 2 PO 4 ·2H 2O and Na 2 HPO 4 12H 2 O was fully dissolved, and then deionized water was added to make the solution to 1 L to obtain a phosphate buffer solution;

[0091] ②, add 500 mL of fresh domestic sewage that has been acclimatized in the anolyte for 2 months into 500 mL of the anolyte to obtain a culture medium solution;

[0092] ③. Dissolve potassium ferrocyanide in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50mmol / L, which is the cathode liquid;

[0093] (2) Training start:

[0094] The culture medium solution is added into the anode chamber of the photocatalytic / microbial coupled anode microbial fuel cell, the photocatalytic / microbial coupled anode is immersed in the culture medium solution, the reactor is sealed to maintain an anaerobic state, and an external resistance of 1000Ω is applied. An LED light strip composed of 6 LED lamp beads with a power of 1W is inserted into the quartz glass tube of the reactor as a light source. The culture medium solution is replaced every 24 hours, and the photocatalytic / microbial coupled anode and the carbon brush cathode are respectively connected to the data acquisition system with wires. The output voltage change of the photocatalytic / microbial coupled anode microbial fuel cell is monitored by the data acquisition system. When the output voltage of the photocatalytic / microbial coupled anode microbial fuel cell reaches 0.3V~0.6V, the preparation of the photocatalytic / microbial coupled anode containing electrogenic bacteria is completed.

[0095] Comparative Example 1: The difference between this example and Example 1 is that the anode is a graphene-modified carbon felt anode containing electrogenic bacteria;

[0096] The method for preparing the graphene-modified carbon felt anode containing electrogenic bacteria is specifically completed according to the following steps:

[0097] 1. Preparation of graphene-modified carbon felt:

[0098] ①, sequentially soak the carbon felt block (size 2cm×3cm×0.5cm) in acetone (purity 99.5%) and anhydrous ethanol (purity 99.7%) for 30 min, then immerse it in anhydrous ethanol for ultrasonic treatment for 30 min, and then immerse it in deionized water for ultrasonic treatment for 1 h. After taking it out, place the carbon felt in an oven at 60°C for 6 h to obtain the cleaned carbon felt;

[0099] ②, 5 mL of graphene oxide dispersion was coated on one surface of the carbon felt (size 2 cm × 3 cm), and placed in an oven at 60 ° C to dry, and repeated 3 times to obtain graphene oxide modified carbon felt;

[0100] ③. In a three-electrode system, the graphene oxide-modified carbon felt was immersed in a 0.5 mol / L Na 2 SO 4 In the electrolyte, a constant voltage of -1.2 V was applied to the graphene oxide modified carbon felt by the chronoamperometry of the electrochemical workstation for 10 min, and then it was thoroughly rinsed with deionized water and dried at 60 ° C for 4 h to obtain graphene modified carbon felt (rGO / CF); two,

[0102] (1) Prepare anolyte, culture medium solution and catholyte:

[0103] ①, add 1g of anhydrous sodium acetate, 100mL of phosphate buffer solution and 5mg of sulfamethoxazole to deionized water and make the volume to 1000mL to obtain an anolyte;

[0104] The phosphate buffer solution described in step (1) ① is prepared as follows: weigh 3.1 g NH 4 Cl, 1.3 g KCl, 33.2 g NaH 2 PO 4 ·2H 2 O and 103.2g Na 2 HPO 4 12H 2 O into a 1L volumetric flask, then pour 500mL of deionized water into the volumetric flask and stir with a magnetic stirrer to make NH 4 Cl, KCl, NaH 2 PO 4 ·2H 2 O and Na 2 HPO 4 12H 2 O was fully dissolved, and then deionized water was added to make the solution to 1 L to obtain a phosphate buffer solution;

[0105] ②, add 500 mL of fresh domestic sewage that has been acclimatized in the anolyte for 2 months into 500 mL of the anolyte to obtain a culture medium solution;

[0106] ③. Dissolve potassium ferrocyanide in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50mmol / L, which is the cathode liquid;

[0107] (2) Training start:

[0108] The culture medium solution is added into the anode chamber of the photocatalytic / microbial coupled anode microbial fuel cell, the graphene modified carbon felt (rGO / CF) is immersed in the culture medium solution, the reactor is sealed to maintain an anaerobic state, and an external resistance value of 1000Ω is applied, the culture medium solution is replaced every 24 hours, and the graphene modified carbon felt (rGO / CF) is used as an anode and a carbon brush cathode, respectively, connected to a data acquisition system with a wire, and the output voltage change of the photocatalytic / microbial coupled anode microbial fuel cell is monitored by the data acquisition system. When the output voltage of the photocatalytic / microbial coupled anode microbial fuel cell reaches 0.3V to 0.6V, a graphene modified carbon felt anode containing electrogenic bacteria is obtained. Other steps and parameters are the same as those in Example 1.

[0109] Test method:

[0110] 1. Power density test:

[0111] Use the variable resistance method. When the periodic voltage reaches the maximum and stabilizes for a period of time, start the test. Starting from the 10000Ω external resistance, select 12 external resistances (10000Ω, 8000Ω, 6000Ω, 4000Ω, 2000Ω, 1000Ω, 800Ω, 600Ω, 400Ω, 200Ω, 100Ω, 50Ω,), and change the external resistance from large to small. After the system runs stably for 30 minutes at each external resistance, use a multimeter to record the corresponding output voltage and electrode potential (calculated based on the reference electrode), then replace the next external resistance and repeat the above operation, and obtain the output voltage and electrode potential of the system at each resistance value in turn. Calculate the output current at different resistance values ​​through Ohm's law, calculate the power density at different external resistances based on the output voltage, output current, and anode effective area, and draw the corresponding power density curve with the output current as the horizontal axis and the power density as the vertical axis, see Figure 2 As shown;

[0112] Figure 2 The power density diagram of the photocatalytic / microbial coupled anode microbial fuel cell, in which 5mg-D / B / rGO / CF-light is Example 1 and 5mg-rGO / CF-dark is Control Example 1;

[0113] from Figure 2 It can be seen that the maximum power density of the photocatalytic / microbial coupled anode microbial fuel cell in Example 1 is 912.6 mW / m 2 The maximum power density of the microbial fuel cell in Control Example 1 is 154.7 mW / m 2 .

[0114] 2. Degradation performance test:

[0115] The residual SMX concentration in the reaction solution was determined by ultrahigh-performance liquid chromatography (UPLC) equipped with an ACQUITY UPLC C18 (150 mm × 4.6 mm, 5 μm) column. The wavelength of the UV / visible detector was set to 265 nm. The mobile phase consisted of acetonitrile and 0.1% formic acid (30:70), the flow rate was 0.1 mL / min, and the sampling volume was 10 μL. The time was used as the horizontal axis and the ratio of the residual concentration to the initial concentration (C t / C 0 ) as the ordinate to obtain the degradation performance diagram of SMX, see Figure 3 As shown;

[0116] Figure 3 This is a performance diagram of the degradation of sulfamethoxazole using a photocatalytic / microbial coupled anode microbial fuel cell. In the figure, D / B / rGO / CF-light is Example 1, and rGO / CF-dark is Control Example 1;

[0117] from Figure 3 It can be seen that within 96 hours, the degradation rate of sulfamethoxazole in Control Example 1 was 60.1%, while the degradation rate of sulfamethoxazole in the photocatalytic / microbial coupled anode microbial fuel cell (PB-MFC) in Example 1 reached 72.6%. This shows that compared with ordinary microbial fuel cells, the microbial fuel cell using the anode coupled with photocatalyst and microorganisms has improved the degradation effect of SMX, and the efficient degradation of SMX is achieved through the synergistic cooperation of the microbial degradation process of pollutants and the photocatalytic process.

Claims

1. A photocatalytic / microbial coupled anode microbial fuel cell, characterized in that The reactor of the microbial fuel cell consists of two chambers: a cathode chamber and an anode chamber; The top of the anode chamber and the cathode chamber are respectively provided with three holes, namely, the anode port, the cathode port, and the sampling and liquid replacement port; The anode chamber and the cathode chamber are separated by a cation exchange membrane; The anode chamber is filled with anolyte, and the anode is arranged in the anolyte through the anode port; A quartz glass tube is embedded in one side of the anode chamber for placing a light source; The cathode chamber is filled with cathode liquid, and the cathode is arranged in the cathode chamber through the cathode port; The photocatalytic / microbial coupled anode microbial fuel cell is provided with a resistor outside, one end of the two wires is connected to the resistor respectively, and the other end is connected to the anode and the cathode respectively to form a loop; The anode is a photocatalytic / microbial coupling anode containing electrogenic bacteria; the photocatalytic / microbial coupling anode containing electrogenic bacteria is composed of graphene-modified carbon felt, BiVO4 photocatalyst and DTMS hydrophobic layer.

2. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The light source is an LED lamp; the cathode is a carbon brush cathode; the preparation method of the anolyte is as follows: 1g of anhydrous sodium acetate, 100mL of phosphate buffer solution and 5mg of sulfamethoxazole are added to deionized water to make the volume to 1000mL to obtain the anolyte; the preparation method of the catholyte is as follows: potassium ferrocyanide is dissolved in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50mmol / L, which is the catholyte.

3. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The preparation method of the photocatalytic / microbial coupled anode is specifically completed according to the following steps:

1. Preparation of graphene-modified carbon felt: ①, soak the carbon felt block in acetone and anhydrous ethanol for a period of time, then immerse it in anhydrous ethanol for ultrasonic treatment, and then immerse it in deionized water for ultrasonic treatment, take it out and place it in an oven to dry, so as to obtain the cleaned carbon felt; ②, coating the graphene oxide dispersion on one surface of the carbon felt, placing it in an oven to dry, and repeating 2 to 4 times to obtain the graphene oxide modified carbon felt; ③. Under the three-electrode system, immerse the graphene oxide modified carbon felt in Na2SO4 electrolyte, apply a constant voltage of -1.2V to the graphene oxide modified carbon felt for 5min to 10min using the chronoamperometry of the electrochemical workstation, then rinse with deionized water and dry to obtain graphene modified carbon felt; 2. Preparation of BiVO4 / graphene modified carbon felt: ①, Mix BiVO4, Nafion solution and isopropanol, then ultrasonicate and magnetically stir for a period of time to obtain a uniform BiVO4 paste; ②, evenly coating the BiVO4 paste on a surface of the graphene-modified carbon felt that does not contain graphene, and then drying it in an oven for a period of time to obtain BiVO4 / graphene-modified carbon felt; 3. Preparation of hydrophobically modified BiVO4 / graphene-modified carbon felt coupled anode: ①, adding dodecyltrimethoxysilane to anhydrous ethanol, and ultrasonicating for a period of time to obtain an ethanol solution of dodecyltrimethoxysilane; ② Use a pipette to absorb the ethanol solution of dodecyltrimethoxysilane, apply it on a surface of BiVO4 / graphene-modified carbon felt containing BiVO4, and then place it in an oven to dry for a period of time to obtain a hydrophobic modified BiVO4 / graphene-modified carbon felt coupled anode, which is a photocatalytic / microbial coupled anode.

4. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The size of the carbon felt block described in step 1① is 2cm×3cm×0.5cm; in step 1①, the carbon felt block is soaked in acetone and anhydrous ethanol for 20min to 30min respectively, then immersed in anhydrous ethanol for ultrasonic treatment for 30min to 60min, and then immersed in deionized water for ultrasonic treatment for 30min to 60min. After taking out, the carbon felt is placed in an oven at a temperature of 60℃ to 70℃ and dried for 5h to 7h to obtain the cleaned carbon felt.

5. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The graphene oxide dispersion described in step 1② is a single-layer graphene oxide dispersion with a concentration of 2 mg / mL, the solvent is ethylene glycol, the average radial size of graphene oxide is 5 μm to 8 μm, and the thickness is 1 nm; the concentration of the Na2SO4 electrolyte described in step 1③ is 0.5 mol / L; the drying temperature described in step 1③ is 60°C to 70°C, and the drying time is 3h to 5h.

6. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The mass volume ratio of BiVO4, Nafion solution and isopropanol described in step 2① is 240mg:600μL:400μL; the mass fraction of the Nafion solution described in step 2① is 5%; the ultrasonic time described in step 2① is 5min~10min; the magnetic stirring time described in step 2① is 20h~24h, and the speed of magnetic stirring is 800r / min.

7. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The ratio of the volume of the BiVO4 paste described in step 2② to the surface area of ​​the graphene-modified carbon felt is 1000 μL: (5 cm 2 ~7cm 2 ); the drying temperature in step 2② is 50°C to 70°C, and the drying time is 10h to 12h.

8. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The volume ratio of dodecyltrimethoxysilane to anhydrous ethanol described in step 3① is (50μL~60μL):10mL; the ultrasonic time described in step 3① is 40min~60min; the volume ratio of the ethanol solution of dodecyltrimethoxysilane described in step 3② to a surface area of ​​BiVO4 / graphene modified carbon felt is 5mL:(5cm 2 ~7cm 2 ); the drying temperature in step 3② is 50℃~70℃, and the drying time is 20h~24h.

9. A photocatalytic / microbial coupled anode microbial fuel cell according to claim 1, characterized in that The method for preparing the photocatalytic / microbial coupled anode containing electrogenic bacteria is specifically prepared according to the following steps: (1) Prepare anolyte, culture medium solution and catholyte: ①, add 1g of anhydrous sodium acetate, 100mL of phosphate buffer solution and 5mg of sulfamethoxazole to deionized water and make the volume to 1000mL to obtain an anolyte; The preparation method of the phosphate buffer solution described in step (1) ① is as follows: weigh 3.1 g NH4Cl, 1.3 g KCl, 33.2 g NaH2PO4·2H2O and 103.2 g Na2HPO4·12H2O and place them in a 1L volumetric flask, then pour 500 mL of deionized water into the volumetric flask, use a magnetic stirrer to stir to fully dissolve NH4Cl, KCl, NaH2 PO4·2H2O and Na2HPO4·12H2O, then add deionized water to make the solution dilute to 1L to obtain a phosphate buffer solution; ②, add 500 mL of fresh domestic sewage that has been acclimatized in the anolyte for 2 months into 500 mL of the anolyte to obtain a culture medium solution; ③. Dissolve potassium ferrocyanide in deionized water to obtain a potassium ferrocyanide solution with a concentration of 50mmol / L, which is the cathode liquid; (2) Training start: The culture medium solution is added into the anode chamber of the photocatalytic / microbial coupled anode microbial fuel cell, and the cathode liquid is added into the cathode chamber, so that the photocatalytic / microbial coupled anode is immersed in the culture medium solution, the reactor is sealed to maintain an anaerobic state, and an external resistance of 1000Ω is applied. An LED light strip composed of 6 LED lamp beads with a power of 1W is inserted into the quartz glass tube of the reactor as a light source. The culture medium solution is replaced every 24 hours, and the photocatalytic / microbial coupled anode and the carbon brush cathode are respectively connected to the data acquisition system with wires. The output voltage change of the photocatalytic / microbial coupled anode microbial fuel cell is monitored by the data acquisition system. When the output voltage of the photocatalytic / microbial coupled anode microbial fuel cell reaches 0.3V~0.6V, a photocatalytic / microbial coupled anode containing electrogenic bacteria is obtained.

10. The use of a photocatalytic / microbial coupled anode microbial fuel cell as claimed in claim 1, characterized in that A photocatalytic / microbial coupled anode microbial fuel cell is used for enhanced degradation of sulfamethoxazole.

Images