阅读说明：本技术 一种微生物燃料电池用纳米纤维/产电菌薄膜制备方法 (Preparation method of nanofiber/electricity-producing bacterium film for microbial fuel cell ) 是由 李从举 张秀玲 于 2019-09-09 设计创作，主要内容包括：本发明提供一种微生物燃料电池用纳米纤维/产电菌薄膜制备方法,属于微生物燃料电池技术领域。该方法首先利用静电纺丝技术制备纳米纤维,然后将制得的纳米纤维与产电菌采用共抽滤的方式制得纳米纤维/产电菌薄膜,作为阳极材料。本发明实现了产电菌与电极材料的有效接触面积的增加,产电菌在其内表面的附着数量和内表面利用率的大大提高,电子在产电菌与电极界面的传递效率明显提升,电池输出功率密度的提高。本发明具有性能优异、工艺简单、易规模化生产、成本低廉等优点,在微生物燃料电池领域具有重要的应用价值。(The invention provides a preparation method of a nanofiber/electricity-producing bacterium film for a microbial fuel cell, and belongs to the technical field of microbial fuel cells. The method comprises the steps of firstly preparing nano fibers by using an electrostatic spinning technology, and then preparing the nano fibers/electrogenic bacteria film as an anode material by using the prepared nano fibers and electrogenic bacteria in a co-suction filtration mode. The invention realizes the increase of the effective contact area of the electrogenic bacteria and the electrode material, greatly improves the attachment quantity of the electrogenic bacteria on the inner surface and the utilization rate of the inner surface, obviously improves the transmission efficiency of electrons on the interface of the electrogenic bacteria and the electrode, and improves the output power density of the battery. The invention has the advantages of excellent performance, simple process, easy large-scale production, low cost and the like, and has important application value in the field of microbial fuel cells.)

1. A preparation method of nanofiber/electricity-producing bacteria film for microbial fuel cell is characterized by comprising the following steps: firstly, preparing nano-fiber by using an electrostatic spinning technology, and then, carrying out suction filtration on the prepared nano-fiber and electrogenic bacteria by using a vacuum pump to prepare a nano-fiber/electrogenic bacteria film as an anode material.

2. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 1, wherein: the nano-fiber is directly obtained from a conductive polymer through an electrostatic spinning technology, or is a carbonized conductive nano-fiber.

3. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 2, wherein: the conductive polymer is polyaniline or polythiophene, and the carbonized conductive nanofiber comprises polyacrylonitrile, polyvinylpyrrolidone and polymethyl methacrylate.

4. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 1, wherein: the electrostatic spinning technology specifically comprises the following steps: transferring the spinning solution into an injector and placing the injector on an injection pump, and applying voltage14-30kV, and the feeding rate is 2-12uL min^-1The receiving distance is 8-20cm, the nozzle size is 19-27G, the environment relative humidity is 22-45%, and the temperature is 20-40 ℃, so that the nano-fiber is prepared.

5. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 1, wherein: the nano-fiber is prepared by adopting one of the methods of high-speed centrifugal spinning, solution jet spinning, catalytic extrusion, stretching, template synthesis, self-assembly and microphase separation.

6. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 5, wherein: the high-speed centrifugal spinning method comprises the following specific steps: the spinning solution is prepared by high-speed centrifugal spinning at 25000 r/min or more; the solution jet spinning method comprises the following specific steps: the solution spraying flow is 5-120uL/min, the airflow pressure is 0.06-1MPa, and the spraying distance is 5-40 cm; the stretching method comprises the following specific steps: the tensile strength of the nanofiber is 1.0-8.0 GPa, and the elongation at break is 10-30%.

7. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 1, wherein: the electrogenic bacteria include Geobacter, Shewanella oneidensis MR.1.

8. The method for preparing nanofiber/electrogenic bacteria film for microbial fuel cell according to claim 1, wherein: the electrogenic bacteria are aerobically cultured in a shaking water bath at 25-35 ℃ on a TSB culture medium for 8-15 h.

Technical Field

The invention relates to the technical field of microbial fuel cells, in particular to a preparation method of a nanofiber/electricity-generating bacterium film for a microbial fuel cell.

Background

A Microbial Fuel Cell (MFC) is an energy conversion device that catalytically degrades organic substances using electricity-generating microbes to convert chemical energy stored in the organic substances into electrical energy. Because of the advantages of self-sustainable bioremediation and electricity generation, the method plays an important role in the fields of clean environment, energy storage and conversion. How to improve the comprehensive performance indexes of the microbial fuel cell, including improving the power output level, shortening the starting time of the device and the like, is the key research point of microbial power generation. The reasonable structural design of the anode (comprising two parts of the electrogenic bacteria and the current collector) to increase the electrode area to which the electrogenic bacteria can be attached is considered to be a key for solving the problems. By virtue of their high specific surface area, anodes having a porous structure have long received attention. However, the larger size of the bacteria (e.g., 2.5 μm long by 0.5 μm wide by Shewanella) makes it difficult for the bacteria to enter and attach to the inner surface of the meso/microporous electrode, thereby limiting the surface area of the electrode per unit mass and unit volume, resulting in lower bacterial loads and limited power density.

The electrospun nanofiber has the characteristics of natural macroporous structure (between 5 and 20 mu m), large specific surface area, high porosity and the like, so that the internal space of the electrospun nanofiber cannot be blocked by organisms while the electrospun nanofiber is attached and grown in a large area, and the mass transfer of active components such as substrates, protons and the like participating in the reaction in pores is completely unlimited. Meanwhile, the electrostatic spinning carbon-based nanofiber can construct a larger specific surface area and an effective space structure, and provides more attachment sites, electron transfer channels and nutrient substance transmission. The three-dimensional interactive macroporous structure formed by the nanofibers and the electrogenic bacteria fully utilizes the inner surface of the electrode, can rapidly transmit electrons generated by the electrogenic bacteria, and improves the output power.

Disclosure of Invention

The invention aims to provide a preparation method of a nanofiber/electrogenesis bacteria film for a microbial fuel cell, which can be used for preparing anode electrode materials of the microbial fuel cell.

According to the method, the electrogenic bacteria and the conductive nanofibers are subjected to suction filtration together to realize the electrogenic bacteria-nanofiber three-dimensional macroporous interwoven structure, so that charge transfer in the metabolism process of the electrogenic bacteria is promoted. Meanwhile, the electrogenic bacteria are dispersed in the three-dimensional interaction structure of the electrode, so that the inner surface of the electrode is fully utilized, and the electrogenic bacteria attachment amount of the electrode is greatly increased. In addition, the method can enable the formation of the biological membrane on the surface of the electrode to be quicker and shorten the starting time. Therefore, the method can be used for designing and preparing the anode electrode of the microbial fuel cell, realize the quick transfer of extracellular charges and improve the output power density of the cell.

The method comprises the steps of firstly preparing nano fibers by using an electrostatic spinning technology, and then carrying out suction filtration on the prepared nano fibers and electrogenic bacteria by using a vacuum pump to prepare a nano fiber/electrogenic bacteria film as an anode material.

Wherein, the nano-fiber is directly obtained by a conductive polymer electrostatic spinning technology or is a carbonized conductive nano-fiber.

The conductive polymer is polyaniline or polythiophene, and the carbonized conductive nanofiber comprises polyacrylonitrile, polyvinylpyrrolidone, polymethyl methacrylate and the like.

The electrostatic spinning technology specifically comprises the following steps: transferring the spinning solution into an injector and placing on an injection pump, wherein the applied voltage is 14-30kV, and the feeding speed is 2-12uL min^-1The receiving distance is 8-20cm, the nozzle size is 19-27G, the environment relative humidity is 22-45%, and the temperature is 20-40 ℃, so that the nano-fiber is prepared.

The nano-fiber is prepared by adopting one of the methods of high-speed centrifugal spinning, solution jet spinning, catalytic extrusion, stretching, template synthesis, self-assembly, microphase separation and the like. The high-speed centrifugal spinning method comprises the following specific steps: the spinning solution is prepared by high-speed centrifugal spinning at 25000 r/min or more; the solution jet spinning method comprises the following specific steps: the solution spraying flow is 5-120uL/min, the airflow pressure is 0.06-1MPa, and the spraying distance is 5-40 cm; the stretching method comprises the following specific steps: the tensile strength of the nanofiber is 1.0-8.0 GPa, and the elongation at break is 10-30%.

The electrogenic bacteria include Geobacter, Shewanella oneidensis MR.1, etc.

The electrogenic bacteria are prepared by aerobic culture in TSB (BD biosciences) culture medium at 25-35 deg.C in shaking water bath for 8-15 h.

And (3) fully contacting the nano fibers with the bacterial suspension in the solution, and filtering the suspension by adopting a co-filtration mode to obtain the three-dimensional interwoven porous anode material. The ratio of bacteria to nanofibers can be controlled by fixing the amount (weight) of nanofibers and adjusting the amount of bacterial suspension in the growth medium.

The technical scheme of the invention has the following beneficial effects:

1) the nanofiber has the characteristics of natural macroporous structure, large specific surface area, high porosity, good mechanical property, easiness in large-scale production and the like, and can improve the attachment amount of electrogenic bacteria; 2) the construction of a three-dimensional macroporous interweaving structure is realized, and the utilization rate of the inner surface of the electrode is improved; 3) the conductivity of the electrode is increased, and the transfer rate of extracellular charges is improved; 4) the method has the advantages of realizing the rapid formation of the electrode, shortening the preparation time of the anode of the traditional MFC, ensuring the attachment, the propagation, the growth and the like of microorganisms on the anode.

Drawings

FIG. 1 is a schematic diagram of a process for preparing a nanofiber/electricigen film for a microbial fuel cell according to the present invention;

FIG. 2 is an image of a nanofiber in an embodiment of the invention;

FIG. 3 is a schematic diagram of a microbial fuel cell according to an embodiment of the present invention.

Wherein: 1-a battery anode; 2-a battery cathode; 3-a proton exchange membrane; 4-electrogenesis bacteria; 5-a catalyst; 6-anode substrate; 7-a cathode substrate; 8-external resistor.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The invention provides a preparation method of a nanofiber/electricity generating bacterium film for a microbial fuel cell.

As shown in figure 1, the method firstly utilizes an electrostatic spinning technology to prepare the nano-fiber, and then the prepared nano-fiber and the electrogenic bacteria are subjected to suction filtration to prepare the nano-fiber/electrogenic bacteria film as an anode material. The method specifically comprises the following steps: the nanofiber is prepared by using an electrostatic spinning technology, and the prepared nanofiber is a conductive nanofiber, can be directly obtained by electrostatic spinning of a conductive polymer (such as polyaniline, polythiophene and the like) and can also be a nanofiber which is conductive after carbonization (such as polyacrylonitrile, polyvinylpyrrolidone, polymethyl methacrylate and the like). And then, carrying out suction filtration on the conductive nano-fibers and the electrogenic bacteria to obtain the three-dimensional interwoven porous anode material. The nano-fiber prepared by the method can also adopt, but is not limited to, high-speed centrifugal spinning, solution jet spinning, catalytic extrusion, stretching, template synthesis, self-assembly, microphase separation and other methods. The electrogenic bacteria include but are not limited to Geobacter, Shewanella oneidensis MR.1 and other electrogenic microorganisms.

FIG. 2 is a scanning electron microscope image of the nanofibers of the present invention. The diameter of the nano-fiber is small, the nano-fiber has the diameter of 200-500nm, the specific surface area is large, and the nano-fiber has a micron-scale macroporous structure, so that the loading capacity of the electrogenic bacteria (with the diameter of 2-3 microns) on the conductive nano-fiber and the internal utilization rate of the electrode can be improved. The anode structure of the electrode is improved, the conductivity and the extracellular charge transfer speed are improved, and the construction of a macroporous three-dimensional interwoven structure and the improvement of power density are realized.

FIG. 3 is a schematic diagram of a microbial fuel cell according to the present invention. Wherein, 1 is the battery anode, 2 is the battery cathode, 3 is the proton exchange membrane, 4 is the electrogenesis fungus, 5 is the catalyst, 6 is the anode substrate, 7 is the cathode substrate, 8 is external resistance. MFC consists of an anaerobic anode compartment and an aerobic cathode compartment. In the anode chamber, nutrients in the anolyte are oxidized under the action of electroactive microorganisms to generate electrons, protons and metabolites. The nutrients include, but are not limited to, glucose, sucrose, etc., and in the case of glucose, the oxidation reaction at the anode takes place as C₆H₁₂O₆+6H₂O→6CO₂+24H⁺+24e^-. Normally, an electroactive microbial membrane grows and breeds by adhering to the surface of the anode, eventually forming an electrogenic biofilm by which the MFC relies to oxidize the substrate in the anode chamber to produce electrons and protons. Electrons generated by the electrogenic biofilm at the anode are transported to the electrode surface and then through an external circuit to the cathode. Protons are released into solution and migrate through a Proton Exchange Membrane (PEM) to the cathode. On the cathode surface, a substance in an oxidized state (e.g., O)₂Etc.) combines with the protons and electrons transferred from the anode to generate water through reduction reaction, and the reaction formula is 6O₂+24H⁺+24e^-→12H₂And O. The anode matrix mainly comprises ammonium chloride, sodium chloride, calcium chloride, sodium bicarbonate and phosphoric acidPotassium hydrogen, dipotassium hydrogen phosphate, ferric sulfate, magnesium sulfate, manganese sulfate, cobalt sulfate, sodium acetate and the like. The cathode matrix mainly comprises the following components: potassium ferricyanide, potassium hydrogen phosphate, dipotassium hydrogen phosphate, and the like.

The following description is given with reference to specific examples.

First step, preparation of PAN nanofibers

2.1g polyacrylonitrile PAN (Mw 150,000) powder was dissolved in 15-20mL of N, N dimethylformamide (DMF solvent, stirred overnight to form a homogeneous solution, then the prepared solution was placed in a 20mL syringe using a 20-24# metal needle, the advancing rate of the solution was maintained at 0.6-1.0mL/h, the distance between the aluminum foil of the receiving plate and the needle tip was 15-20cm, the positive voltage was applied at 15-20.0kV and the negative voltage was-2 kV. the relative humidity of the spinning environment was 20-35% and the temperature was 40-60 ℃.

Second, the PAN nanofibers are carbonized

Cutting the nanofiber membrane into a crucible with the size and the shape, placing the crucible in a high-temperature-resistant crucible, firstly, preserving the heat at the temperature of 230 ℃ and 280 ℃ in a box-type furnace for 2h at the heating rate of 1 ℃/min, and naturally cooling; and then, preserving the heat for 1h at the temperature of 700-800 ℃ in a tube furnace in the Ar atmosphere, and naturally cooling to obtain the conductive carbon nanofiber.

Thirdly, compounding the carbon nano fiber with the electrogenic bacteria

Cutting the prepared carbon nanofibers into the size needed by a suction filtration device, placing the carbon nanofibers on the suction filtration device, and combining the electrogenic bacteria solution with the nanofibers by adopting a static or dynamic suction filtration mode to obtain the nanofiber/electrogenic bacteria film anode material.

The method forms a composite film with a mutual weaving structure in a mode of common suction filtration of the electrostatic spinning conductive carbon-based nano fiber and the electrogenic bacteria, and the composite film is used as an anode material of the high-efficiency microbial fuel cell. The method can ensure that bacteria are fully dispersed into the interior and the surface of a three-dimensional interaction structure formed by the carbon-based nano fibers, and the number of electricity-generating bacteria in the electrode in unit volume is increased. Secondly, the bacteria-carbon-based nanofiber three-dimensional interwoven conductive network promotes charge transfer in the bacterial metabolism process and can rapidly transmit electrons generated by the electrogenic bacteria; and thirdly, nitrogen is doped in the conductive nano-fibers, so that oxygen functional groups on the graphitized microcrystal structure can be eliminated, the electronic conductivity and the capacitance of the micron-sized fiber yarns are improved, and the electron transfer is further promoted. Fourthly, the rapid formation of the electrode is realized by one step by using a common suction filtration method, the preparation time of the traditional MFC anode is shortened, and the attachment, the propagation and the growth of microorganisms on the anode are ensured. A double-chamber microbial fuel cell system is constructed through the strategy, and the problems of low output power, poor stability and the like of the microbial fuel cell are solved.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.