MFC sensor loaded with interpenetrating network nanofiber anode and application of MFC sensor

Abstract

The invention belongs to the technical field of biosensors and environmental monitoring, and particularly relates to an MFC sensor loaded with an interpenetrating network nanofiber anode and application of the MFC sensor. Interpenetrating network nanofibers are prepared by adopting an electrostatic spinning technology and are loaded on a stainless steel mesh bracket to serve as a sensor anode electrode, and a titanium wire is connected with an air cathode through an external circuit to assemble the MFC sensor. The nanofiber has ultra-long length, high length-width ratio, specific pore structure, great specific surface area and high porosity, and has good biological compatibility with electrogenesis microorganisms, and the one-dimensional nanostructure can promote transmission of electrons from a biological membrane to an anode, so that an electric signal output by the sensor is enhanced. Therefore, when the prepared novel MFC sensor is applied to concentration analysis of pollutants in wastewater and early warning of toxic substances, the sensitivity can be greatly improved, and the response time can be greatly shortened.

Description

Technical Field

[0001] This invention belongs to the field of biosensor and environmental monitoring technology, specifically relating to an MFC sensor with a load interpenetrating network nanofiber anode and its application. Background Technology

[0002] Bioelectrochemical systems (BES) are a novel water treatment technology that has emerged in recent years. They not only degrade organic pollutants but also recover nutrients and bioelectricity from wastewater, achieving wastewater resource recovery. BES relies on electrochemically active microorganisms that form electrode biofilm structures to exchange electrons with solid-phase electrodes while conducting catalytic reactions. Early applications of BES primarily focused on recovering electrical energy during pollutant removal to achieve low-energy wastewater treatment. Currently, BES has evolved into a multifunctional platform technology with applications in environmental monitoring and remediation, food safety, healthcare, and water quality early warning systems.

[0003] One of the most basic forms of microbial electrochemical sensors is the microbial fuel cell (MFC). It typically uses a bioanode as the sensing element and organic pollutants in the water as the substrate for electroactive microorganisms. Based on the electrogenic respiratory metabolic mechanism of these microorganisms, changes in the concentration of degradable organic pollutants are directly converted into continuous online changes in electrical signals such as current, coulombic flux, and voltage. Under certain conditions, the peak value of the stable electrical signal generated by the battery exhibits a good linear relationship with the concentration of organic pollutants within a certain range, thus it can be used for concentration detection in various wastewaters. Furthermore, when toxic substances enter the anode chamber of the MFC, they inhibit the metabolism and extracellular electron transfer processes of the anodic electrochemical microorganisms, leading to a weakening of the output electrical signal. When a certain threshold is reached, an alarm signal is triggered. The magnitude of the weakening of the electrogenic signal is correlated with the concentration of the toxic substance; therefore, the MFC sensor can also detect the toxicity level of a sample.

[0004] Compared to other types of sensors, MFC sensors have the following advantages: 1) The water sample being tested can usually be directly used as an inoculum source for microorganisms and a culture medium to maintain their activity; 2) The bio-anode, as the sensing element, has self-renewal and repair capabilities, making the maintenance of MFC sensors simple and stable; 3) MFC sensors convert low-grade chemical energy in organic wastewater into electrical energy, directly outputting electrical signals without the need for signal conversion devices; 4) Essentially a galvanic cell, it can self-drive the output of electrical signals without an external power source; 5) The electroactive microorganisms at the anode can originate from indigenous microorganisms in the water body being tested; 6) The detection process usually does not require the addition of additional microorganisms or chemicals, resulting in low operating costs and simple operation. Furthermore, MFC sensors also feature miniaturization, intelligence and integration, portability, wide applicability, long service life, and real-time on-site monitoring.

[0005] The anode, as a crucial component in an MFC (microbial fuel cell) that directly contacts electrogenic bacteria, serves as the carrier for the biofilm formation and attachment of these microorganisms. Its material composition and surface structure directly influence the bacterial adsorption capacity, oxidation reaction, and electron transfer efficiency from the biofilm to the anode, significantly impacting the electrogenic performance and signal output of the MFC sensor. However, existing MFC sensors used for wastewater detection and toxicity early warning suffer from low mass transfer rates of pollutants from the anolyte to the sensitive anode element, hindering electron transfer from the biofilm. This results in low MFC electrogenic capacity, weak electrical signal output, and ultimately, a series of problems such as excessively long response time, low sensitivity, poor reproducibility and stability, excessively high detection limits, narrow linear range, and excessively low detection upper limits. Therefore, it is necessary to develop a novel anode structure for MFC sensors to improve their pollutant detection capabilities. Summary of the Invention

[0006] In view of this, one of the objectives of the present invention is to provide an interpenetrating network nanofiber for fabricating an anode of an MFC sensor.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] Interpenetrating network nanofibers for preparing the anode of an MFC sensor are prepared by the following method:

[0009] 1) Melt the polymer to obtain a polymer melt; or prepare a polymer solution using an organic solvent or an organic solvent containing conductive nanoparticles;

[0010] 2) The polymer solution or polymer melt obtained in step 1) is electrospinned to form interpenetrating network nanofibers.

[0011] This invention focuses on improving the mass transfer process and electron transfer efficiency of MFC sensor anodes to pollutants, and designs and develops a novel MFC sensor anode structure and its control mode. By optimizing the flow distribution of the MFC anode and thereby increasing the surface shear rate of the bio-anode, the adsorption and mass transfer capacity of the anode for pollutants is enhanced, further increasing the number of electrogenic bacteria attached. This aims to improve the sensitivity of the MFC sensor, lower the detection limit, shorten the response time, and broaden the linear range, while also providing good reproducibility and recovery performance. The interpenetrating network nanofibers prepared by electrospinning technology in this invention possess ultra-long length, high aspect ratio, specific pore structure, extremely large specific surface area, and high porosity, making them an excellent choice for MFC sensor anodes. The unique interpenetrating network nanofiber structure of this anode is beneficial for increasing the amount of electrogenic bacteria attached, and its one-dimensional nanostructure can promote electron transfer by nanofibers, cilia, and flagella on the cell membrane of electrogenic bacteria, further reducing their internal resistance. Meanwhile, nanofibers have good biocompatibility with electrogenic microorganisms, which is conducive to obtaining biofilms with low density, high porosity and low extracellular polymer content, thereby improving the efficiency of electron transfer from the biofilm to the anode, which can greatly improve its sensitivity and shorten the response time.

[0012] Preferably, the polymer includes polysulfone, polyethersulfone, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-co-polyhexafluoropropylene, polyimide, poly(isophthalamide), polyvinylpyrrolidone, polyvinyl alcohol, butyral, polyethyleneimine, polyetherimide, polyamide, polylactic acid, chitosan, chitosan, glucan, carboxymethyl chitosan, lignin, polysulfonamide, polyetherimide, polyamic acid, polyamide-6, nylon-66, aramid, polyamide-based n-halogenamine, and polycaprolactam. Polyethylene, polyvinyl chloride, polypropylene, polyethylene oxide, polyurethane, polyphenylene sulfide, alginate, dextran, ethylene-vinyl alcohol copolymer, polytetrafluoroethylene, polyarylene sulfide, polyvinyl alcohol, poly(arylene sulfide), oxidized poly(arylene sulfide), polyethylene glycol, polymethyl methacrylate, polycaprolactone, polystyrene, polyaniline, polypyrrole, poly3,4-ethylenedioxythiophene, cellulose acetate, cellulose acetate, and cellulose triacetate are selected from one or more of these polymers; the polymer concentration is 5 wt% to 100 wt%.

[0013] The organic solvent includes any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, deionized water, acetone, butanone, ethanol, isopropanol, fluoroisopropanol, formic acid, acetic acid, trifluoroethanol, dimethyl sulfoxide, dichloromethane, chloroform, butyrate, bromopropyne, 1,3-dimethyl-2-imidazolinone, benzoic acid dianhydride, diaminodiphenyl ether, dialcyldimethylammonium chloride, tetrahydrofuran, benzoic acid dianhydride, trifluoroacetic acid, and m-cresol.

[0014] The conductive nanoparticles include any one or more of Si3N4, silver nanoparticles, gold nanoparticles, activated carbon, graphene, carbon black, graphite, GO, TiO2, ZnO, MoS2, Mo2C, Co3O4, MoO3, NiMoO4, montmorillonite, nanoclay, Fe2O3, and carbon nanotubes; the concentration of the conductive nanoparticles is 0.1 wt% to 10 wt%.

[0015] Preferably, the polymer includes one or more of polyacrylonitrile, polyvinylidene fluoride, polyimide, chitosan, polyaniline, and polypyrrole.

[0016] Preferably, the solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, formic acid, and dimethyl sulfoxide.

[0017] Preferably, the conductive nanoparticles include one or more of silver nanoparticles, activated carbon, graphene, and MoS2.

[0018] Preferably, the polymer concentration is 10-30 wt / v.

[0019] Preferably, in step 1), the preparation conditions of the polymer solution include: 50-70 °C. o Heat and stir at temperature C for 2-10 hours.

[0020] Preferably, the electrospinning parameters include: needle diameter of 0.05~10.0 mm, injection flow rate of 0.001~15 mL / h, spinning voltage of 5~100 kV, receiving distance of 2~50 cm, and rotation speed of the collecting device of 50~2000 rpm.

[0021] Even more preferred is a receiving distance of 5-50 cm.

[0022] Even more preferred, the spinning voltage is 5-80 kV.

[0023] Preferably, the spun nanofiber membrane is 50-100 o Dry at C for 2-8 hours.

[0024] As a preferred embodiment, the electrospinning specifically includes: loading a polymer solution or polymer melt into different syringes, electrospinning them side by side, with the needles moving back and forth with a slide bar, and a collector collecting the nanofibers ejected from the needles under the action of a high-voltage electrostatic field.

[0025] Preferably, the nanofiber diameter is 5 nm to 15 μm, more preferably 290 nm, 5 nm, 15 μm, 381 nm, 820 nm or 506 nm.

[0026] Preferably, the average pore size of the nanofiber membrane is 0.25 μm to 3.6 μm, more preferably 0.7 μm, 0.89 μm, 3.6 μm, 3.2 μm, 2.2 μm or 0.25 μm.

[0027] Preferably, the porosity of the nanofiber membrane is 75.9% to 94.6%, more preferably 94.6%, 88.3%, 75.9%, 79.8%, 86.5% or 82.5%.

[0028] Preferably, the surface area of ​​the nanofiber membrane is 42.56 m². 2 / g~289.56 m 2 / g, more preferably 289.56m 2 / g, 156.23 m 2 / g, 42.56 m 2 / g, 56.24 m 2 / g, 143.21 m 2 / g or 139.56 m 2 / g.

[0029] The second objective of this invention is to provide an application of the aforementioned interpenetrating network nanofibers in the preparation of the anode electrode of an MFC sensor for pollutant concentration analysis and toxic substance early warning.

[0030] The third objective of this invention is to provide an MFC sensor for pollutant concentration analysis and toxic substance early warning.

[0031] To achieve the above objectives, the present invention adopts the following technical solution:

[0032] An MFC sensor for pollutant concentration analysis and toxic substance early warning, wherein the anode of the MFC sensor comprises the aforementioned interpenetrating network nanofibers.

[0033] Preferably, the interpenetrating network nanofibers are loaded onto a stainless steel mesh support as the anode electrode of the sensor, and the MFC sensor is assembled by connecting the air cathode via titanium wires through an external circuit.

[0034] Preferably, the method for preparing the anode electrode includes: using a stainless steel mesh as a support for the anode electrode, cutting out nanofiber membranes of the same size, pre-treating them, and then fixing them to one side of the support with titanium wires to serve as the anode electrode, with the extended titanium wires used as the conductors of the anode electrode.

[0035] Preferably, the generating device of the MFC sensor includes battery chambers that cooperate with each other, which are separated into an anode chamber and a cathode chamber by a diaphragm. Interpenetrating network nanofibers are used for the MFC sensor anode and are placed in the anode chamber. An air cathode is placed on one side of the cathode chamber. A titanium wire is connected to an external resistor with a constant resistance of 300 ohms. The anode and the air cathode are connected through an external circuit to form a closed loop.

[0036] Preferably, the air cathode material of the MFC sensor includes any one or more of the following: graphite sheet, graphite paper, graphite plate, (polycrystalline) carbon rod, carbon fiber yarn, carbon cloth, carbon felt, carbon paper, carbon plate, carbon brush, carbon mesh, carbon-based sponge, and sponge carbon fiber.

[0037] Preferably, the air cathode material is loaded with a metal catalyst Pt / C at a loading of 0.1~0.8 mg / cm³. 2 0.2 M PBS was injected into the cathode chamber.

[0038] Preferably, the anode chamber of the MFC sensor is kept in an anaerobic environment with a dissolved oxygen concentration of no more than 0.1 mg / L. The nanofiber anode is immersed in an inoculation solution rich in electrogenic bacteria and an anode nutrient solution, so that electroactive microorganisms attach to the surface of the nanofiber anode to form a biofilm, and finally form a microbial electrode with a stable electrode potential.

[0039] Preferably, the anolyte contains 1 g / L sodium acetate solution, 0.13 g / L KCl solution, 0.31 g / L NH4Cl solution, 10 mL / L trace element solution, 5 mL / L vitamin solution, and phosphate buffer solution (PBS) with a concentration of not less than 0.1 mol / L and a pH of 7-8.

[0040] The fourth objective of this invention is to provide an application of the aforementioned MFC sensor in detecting the concentration of pollutants and / or providing early warning of toxic substances in water bodies.

[0041] To achieve the above objectives, the present invention adopts the following technical solution:

[0042] The aforementioned MFC sensor is used in detecting the concentration of pollutants in water bodies and / or providing early warning of toxic substances.

[0043] Preferably, the water body includes one or more of the following: livestock and poultry breeding wastewater, brewing wastewater, domestic sewage, food processing wastewater, pharmaceutical wastewater, polluted surface water, and various industrial wastewater; the toxic substances include Hg, Cd, Pb, As, and Cu. 2+ Any one or more of Zn, Ni, and Cr(VI).

[0044] More preferably, the water body includes one or more of poultry and livestock breeding wastewater, brewing wastewater, and domestic sewage; the toxic substance includes Cu. 2+ Any one or both of Cr(VI).

[0045] The fifth objective of this invention is to provide a method for detecting the concentration of pollutants and / or toxic substances in water using the aforementioned MFC sensor.

[0046] To achieve the above objectives, the present invention adopts the following technical solution:

[0047] A method for detecting the concentration of pollutants and / or toxic substances in water using the aforementioned MFC sensor.

[0048] The anode loaded with nanofiber membrane was immersed in simulated test water to directionally acclimate and enrich the bacterial community that could stably exist in the test water environment; the MFC sensor was activated to test simulated water with biochemical oxygen demand concentrations of 5 mg / L, 50 mg / L, 100 mg / L, 200 mg / L and 300 mg / L, and a standard curve was obtained; the water sample to be tested was detected using the aforementioned MFC sensor, and the BOD value of the water sample to be tested was calculated according to the standard curve;

[0049] And / or use the aforementioned MFC sensor to detect the water sample to be tested, and determine whether the water sample contains toxic substances and analyze the strength of toxicity based on the change in current signal.

[0050] As a preferred method, when detecting pollutant concentration, the pH of the water sample to be tested is adjusted to 7-8 with hydrochloric acid or sodium hydroxide, and then 0.1M PBS is added (the water sample to be tested is mixed with PBS at a ratio of 4:1). N2 is then introduced to remove dissolved oxygen from the solution, and then injected into the anode chamber. The MFC sensor is then run, and voltage acquisition software is used to acquire voltage data.

[0051] As a preferred method, the BOD value of the test water body is calculated according to the following formulas (1) and (2) and the coulometric BOD calculation formula (3):

[0052] (1)

[0053] (2)

[0054] (3)

[0055] Where: I is current (A); U is voltage (V); R is external resistance (Ω); Q is charge (C); t is time (s); F is Faraday constant (96485 C / mol); V An Anode chamber volume (L); BOD Q The calculated BOD value (mg / L).

[0056] As a preferred method, when detecting toxic substances, the anolyte in the MFC is replaced with the water sample to be tested. Then, N2 is aerated in the anolyte to remove dissolved oxygen, followed by injection into the anode chamber. 0.2 M PBS is injected into the cathode chamber, the MFC sensor is run, and the changes in the voltage output signal are recorded to observe whether an alarm signal is triggered.

[0057] Preferably, the electrical signal indicators for toxic substance warning include one or more of the following: change in current (ΔI) and inhibition rate (IR).

[0058] Preferably, the change in current (ΔI) is defined as the difference in output current of the MFC sensor before and after exposure to toxic substances, and its calculation is given in formula (4):

[0059] (4)

[0060] The suppression ratio (IR) is defined as the percentage change in the electrical signal relative to its initial value, and its calculation is given by formula (5):

[0061] (5)

[0062] In the formula I nor Current output (mA) before exposure to toxic substances; I tox The current output (mA) after exposure to toxic substances.

[0063] The beneficial effects of this invention are as follows:

[0064] The interpenetrating network nanofibers provided by this invention are produced by melting a polymer, or by preparing a polymer solution using an organic solvent or an organic solvent containing conductive nanoparticles, and then using an electrospinning device to overcome the surface tension of the solution / melt under the action of a high-voltage electrostatic field to obtain nanofibers on a collector. These interpenetrating network nanofibers possess ultra-long length, high aspect ratio, specific pore structure, extremely large specific surface area, and high porosity. When used as the nanofiber anode in an MFC sensor, the large specific surface area of ​​the interpenetrating network nanofibers significantly increases the amount of electrogenic bacteria attached, and its one-dimensional nanostructure promotes electron transfer through the nanofibers, cilia, and flagella on the cell membrane of electrogenic bacteria. Simultaneously, the nanofibers exhibit good biocompatibility with electrogenic microorganisms, which is beneficial for obtaining low-density, high-porosity biofilms with low extracellular polymer content, thereby improving the efficiency of electron transfer from the biofilm to the anode. Therefore, applying the MFC sensor with the interpenetrating network nanofiber anode of this invention to the detection of organic pollutant concentrations and early warning of toxic substances in wastewater can greatly improve its sensitivity and shorten the response time. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of an MFC sensor.

[0066] Figure 2 This is a graph showing the detection results of the interpenetrating network nanofiber anode. Detailed Implementation

[0067] The technical solution of the present invention will be described more clearly and completely below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0068] In this embodiment of the invention, the MFC sensor generating device includes a battery cavity that works together with each other. The battery cavity is divided into an anode chamber and a cathode chamber by a diaphragm. Interpenetrating network nanofibers are used for the MFC sensor anode. The anode electrode is placed in the anode chamber, and the air cathode is placed on one side of the cathode chamber. A titanium wire is connected to an external resistor with a constant resistance of 300 ohms. The anode and the air cathode are connected through an external circuit to form a closed loop.

[0069] Preferably, the air cathode material is selected from any one of graphite sheet, graphite paper, graphite plate, (polycrystalline) carbon rod, carbon fiber yarn, carbon cloth, carbon felt, carbon paper, carbon plate, carbon brush, carbon mesh, carbon-based sponge, and sponge carbon fiber.

[0070] Preferably, the air cathode material is loaded with a metal catalyst Pt / C at a loading of 0.1~0.8 mg / cm³. 2 0.2 M PBS was injected into the cathode chamber.

[0071] Preferably, the anode chamber of the MFC sensor maintains an anaerobic environment with a dissolved oxygen concentration of no more than 0.1 mg / L. The nanofiber anode is immersed in an inoculation solution rich in electrogenic bacteria and an anode nutrient solution, so that electroactive microorganisms attach to the surface of the nanofiber anode to form a biofilm, ultimately forming a microbial electrode with a stable electrode potential.

[0072] Preferably, the anode nutrient solution comprises 1 g / L sodium acetate solution, 0.13 g / L KCl solution, 0.31 g / L NH4Cl solution, 10 mL / L trace element solution, 5 mL / L vitamin solution, and phosphate buffer solution (PBS) with a concentration of not less than 0.1 mol / L and a pH of 7-8.

[0073] In this embodiment of the invention, the novel MFC sensor is applied to the detection of pollutant concentrations. First, the anode loaded with nanofiber membrane is immersed in simulated test water to acclimate and enrich the microbial community that can stably exist in the test water environment until the MFC sensor reaches a stable state. Then, the microbial electrochemical sensor is started to test simulated water bodies with biochemical oxygen demand (BOD) concentrations of 5 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, and 300 mg / L, respectively, to obtain standard curves.

[0074] The BOD value of the test water body is calculated according to the following formulas (1) and (2) and the coulometric BOD calculation formula (3):

[0075] (1)

[0076] (2)

[0077] (3)

[0078] Where: I is current (A); U is voltage (V); R is external resistance (Ω); Q is charge (C); t is time (s); F is Faraday constant (96485 C / mol); V An Anode chamber volume (L); BOD Q The calculated BOD value (mg / L).

[0079] In this embodiment of the invention, the novel MFC sensor is applied to toxicity early warning. Test water containing heavy metal ions is mixed with PBS at a 4:1 ratio, and N2 is introduced to remove dissolved oxygen from the solution. The solution is then injected into the anode chamber, the MFC sensor is run, and changes in the voltage output signal are recorded to observe whether an early warning signal is triggered. When the MFC sensor is used for toxic substance detection, the difference in current signal before and after exposure to the toxic substance is typically used to analyze the toxicity level. Commonly used electrical signal indicators include current change (ΔI) and inhibition rate (IR).

[0080] The change in current (ΔI) is defined as the difference in output current of the MFC sensor before and after exposure to toxic substances, and its calculation is given in formula (4):

[0081] (4)

[0082] The suppression ratio (IR) is defined as the percentage change in the electrical signal relative to its initial value, and its calculation is given by formula (5):

[0083] (5)

[0084] In the formula I nor Current output (mA) before exposure to toxic substances; Itox The current output (mA) after exposure to toxic substances.

[0085] Example 1

[0086] (1) Preparation of polyaniline nanofiber membrane

[0087] Dissolve 10 g of polyaniline in 90 mL of N-methylpyrrolidone, 60 o A homogeneous solution of 10 wt / v% was prepared by heating and stirring at C for 2 h. This solution was then added to different syringes with needles of 2 mm diameter, moving back and forth with a slide bar at a flow rate of 15 mL / h. The syringe was positioned 25 cm from a rotating metal drum at a rotation speed of 1000 rpm. A drum collector, operating under a 15 kV DC voltage, collected the nanofibers ejected from the needles. The fibers had a diameter of 290 nm, an average pore size of 0.7 μm, a porosity of 94.6%, and a surface area of ​​289.56 m². 2 / g, then place the spun nanofiber membrane at 60 o Dry in a vacuum drying oven for 5 hours, and finally store in a desiccator for later use.

[0088] (2) MFC sensor

[0089] A 60-mesh stainless steel mesh was cut into 4 cm diameter circles to serve as the anode support for the MFC sensor. Simultaneously, electrospun polyaniline nanofiber membranes of the same or larger size were cut and fixed to one side of the support by titanium wires. The extended titanium wires on the other side served as the conductors for the anode electrode. The external circuit was connected to an external resistor with a fixed resistance of 300 Ω via the titanium wires. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and sodium acetate anode nutrient solution filled with N2. The cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the sensor was started under constant temperature conditions until the voltage output stabilized.

[0090] (3) Detection of livestock and poultry breeding wastewater

[0091] Livestock farming wastewater was selected as the test sample. It was first diluted 20 times, and then the pH was adjusted to 7.15 with sodium hydroxide or hydrochloric acid. Next, 0.5 M PBS was mixed with the test water at a ratio of 1:4, resulting in a wastewater containing 0.1 M PBS. 0.2 M PBS was injected into the cathode chamber. N2 was then aerated in the mixed solution to remove dissolved oxygen, followed by injection into the anode chamber of the microbial electrochemical sensor. The MFC sensor was run, and the voltage was recorded using data acquisition software. Based on the standard curve and the dilution factor, the BOD value of the livestock farming wastewater was determined to be 5116.5 mg / L.

[0092] Example 2

[0093] (1) Polypyrrole nanofiber membrane

[0094] Dissolve 12 g of polypyrrole in 90 mL of N,N-dimethylacetamide, 50 o A homogeneous solution of 12 wt / v% was prepared by heating and stirring at C for 4 h. This solution was then added to different syringes with a needle diameter of 0.05 mm, which moved back and forth with a slide bar. The injection flow rate was 0.001 mL / h. The syringe was 5 cm away from a rotating metal drum, which rotated at 50 rpm. A drum collector collected the nanofibers ejected from the needle under a 5 kV DC voltage. The fibers had a diameter of 5 nm, an average pore size of 0.89 μm, a porosity of 88.3%, and a surface area of ​​156.23 m². 2 / g, then place the spun nanofiber membrane at 50 o Dry in a vacuum drying oven for 6 hours, and finally store in a desiccator for later use.

[0095] (2) MFC sensor

[0096] An 80-mesh stainless steel mesh was cut into 4 cm diameter circles to serve as the anode support for the MFC sensor. Simultaneously, electrospun polypyrrole nanofiber membranes of the same or larger size were cut and fixed to one side of the support by titanium wires. The extended titanium wires on the other side served as the conductors for the anode electrode. The external circuit was connected to an external resistor with a fixed resistance of 300 Ω via the titanium wires. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and N2-filled sodium acetate anode nutrient solution, while the cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the sensor was started under constant temperature conditions until the voltage output stabilized.

[0097] (3) Beer wastewater testing

[0098] Beer wastewater was selected as the test sample. It was first diluted 20 times, and then the pH was adjusted to 7.45 using sodium hydroxide or hydrochloric acid. Next, 0.5 M PBS was mixed with the test water at a ratio of 1:4, resulting in a test wastewater containing 0.1 M PBS. 0.2 M PBS was injected into the cathode chamber. N2 was then aerated in the mixed solution to remove dissolved oxygen, followed by injection into the anode chamber of the microbial electrochemical sensor. The MFC sensor was run, and the voltage was recorded using data acquisition software. Based on the standard curve, the BOD value of the beer wastewater was determined to be 2036.2 mg / L.

[0099] Example 3

[0100] (1) Preparation of composite nanofiber membranes

[0101] Activated carbon particles were uniformly dispersed in N,N-dimethylformamide solvent to a concentration of 5 wt%, and then polyacrylonitrile powder was added (the concentration of polyacrylonitrile after adding the powder was 30 wt / v%).o A solution containing activated carbon was prepared by heating and stirring at C for 6 h. This solution was then added to different syringes with a needle diameter of 10.0 mm, which moved back and forth with a slide rod. The injection flow rate was 15 mL / h. The syringe was 50 cm away from a rotating metal drum, which rotated at 2000 rpm. A drum collector collected the composite nanofibers ejected from the needle under an 80 kV DC voltage. The fibers had a diameter of 15 μm, an average pore size of 3.6 μm, a porosity of 75.9%, and a surface area of ​​42.56 m². 2 / g, then place the spun composite nanofiber membrane at 70 o Dry in a vacuum drying oven for 8 hours, and finally store in a desiccator for later use.

[0102] (2) MFC sensor

[0103] A 100-mesh stainless steel mesh was cut into circles with a diameter of 4 cm to serve as the anode support for the MFC sensor. Simultaneously, an electrospun composite nanofiber membrane of the same or larger size was cut and fixed to one side of the support by titanium wires. The extended titanium wires on the other side served as the conductors for the anode electrode. The external circuit was connected to an external resistor with a fixed resistance of 300 Ω via the titanium wires. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and sodium acetate anode nutrient solution filled with N2. The cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the sensor was started under constant temperature conditions until the voltage output stabilized.

[0104] (3) Domestic sewage testing

[0105] Domestic sewage was selected as the test sample. The pH of the wastewater was adjusted to 7.05 using sodium hydroxide or hydrochloric acid. Then, 0.5M PBS was mixed with the test water at a ratio of 1:4, so that the wastewater contained 0.1M PBS. 0.2M PBS was injected into the cathode chamber. Next, N2 was aerated in the mixed solution to remove dissolved oxygen, and then injected into the anode chamber of the microbial electrochemical sensor. The MFC sensor was run, and the voltage was recorded using data acquisition software. According to the standard curve, the BOD value of the domestic sewage was obtained as 286.2 mg / L.

[0106] Example 4

[0107] (1) Preparation of composite nanofiber membranes

[0108] Graphene was uniformly dispersed in dimethyl sulfoxide solvent to a concentration of 0.1 wt%, and then polyvinylidene fluoride powder was added to achieve a polyvinylidene fluoride mass concentration of 25 wt%. oA homogeneous and stable solution containing graphene was prepared by heating and stirring at C for 5 h. This solution was then added to different syringes with needles of 8.0 mm diameter, moving back and forth with a slide bar. The injection flow rate was 10 mL / h. The syringe was 30 cm away from a rotating metal drum, which rotated at 1500 rpm. A drum collector collected the composite nanofibers ejected from the needles under a 60 kV DC voltage. The fibers had a diameter of 381 nm, an average pore size of 3.2 μm, a porosity of 79.8%, and a surface area of ​​56.24 m². 2 / g, then place the spun composite nanofiber membrane at 80 o Dry in a vacuum drying oven for 2 hours, and finally store in a desiccator for later use.

[0109] (2) MFC sensor

[0110] A 70-mesh stainless steel mesh was cut into 4 cm diameter circles to serve as the anode support for the MFC sensor. Simultaneously, an electrospun composite nanofiber membrane of the same or larger size was cut and fixed to one side of the support by titanium wires. The extended titanium wires on the other side served as the conductors for the anode electrode. The external circuit was connected to an external resistor with a fixed resistance of 300 Ω via the titanium wires. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and N2-filled sodium acetate anode nutrient solution, while the cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the sensor was started under constant temperature conditions until the voltage output stabilized.

[0111] (3) Contains Cu 2+ Simulated wastewater detection

[0112] The anolyte in the MFC was replaced with simulated wastewater containing 0.82 g / L NaAc, 0.13 g / L NH4Cl, and 2 mg / L CuCl2. N2 was then introduced into the anolyte to remove dissolved oxygen, followed by injection into the anode chamber of the microbial electrochemical sensor. 0.2 M PBS was injected into the cathode chamber. The MFC sensor was run, and the voltage drop across the external resistor was recorded every 10 seconds using data acquisition software as a signal indicator. Based on Ohm's law and formula (5), the suppression rate of the MFC sensor for simulated wastewater warning was calculated to be 42.2%, and the suppression rate for CuCl2 was [not specified]. 2+ The response time is 1.2 hours.

[0113] Example 5

[0114] (1) Preparation of composite nanofiber membranes

[0115] Nanoparticles were uniformly dispersed in dimethyl sulfoxide solvent to a concentration of 10 wt%, and then polyimide powder with a mass concentration of 20 wt% was added. oA homogeneous and stable mixed matrix spinning solution containing silver nanoparticles was prepared by heating and stirring at C for 8 h. This solution was then added to different syringes with a needle diameter of 6.0 mm, which moved back and forth with a slide bar. The injection flow rate was 5 mL / h. The syringe was 25 cm away from a rotating metal drum, which rotated at 800 rpm. A drum collector collected the composite nanofibers ejected from the needle under a 35 kV DC voltage. The fiber diameter was 820 nm, the average pore size was 2.2 μm, the porosity was 86.5%, and the surface area was 143.21 m². 2 / g, then place the spun composite nanofiber membrane at 100 o Dry in a vacuum drying oven for 5 hours, and finally store in a desiccator for later use.

[0116] (2) MFC sensor

[0117] A 100-mesh stainless steel mesh was cut into circles with a diameter of 4 cm to serve as the anode support for the MFC sensor. Simultaneously, an electrospun composite nanofiber membrane of the same or larger size was cut and fixed to one side of the support by titanium wires. The extended titanium wires on the other side served as the conductors for the anode electrode. The external circuit was connected to an external resistor with a fixed resistance of 300 Ω via the titanium wires. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and sodium acetate anode nutrient solution filled with N2. The cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the sensor was started under constant temperature conditions until the voltage output stabilized.

[0118] (3) Detection of simulated wastewater containing Cr(VI)

[0119] The anolyte in the MFC was replaced with simulated wastewater containing 0.82 g / L NaAc, 0.13 g / L NH4Cl, and 1 mg / L Cr(VI). N2 was then introduced into the anolyte to remove dissolved oxygen, followed by injection into the anode chamber of the microbial electrochemical sensor. 0.2 M PBS was injected into the cathode chamber. The MFC sensor was run, and the voltage drop across the external resistor was recorded every 10 seconds using data acquisition software as a signal indicator. Based on Ohm's law and formula (5), the suppression rate of the MFC sensor for simulated wastewater warning was calculated to be 35.7%, and the response time to Cr(VI) was 1.8 h.

[0120] Example 6

[0121] (1) Preparation of composite nanofiber membranes

[0122] MoS2 was uniformly dispersed in formic acid to a concentration of 8 wt%, and then chitosan was added to achieve a chitosan concentration of 25 wt%. oA homogeneous and stable solution containing MoS2 was prepared by heating and stirring at C for 10 h. This solution was then added to different syringes with a needle diameter of 5.0 mm, which moved back and forth with a slide bar. The injection flow rate was 6 mL / h. The syringe was 45 cm away from a rotating metal drum, which rotated at 1000 rpm. A drum collector collected the composite nanofibers ejected from the needle under a 55 kV DC voltage. The fibers had a diameter of 506 nm, an average pore size of 0.25 μm, a porosity of 82.5%, and a surface area of ​​139.56 m². 2 / g, then place the spun composite nanofiber membrane at 90°C. o Dry in a vacuum drying oven for 8 hours, and finally store in a desiccator for later use.

[0123] (2) MFC sensor

[0124] A 60-mesh stainless steel mesh was cut into 4 cm diameter circles to serve as the anode support for the MFC sensor. Simultaneously, an electrospun composite nanofiber membrane of the same or larger size was cut and fixed to one side of the support by titanium wires. The extended titanium wires on the other side served as the conductors for the anode electrode. The external circuit was connected to an external resistor with a fixed resistance of 300 Ω via the titanium wires. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and N2-filled sodium acetate anode nutrient solution, while the cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the sensor was started under constant temperature conditions until the voltage output stabilized.

[0125] (3) Contains Cu 2+ Simulated wastewater detection

[0126] The anolyte in the MFC was replaced with simulated wastewater containing 0.82 g / L NaAc, 0.13 g / L NH4Cl, and 4 mg / L CuCl2. N2 was then introduced into the anolyte to remove dissolved oxygen, followed by injection into the anode chamber of the microbial electrochemical sensor. 0.2 M PBS was injected into the cathode chamber. The MFC sensor was run, and the voltage drop across the external resistor was recorded every 10 seconds using data acquisition software as a signal indicator. Based on Ohm's law and formula (5), the suppression rate of the MFC sensor for simulated wastewater warning was calculated to be 59.3%, and the suppression rate for CuCl2 was [not specified]. 2+ The response time is 0.8 h.

[0127] Comparative Example 1

[0128] A 60-mesh stainless steel mesh was cut into 4 cm diameter circles to serve as the anode support for the MFC sensor. Simultaneously, carbon cloth of the same size was cut, pre-treated to remove impurities, and then fixed to one side of the support with titanium wire. The extended titanium wire on the other side served as the conductor for the anode electrode. The external circuit was connected to a fixed 300 Ω external resistor via the titanium wire. The anode chamber of the MFC sensor was inoculated with 10 mL of bacterial solution and N2-filled sodium acetate anode nutrient solution, while the cathode chamber was filled with phosphate buffer solution. A voltage acquisition device was connected, and the system was started under constant temperature conditions until the voltage output stabilized.

[0129] The anolyte in the MFC was replaced with simulated wastewater containing 0.82 g / L NaAc, 0.13 g / L NH4Cl, and 1 mg / L Cr(VI). N2 was then introduced into the anolyte to remove dissolved oxygen, followed by injection into the anode chamber of the microbial electrochemical sensor. 0.2 M PBS was injected into the cathode chamber. The MFC sensor was run, and the voltage drop across the external resistor was recorded every 10 seconds using data acquisition software as a signal indicator. Based on Ohm's law and formula (5), the suppression rate of the MFC sensor for simulated wastewater warning was calculated to be 28.5%, and the response time to Cr(VI) was 3.6 h.

Claims

1. Interpenetrating network nanofibers for preparing the anode of an MFC sensor, characterized in that, The interpenetrating network nanofibers were prepared using the following method: 1) Melt the polymer to obtain a polymer melt; or prepare a polymer solution using an organic solvent or an organic solvent containing conductive nanoparticles; 2) The polymer solution or polymer melt obtained in step 1) is electrospinned to form interpenetrating network nanofibers.

2. The interpenetrating network nanofiber according to claim 1, characterized in that, The polymers include polysulfone, polyethersulfone, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-co-polyhexafluoropropylene, polyimide, poly(isophthalamide), polyvinylpyrrolidone, polyvinyl alcohol, butyral, polyethyleneimine, polyetherimide, polyamide, polylactic acid, chitosan, chitosan, glucan, carboxymethyl chitosan, lignin, polysulfonamide, polyetherimide, polyamic acid, polyamide-6, nylon-66, aramid, polyamide-based n-halogenamine, polycaprolactam, and poly... Ethylene, polyvinyl chloride, polypropylene, polyethylene oxide, polyurethane, polyphenylene sulfide, alginate, dextran, ethylene-vinyl alcohol copolymer, polytetrafluoroethylene, polyarylene sulfide, polyvinyl alcohol, poly(arylene sulfide), oxidized poly(arylene sulfide), polyethylene glycol, polymethyl methacrylate, polycaprolactone, polystyrene, polyaniline, polypyrrole, poly3,4-ethylenedioxythiophene, cellulose acetate, cellulose acetate, and cellulose triacetate are selected from one or more of these polymers; the polymer concentration is 5 wt% to 100 wt%. The organic solvent includes any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, deionized water, acetone, butanone, ethanol, isopropanol, fluoroisopropanol, formic acid, acetic acid, trifluoroethanol, dimethyl sulfoxide, dichloromethane, chloroform, butyrate, bromopropyne, 1,3-dimethyl-2-imidazolinone, benzoic acid dianhydride, diaminodiphenyl ether, dialcyldimethylammonium chloride, tetrahydrofuran, benzoic acid dianhydride, trifluoroacetic acid, and m-cresol. The conductive nanoparticles include any one or more of Si3N4, silver nanoparticles, gold nanoparticles, activated carbon, graphene, carbon black, graphite, GO, TiO2, ZnO, MoS2, Mo2C, Co3O4, MoO3, NiMoO4, montmorillonite, nanoclay, Fe2O3, and carbon nanotubes; the concentration of the conductive nanoparticles is 0.1 wt% to 10 wt%.

3. The interpenetrating network nanofiber according to claim 1, characterized in that, The electrospinning parameters include: needle diameter of 0.05~10.0 mm, injection flow rate of 0.001~15 mL / h, spinning voltage of 5~100 kV, receiving distance of 2~50 cm, and rotation speed of the collecting device of 50~2000 rpm.

4. The interpenetrating network nanofiber according to claim 1, characterized in that, The nanofibers have a diameter of 5 nm to 15 μm.

5. The application of the interpenetrating network nanofibers according to any one of claims 1 to 4 in the preparation of the anode electrode of an MFC sensor for pollutant concentration analysis and toxic substance early warning.

6. An MFC sensor for pollutant concentration analysis and toxic substance early warning, characterized in that, The anode of the MFC sensor comprises the interpenetrating network nanofibers as described in any one of claims 1 to 4.

7. The MFC sensor according to claim 6, characterized in that, The interpenetrating network nanofibers are loaded onto a stainless steel mesh support to serve as the anode electrode of the sensor, and the air cathode is connected to the titanium wire via an external circuit to assemble the MFC sensor.

8. The application of the MFC sensor according to any one of claims 6 to 7 in the detection of water pollutant concentration and / or early warning of toxic substances.

9. The application according to claim 8, characterized in that, The water bodies include any one or more of the following: livestock and poultry breeding wastewater, brewing wastewater, domestic sewage, food processing wastewater, pharmaceutical wastewater, polluted surface water, and various industrial wastewater; the toxic substances include Hg, Cd, Pb, As, and Cu. 2+ Any one or more of Zn, Ni, and Cr(VI).

10. A method for detecting the concentration of pollutants and / or toxic substances in water using the MFC sensor according to any one of claims 6 to 7, characterized in that, The anode loaded with nanofiber membrane is immersed in simulated test water to directionally acclimate and enrich microbial communities that can stably exist in the test water environment; the MFC sensor is activated to test simulated water bodies with biochemical oxygen demand concentrations of 5 mg / L, 50 mg / L, 100 mg / L, 200 mg / L and 300 mg / L, respectively, to obtain a standard curve; the water sample to be tested is detected using the MFC sensor according to any one of claims 6 to 7, and the BOD value of the water sample to be tested is calculated according to the standard curve; And / or use the MFC sensor according to any one of claims 6 to 7 to detect the water sample to be tested, and determine whether the water sample to be tested contains toxic substances and analyze the strength of toxicity based on the change of current signal.

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