Preparation of a bio-gel composite electrode and its application in electrochemical treatment of organic contaminated wastewater

Abstract

The application discloses a preparation method of a bio-gel composite electrode and application thereof in an electrochemical system, and the preparation method comprises the following steps: (1) preparing a first bio-gel base solution containing electroactive microorganisms and a second bio-gel base solution containing functional microorganisms, and respectively shaping and solidifying to obtain a first solid bio-gel and a second solid bio-gel; (2) pasting the first solid bio-gel to a surface of an anode base electrode to obtain a bio-gel composite anode, and pasting the first solid bio-gel and the second solid bio-gel to surfaces of cathode base electrodes in sequence to obtain bio-gel composite cathodes. The DIY bio-gel can be pasted to surfaces of various anode materials or cathode materials after being pre-prepared, and problems such as slow gelation speed, low enrichment capacity and long starting time of bio-anodes and bio-cathodes are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and relates to the preparation of a biogel composite electrode and its application in the electrochemical treatment of organic polluted wastewater. Background Technology

[0002] Bioelectrochemical systems are a novel environmental remediation technology that integrates microbial metabolism and electrochemical principles. They are primarily used in two scenarios: first, for precise monitoring of pollutants in water bodies and real-time capture of pollution signals; and second, for the efficient degradation of pollutants through microbial metabolism, particularly suitable for treating complex and recalcitrant pollutants. Biofilm construction is a crucial element for the stable operation of bioelectrochemical systems, mainly consisting of anodic and cathodic biofilms. The anodic biofilm, centered on electroactive microorganisms, is responsible for converting the chemical energy of pollutants into electrical energy or promoting their oxidative degradation. The cathodic biofilm, on the other hand, performs reduction reactions such as denitrification and heavy metal reduction, achieving deep transformation and removal of pollutants. However, the application of bioelectrochemical systems faces significant technical bottlenecks: biofilm formation is difficult, especially for cathodic biofilms. Due to the unique microenvironment of the cathodic biofilm, the attachment, colonization, and proliferation of microorganisms on the cathodic surface are far more challenging than at the anode, resulting in a long formation cycle and structural instability of the cathodic biofilm. More importantly, the formation of functional biofilms is more difficult. It requires screening for highly adaptable functional microorganisms and ensuring their activity and functional stability on the electrode surface. Traditional technologies struggle to balance microbial activity, membrane structure stability, and functional specificity, resulting in slow system startup, low processing efficiency, and weak shock resistance. Summary of the Invention

[0003] This application provides a DIY (homemade) adhesive biogel technology with characteristics of "rapid response, convenient operation, stable operation, and adaptability to multiple pollutants". Compared with traditional processes, DIY adhesive biogels do not require complex pretreatment and long-term cultivation. They can be directly cut and pasted onto electrode substrates of different materials through pre-made gel modules, which significantly shortens the equipment start-up time. Its unique gel matrix formula and functional microbial community design can not only resist the toxic impact of pollutants and reduce the risk of microbial detachment, but also flexibly adjust the gel layer structure according to the type of pollutant (such as single-layer recognition, double-layer adsorption-degradation synergy), so as to achieve precise treatment of multiple pollutants such as nitrobenzene, heavy metals, nitrogen and phosphorus.

[0004] DIY adhesive biogels, as a novel technology for treating pollutants in wastewater, offer advantages such as rapid response, quick start-up, and easy equipment installation. Traditional biogel cultivation processes are lengthy, have weak shock resistance, and the introduction of highly toxic substances into the water can directly cause microbial detachment or even death. DIY adhesive biogels, on the other hand, offer convenient, rapid, stable, and effective operation.

[0005] This invention provides a process for preparing an electroactive composite biomembrane. This process prepares a DIY biogel that can be adhered to the surface of various anode and cathode materials, effectively solving problems such as slow gelation speed, low enrichment capacity, and long start-up time of bioanodes and biocathodes. At the same time, it adheres a double-layer membrane, with one layer for adsorption and the other for degradation, synergistically promoting the degradation of organic pollutants.

[0006] A method for preparing a biogel composite electrode, comprising: A method for preparing a biogel composite electrode, characterized by comprising: (1) Prepare a first biogel base liquid containing electroactive microorganisms and a second biogel base liquid containing functional microorganisms. Place the first biogel base liquid and the second biogel base liquid in a molding mold and solidify them under nitrogen for 1 to 3 hours to obtain a first solid biogel containing electroactive microorganisms and a second solid biogel containing functional microorganisms. (2) The first solid biogel is attached to the surface of the anode substrate electrode to obtain a biogel composite anode; the first solid biogel and the second solid biogel are attached to the surface of the cathode substrate electrode in sequence to obtain a biogel composite cathode.

[0007] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0008] Optionally, the electrode materials of the anode substrate electrode and the cathode substrate electrode are selected from platinum electrodes, graphite electrodes, iron electrodes, etc., and the substrate electrode of this material has good conductivity, corrosion resistance and chemical stability.

[0009] Optionally, the electroactive microorganisms may be selected from the genera *Geobacterium* and *Shewanella*. Further, the *Geobacterium* genus may be selected from... Geobacter The Shewanella spp. can be selected Shewanellaalgae .

[0010] Optionally, the functional microorganism is an oxidizing functional strain or a reducing functional strain. The oxidizing functional strain includes, but is not limited to, one or more microorganisms with oxidizing functions such as organic matter degradation and ammonia nitrogen oxidation. The reducing functional strain includes, but is not limited to, one or more microorganisms with reducing functions such as denitrification, defluorination, and dechlorination.

[0011] Optionally, the functional microorganism is a reducing microorganism, such as denitrifying bacteria, which may be selected from at least one of the genera *Pseudomonas* or *Alcaligenes*.

[0012] Optionally, the *Pseudomonas* genus may be selected. Pseudomonasstutzeri The genus *Alcaligenes* can be selected. Alcaligenesaquatilis .

[0013] As mentioned above, both electroactive and functional microorganisms are common species in this field and are commercially available.

[0014] Optionally, the first biogel base liquid and the second biogel base liquid include sodium alginate, acrylamide, N,N'-methylenebisacrylamide, ammonium persulfate, polyethylene glycol, cerium dioxide nanoparticles, iron tetroxide nanoparticles, gelatin, nanographene, and corresponding microorganisms and solvents, wherein the corresponding microorganisms are electroactive microorganisms or functional microorganisms.

[0015] Optionally, the OD of the electroactive or functional microorganisms 600 The concentrations are between 1 and 3; based on the mass of the solvent, the sodium alginate has a mass percentage content of 0.2%-2%, the acrylamide has a mass percentage concentration of 10%-20%, the N,N'-methylenebisacrylamide has a mass percentage concentration of 0.001%-0.03%, the ammonium persulfate has a mass percentage concentration of 0.1%-1%, the polyethylene glycol has a mass percentage concentration of 0.1%-3%, the cerium dioxide nanoparticles have a mass percentage concentration of 0.01%-0.1%, the iron oxide nanoparticles have a mass percentage concentration of 0.1%-1%, the gelatin has a mass percentage concentration of 0.1%-3%, and the nanographene has a mass percentage concentration of 0.1%-1%; the solvent is water.

[0016] Furthermore, the OD of the electroactive or functional microorganisms 600 Between 2; based on the mass of the solvent, the mass percentage of sodium alginate is 1%, the mass percentage concentration of acrylamide is 15%, the mass percentage concentration of N,N'-methylenebisacrylamide is 0.015%, the mass percentage concentration of ammonium persulfate is 0.5%, the mass percentage concentration of polyethylene glycol is 2%, the mass percentage concentration of cerium dioxide nanoparticles is 0.05%, the mass percentage concentration of iron oxide nanoparticles is 0.5%, the mass percentage concentration of gelatin is 3%, and the mass percentage concentration of nanographene is 0.5%.

[0017] Preferably, the sodium alginate concentration is 0.2%-2%, that is, based on 100mL of solvent water, the sodium alginate content is 0.2-2g. Sodium alginate has advantages such as good biocompatibility, functional adjustability, and high porosity. If its concentration is too high, the solution viscosity will increase significantly, hindering the cross-linking reaction. If its concentration is too low, it will lead to reduced gel strength, poor swelling effect, and short service life.

[0018] Preferably, the acrylamide concentration is 10%-20%, meaning that the alginate content is 10-20g per 100mL of water. Acrylamide is the core monomer for synthesizing polymeric gels. Through free radical polymerization with a crosslinking agent, it forms a polyacrylamide gel with a three-dimensional network structure. Its essential function is to construct the gel skeleton through polymerization and to endow the gel with biocompatibility to ensure the stability of the biological gel surface structure. Too low a concentration will lead to a decrease in gel strength and stability, while too high a concentration will have a toxic effect on microorganisms.

[0019] Preferably, the concentration of N,N'-methylenebisacrylamide is 0.001%-0.03%, that is, based on 100 mL of water as the solvent, the content of alginate is 0.001~0.03 g. The core function of N,N'-methylenebisacrylamide is to form covalent cross-linking points between polymer chains through free radical polymerization. If its concentration is too high, the gel will harden and become biotoxic; if its concentration is too low, the stability of the gel structure will decrease.

[0020] Preferably, the concentration of ammonium persulfate is 0.1%-1%, that is, based on 100 mL of solvent water, the content of alginate is 0.1-1 g. Ammonium persulfate is a core factor in the rate of gel polymerization. If its concentration is too high, it will easily lead to uneven mixing of monomer and crosslinking agent, resulting in bubbles or local solidification inside the gel. If its concentration is too low, it will slow down the polymerization reaction.

[0021] Preferably, the polyethylene glycol used is polyethylene glycol with an average molecular weight of 4000 and a concentration of 0.1%-3%. That is, based on 100 mL of water as the solvent, the content of polyethylene glycol is 0.1-3 g. As a pore-forming agent and humectant, polyethylene glycol can optimize the material exchange channels inside the gel. If its concentration is too high, it will reduce the mechanical strength of the gel; if the concentration is too low, it will not be conducive to the excretion of microbial metabolites.

[0022] Preferably, the cerium dioxide nanoparticles are commercially available products with a particle size of 50 nm and a purity of 99.99% (CAS: 1306-38-3), prepared at a concentration of 0.01%-0.1%, i.e., the content of cerium dioxide nanoparticles is 0.01~0.1g per 100mL of water. Cerium dioxide has the effect of scavenging reactive oxygen free radicals and can reduce the oxidative stress damage to microorganisms caused by electrochemical reactions. However, excessively high concentrations may produce certain cytotoxicity, while excessively low concentrations will result in insignificant antioxidant effects.

[0023] Preferably, the iron oxide nanoparticles are commercially available products (CAS: 1317-61-9) with a particle size of 100 nm and a purity of 99.5%, and are prepared at a concentration of 0.1%-1%, that is, based on 100 mL of solvent water, the content of iron oxide nanoparticles is 0.1-1 g. Iron oxide can induce microorganisms to produce conductive pili and act as electron junctions. Excessive concentration will lead to nanoparticle aggregation, while insufficient concentration will make it difficult to form an effective electron transfer interface.

[0024] Preferably, the gelatin has a gel strength of 250g, is a commercially available product (CAS: 9000-70-8), and has a mass percentage concentration of 0.1%-3%, meaning that the gelatin content is 0.1-3g per 100mL of water. Gelatin provides abundant biorecognition sites to enhance the adhesion activity of microorganisms in the gel network. Excessive concentration will result in excessive gel viscosity, affecting component dispersion, while insufficient concentration will fail to provide adequate biocompatibility space.

[0025] Preferably, the commercially available graphene nanoparticles (item number N931282) with an average thickness of 5 nm and a conductivity of 1600 S / cm are prepared at a concentration of 0.1%-1%, meaning that the content of graphene nanoparticles is 0.1-1 g per 100 mL of water. Graphene nanoparticles construct macroscopic electron transport pathways; excessively high concentrations can affect the light transmittance of the gel and may physically damage microbial cell membranes, while excessively low concentrations will prevent the formation of a continuous conductive network.

[0026] Optionally, the thickness of both the first and second solid biogels is between 0.2 and 1.5 mm. If the thickness is too thick, contaminants may have difficulty passing through; if the thickness is too thin, insufficient stress may lead to deformation and insufficient enrichment of microorganisms, resulting in a poorer effect.

[0027] Optionally, the cutting dimensions of the first and second solid biogel layers are: length 5-8cm, width 3-6cm, and depth 0.2-1.5mm. If they are too large, the drying time will be too long and they will be inconvenient to use; if they are too small, they will not meet various DIY needs.

[0028] Optionally, the bonding method includes flexible progressive venting bonding, electrically assisted wetting enhancement, and homogeneous wetting bonding.

[0029] Optionally, the bonding process between the first solid biogel and the substrate electrode can be combined with an electrically flexible, progressively degassing bonding method. This method employs a progressive compaction approach from the center to the edge, utilizing the gel's inherent elasticity and applying a constant micro-pressure of 2-5 kPa using a soft roller to ensure no visible air bubbles are trapped at the gel-electrode interface. Excessive pressure can damage the gel surface, while insufficient pressure can lead to air bubble trapping at the electrode interface.

[0030] Optionally, the bonding process between the first solid biogel and the substrate electrode can also be combined with an electro-assisted wetting treatment. A transient pulse voltage of 0.1-1V induces interfacial water migration, enhancing the molecular-level bonding between the gel network and the electrode surface. Excessive voltage can damage the gel, while insufficient voltage will result in weak bonding.

[0031] This application also provides a biogel composite electrode, including a biogel composite anode and a biogel composite cathode; the biogel composite anode includes a base electrode and a first solid biogel adhered to the surface of the base electrode; the biogel composite cathode includes a base electrode and a first solid biogel and a second solid biogel sequentially adhered to the surface of the base electrode; the first solid biogel contains electroactive microorganisms, and the second solid biogel contains functional microorganisms.

[0032] This application also provides an application of the aforementioned biogel composite electrode in an electrochemical system.

[0033] This application also provides the application of the aforementioned biogel composite electrode in the electrochemical treatment of organic polluted wastewater or in toxicity monitoring.

[0034] This application also provides an electrochemical monitoring method for the toxicity of organic pollutants in wastewater, including: (1) The gel biocomposite anode and gel biocomposite cathode are used as working electrodes and connected to different channels of the electrochemical workstation respectively. Each of them forms a three-electrode system with the corresponding counter electrode and reference electrode. At the same time, electrolyte is injected into their respective electrochemical work chambers. (2) Apply the corresponding potential to the gel biocomposite anode and gel biocomposite cathode respectively. The initial current runs stably for 1-2 hours until the current gradually rises and remains stable. This indicates that the gel biocomposite anode and gel biocomposite cathode have been successfully started. (3) After successful startup, when organic pollutants enter the electrochemical chambers of the gel biocomposite anode and gel biocomposite cathode, different current responses will immediately appear, indicating that pollutants have an impact on microbial activity, thus realizing the toxicity monitoring of organic pollutants in wastewater.

[0035] This application also provides an electrochemical treatment method for organic polluted wastewater, comprising: (1) The gel biocomposite anode and gel biocomposite cathode are used as working electrodes and connected to different channels of the electrochemical workstation respectively. Each of them forms a three-electrode system with the corresponding counter electrode and reference electrode. At the same time, electrolyte is injected into their respective electrochemical work chambers. (2) Apply the corresponding potential to the gel biocomposite anode and gel biocomposite cathode respectively. The initial current runs stably for 1-2 hours until the current gradually rises and remains stable. This indicates that the gel biocomposite anode and gel biocomposite cathode have been successfully started. (3) After successful startup, wastewater containing organic pollutants is sent to the electrochemical chambers of the gel biocomposite anode and gel biocomposite cathode respectively to achieve the degradation of organic pollutants in the wastewater.

[0036] Optionally, a potential of 0~0.4V is applied to the anode electrode to ensure the normal physiological metabolism of the anode microorganisms; and a potential of -0.8~-0.4V is applied to the cathode electrode to ensure the normal physiological metabolism of the cathode microorganisms. Applying too high or too low a potential will lead to a decrease in microbial activity and a decrease in the degradation rate.

[0037] Optionally, the organic pollutant in the organic wastewater is p-fluoronitrobenzene.

[0038] Optionally, the initial concentration of the p-fluoronitrobenzene is 40~60 mg / L.

[0039] Compared with the prior art, this application has at least one of the following beneficial effects: (1) Current starts up faster.

[0040] (2) Easy to use and replace quickly.

[0041] (3) The electrode can be customized.

[0042] (4) At the same time, a double-layer membrane is pasted, one layer adsorbs and the other layer degrades, which synergistically promotes the degradation of organic pollutants. Attached Figure Description

[0043] Figure 1 Flowchart for biogel fabrication.

[0044] Figure 2 This is a diagram of a monolayer gel-adhesive electrode (anode).

[0045] Figure 3 This is a diagram of a double-layer gel-adhesive electrode (cathode).

[0046] Figure 4 and Figure 5 The images show the effects of the biogel before and after application in Example 1.

[0047] Figure 6 The image shows the degradation results of p-fluoronitrobenzene in Example 1.

[0048] Figure 7 and Figure 8 The images show the sequential bonding effects of the first solid biogel and the second solid biogel in Example 2.

[0049] Figure 9 The following are the electrode performance test results in Example 2: Figure A shows the starting current of the unmodified electrode under the anode and cathode potentials; Figure B shows the starting current of the bioanode; Figure C shows the starting current of the biocathode; and Figure D shows the resistance of the unmodified electrode, bioanode, and biocathode.

[0050] Figure 10 The following are the current responses of different concentrations of nitrate nitrogen and cadmium to the bio-anode and bio-cathode in Example 2: A is the current response of different concentrations of nitrate nitrogen to the anode, B is the current response of different concentrations of nitrate nitrogen to the cathode, C is the current response of different concentrations of cadmium to the anode, and D is the current response of different concentrations of cadmium to the cathode.

[0051] Figure 11 The following are current response diagrams for the impact of different concentrations of COD (chemical oxygen demand) on the bioanode and biocathode in Example 2: A is the current response diagram of different concentrations of COD on the bioanode, and B is the current response diagram of different concentrations of COD on the biocathode.

[0052] Figure 12 This is a cyclic voltammetry curve of the bioanode and biocathode in Example 2 before and after exposure to pollutants. Figure 13 The graph shows the viable bacteria count results in the cathode electrode gels of Examples 1-2 and Comparative Examples 1-2.

[0053] Figure 14 The diagram shows the microbial activity of Examples 1 and 2 under toxic shock (single-layer bacteria correspond to the cathode of Example 1, and double-layer bacteria correspond to the cathode of Example 2).

[0054] Figure 15 This is a detailed comparison chart of the microbial activities of Example 1 and Example 2 under toxic shock.

[0055] Figure 16 The results show the comparison of ammonium nitrogen permeation performance between Example 1 and Example 2 (where the single-layer gel corresponds to the cathode of Example 1, and the double-layer gel corresponds to the cathode of Example 2).

[0056] Figure 17 This is a comparison of COD permeation performance between Example 1 and Example 2 (where the single-layer gel corresponds to the cathode of Example 1, and the double-layer gel corresponds to the cathode of Example 2).

[0057] Figure 18 This is a comparison of the nitrate nitrogen permeation performance between Example 1 and Example 2 (where the single-layer gel corresponds to the cathode of Example 1, and the double-layer gel corresponds to the cathode of Example 2).

[0058] Figure 19 This is a diagram showing the degradation results of p-fluoronitrobenzene in Example 2.

[0059] Figure 20 and Figure 21 This is a comparison image of the anolyte biogel before and after stretching in Example 2.

[0060] Figure 22 The graph shows the stress variation results of the cathode electrode gel in Examples 1-2 and Comparative Example 1. Detailed Implementation

[0061] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0063] Preparation of an electroactive composite biomembrane electrode, referenced Figure 1 ,include: S1. Add a certain amount of sodium alginate to distilled water, dissolve it completely, add a certain amount of acrylamide and NN methylenebisacrylamide, and finally add ammonium persulfate to mix it evenly. S2. Add the bacterial solution required for the cathode or anode to the mixture to form a biogel base solution.

[0064] S3. A certain amount of base liquid is added to a specific module and solidified under nitrogen conditions to form a bioelectrode gel of a certain size and thickness.

[0065] S4. Cut the bioelectrode gel according to the size and shape of different electrodes to form a bioelectrode gel of a certain size and thickness.

[0066] S5. The cut bioelectrode gel can be pasted onto the required electrode and the corresponding voltage can be applied to it.

[0067] S6. After long-term use, the effect of the bio-gel electrode will deteriorate. Remove the bio-gel electrode and replace it quickly to continue using it.

[0068] A schematic diagram of the bioelectrode gel after it has been attached to the electrode is shown below. Figure 1 As shown in the diagram, a schematic diagram of the sequential bonding of two layers of biogel electrodes is as follows. Figure 2 As shown.

[0069] Construction and contaminant recognition response of bioelectrochemical systems: (1) The prepared gel biocomposite anode and gel biocomposite cathode were respectively used as working electrodes and installed in the bioelectrochemical system, connected to the electrochemical workstation, and relevant data information was collected. (2) Apply the corresponding potential to the gel biocomposite anode and gel biocomposite cathode respectively. The initial current runs stably for 1-2 hours until the current gradually rises and remains stable. This indicates that the gel biocomposite anode and gel biocomposite cathode have been successfully started. (3) When pollutants enter the bioanode chamber and the biocathode chamber, different current responses immediately appear, indicating that the pollutants have an impact on the activity of microorganisms; (4) After the current stabilizes for a period of time, the gel bioelectrode will form a real biofilm, and the bioelectrochemical system can be quickly started, monitored and degraded organic pollutants in wastewater.

[0070] A potential of 0~0.4V is applied to the anode electrode to ensure the normal physiological metabolism of the anode microorganisms; a potential of -0.8~-0.4V is applied to the cathode electrode to ensure the normal physiological metabolism of the cathode microorganisms. Applying too high or too low a potential will lead to a decrease in microbial activity and a decrease in the degradation rate.

[0071] The following is a description using specific embodiments: Electrogenic bacteria used in the following examples Shewanellavesiculosa and denitrifying bacteria Pseudomonasstutzeri All of these can be obtained through retail purchases.

[0072] Electrogenic bacteria Shewanellavesiculosa Purchased from the Culture Collection Center, accession number CGMCCNO.1.15835.

[0073] Denitrifying bacteria Pseudomonasstutzeri Purchased from the Culture Collection Center, accession number CGMCCNO.1.15316.

[0074] Example 1 The anode and cathode materials used in this embodiment are both graphite electrodes with dimensions of 2cm*2cm*1mm.

[0075] The specific preparation method of the composite electrode is as follows: (1) Dissolve 1 wt% (0.25 g) sodium alginate in 25 mL of distilled water. After complete dissolution, add 10 wt% (2.5 g) acrylamide. After complete dissolution and uniform mixing of sodium alginate and acrylamide, add 0.015 wt% (3.75 mg) N,N'-methylenebisacrylamide, then add 0.5 wt% (0.125 g) ammonium persulfate, 3 wt% (0.75 g) gelatin, and 2 wt% (0.5 g) polyethylene glycol (PEG-4000). Stir until transparent and homogeneous. Then add 0.5 wt% (0.125 g) graphene nanoparticles, 0.5 wt% (0.125 g) iron oxide nanoparticles, and 0.05 wt% (12.5 mg) cerium dioxide nanoparticles, and perform ultrasonic treatment to ensure uniform dispersion of the nanomaterials. After stirring evenly, add electrogenic bacteria ( Shewanellavesiculosa Add the solution (until the OD value is 2) and mix well to obtain the anode electrode biogel base solution.

[0076] (2) Dissolve 1 wt% (0.25 g) sodium alginate in 25 mL of distilled water. After complete dissolution, add 10 wt% (2.5 g) acrylamide. After complete dissolution and thorough mixing of sodium alginate and acrylamide, add 0.015 wt% (3.75 mg) N,N'-methylenebisacrylamide. Then, add 0.5 wt% (0.125 g) ammonium persulfate, 3 wt% (0.75 g) gelatin, and 2 wt% (0.5 g) polyethylene glycol (PEG-4000). Stir until transparent and homogeneous. Subsequently, add 0.5 wt% (0.125 g) graphene nanoparticles, 0.5 wt% (0.125 g) iron oxide nanoparticles, and 0.05 wt% (12.5 mg) cerium dioxide nanoparticles, and perform ultrasonic treatment to ensure uniform dispersion of the nanomaterials. After thorough stirring, add the desired electrogenic bacteria. Shewanellavesiculosa and cathode denitrifying bacteria Pseudomonasstutzeri Add the solution (until the respective OD values ​​are 2) and mix well to obtain the cathode electrode biogel substrate solution.

[0077] (3) The obtained anodic electrode biogel base liquid and cathode electrode biogel base liquid were placed in molds with a length of 5cm, a width of 4cm and a thickness of 1mm respectively for shaping, and then placed in N2 for drying and curing (30℃, 8h) to obtain anodic electrode biogel and cathode electrode biogel respectively.

[0078] (4) Cut the obtained first and second solid biogels to a size of 2cm*2cm*1mm. First, use a flexible, progressive air-explosion method to attach the first and second solid biogels to the surfaces of the anode and cathode substrate electrodes. After attachment, the electrode edges can be sealed to obtain a biogel composite anode and cathode. The electrode attachment effect should ensure that there are no visible air bubbles. To ensure the electron transfer efficiency between the microorganisms and the electrodes, the electrode surface should be slightly wetted with M9 electrolyte before attachment. Then, the gel is vertically covered, and a constant micro-pressure of 3kPa is applied using a soft roller to remove residual air bubbles at the interface. Before attaching the gel to the electrodes, the following steps should be taken: Figure 4 As shown, the biogel electrode after attaching a single layer of gel is as follows: Figure 5 As shown.

[0079] (5) Place the prepared biogel electrode in the bioanode chamber and biocathode chamber for cultivation. The specific operation is as follows: A dual-channel or multi-channel electrochemical workstation is used. The working electrode port of channel 1 is connected to the biogel anode, and the counter electrode (platinum electrode) and reference electrode (Ag / AgCl) are connected to form electrochemical workstation 1. The working electrode port of channel 2 is connected to the biogel cathode, and the counter electrode (platinum electrode) and reference electrode (Ag / AgCl) are connected to form electrochemical workstation 2. Electrochemical workstation 1 and electrochemical workstation 2 form a complete monitoring system.

[0080] Electrolyte was injected into both the bioanode and biocathode chambers. A potential of 0.2V was applied to the biogel anode and a potential of -0.5V was applied to the biogel cathode. The biogel anode and biogel cathode were cultured, and the current was observed after a period of time. If the current gradually increased and then remained stable, the start-up was considered successful.

[0081] Both the anode chamber and the cathode chamber use M9 electrolyte solution (mass percentage): The ingredients are: ammonium chloride 0.01%, sodium chloride 0.05%, potassium dihydrogen phosphate 0.44%, dipotassium hydrogen phosphate 0.34%, magnesium sulfate 0.01%, sodium bicarbonate 0.20%, and deionized water as the solvent.

[0082] (6) After the current stabilizes, different concentrations of pollutants such as COD, nitrate, and cadmium are added to the electrolyte in the anode and cathode chambers, respectively. If a significant current response occurs, it indicates that the pollutants are effectively monitored. The results show that the electrode biogel prepared in this embodiment can be started in 2 hours and has a monitoring effect on pollutants such as COD, nitrate, and cadmium.

[0083] (7) After successful startup, p-fluoronitrobenzene was added to the anode chamber and cathode chamber respectively, with an initial concentration of 50 mg / L. Samples were taken at 3-hour intervals to measure the p-fluoronitrobenzene concentration. After 24 hours, it was found that the p-fluoronitrobenzene at the cathode had degraded by about 80%. Figure 6 After 48 hours, observe its viscosity. If it can still be adsorbed onto the electrode surface, the biogel of the electrode can be judged to be effective.

[0084] Example 2 The anode and cathode materials used in this embodiment are graphite electrodes with dimensions of 2cm*2cm*1mm.

[0085] The specific preparation method is as follows: (1) Dissolve 1 wt% (0.25 g) sodium alginate in 25 mL of distilled water. After complete dissolution, add 15 wt% (3.75 g) acrylamide. After complete dissolution and thorough mixing of sodium alginate and acrylamide, add 0.015 wt% (3.75 mg) N,N'-methylenebisacrylamide. Then, add 0.5 wt% (0.125 g) ammonium persulfate, 3 wt% (0.75 g) gelatin, and 2 wt% (0.5 g) polyethylene glycol (PEG-4000). Stir until transparent and homogeneous. Subsequently, add 0.5 wt% (0.125 g) graphene nanoparticles, 0.5 wt% (0.125 g) iron oxide nanoparticles, and 0.05 wt% (12.5 mg) cerium dioxide nanoparticles. Sonicate the mixture to ensure uniform dispersion of the nanomaterials. After thorough mixing, add the desired electrogenic bacteria. Shewanellavesiculosa Add the solution (until the OD value is 2) and mix well to obtain a biogel base solution containing electrogenic bacteria.

[0086] (2) Dissolve 1 wt% (0.25 g) sodium alginate in 25 mL of distilled water. After complete dissolution, add 15 wt% (3.75 g) acrylamide. After complete dissolution and thorough mixing of sodium alginate and acrylamide, add 0.015 wt% (3.75 mg) N,N'-methylenebisacrylamide. Then, add 0.5 wt% (0.125 g) ammonium persulfate, 3 wt% (0.75 g) gelatin, and 2 wt% (0.5 g) polyethylene glycol (PEG-4000). Stir until transparent and homogeneous. Subsequently, add 0.5 wt% (0.125 g) graphene nanoparticles, 0.5 wt% (0.125 g) iron oxide nanoparticles, and 0.05 wt% (12.5 mg) cerium dioxide nanoparticles. Sonicate the mixture to ensure uniform dispersion of the nanomaterials. After thorough stirring, add the required cathodic denitrifying bacteria. Pseudomonasstutzeri Add the solution (until the OD value is 2) and mix well to obtain a biogel base solution containing denitrifying bacteria.

[0087] (3) The obtained biogel base liquid containing electrogenic bacteria and denitrifying bacteria were placed in molds with a length of 5cm, a width of 4cm and a thickness of 1mm respectively, and dried in N2 (30℃, 8h) to obtain the first solid biogel containing electrogenic bacteria and the second solid biogel containing denitrifying bacteria, both with a thickness of about 1mm.

[0088] (4) The first and second solid biogels were cut to a size of 2cm*2cm*1mm. First, the first solid biogel was pasted onto the surface of the anode substrate electrode using a flexible progressive venting method. When pasting the cathode, the first layer was first pasted and the interface was wetted, and then the second solid biogel was pasted on top of it. After pasting, the electrode edges were sealed to obtain a biogel composite anode and cathode. The electrode pasting effect should ensure that there are no visible air bubbles and that the electrodes can still be firmly adsorbed on the electrode surface after 48 hours of wastewater rinsing. To ensure the electron transfer efficiency between the microorganisms and the electrodes, the electrode surface should be slightly wetted with M9 electrolyte before pasting. Then, the gel was vertically covered and a constant micro pressure of 3kPa was applied using a soft roller. For the double-layer structure of the cathode, the interface of the two gel layers should be homogenized and wetted to prevent interlayer peeling caused by water rinsing. The first and second solid biogels were pasted onto the surface of the cathode substrate electrode in sequence ( Figure 7 and Figure 8 That is, a first solid biogel is first pasted onto the same surface of the cathode substrate, and then a second solid biogel is pasted onto it to obtain a biogel composite cathode.

[0089] (5) The prepared biogel composite electrodes were placed in the bioanode chamber and the biocathode chamber, respectively, for cultivation (electrode connection method is the same as in Example 1). Potentials of 0.2V and -0.5V were applied to the biogel composite anode and the biogel composite cathode, respectively, for cultivation. After a period of time, the current was observed. If the current gradually increased and remained stable, the start-up was considered successful. M9 electrolyte solution (same as in Example 1) was used in both the anode chamber and the cathode chamber.

[0090] (6) After the current stabilizes, different concentrations of pollutants such as COD, nitrate, and cadmium are added to the electrolyte in the anode and cathode chambers, respectively. If a significant current response is observed, it indicates that the pollutants are effectively monitored. The results are as follows: Figure 10 and Figure 11 As shown.

[0091] This embodiment examines the effect of bioanodes on different concentrations of NO3. - -N (20, 50, 100, 200, 500 mg·L -1 The current response of ) is as follows Figure 10 As shown in Figure A, the bioanolytical current decreased after nitrate injection, and the decrease increased with increasing concentration. (500 mg L) -1 The current decreased by 35.05%; the effects of the biocathode on different concentrations of NO3 were also investigated. - -N (20, 50, 100, 200, 500 mg·L -1 The current response of ) is as follows Figure 10 As shown in Figure B, the response of the biocathode to nitrate exhibits a significant positive correlation trend; the reduction current increases rapidly after nitrate injection (20-500 mg / L). -1 The increase in current within the range showed a good linear relationship with concentration; the effects of bioanodes and biocathodes on the heavy metal Cd were also investigated. 2+ (20, 50, 100, 200, 500mg L -1 The response behavior of the bioanode is as follows: Figure 10 As shown in C, Cd 2+ The bioanolyte current decreased rapidly after injection, and the decrease was positively correlated with the concentration. Within 30 minutes, the current inhibition rate was related to Cd. 2+ The concentration showed a good linear relationship; the response results of the bioanode were as follows: Figure 10 As shown in Figure D, the biocathode for Cd 2+ The response exhibits different characteristics: the instantaneous current rises slightly at low concentrations, possibly related to Cd. 2+ The reduction process is related to the weak oxidant, and the current decreases significantly with prolonged exposure time or increased concentration, indicating that toxic inhibition is dominant.

[0092] This embodiment also investigated the current response of the bioanode to different concentrations of COD. Under steady-state operating conditions of the bioanode, different concentrations of COD (calculated as sucrose, with concentration gradients of 20, 50, 100, 200, and 500 mg / L) were sequentially injected. -1 Record the current response curve, and the results are as follows: Figure 11 As shown, the results indicate that the bioanolyte current increases with increasing COD concentration, with a response appearing after 20 minutes, and the response time shortening with increasing concentration. Figure 11 (A). As COD concentration increases, the biocathode current shows a decreasing trend, and the response appears after 20 minutes. Figure 11 (B)

[0093] The above results show that the electrode biogel prepared by the present invention can be started in 2 hours and has a monitoring effect on pollutants such as COD, nitrate, and cadmium.

[0094] (7) After successful startup, p-fluoronitrobenzene was added to the anode chamber and cathode chamber respectively, with an initial concentration of 50 mg / L. Samples were taken at 3-hour intervals to measure the p-fluoronitrobenzene concentration. After 24 hours, it was found that the p-fluoronitrobenzene degradation at the cathode exceeded 90%. Figure 19 The results showed that the two layers of gel on the cathode electrode were significantly better than those in Example 1, indicating that there was a synergistic effect between them. After 48 hours, the adhesion of the gel was observed, and it was determined that the biogel on the electrode was effective.

[0095] This embodiment also compares the performance of different electrodes, and the results are as follows: Figure 9 As shown in the figure, A is the starting current diagram of the unmodified electrode under anodic and cathodic potentials; B is the starting current diagram of the bio-anodide; C is the starting current diagram of the bio-cathode; and D is the resistance diagram of the unmodified electrode, bio-anodide, and bio-cathode. The results in Figure A show that the electrode without biomembrane modification exhibits only a weak background current (<0.05 A m) after applying a potential. -2 This indicates that the substrate material itself does not possess significant catalytic activity. In contrast, hydrogel bioanodes supported on biofilms ( Figure 9 (B) After applying a potential of 0.2 V, the current density rapidly increases and stabilizes at 0.11 A / m within 30 min. -2 Hydrogel biocathode ( Figure 9 (C) After applying a potential of -0.5 V, the current density stabilizes at -0.12 mA m. -2 This result demonstrates that electroactive microorganisms embedded in the hydrogel successfully constructed an efficient extracellular electron transport pathway. Electrochemical impedance spectroscopy (EIS) tests were performed on different electrodes using an electrochemical workstation. The EIS results showed that ( Figure 9 (D) The Rct of the electrode after loading the biomembrane decreased significantly from 250.92 Ω to 113.45 Ω of the electrode without biomembrane, indicating that the three-dimensional conductive network constructed by the biomembrane and graphene effectively reduced the interfacial electron transfer energy barrier.

[0096] To further reveal the impact of pollutants on the electron transport activity of biomembranes, this embodiment also measured the cyclic voltammetry curves of the bioanode and biocathode before and after pollutant exposure. The results are as follows: Figure 12 As shown in the figure, A is the cyclic voltammogram of the bioanodide, and B is the cyclic voltammogram of the biocathode. The results show that the oxidation peak current (around 0.2V) of the bioanodide is significantly enhanced after COD exposure, indicating an increase in the metabolic activity of organic matter; Cd 2+ The oxidation peak current decreased significantly after exposure, and the peak potential shifted positively, indicating damage to the electron transport chain; the CV curve of the biocathode showed that the reduction peak current near -0.3 V was significantly enhanced after nitrate exposure, confirming its reduction response to the electron acceptor; Cd 2+The reduction peak current decreased after exposure, consistent with the current decay trend.

[0097] Compared to preparing a single-layer mixed bacterial biogel by bonding a bilayer gel to the cathode surface, the bilayer biogel constructed layer by layer using two pure bacterial gels can significantly improve the activity and stability of the strains by avoiding growth competition, metabolic inhibition, and imbalance of the bacterial population through physical isolation. At the same time, it can regulate the microenvironment, mechanical properties, and pore structure of each layer of gel according to the physiological needs of different strains, achieving precise adaptation of growth conditions. Its layered structure can also realize functional partitioning and sequential reaction, which is more conducive to cascade catalysis, product enrichment and separation purification. Moreover, it has stronger structural stability and anti-interference ability, and its modular design is more flexible, showing better application potential in biomimetic construction, biosynthesis, and biocatalysis.

[0098] Comparative Example 1 The difference from Example 1 is that N,N'-methylenebisacrylamide solution is not added. Everything else remains the same as in Example 1.

[0099] Comparative Example 2 The difference from the preparation of the biocathode in Example 1 is that the autotrophic hydrogen-type denitrifying bacteria solution is introduced into the reactor, and then the base electrode is directly placed into the cathode chamber for cultivation. The rest is the same as in Example 1.

[0100] This application observes the number of viable bacteria in the cathode electrode gels of different embodiments and comparative examples under a microscope. The results of the viable bacteria counts in Examples 1-2 and Comparative Examples 1-2 are as follows: Figure 13 As shown, the results indicate that the number of active bacteria in the electrode biogel prepared using the present invention is better than that in the comparative example, and the number of microorganisms in Example 2 is greater than that in Example 1.

[0101] This application describes the detection of microbial activity in the cathode gels of Example 1 and Example 2. The specific procedure is as follows: the gel is first soaked in pure water; after the gel absorbs water and swells, it is ultrasonically broken up; after breaking up, a sample is taken and measured using a microplate reader. The results are as follows... Figure 14 As shown, the results indicate that the microbial activity of Example 2 is superior to that of Example 1, and it still retains a certain level of activity even after being subjected to toxic shocks.

[0102] Further comparison of the microbial activity of the cathode gels of Example 1 and Example 2 after toxic shock yielded the following results: Figure 15 As shown, the results indicate that the enzyme activity of Example 2 was significantly higher than that of Example 1, and Example 2 was still higher than that of Example 1 after being subjected to toxic shock.

[0103] This application also includes permeability tests on the cathode gels of Example 1 and Example 2 using different materials: Gel permeability test for ammonium nitrogen: The test method involves adding a certain concentration of ammonium nitrogen solution to one side of a two-chamber membrane reactor and adding pure water to the other side, with a gel separating the two. The concentration of the pure water is sampled and measured at regular intervals. Results are as follows... Figure 16 As shown, the results indicate that the permeability of the gel prepared in this application is significantly better than that of the untreated gel, and the permeability of ammonium nitrogen in Example 2 (bilayer gel) is significantly higher than that in Example 1 (monolayer gel).

[0104] COD permeability test of gel: The test method involves adding a certain concentration of COD solution to one side of a two-chamber reactor and pure water to the other side, separated by a gel. The concentration of the pure water is sampled and tested at regular intervals. Results are as follows... Figure 17 As shown, the results indicate that the permeability of the gel prepared in this application is significantly better than that of the untreated gel, and the COD permeability of Example 2 (bilayer gel) is significantly higher than that of Example 1 (monolayer gel).

[0105] Gel permeability test for nitrate nitrogen: The test method involves adding a certain concentration of nitrate nitrogen solution to one side of a two-chamber reactor and adding pure water to the other side, with a gel separating the two chambers. The concentration of the pure water is sampled and measured at regular intervals. Results are as follows... Figure 18 As shown, the results indicate that the permeability of the gel prepared in this application is significantly better than that of the untreated gel, and the permeability of nitrate nitrogen in Example 2 (bilayer gel) is significantly higher than that in Example 1 (monolayer gel).

[0106] in, Figures 16-18 The untreated gel in this context refers to a blank control gel prepared solely from sodium alginate, acrylamide, N,N'-methylenebisacrylamide, ammonium persulfate, and deionized water, using the same preparation process as the cathode gel in Example 2, but without the addition of graphene nanoparticles, iron oxide nanoparticles, cerium dioxide nanoparticles, polyethylene glycol, gelatin, or any microorganisms, and solidified under the same nitrogen atmosphere.

[0107] This application also includes tensile tests on the biogels of Examples 1-2 and Comparative Example 1 using an electronic universal testing machine: First, measure the sample size and mark the gauge length. Turn on the electronic universal testing machine and preheat it. In the software, select the tensile mode, enter the sample information and test rate, clamp the sample in the center between the upper and lower clamps, and complete the zeroing of force and displacement. Start the equipment to load at a uniform speed until the sample breaks. The system automatically collects data such as force and displacement and calculates indicators such as yield strength, tensile strength, and elongation after fracture. After the test, remove the sample, clean the clamps, and reset the equipment.

[0108] Figure 20 This is a diagram showing the state of the anolyte biogel before stretching in Example 2. Figure 21This is a diagram showing the state of the anolyte biogel after stretching in Example 2. Figure 22 The figures show the cathode tensile test results of Examples 1, 2, and Comparative Example 2 (all are tested cathodes). The results show that the membrane prepared by the method of this application has a good tensile strength.

[0109] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a biogel composite electrode, characterized in that, include: (1) Prepare a first biogel base liquid containing electroactive microorganisms and a second biogel base liquid containing functional microorganisms. Place the first biogel base liquid and the second biogel base liquid in a molding mold and solidify them under nitrogen for 1 to 3 hours to obtain a first solid biogel containing electroactive microorganisms and a second solid biogel containing functional microorganisms. (2) The first solid biogel is attached to the surface of the anode substrate electrode to obtain a biogel composite anode; the first solid biogel and the second solid biogel are attached to the surface of the cathode substrate electrode in sequence to obtain a biogel composite cathode.

2. The preparation method according to claim 1, characterized in that, The first biogel base liquid and the second biogel base liquid include sodium alginate, acrylamide, N,N'-methylenebisacrylamide, ammonium persulfate, polyethylene glycol, cerium dioxide nanoparticles, iron tetroxide nanoparticles, gelatin, nanographene, and corresponding microorganisms and solvents. The corresponding microorganisms are electroactive microorganisms or functional microorganisms.

3. The preparation method according to claim 2, characterized in that, The OD of the electroactive or functional microorganisms 600 The concentrations are between 1 and 3; based on the mass of the solvent, the sodium alginate has a mass percentage content of 0.2%-2%, the acrylamide has a mass percentage concentration of 10%-20%, the N,N'-methylenebisacrylamide has a mass percentage concentration of 0.001%-0.03%, the ammonium persulfate has a mass percentage concentration of 0.1%-1%, the polyethylene glycol has a mass percentage concentration of 1%-5%, the cerium dioxide nanoparticles have a mass percentage concentration of 0.01%-0.1%, the iron oxide nanoparticles have a mass percentage concentration of 0.1%-1%, the gelatin has a mass percentage concentration of 1%-5%, and the nanographene has a mass percentage concentration of 0.1%-1%; the solvent is water.

4. The preparation method according to claim 1, characterized in that, The thickness of both the first and second solid biogels is between 0.2 and 1.5 mm.

5. The preparation method according to claim 1, characterized in that, The electrode materials of the anode base electrode and the cathode base electrode are each independently selected from platinum electrode, graphite electrode, and iron electrode.

6. The preparation method according to claim 1, characterized in that, The bonding methods include flexible progressive air-venting bonding, electrically assisted wetting enhancement, and homogeneous wetting bonding.

7. A biogel composite electrode, characterized in that, Prepared by the method of claim 1, comprising a biogel composite anode and a biogel composite cathode; the biogel composite anode comprises a base electrode and a first solid biogel adhered to the surface of the base electrode; the biogel composite cathode comprises a base electrode and a first solid biogel and a second solid biogel sequentially adhered to the surface of the base electrode; the first solid biogel contains electroactive microorganisms, and the second solid biogel contains functional microorganisms.

8. The application of the biogel composite electrode as described in claim 7 in the electrochemical treatment of organic polluted wastewater or in toxicity monitoring.

9. An electrochemical monitoring method for the toxicity of organic pollutants in wastewater, characterized in that, include: (1) The gel biocomposite anode and gel biocomposite cathode prepared according to claim 1 are connected to different channels of the electrochemical workstation as working electrodes, and each forms a three-electrode system with the corresponding counter electrode and reference electrode, while injecting electrolyte into their respective electrochemical work chambers. (2) Apply the corresponding potential to the gel biocomposite anode and gel biocomposite cathode respectively. The initial current runs stably for 1-2 hours until the current gradually rises and remains stable. This indicates that the gel biocomposite anode and gel biocomposite cathode have been successfully started. (3) After successful startup, when organic pollutants enter the electrochemical chambers of the gel biocomposite anode and gel biocomposite cathode, different current responses will immediately appear, indicating that pollutants have an impact on microbial activity, thus realizing the toxicity monitoring of organic pollutants in wastewater.

10. An electrochemical treatment method for organic polluted wastewater, characterized in that, include: (1) The gel biocomposite anode and gel biocomposite cathode prepared according to claim 1 are connected to different channels of the electrochemical workstation as working electrodes, and each forms a three-electrode system with the corresponding counter electrode and reference electrode, while injecting electrolyte into their respective electrochemical work chambers. (2) Apply the corresponding potential to the gel biocomposite anode and gel biocomposite cathode respectively. The initial current runs stably for 1-2 hours until the current gradually rises and remains stable. This indicates that the gel biocomposite anode and gel biocomposite cathode have been successfully started. (3) After successful startup, wastewater containing organic pollutants is sent to the electrochemical chambers of the gel biocomposite anode and gel biocomposite cathode respectively to achieve the degradation of organic pollutants in the wastewater.

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