Biological electrode for monitoring toxicity of water body as well as preparation and application of biological electrode

Abstract

The invention discloses a biological electrode for water toxicity monitoring and preparation and application thereof.The preparation method of the electrode comprises the steps that two substrate electrodes are connected with a positive electrode and a negative electrode of a power source of an electrochemical workstation respectively and then inserted into a reaction chamber, biological anode electrodeposition liquid or biological cathode electrodeposition liquid is added into the reaction chamber, voltage is applied for electrodeposition reaction, and the electrode is obtained; an electroactive biological membrane grows on a substrate electrode connected with a positive electrode of a power supply, and a biological anode electrode and a biological cathode electrode are prepared respectively. Before the water body monitoring sensor is started, the interpenetrating network double-ion cross-linked microbial gel is constructed through electro-deposition, biological membranes are attached to the anode material and the cathode material and serve as working electrodes respectively, a sensing system is constructed, the high electron transfer rate and stability are achieved, and the water body monitoring sensor can be applied to water body monitoring. The problems that the biological membrane is low in enrichment speed, easy to fall off, slow in starting and the like can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of water body monitoring, and in particular to a bioelectrode for water body toxicity monitoring and a preparation method and application thereof. Background Art

[0002] Water is the material basis for human survival. It not only provides a basis for living things, but also participates in climate regulation, agricultural irrigation and industrial production. However, the current water pollution problem is becoming increasingly serious. The discharge of industrial wastewater, domestic sewage and agricultural non-point source pollution make the water contain a large amount of harmful substances, such as heavy metals, organic matter, nutrients, etc. These pollutants not only affect the quality of water, but also poison aquatic organisms and destroy the stability of the ecosystem. At the same time, polluted water may also be transmitted through the food chain, posing a threat to human health. Water environment toxicity monitoring is essential for protecting water resources and biodiversity. By real-time and accurate monitoring of water bodies, we can timely understand the quality of water bodies and grasp the types, concentrations and distribution of pollutants. Therefore, water toxicity monitoring is of great significance to solving water environment pollution problems.

[0003] Microbial electrochemical sensors (bioelectrodes) with electroactive biofilm as sensitive elements are a new type of online water quality monitoring technology. When toxic substances stimulate microorganisms, the growth and metabolic activities of microorganisms will respond and change, and the signal will be transmitted to the collection system to achieve real-time early warning of water pollution. Electroactive microorganisms attach to the electrode surface by forming biofilms, but the biofilm cultivation process is relatively long, the enrichment capacity is low, and the entry of highly toxic substances into the water will directly cause the microorganisms to fall off or even die.

[0004] For example, patent document CN 116660340 A discloses a biocathode toxicity sensing element, a biocathode toxicity sensor and its application. In the patent document, toxicity monitoring is performed by directly inoculating bacteria in a reactor for cultivation. However, the cultivation time is relatively long. When toxic substances enter the water again, the activity of microorganisms will be reduced, making it difficult to reach the initial monitoring sensitivity level.

[0005] Patent document CN 112305029 A discloses a method for rapid prototyping of electrode biofilm and a microbial electrochemical sensor. In the patent document, an electrode biofilm is rapidly formed by enriching a mixed solution of electroactive bacteria and an adhesive, but its conductivity is lower than that of an uncross-linked sodium alginate film, which affects the electron mass transfer rate.

[0006] Patent document CN 103940883 A discloses a preparation method, application, device and detection method of a disposable microbial membrane sensor that can quickly detect biological toxicity in water. In the patent document, the microbial attachment capacity is improved by dripping a solidifying liquid and applying pressure with a fixture. However, this method is complicated to operate, and it is difficult to ensure the activity of microorganisms. It has the disadvantages of low biocurrent and insensitive monitoring of various toxic substances. Summary of the invention

[0007] Based on the technical problems existing in the prior art, the present application proposes a rapid preparation process for a biosensor toxicity monitoring probe. Before the water body monitoring sensor is started, an interpenetrating network double-ion cross-linked microbial gel is constructed by electrodeposition, and the biofilm is attached to the anode material and the cathode material and used as working electrodes respectively to construct a sensing system with high electron transfer rate and stability, which can effectively solve the problems of slow biofilm enrichment, easy shedding, slow startup, etc.

[0008] A method for preparing a bioelectrode for water toxicity monitoring, comprising:

[0009] The two substrate electrodes are respectively connected to the positive and negative electrodes of the power supply of the electrochemical workstation and then inserted into the reaction chamber, a bioanode electrodeposition solution or a biocathode electrodeposition solution is added into the reaction chamber, a voltage is applied to perform an electrodeposition reaction, and an electroactive biofilm is grown on the substrate electrode connected to the positive electrode of the power supply, thereby preparing a bioanode electrode and a biocathode electrode respectively;

[0010] Preparation of the biological anode electrodeposition solution: sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in a solvent to obtain a mixed solution A, nano-scale conductive materials are fully dispersed in an oxidative bacterial solution to obtain a mixed solution B, and the mixed solution A and the mixed solution B are mixed according to a ratio to obtain the biological anode electrodeposition solution;

[0011] Preparation of the biological cathode electrodeposition solution: sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in water to obtain a mixed solution A, nano-scale conductive materials are fully dispersed in a reducing bacterial solution to obtain a mixed solution C, and the mixed solution A and the mixed solution C are mixed according to a ratio to obtain the biological cathode electrodeposition solution.

[0012] The present invention adopts the electrodeposition double ion cross-linking method to enhance the cross-linking between ions and improve its stability; disodium calcium ethylenediaminetetraacetate is added to the electrodeposition solution, and disodium calcium ethylenediaminetetraacetate can form a stable complex with a variety of metal ions, and the Fe in the stainless steel metal fiber sintered felt mesh stainless steel electrode plate is electrodeposited. 3+ Double ion cross-linking ensures the stability of the membrane. The conductive material is evenly mixed with the corresponding bacterial solution and then mixed with a mixture of sodium alginate and calcium disodium ethylenediaminetetraacetate.

[0013] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution, but are merely further supplements or preferences. Under the premise that there are no technical or logical contradictions, each optional method can be combined with the above-mentioned overall solution separately, and multiple optional methods can also be combined.

[0014] Sodium alginate has good biocompatibility and high porosity. If its concentration is too low, its spatial grid structure will be loose, resulting in reduced gel strength. If its concentration is too high, the solution viscosity will increase significantly, hindering ion diffusion and cross-linking reactions. Calcium disodium ethylenediaminetetraacetate is used to ensure the stability of the biofilm surface structure. If its concentration is too low, the gel strength and stability will decrease. If its concentration is too high, it will be toxic to microorganisms. Optionally, in the mixed solution of sodium alginate and calcium disodium ethylenediaminetetraacetate, the mass percentage concentration of sodium alginate is 1-3%, the mass percentage concentration of calcium disodium ethylenediaminetetraacetate is 1-3%, and the solvent is water.

[0015] Optionally, in the mixed solution A, the mass percentage concentration of sodium alginate is 1-3%, the mass percentage concentration of calcium disodium ethylenediaminetetraacetate is 1-3%, and the solvent is water.

[0016] Optionally, in the mixed solution B, the OD600 value of the oxidative bacterial solution is 1; the volume ratio of the mixed solution B to the mixed solution A is 1:5; the amount of the nano-scale conductive material added is 0.15 to 0.3 g / L according to its concentration in the bioanode electrodeposition solution. -1 count.

[0017] Optionally, in the mixed solution C, the OD600 value of the reducing bacterial culture liquid is 1; the volume ratio of the mixed solution C to the mixed solution A is 1:5; the amount of the nano-scale conductive material added is such that its concentration in the biological cathode electrodeposition solution is 0.15 to 0.3 g / L -1 count.

[0018] A voltage that is too low will reduce the adsorption and deposition rate of biomolecules on the electrode surface, while a voltage that is too high will cause excessive corrosion and loss of the electrode, destroying the biomolecule structure; a deposition time that is too short will result in insufficient microbial biomass on the coating, while a deposition time that is too long will increase the thickness of the deposit, affecting the molecular mass transfer rate; within this preferred range, the adsorption and deposition rate of biomolecules on the electrode surface, the biomolecule structure, the microbial biomass on the coating, and the thickness of the deposit can all be within a relatively favorable range. More preferably, the conditions for the electrodeposition reaction are: a voltage of 2-8V and a deposition time of 1-5min.

[0019] Optionally, the base electrode is a stainless steel electrode, a pure iron electrode, an iron alloy electrode or an iron-based composite material electrode.

[0020] Optionally, the oxidizing bacteria are electrogenic bacteria, which have good electrogenic performance, efficient electron transfer ability, and rapid film-forming ability. The electrogenic bacteria are conventional electrogenic bacteria in the field of electrochemical treatment of sewage, and are widely present in the natural environment, such as Geobacter, Shewanella, etc. There are no requirements for specific strains, and the strains can be isolated and cultured by conventional methods or commercially available. They can also be purchased from the Microbiological Protection Center, for example, Shewanella vesiculosa with a preservation number of CGMCCNO.1.15835, Shewanella algae with a preservation number of CGMCC NO.1.8754, etc.

[0021] Optionally, the reducing bacteria are denitrifying bacteria, which have the characteristics of short acclimation period, fast startup speed and rapid establishment of nitrification system. The denitrifying bacteria are conventional denitrifying bacteria in the field of sewage electrochemical treatment, which are widely present in the natural environment, for example, Pseudomonas, Alcaligenes, etc. There are no requirements for specific strains, and the strains can be separated and cultured by conventional methods or commercially available. It can also be purchased from the Microbiological Protection Center, for example, Pseudomonas stutzeri with a preservation number of CGMCC NO.1.15316 and Alcaligenes aquatilis with a preservation number of CGMCCNO.1.9053.

[0022] Optionally, the nano-scale conductive material is nano-scale carbon black or nano-scale graphene, which has high conductivity and excellent electrocatalytic performance. Too high a concentration will affect the electron transfer efficiency, and too low a concentration will reduce the conductivity. The nano-scale conductive materials are all commercially available. Preferably, the amount of the nano-scale conductive material added is 0.15 to 0.3 g / L in its concentration in the bio-anode electrodeposition solution or the bio-cathode electrodeposition solution. -1 It is appropriate.

[0023] The present application also provides a bioanode or biocathode prepared by the preparation method.

[0024] The present application provides an electrochemical monitoring method for water toxicity, comprising:

[0025] The bioanode is used as the working electrode, and is connected to an electrochemical workstation together with a counter electrode and a reference electrode to construct an electrochemical monitoring system. A potential of -0.2V to 0.2V is applied to the bioanode to start the bioanode. After the bioanode is successfully started, when the wastewater enters the bioanode working room, it is determined whether there are toxic substances in the wastewater based on the current response; the bioanode is the bioanode prepared in this application.

[0026] The present application also provides an electrochemical monitoring method for water toxicity, comprising:

[0027] The biocathode is used as the working electrode, and is connected to an electrochemical workstation together with a counter electrode and a reference electrode to construct an electrochemical monitoring system. A -0.4V to -0.8V potential is applied to the biocathode to start the biocathode. After the biocathode is successfully started, when the wastewater enters the biocathode working room, it is determined whether there are toxic substances in the wastewater based on the current response; the biocathode is the biocathode prepared in this application.

[0028] During the monitoring process, a potential of -0.2 to 0.2 V was applied to the bioanode to ensure the normal physiological metabolism of the anode microorganisms; a potential of -0.4 V to -0.8 V was applied to the biocathode to ensure the normal physiological metabolism of the cathode microorganisms.

[0029] The bioelectrode of the present application has a short startup time and can be successfully started in 1 to 2 hours.

[0030] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0031] (1) The present application enriches the biofilm on the surface of the anode material and the cathode material by electrodeposition, which can effectively solve the problems of slow film formation speed, low enrichment capacity and long start-up time of the bioanode and the biocathode. At the same time, the anode biofilm and the cathode biofilm are prepared by the double ion cross-linking method, which can effectively solve the problems of low biofilm mass transfer rate and low current.

[0032] (2) Compared with the direct coating disclosed in CN 112305029 A, the bioanode and biocathode prepared in this application have significantly improved currents and have the characteristics of high monitoring sensitivity and high conductivity.

[0033] (3) Compared with the microorganisms directly entering the sensor disclosed in CN 116660340 A, the bioanode and biocathode prepared in the present application cultivate biofilms significantly faster than the comparative example, and have the characteristics of stable biofilms and fast startup speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the full process flow chart of this application;

[0035] Figure 2 This is a schematic diagram of the electrode structure of this application;

[0036] Figure 3 This is a graph showing the current response of the bioanode in Example 1 to the impact of different toxic substances;

[0037] Figure 4 This is a graph showing the current response of the biocathode in Example 1 to the impact of different toxic substances.

[0038] The reference numerals shown in the figures are as follows:

[0039] 1. Base electrode; 2. Artificial biofilm. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0042] The structure of the bioanode or biocathode of the present application is as follows Figure 2 As shown, it includes a substrate electrode 1 and an artificial biofilm 2 located on the surface thereof, wherein the artificial biofilm is an interpenetrating network double ion cross-linked microbial gel constructed by electrodeposition.

[0043] Preparation of bioelectrodes and their use in water toxicity monitoring Figure 1 As shown, including:

[0044] S1 prepares a mixed solution of sodium alginate and calcium disodium ethylenediaminetetraacetate, adds oxidative bacteria and a mixed solution of nano-scale conductive materials, and prepares a biological anode electrodeposition solution.

[0045] S2 prepares a mixed solution of sodium alginate and calcium disodium ethylenediaminetetraacetate, adds reducing bacteria and a mixed solution of nano-scale conductive materials, and prepares a biological cathode electrodeposition solution.

[0046] The S3 anode material and cathode material are used as working electrodes respectively, and the above-mentioned electrodeposition solution is deposited in a 2-8V electrochemical system for 1-5 minutes.

[0047] In this step, the bioanode and biocathode are prepared separately. The process of preparing the bioanode is as follows: the anode material (base electrode) is connected to the positive and negative poles of the power supply of the electrochemical workstation respectively, a bioanode electrodeposition liquid is added to the reaction chamber, a voltage is applied, and a biofilm is grown on the anode material connected to the positive pole of the power supply to obtain the bioanode; when preparing the biocathode, the biocathode electrodeposition liquid is replaced in the reaction chamber to obtain the biocathode.

[0048] S4 is connected to the toxicity monitoring system, and corresponding electric potentials are applied to start the bioanode and biocathode.

[0049] In this step: the bioanode and the biocathode are respectively used as working electrodes to construct a three-electrode system. The bioanode is used as the working electrode, and together with the counter electrode and the reference electrode, a three-electrode system is formed, which is connected to the electrochemical workstation; the biocathode is used as the working electrode, and together with the counter electrode and the reference electrode, a three-electrode system is formed, which is connected to the electrochemical workstation; the two three-electrode monitoring systems are independent of each other.

[0050] S5 When toxic substances impact the bioanode or biocathode, an electric current response occurs immediately, allowing real-time monitoring.

[0051] After the S6 toxic shock current tends to be stable, the bioelectrode is taken out and replaced with a newly prepared bioelectrode to observe the current start-up and monitor changes.

[0052] The following is described with specific examples:

[0053] In the following examples, all the raw materials used are commercially available.

[0054] Example 1

[0055] The anode material and cathode material used in this embodiment are both stainless steel electrode plates (stainless steel metal fiber sintered felt mesh) with a specification of 1 cm*1 cm*1 mm.

[0056] The methods for electrode preparation and toxicity monitoring are as follows:

[0057] (1) Prepare a mixed solution A of sodium alginate and calcium disodium ethylenediaminetetraacetate: dissolve 1g of sodium alginate (2wt%) in 50mL of distilled water, add 1.5g of calcium disodium ethylenediaminetetraacetate (3wt%) and mix well; prepare a mixed solution B of oxidative bacteria and graphene: add 0.001g of graphene (nanoscale) to 1mL of oxidative bacteria (Geobacter) solution (OD600 value is 1) and mix well. Take 5mL of mixed solution A and 1mL of mixed solution B and mix well to obtain a bioanodic electrodeposition solution.

[0058] (2) Prepare a mixed solution A of sodium alginate and calcium disodium ethylenediaminetetraacetate: dissolve 1g of sodium alginate (2wt%) in 50mL of distilled water, add 1.5g of calcium disodium ethylenediaminetetraacetate (3wt%) and mix well; prepare a mixed solution C of reducing bacteria and graphene: add 0.001g of graphene (nanoscale) to 1mL of reducing bacteria (Pseudomonas) bacterial solution (OD600 value is 1) and mix well. Take 5mL of mixed solution A and 1mL of mixed solution C and mix well to obtain a biological cathode electrodeposition solution.

[0059] (3) Preparation of the bioanode: The electrode material (stainless steel metal fiber sintered felt mesh) is connected to the positive and negative electrodes of the electrochemical workstation respectively. The stainless steel electrode plates connected to the positive and negative electrodes are located in the same reaction chamber (20 mL reaction chamber). The bioanode electrodeposition solution of step (1) is added into the reaction chamber. The voltage is set to 5 V. After power is turned on, a biofilm is deposited on the stainless steel electrode connected to the positive electrode of the power supply. The deposition time is 1 min to prepare the bioanode.

[0060] Preparation of the biocathode: The electrode material (stainless steel metal fiber sintered felt mesh) is connected to the positive and negative poles of the electrochemical workstation respectively. The stainless steel electrode plates connected to the positive and negative poles are located in the same reaction chamber (20 mL reaction chamber). The biocathode electrodeposition solution of step (2) is added into the reaction chamber. The voltage is set to 5 V. After power is turned on, a biofilm is deposited on the stainless steel electrode connected to the positive pole of the power supply. The deposition time is 1 min to prepare a biocathode.

[0061] (4) The prepared bioanode and biocathode are installed as working electrodes in the microbial sensor, and the toxicity monitoring sensor is connected to the electrochemical workstation to collect data information:

[0062] Specifically, the bioanode prepared in step (3) is used as a working electrode, and is connected to an electrochemical workstation together with a counter electrode and a reference electrode. The working electrode, the counter electrode and the reference electrode are placed in an anode reaction chamber to form a three-electrode monitoring system.

[0063] The biological cathode prepared in step (3) is used as a working electrode, and connected to an electrochemical workstation together with a counter electrode and a reference electrode. The working electrode, the counter electrode and the reference electrode are placed in a cathode reaction chamber to form a three-electrode monitoring system;

[0064] The monitoring system formed by the bioanode and the monitoring system formed by the biocathode are independent of each other.

[0065] In this embodiment, the counter electrode and the working electrode have the same base electrode, that is, a stainless steel metal fiber sintered felt mesh, and the reference electrode is a silver / silver chloride reference electrode.

[0066] (5) In the three-electrode system constructed by the bioanode in step (4), simulated domestic sewage is added into the reaction chamber, and a potential of 0.2 V is applied to the bioanode; in the three-electrode system constructed by the biocathode in step (4), simulated domestic sewage is added into the reaction chamber, and a potential of -0.5 V is applied to the biocathode. The bioanode and biocathode are cultured separately, and the initial current runs stably for 1-2 hours until the current remains stable, which means that the bioanode and biocathode are successfully started.

[0067] Simulated domestic sewage (mg L -1 ):

[0068] Trace element configuration: Boric acid 150mg L -1 , Zinc sulfate heptahydrate 120mg L -1 , manganese chloride heptahydrate 120mg L -1 , copper sulfate pentahydrate 30mg L -1 , Sodium molybdate 65mg L -1 , Nickel chloride 50 mg L -1 , cobalt chloride hexahydrate 210 mg L -1 , potassium iodide 30mg L -1 .

[0069] In the three-electrode system of the bioanode, 4 mL of the above-prepared trace element solution (prepared with one liter of simulated domestic sewage) and 40 mg L ammonium nitrogen were taken. -1 , potassium dihydrogen phosphate - phosphorus 5mg L -1 , COD 200mg L -1 .

[0070] In the three-electrode system of the biocathode, 4 mL of the above-prepared trace element solution (prepared with one liter of simulated domestic sewage) and 40 mg L ammonium nitrogen were added. -1 , potassium dihydrogen phosphate - phosphorus 5mg L -1 , COD 20mg L -1 , nitrate nitrogen 100mg L -1 .

[0071] (6) Add the simulated domestic sewage in the anode reaction chamber to a final concentration of 150 mg / L -1 Dichlorophenol, 100mgL -1 Hexavalent chromium ions and 100mgL -1 The cathode reaction chamber was operated in the same way as nitrobenzene. The current reaction was observed. When toxic substances with different concentrations entered the bioanode chamber or the biocathode chamber, different current responses immediately appeared, indicating that the impact of toxic substances on the activity of microorganisms was affected. This proved that the prepared bioanode or biocathode could stably monitor toxic substances in water. The monitoring results are shown in Table 1.

[0072] When different toxic substances enter the bioanode working room, the current response of the bioanode to the impact of different toxic substances is as follows: Figure 3 As shown in the figure, when different toxic substances enter the biocathode working room, the current response of the biocathode to the impact of different toxic substances is as follows Figure 4 shown.

[0073] (7) When the toxic impact current tends to be stable, replace the new bioanode or biocathode, repeat steps (5)-(6), observe the current start-up, monitor the changes, and continuously monitor the toxic substances in the water flowing through the anode reaction chamber or cathode reaction chamber. The recovered bioanode or biocathode can be reused as a base electrode.

[0074] Example 2

[0075] The anode material and cathode material used in this embodiment are stainless steel electrode plates with a specification of 1 cm*1 cm*1 mm.

[0076] The specific preparation method is as follows:

[0077] (1) Prepare a mixed solution A of sodium alginate and calcium disodium ethylenediaminetetraacetate: dissolve 2.5g sodium alginate (5wt%) in 50mL distilled water, add 1g calcium disodium ethylenediaminetetraacetate (2wt%) and mix evenly; prepare a mixed solution B of oxidative bacteria and graphene: add 0.001g graphene (nanoscale) to 1mL oxidative bacteria (Geobacter) solution (OD600 value is 1) and mix evenly. Take 5mL of mixed solution A and 1mL of mixed solution B and mix evenly to obtain a bioanodic electrodeposition solution.

[0078] (2) Prepare a mixed solution A of sodium alginate and calcium disodium ethylenediaminetetraacetate: dissolve 2.5g sodium alginate (5wt%) in 50mL distilled water, add 1g calcium disodium ethylenediaminetetraacetate (2wt%) and mix well; prepare a mixed solution C of reducing bacteria and graphene: add 0.001g graphene (nanoscale) to 1mL reducing bacteria (Pseudomonas) solution (OD600 value is 1) and mix well. Take 5mL of mixed solution A and 1mL of mixed solution C and mix well to obtain a biocathode electrodeposition solution.

[0079] Steps (3) to (7) are the same as in Example 1. The monitoring results are shown in Table 1.

[0080] Comparative Example 1

[0081] The difference from Example 1 is that no calcium disodium ethylenediaminetetraacetic acid solution is added. The rest is consistent with Example 1, and the monitoring results are shown in Table 1.

[0082] Comparative Example 2

[0083] In the preparation of the electrode: 5 mL of the mixed solution A in Example 1 is taken and mixed with 1 mL of the same bacterial solution as in Example 1 (OD600 value is 1) to obtain a mixed solution D, except that no graphene is added to the bacterial solution; the mixed solution D is directly coated on the surface of the foundation electrode, except that no electrodeposition step is performed.

[0084] The start-up and monitoring process of the electrode is the same as in Example 1, and the monitoring results are shown in Table 1.

[0085] Comparative Example 3

[0086] The conventional method of using microbial strains to directly enter the sensor to start the culture was adopted. The monitoring process was the same as in Example 1. The monitoring results are shown in Table 1.

[0087] Table 1 Biofilm initiation and toxicity monitoring of Examples 1-2 and Comparative Examples 1-3

[0088] Effect example Start-up time (h) Toxicity Monitoring Response Example 1 1-2 Immediate response within 20 seconds; peak current response within 30 minutes Example 2 1-2 Immediate response within 1 minute; peak current response within 30 minutes Comparative Example 1 1-2 Immediate response within 30 seconds; peak current response within 1 hour Comparative Example 2 3-4 Immediate response within 30 seconds; peak current response within 1 hour Comparative Example 3 30-60 Immediate response within 30 seconds; peak current response within 2 hours

[0089] From the results in Table 1, it can be seen that for toxic substances of different concentrations, the bioanode and biocathode prepared in Example 1 of the present application both responded immediately within 20 seconds; the response peak current appeared within 30 minutes, and the start-up time and toxicity response time were significantly lower than all comparative examples.

[0090] It can be seen from the results of Example 1 and Example 2 that under the preferred preparation conditions of Example 1, the bioanode and the biocathode respond immediately within 20 seconds when performing toxicity monitoring, and a response peak current appears within 30 minutes.

[0091] Changing the sodium alginate concentration in Example 2 may have an adverse effect on electron transfer due to the increase in membrane thickness, and the response time of its bioanode and biocathode are both prolonged, but its start-up time is still significantly better than that of Comparative Examples 2 and 3.

[0092] At the same time, through experimental comparison and observation with Comparative Example 1, it was found that when calcium disodium ethylenediaminetetraacetic acid was added for dual ion cross-linking, the microbial gel with calcium ion cross-linking was more stable and not easy to break or deform. If there was no immediate toxic impact, the biofilm would remain in the sensor longer.

[0093] It can be seen from the results of Example 1 and Comparative Example 2 that, compared with direct coating, the current of the bioanode and biocathode prepared in the present application is significantly improved for toxic substances of different concentrations, and has the characteristics of high monitoring sensitivity and high conductivity.

[0094] It can be seen from the results of Example 1 and Comparative Example 3 that, compared with microorganisms directly entering the sensor, for different concentrations of toxic substances, the bioanode and biocathode prepared in the present application cultivate biofilms significantly faster than Comparative Example 3, and have the characteristics of stable biofilms and fast startup speed.

[0095] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a bioelectrode for water toxicity monitoring, characterized in that: include: The two substrate electrodes are respectively connected to the positive and negative electrodes of the power supply of the electrochemical workstation and then inserted into the reaction chamber, a bioanode electrodeposition solution or a biocathode electrodeposition solution is added into the reaction chamber, a voltage is applied to perform an electrodeposition reaction, and an electroactive biofilm is grown on the substrate electrode connected to the positive electrode of the power supply, thereby preparing a bioanode electrode and a biocathode electrode respectively; Preparation of the biological anode electrodeposition solution: sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in a solvent to obtain a mixed solution A, nano-scale conductive materials are fully dispersed in an oxidative bacterial solution to obtain a mixed solution B, and the mixed solution A and the mixed solution B are mixed according to a ratio to obtain the biological anode electrodeposition solution; Preparation of the biological cathode electrodeposition solution: sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in water to obtain a mixed solution A, nano-scale conductive materials are fully dispersed in a reducing bacterial solution to obtain a mixed solution C, and the mixed solution A and the mixed solution C are mixed according to a ratio to obtain the biological cathode electrodeposition solution.

2. The preparation method according to claim 1, characterized in that: In the mixed solution A, the mass percentage concentration of sodium alginate is 1-3%, the mass percentage concentration of calcium disodium ethylenediaminetetraacetate is 1-3%, and the solvent is water.

3. The preparation method according to claim 2, characterized in that: In the mixed solution B, the OD600 value of the oxidative bacterial solution is 1; the volume ratio of the mixed solution B to the mixed solution A is 1:5; the amount of the nano-scale conductive material added is such that its concentration in the bioanode electrodeposition solution is 0.15 to 0.3 g / L -1 count.

4. The preparation method according to claim 2, characterized in that: In the mixed solution C, the OD600 value of the reducing bacterial solution is 1; the volume ratio of the mixed solution C to the mixed solution A is 1:5; the amount of the nano-scale conductive material added is such that its concentration in the biological cathode electrodeposition solution is 0.15 to 0.3 g / L -1 count.

5. The preparation method according to claim 1, characterized in that: The conditions of the electrodeposition reaction are: voltage of 2-8V and deposition time of 1-5min.

6. The preparation method according to claim 1, characterized in that: The base electrode is a stainless steel electrode, a pure iron electrode, an iron alloy electrode or an iron-based composite material electrode; The oxidative bacteria are electrogenic bacteria; The reducing bacteria are denitrifying bacteria; The nano-scale conductive material is nano-scale electric carbon black or nano-scale graphene.

7. A bioanode or biocathode prepared by the preparation method according to any one of claims 1 to 6.

8. An electrochemical monitoring method for water toxicity, characterized in that: include: The bioanode is used as a working electrode, and is connected to an electrochemical workstation together with a counter electrode and a reference electrode to construct an electrochemical monitoring system. A potential of -0.2V to 0.2V is applied to the bioanode to start the bioanode. After the bioanode is successfully started, when wastewater enters the bioanode working room, it is determined whether there are toxic substances in the wastewater based on the current response; the bioanode is a bioanode prepared by the preparation method according to any one of claims 1 to 6.

9. An electrochemical monitoring method for water toxicity, characterized in that: include: The biocathode is used as a working electrode and connected to an electrochemical workstation together with a counter electrode and a reference electrode to construct an electrochemical monitoring system, and a -0.4V to -0.8V potential is applied to the biocathode to start the biocathode. After the biocathode is successfully started, when wastewater enters the biocathode working room, it is determined whether there are toxic substances in the wastewater based on the current response; the biocathode is a biocathode prepared by the preparation method according to any one of claims 1 to 6.

10. The electrochemical monitoring method according to claim 8 or 9, characterized in that: The startup time is 1 to 2 hours.

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