A biological electrode for water toxicity monitoring and its preparation and application

Abstract

The application discloses a bioelectrode for water toxicity monitoring and a preparation and application thereof. The electrode preparation comprises the following steps: two substrate electrodes are respectively connected with a positive electrode and a negative electrode of a power supply of an electrochemical workstation, and then inserted into a reaction chamber; a biological anode electrodeposition solution or a biological cathode electrodeposition solution is added into the reaction chamber; a voltage is applied to perform an electrodeposition reaction; and an electroactive biological membrane is grown on the substrate electrode connected with the positive electrode of the power supply, so as to respectively prepare a biological anode electrode and a biological cathode electrode. Before a water monitoring sensor is started, an interpenetrating network double-ion cross-linked microbial gel is constructed through electrodeposition, the biological membrane is attached to an anode material and a cathode material and respectively serves as a working electrode, a sensing system is constructed, has a high electron transfer rate and stability, and can effectively solve problems of slow enrichment speed, easy falling off and slow starting of the biological membrane.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water body monitoring, and particularly relates to a biological electrode for water body toxicity monitoring and a preparation and application thereof. BACKGROUND

[0002] Water is the material basis for human survival. It not only provides the basis for life, but also participates in climate regulation, agricultural irrigation and industrial production. However, the current water pollution problem is becoming increasingly serious. Industrial wastewater, domestic sewage discharge and agricultural non-point source pollution make the water body contain a large amount of harmful substances such as heavy metals, organic matter and nutrients. These pollutants not only affect the quality of water, but also cause harm to aquatic organisms and destroy the stability of the ecological system. At the same time, the polluted water body can also be transmitted through the food chain and pose a threat to human health. Water environmental toxicity monitoring is crucial for protecting water resources and biodiversity. Through real-time and accurate monitoring of water bodies, the quality of water bodies, the types, concentrations and distribution of pollutants can be understood in a timely manner. Therefore, water toxicity monitoring is of great significance to solve the problem of water environmental pollution.

[0003] Microbial electrochemical sensors (biological electrodes) with electroactive biofilms as sensitive elements are a new type of online water quality monitoring technology. When stimulated by toxicity, the growth and metabolism of microorganisms will change in response, and the signal will be transmitted to the collection system to achieve real-time early warning of the polluted environment of water bodies. Electroactive microorganisms are attached to the electrode surface by forming biofilms, but the biofilm culture process is relatively long, the enrichment capacity is low, and when toxic substances enter the water body, it will directly lead to the shedding and even death of microorganisms.

[0004] For example, CN 116660340 A patent document discloses a biological cathode toxicity sensing element, a biological cathode toxicity sensor and its application. In this patent document, toxicity monitoring is carried out by directly inoculating bacteria in the reactor for culture, but the culture time is relatively long, and when toxic substances re-enter the water body, the microbial activity will be reduced, making it difficult to achieve the initial monitoring sensitivity level.

[0005] CN 112305029 A patent document discloses an electrode biofilm rapid forming method and a microbial electrochemical sensor. In this patent document, electroactive bacteria and adhesive mixed solution are rapidly formed into an electrode biofilm, but its conductivity is lower than that of uncrosslinked sodium alginate film, which will affect the electron transfer rate.

[0006] CN 103940883 A patent document discloses a preparation method, application, device and detection method of a disposable microbial membrane sensor capable of rapidly detecting water body biological toxicity. In the patent document, the microbial loading capacity is improved by adding a curing liquid and using a fixator to apply pressure, but the method is complex to operate and difficult to ensure microbial activity, and has the disadvantages of low biological current and poor sensitivity to monitoring of various toxic substances. SUMMARY

[0007] Based on the technical problems existing in the prior art, the present application proposes a biological sensor toxicity monitoring probe rapid preparation process. Before the water body monitoring sensor is started, an interpenetrating network double-ion cross-linked microbial gel is constructed by electrodeposition, a biological membrane is loaded on an anode material and a cathode material and respectively serves as a working electrode, and a sensing system is constructed, which has high electron transfer rate and stability, and can effectively solve the problems of slow enrichment speed, easy falling off and slow start of the biological membrane.

[0008] A preparation method of a biological electrode for water body toxicity monitoring, comprising:

[0009] After two base electrodes are respectively connected with positive and negative poles of a power supply of an electrochemical workstation and inserted into a reaction chamber, biological anode electrodeposition liquid or biological cathode electrodeposition liquid is added into the reaction chamber, voltage is applied to perform electrodeposition reaction, and electroactive biological membrane is grown on the base electrode connected with the positive pole of the power supply, to respectively prepare a biological anode electrode and a biological cathode electrode.

[0010] The biological anode electrodeposition liquid is prepared as follows: sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in a solvent to obtain a mixed solution A, and nanoscale conductive material is fully dispersed in an oxidative bacterial liquid to obtain a mixed solution B, and the mixed solution A and the mixed solution B are mixed according to a proportion to obtain the biological anode electrodeposition liquid.

[0011] The biological cathode electrodeposition liquid is prepared as follows: sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in water to obtain a mixed solution A, and nanoscale conductive material is fully dispersed in a reducing bacterial liquid to obtain a mixed solution C, and the mixed solution A and the mixed solution C are mixed according to a proportion to obtain the biological cathode electrodeposition liquid.

[0012] The electrodeposition double-ion cross-linking method adopted in the present application can enhance ion cross-linking and improve stability; calcium disodium ethylenediaminetetraacetate is added in the electrodeposition liquid, calcium disodium ethylenediaminetetraacetate can form stable complexes with various metal ions, electrodeposition and sintering of the stainless steel metal fiber felt net stainless steel electrode plate inside Fe 3+ Double-ion cross-linking ensures the stability of the membrane. The conductive material is uniformly mixed with the corresponding bacterial liquid and then mixed with the sodium alginate and calcium disodium ethylenediaminetetraacetate mixed solution.

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

[0014] Sodium alginate has good biocompatibility and high porosity. A low concentration of sodium alginate loosens its spatial grid structure, reducing gel strength. A high concentration significantly increases solution viscosity, hindering ion diffusion and cross-linking reactions. Calcium disodium EDTA ensures the stability of the biofilm surface structure. A low concentration can reduce gel strength and stability, while a high concentration can be toxic to microorganisms. Optionally, the mixture of sodium alginate and calcium disodium EDTA has a mass percentage concentration of 1-3% sodium alginate and 1-3% calcium disodium EDTA, 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 edetate 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 such that its concentration in the bioanode electrodeposition solution is 0.15 to 0.3 g / L -1 count.

[0017] Optionally, 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.

[0018] Too low a voltage will reduce the adsorption and deposition rate of biomolecules on the electrode surface, while too high a voltage will cause excessive corrosion and wear of the electrode, damaging the biomolecule structure. Too short a deposition time will result in insufficient microbial biomass on the coating, while too long a deposition time 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 deposit thickness are all within a relatively favorable range. More preferably, the electrodeposition reaction conditions are: a voltage of 2-8V and a deposition time of 1-5 minutes.

[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 electric-producing bacteria, which have good electric-producing performance, high efficient electron transfer ability and fast film forming ability. The electric-producing bacteria are conventional electric-producing bacteria in the field of electrochemical treatment of wastewater, and widely exist in natural environment, such as Geobacter, Shewanella, etc. There is no requirement for specific strains, and the strains can be obtained by self-isolation and culture according to conventional method or purchased on the market. The strains can also be purchased from the microbial protection center, such as Shewanella vesiculosa with preservation number of CGMCC NO.1.15835, Shewanella algae with preservation number of CGMCC NO.1.8754, etc.

[0021] Optionally, the reducing bacteria are denitrifying bacteria, which have the characteristics of short domestication period, fast start-up speed and fast establishment of nitrification system. The denitrifying bacteria are conventional denitrifying bacteria in the field of electrochemical treatment of wastewater, and widely exist in natural environment, such as Pseudomonas, Alcaligenes, etc. There is no requirement for specific strains, and the strains can be obtained by self-isolation and culture according to conventional method or purchased on the market. The strains can also be purchased from the microbial protection center, such as Pseudomonas stutzeri with preservation number of CGMCC NO.1.15316, Alcaligenes aquatilis with preservation number of CGMCC NO.1.9053, etc.

[0022] Optionally, the nanoscale conductive material is nanoscale electric carbon black or nanoscale graphene, which has high conductivity and excellent electrocatalytic performance. If the concentration of the nanoscale conductive material is too high, the electron transfer efficiency will be affected, and if the concentration of the nanoscale conductive material is too low, the conductivity will be reduced. The nanoscale conductive material can be purchased on the market. Preferably, the addition amount of the nanoscale conductive material is 0.15-0.3 g / L in the biological anode electrodeposition solution or the biological cathode electrodeposition solution. -1 It is appropriate.

[0023] The application also provides a biological anode or a biological cathode prepared by the preparation method.

[0024] The application provides an electrochemical monitoring method for water body toxicity, which comprises the following steps:

[0025] An electrochemical working station is connected with a biological anode as a working electrode, a counter electrode and a reference electrode to construct an electrochemical monitoring system. A potential of-0.2 V to 0.2 V is applied to the biological anode to start the biological anode. After the biological anode is successfully started, when wastewater enters the working chamber of the biological anode, whether the wastewater contains toxic substances is judged according to the current response. The biological anode is the biological anode prepared by the preparation method.

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

[0027] An electrochemical monitoring system is constructed by connecting a biological cathode as a working electrode, a counter electrode and a reference electrode to an electrochemical workstation, a potential of-0.4 V to-0.8 V is applied to the biological cathode to start the biological cathode, and after the biological cathode is successfully started, whether the wastewater contains toxic substances is judged according to the current response when the wastewater enters the working chamber of the biological cathode; the biological cathode is the biological cathode prepared in the application.

[0028] During the monitoring process, a potential of-0.2 V to 0.2 V is applied to the biological anode to ensure the normal physiological metabolism of the anodic microorganisms, and a potential of-0.4 V to-0.8 V is applied to the biological cathode to ensure the normal physiological metabolism of the cathodic microorganisms.

[0029] The biological electrode of the application has a short starting time, and can be successfully started in 1-2 hours.

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

[0031] (1) The application can effectively solve the problems of slow film formation speed, low enrichment capacity and long starting time of the biological anode and the biological cathode by electrodepositing and enriching the biofilm on the surface of the anode material and the cathode material, and can effectively solve the problems of low mass transfer rate and low current of the biofilm by preparing the anodic biofilm and the cathodic biofilm through a double-ion crosslinking method.

[0032] (2) Compared with the direct coating disclosed in CN 112305029 A, the current of the biological anode and the biological cathode prepared in the application is significantly improved, and the application has 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 biological anode and the biological cathode prepared in the application have a significantly faster biofilm culture time than the comparative example, and have the characteristics of stable biofilm and fast starting speed. DETAILED DESCRIPTION

[0034] Figure 1 is a process flowchart of the application;

[0035] Figure 2 is an electrode structure schematic diagram of the application;

[0036] Figure 3 is a current response result graph of the biological anode in Example 1 to the impact of different toxic substances;

[0037] Figure 4 is a current response result graph of the biological cathode in Example 1 to the impact of different toxic substances.

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

[0039] 1, base electrode; 2, artificial biofilm. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] 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 the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments and is not intended to limit the present application.

[0042] The structure of the biological anode or biological cathode of the present application is shown in Figure 2 which includes a base electrode 1 and an artificial biofilm 2 located on the surface of the base electrode, the artificial biofilm being an interpenetrating network double-ion cross-linked microbial gel constructed by electrodeposition.

[0043] The preparation of the biological electrode and the process for monitoring the toxicity of a water body are shown in Figure 1 which include:

[0044] S1, preparation of a mixed solution of sodium alginate and calcium disodium ethylenediaminetetraacetate, addition of a mixed solution of oxidizing bacteria and nanoscale conductive material, preparation of a biological anode electrodeposition solution.

[0045] S2, preparation of a mixed solution of sodium alginate and calcium disodium ethylenediaminetetraacetate, addition of a mixed solution of reducing bacteria and nanoscale conductive material, preparation of a biological cathode electrodeposition solution.

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

[0047] In this step, the biological anode and the biological cathode are prepared separately. The process for preparing the biological anode is as follows: the anode material (base electrode) is respectively connected to the positive and negative poles of the power supply of the electrochemical workstation, the biological anode electrodeposition solution is added to the reaction chamber, and a voltage is applied to grow a biological film on the anode material connected to the positive pole of the power supply, thereby obtaining the biological anode; when preparing the biological cathode, the biological cathode electrodeposition solution is replaced in the reaction chamber, thereby obtaining the biological cathode.

[0048] S4, connection of a toxicity monitoring system, application of corresponding potentials, and start of the biological anode and the biological cathode.

[0049] In this step: the biological anode and the biological cathode are respectively used as the working electrode to construct a three-electrode system, the biological anode is used as the working electrode to form a three-electrode system with the counter electrode and the reference electrode, and is connected to the electrochemical workstation; the biological cathode is used as the working electrode to form a three-electrode system with the counter electrode and the reference electrode, and is connected to the electrochemical workstation; the two three-electrode monitoring systems are independent of each other.

[0050] S5When the toxic substance impacts the biological anode or the biological cathode, an electric current response occurs immediately, and real-time monitoring is performed.

[0051] S6After the toxic impact current tends to be stable, the biological electrode is taken out, a newly prepared biological electrode is replaced, and the current start-up and monitoring changes are observed.

[0052] The following is described with specific examples:

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

[0054] Example 1

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

[0056] The electrode preparation and toxicity monitoring method is as follows:

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

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

[0059] (3) Preparation of the biological anode: the electrode material (sintered felt net of stainless steel metal fiber) is connected to the positive and negative poles of the power supply 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 biological anode electrodeposition solution of step (1) is added into the reaction chamber, the voltage is set to 5 V, and after power-on, the biological film is deposited on the stainless steel electrode connected to the positive pole of the power supply, the deposition time is 1 min, and the biological anode is prepared.

[0060] Preparation of the biological cathode: the electrode material (sintered felt net of stainless steel metal fiber) is connected to the positive and negative poles of the power supply 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 biological cathode electrodeposition solution of step (2) is added into the reaction chamber, the voltage is set to 5 V, and after power-on, the biological film is deposited on the stainless steel electrode connected to the positive pole of the power supply, the deposition time is 1 min, and the biological cathode is prepared.

[0061] (4) The prepared biological anode and biological cathode are respectively loaded into the microbial sensor as the working electrode, the toxicity monitoring sensor is connected to the electrochemical workstation, and data information is collected:

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

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

[0064] The monitoring system composed of the biological anode and the monitoring system composed of the biological cathode are independent of each other.

[0065] In this embodiment, the base electrode of the counter electrode and the working electrode is the same, i.e. the sintered felt net of stainless steel metal fiber, and the reference electrode is a silver / silver chloride reference electrode.

[0066] (5) In the three-electrode system constructed by the biological anode in step (4), simulated domestic sewage is added into the reaction chamber, and an electric potential of 0.2 V is applied to the biological anode; in the three-electrode system constructed by the biological cathode in step (4), simulated domestic sewage is added into the reaction chamber, and an electric potential of -0.5 V is applied to the biological cathode, and the biological anode and the biological cathode are cultured respectively, and the initial current is stably operated for 1-2 hours until the current remains stable, which is considered as the successful start of the biological anode and the biological cathode.

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

[0068] Microelement configuration: Boric acid 150 mg / L -1 Zinc sulfate heptahydrate 120 mg / L -1 Manganese chloride heptahydrate 120 mg / L -1 Copper sulfate pentahydrate 30 mg / L -1 Sodium molybdate 65 mg / L -1 Nickel chloride 50 mg / L -1 Cobalt chloride hexahydrate 210 mg / L -1 Potassium iodide 30 mg / L -1 .

[0069] In the three-electrode system of the biological anode, 4 mL of the above microelement solution (1 L of simulated domestic sewage) was taken, ammonium nitrogen 40 mg / L -1 Potassium dihydrogen phosphate-phosphorus 5 mg / L -1 COD 200 mg / L -1 .

[0070] In the three-electrode system of the biological cathode, 4 mL of the above microelement solution (1 L of simulated domestic sewage) was taken, ammonium nitrogen 40 mg / L -1 Potassium dihydrogen phosphate-phosphorus 5 mg / L -1 COD 20 mg / L -1 Nitrate nitrogen 100 mg / L -1 .

[0071] (6) 150 mg / L -1 of dichlorophenol, 100 mg / L -1 of hexavalent chromium ions and 100 mg / L -1 of nitrobenzene were added to the simulated domestic sewage in the anode reaction chamber, and the same operation was performed in the cathode reaction chamber. The current response was observed when different toxic substances entered the biological anode working chamber or the biological cathode working chamber, and it was immediately determined that the impact of toxic substances on microbial activity had an effect, proving that the prepared biological anode or biological cathode could stably monitor toxic substances in water. The monitoring results are shown in Table 1.

[0072] When different toxic substances enter the biological anode working chamber, the current response of the biological anode to the impact of different toxic substances is shown in Table 2. Figure 3 When different toxic substances enter the biological cathode working chamber, the current response of the biological cathode to the impact of different toxic substances is shown in Table 3. Figure 4

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

[0074] Example 2

[0075] The anode material and cathode material used in this example are stainless steel electrode plates with a size 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 2.5 g of sodium alginate (5 wt%) in 50 mL of distilled water, add 1 g of calcium disodium ethylenediaminetetraacetate (2 wt%) and mix uniformly; prepare a mixed solution B of oxidizing bacteria and graphene: add 0.001 g of graphene (nanoscale) to 1 mL of oxidizing bacteria (Geobacter) bacterial solution (OD600 value of 1) and mix uniformly. Mix 5 mL of mixed solution A and 1 mL of mixed solution B uniformly to obtain a biological anode electrodeposition solution.

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

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

[0080] Comparative Example 1

[0081] The difference from Example 1 is that no calcium disodium ethylenediaminetetraacetate solution is added. The rest is the same as Example 1, and the monitoring results are shown in Table 1.

[0082] Comparative Example 2

[0083] In the preparation of the electrode: take 5 mL of mixed solution A in Example 1, mix with 1 mL of the same bacterial solution (OD600 value of 1) as in Example 1 to obtain mixed solution D, the difference being that no graphene is added to the bacterial solution; coat the mixed solution D directly on the base electrode surface, the difference being that no electrodeposition step is performed.

[0084] The start-up and monitoring process of the electrodes were 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 directly into the sensor start-up culture was used, the monitoring process was the same as in Example 1, and the monitoring results are shown in Table 1.

[0087] Table 1: Start-up and toxicity monitoring of biofilms in 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 response current occurs within 30 minutes Example 2 1-2 Immediate response within 1 minute; peak response current occurs within 30 minutes Comparative Example 1 1-2 Immediate response within 30 seconds; peak response current occurs within 1 hour Comparative Example 2 3-4 Immediate response within 30 seconds; peak response current occurs within 1 hour Comparative Example 3 30-60 Immediate response within 30 seconds; peak response current occurs within 2 hours

[0089] As can be seen from the results in Table 1, for different concentrations of toxic substances, the bio-anode and bio-cathode prepared in Example 1 both responded immediately within 20 seconds; the peak response current appeared within 30 minutes, and the start-up time and toxicity response time were significantly lower than all the comparative examples.

[0090] As can be seen from the results in Example 1 and Example 2, under the preferred preparation conditions of Example 1, the bio-anode and bio-cathode responded immediately within 20 seconds when performing toxicity monitoring, and the peak response current appeared within 30 minutes.

[0091] In Example 2, changing the concentration of sodium alginate may have had an adverse effect on electron transfer due to the increase in film thickness, which prolonged the response time of the bio-anode and bio-cathode, but the start-up time was still significantly better than that of Comparative Examples 2 and 3.

[0092] At the same time, through comparison with the test of Comparative Example 1, it was found that when calcium disodium ethylenediaminetetraacetate was added for double-ion crosslinking, the microbial gel with calcium ion crosslinking was more stable and less likely to break or deform, and if there was no immediate toxic shock, the biofilm could remain in the sensor for a longer time.

[0093] As can be seen from the results in Example 1 and Comparative Example 2, compared with direct coating, the current of the bio-anode and bio-cathode prepared in the application was significantly improved for different concentrations of toxic substances, and had the characteristics of high monitoring sensitivity and high conductivity.

[0094] As can be seen from the results in Example 1 and Comparative Example 3, compared with the direct entry of microorganisms into the sensor, the culture time of the bio-anode and bio-cathode prepared in the application was significantly faster than that of Comparative Example 3 for different concentrations of toxic substances, and had the characteristics of stable biofilm and fast start-up speed.

[0095] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, several modifications 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 should be subject to the appended claims.

Claims

1. A method for preparing a bioelectrode for water toxicity monitoring, characterized in that: include: The two substrate electrodes are connected to the positive and negative poles of the electrochemical workstation power supply, respectively, and then inserted into the reaction chamber. A bioanode electrodeposition solution or a biocathode electrodeposition solution is added into the reaction chamber, and a voltage is applied to perform an electrodeposition reaction. An electroactive biofilm grows on the substrate electrode connected to the positive pole of the power supply, thereby preparing a bioanode electrode and a biocathode electrode, respectively. Preparation of the bio-anodic electrodeposition solution: Sodium alginate and calcium disodium ethylenediaminetetraacetate are fully dissolved in a solvent to obtain a mixed solution A, a nano-scale conductive material is 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 proportion to obtain the bio-anodic electrodeposition solution; Preparation of the biological cathode electrodeposition solution: Sodium alginate and calcium disodium edetate 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 edetate 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 0.15 to 0.3 g / L at its concentration in the bioanode electrodeposition solution. -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 biocathode 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, 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 oxidizing 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 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 chamber, it is determined whether toxic substances exist 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 is connected to an electrochemical workstation together with a counter electrode and a reference electrode to construct an electrochemical monitoring system. A potential of -0.4V to -0.8V is applied to the biocathode to start the biocathode. After the biocathode is successfully started, when wastewater enters the biocathode working chamber, it is determined whether there are toxic substances in the wastewater based on the current response; the biocathode is a biocathode prepared according to the preparation method described in 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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