Photocatalytic microbial fuel cell sensor and application thereof

Abstract

The application discloses a photocatalytic microbial fuel cell sensor, which comprises an anode chamber provided with a microbial anode and a cathode chamber provided with a cathode, the cathode comprises a cathode carrier material and a semiconductor material loaded on the cathode carrier material, and the semiconductor material is a narrow-band-gap semiconductor material; the narrow-band-gap semiconductor material can make the cathode generate a stable current under light conditions, and the generated stable current is the same as or close to the current generated by the microbial anode. The photocatalytic microbial fuel cell sensor has the advantages of wide detection range, high detection sensitivity, wide application range, high stability, good repeatability and the like, can be widely applied to monitoring and early warning of water quality, has high use value and good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biosensors, and particularly relates to a photocatalytic microbial fuel cell sensor and application thereof. BACKGROUND

[0002] With the rapid increase of industrial wastewater discharge, a large amount of wastewater containing heavy metals and organic pollutants is discharged into the environment, threatening the water body ecology and human health, and even causing irreversible damage. Therefore, it is essential to obtain a sustainable, low-cost and rapid response detection method for the monitoring and early warning of heavy metals and organic pollutants in water, and for the repair of the ecological system.

[0003] Microbial fuel cell (MFC) is a device that converts chemical signals into electrical signals by using microorganisms to oxidize and reduce pollutants. Due to its excellent stability and self-powered characteristics, it has been widely studied in the field of sensors. In general, in the MFC biosensor, the anode chamber is used to culture and enrich the electroactive biofilm as the sensing element; when the measured substance contacts with the biofilm, the metabolism of the microorganisms in the biofilm will be affected, resulting in the change of the corresponding electrical signal, which is the basic principle of MFC detection. However, the existing microbial fuel cell as a sensor has low detection sensitivity due to the tolerance of microorganisms to toxic substances, and there are still difficulties in practical application. Therefore, it is very important to develop new biosensor strategies to improve the detection sensitivity of MFC.

[0004] At present, the photocatalytic microbial fuel cell formed by combining the cathode made of semiconductor material with the microbial anode has been studied for the degradation of pollutants and energy storage. However, so far, there is no related report on the sensor based on the photocatalytic microbial fuel cell constructed by the cathode made of semiconductor material. In addition, according to the previous research of the present inventor, it is found that the existing photocatalytic microbial fuel cell cannot be used as a sensor to detect target substances (such as heavy metals and organic pollutants) in water. The fundamental reason is that, on the one hand, the semiconductor material used to construct the cathode can only generate microamperes or even lower current without external bias, which has a very low contribution to the current of the microbial fuel cell, and thus it is difficult to improve the power generation performance of the photocatalytic microbial fuel cell. As a result, when the photocatalytic microbial fuel cell is used as a sensor, the current generated by the battery is still small, and thus the signal change of the current is weak, and it is difficult to detect the signal change of the current, and thus the detection effect is poor. On the other hand, the narrow-bandgap semiconductor material capable of generating large current under light conditions is prone to photo-corrosion due to the narrow band gap width, that is, the redox reaction occurs in the material itself, resulting in unstable current generated by the photocatalytic microbial fuel cell, that is, the photocatalytic microbial fuel cell cannot be used as a sensor to detect target substances because it cannot form a stable electric signal. It can be seen that the photocatalytic microbial fuel cell for treating organic pollutants or heavy metals at the present stage cannot be used as a sensor for water quality monitoring and early warning. Therefore, how to obtain a suitable narrow-bandgap semiconductor material so that the cathode loaded with the narrow-bandgap semiconductor material can generate stable current under light conditions, and the stable current generated is the same as or close to the current generated by the microbial anode, which is of great significance for constructing a photocatalytic microbial fuel cell sensor with wide detection range, high detection sensitivity, wide application range, high stability and good repeatability, and realizing water quality monitoring and early warning by using the sensor. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a photocatalytic microbial fuel cell sensor with wide detection range, high detection sensitivity, wide application range, high stability and good repeatability, and application thereof.

[0006] To solve the above technical problems, the present application adopts the following technical solutions.

[0007] A photocatalytic microbial fuel cell sensor, comprising an anode chamber provided with a microbial anode and a cathode chamber provided with a cathode, the cathode comprising a cathode carrier material and a semiconductor material loaded on the cathode carrier material, the semiconductor material being a narrow-band-gap semiconductor material; the narrow-band-gap semiconductor material enables the cathode to generate a stable current under light conditions, and the generated stable current is the same as or close to the current generated by the microbial anode.

[0008] The photocatalytic microbial fuel cell sensor described above is further improved, wherein the narrow-band-gap semiconductor material is one of CuO / ZnO, TiO2, Fe2O3, CdS and Cu2S, or the narrow-band-gap semiconductor material is a heterojunction semiconductor material composed of two or three of CuO / ZnO, TiO2, Fe2O3, CdS and Cu2S.

[0009] The photocatalytic microbial fuel cell sensor described above is further improved, wherein when the narrow-band-gap semiconductor material is CuO / ZnO, the preparation method of the cathode comprises the following steps: taking the cathode carrier material as a working electrode, placing the working electrode, a reference electrode and a counter electrode in a mixed solution of zinc nitrate and copper acetate, performing electrodeposition by adopting a constant current deposition method to make CuO / ZnO deposit on the surface of the cathode carrier material, and annealing to obtain the cathode; the electrodeposition time is 15 min; the annealing is performed at a temperature of 500 ℃; the annealing time is 1 h; the reference electrode is a saturated calomel electrode; the counter electrode is a platinum electrode; the molar ratio of the zinc nitrate to the copper acetate is 5:1; the zinc nitrate is zinc nitrate hexahydrate; the copper acetate is anhydrous copper acetate; the cathode carrier material is any one of conductive glass, carbon felt and stainless steel mesh; and the conductive glass is any one of FTO conductive glass and ITO conductive glass.

[0010] The photocatalytic microbial fuel cell sensor described above is further improved, wherein the microbial anode comprises an anode carrier material and a microbial film loaded on the anode carrier material; the microbial anode is prepared by mixing the anode carrier material with sludge and then culturing; and the preparation method of the microbial anode comprises the following steps: placing the anode carrier material in sludge for culturing to make the microorganisms load on the anode carrier material and form a microbial film, thereby obtaining the microbial anode; the sludge is residual sludge in a secondary sedimentation tank of a sewage treatment plant; sodium acetate aqueous solution is further added during the culturing, the volume ratio of the sodium acetate solution to the sludge is 1:1, the concentration of the sodium acetate solution is 1 M; and the culturing time is 3 days; and the anode carrier material is any one of carbon felt and stainless steel mesh.

[0011] The photocatalytic microbial fuel cell sensor is further improved, the microbial anode and the cathode are connected through a wire, the resistance of the wire is 1000Ω, the wire is a titanium wire, a proton exchange membrane is arranged between the anode chamber and the cathode chamber, sampling holes are arranged at the top of the anode chamber and the cathode chamber, the electrolyte used in the anode chamber is obtained by mixing sodium acetate, vitamins, minerals and a phosphate buffer solution, and the electrolyte used in the cathode chamber is obtained by mixing potassium ferricyanide and a phosphate buffer solution.

[0012] The photocatalytic microbial fuel cell sensor is further improved, the photocatalytic microbial fuel cell sensor further comprises a light irradiation device, and the light source used in the light irradiation device is a xenon lamp.

[0013] As a general technical concept, the application also provides an application of the photocatalytic microbial fuel cell sensor in water quality monitoring and early warning.

[0014] The application is further improved, and the photocatalytic microbial fuel cell sensor is used to detect a target detection object in water, and the application comprises the following steps:

[0015] (1) adding a water body to be detected containing a target detection object into an anode chamber of the photocatalytic microbial fuel cell sensor, and obtaining a current inhibition rate of the target detection object in the water body to be detected after the current is stable;

[0016] (2) according to the current inhibition rate of the target detection object obtained in step (1), calculating the concentration of the target detection object in the water body to be detected by using a linear equation of the concentration of the target detection object and the current inhibition rate, and completing the monitoring and early warning of the water quality.

[0017] The application is further improved, and before the water body to be detected containing the target detection object is added in step (1), the following treatment is further included: starting the photocatalytic microbial fuel cell sensor under light irradiation conditions until the generated current of the photocatalytic microbial fuel cell sensor reaches a stable state.

[0018] The application is further improved, and in step (2), when the target detection object is cadmium ions, the linear equation of the concentration of the target detection object and the current inhibition rate is as follows:

[0019] IR = 12.425C + 14.847 (R 2 = 0.973) (1).

[0020] In formula (1), IR is the current inhibition rate, which is calculated according to formula (2), C is the concentration of Cd 2+ in the water body to be detected, and R is the current inhibition rate.

[0021] The formula (2) is as follows:

[0022] IR = (I1 - I2) x 100% / I2 (2);

[0023] In formula (2), I1 and I2 are current values before and after adding the target detection object into the water body to be detected.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] (1) The present application provides a photocatalytic microbial fuel cell sensor, which comprises an anode chamber provided with a microbial anode and a cathode chamber provided with a cathode, wherein the cathode comprises a cathode carrier material and a semiconductor material loaded on the cathode carrier material, and the semiconductor material is a narrow-band-gap semiconductor material, which can generate a stable current under light conditions, and the generated stable current is the same as or close to the current generated by the microbial anode. In the present application, the narrow-band-gap semiconductor material is loaded on the cathode carrier material, and the photocatalytic microbial fuel cell constructed in this way can generate a larger stable current. When used as a sensor for detection, the current change signal is stronger, and thus the accurate detection of target substances can be realized by obtaining the current change data of the battery. At the same time, the narrow-band-gap semiconductor material used can generate a larger stable current, has stronger light corrosion resistance, and exhibits very excellent light stability, thus being beneficial to improving the stability and service life of the photocatalytic microbial fuel cell sensor. In addition, in the present application, there is a synergistic promotion effect between the cathode and the microbial anode, which is beneficial to improving the detection range, detection accuracy and detection sensitivity of the photocatalytic microbial fuel cell sensor. Specifically, on the one hand, both the cathode and the microbial anode can generate a larger stable current, and the stable currents generated by the two are the same or close to each other, which makes the photocatalytic microbial fuel cell have better power generation performance, and is beneficial to improving the detection accuracy and detection range of the sensor, on the other hand, the electrons generated by the microbial anode can combine with the photo-generated holes on the cathode when being transferred to the cathode, which promotes the separation of photo-generated electrons and holes on the cathode, thus making the sensor have a faster electrical signal change, thereby significantly improving the detection sensitivity of the sensor. In addition, in the present application, the microbial anode and the cathode are respectively arranged in two chambers, which avoids the damage and inactivation of the microorganisms in the microbial anode by the semiconductor material, and thus the sensing element is not damaged. The photocatalytic microbial fuel cell sensor of the present application has the advantages of wide detection range, high detection sensitivity, wide application range, high stability and good repeatability, and can be widely applied to the monitoring and early warning of water quality, has high use value and good application prospect.

[0026] (2) Compared with the conventional microbial fuel cell sensor by optimizing the anode biofilm, the photocatalytic cathode constructed by the narrow-bandgap semiconductor material (especially the CuO / ZnO heterojunction semiconductor material) capable of generating stable current under light conditions in the photocatalytic microbial fuel cell sensor of the application has wider applicability, which makes the microbial anode used in the application not only limited to the biofilm cultured in the sludge of sewage treatment plant, but also applicable to other biofilms after anode optimization culture. It can be seen that the photocatalytic microbial fuel cell sensor of the application can realize accurate detection of different target substances by using different characteristics of the biofilm in the microbial anode, thereby being applicable to the monitoring and early warning of different water quality conditions, and having very high use value.

[0027] (3) The application also provides an application of the photocatalytic microbial fuel cell sensor in water quality monitoring and early warning, which specifically detects the target substance in the water body by using the photocatalytic microbial fuel cell sensor, obtains the content of the target substance in the water body, and thereby realizes the monitoring and early warning of the water quality, and has the advantages of simple process, convenient operation, low cost, high treatment efficiency, high accuracy and the like, and has important significance for effectively monitoring the water quality. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be described clearly and completely below in combination with the drawings of the embodiments of the application.

[0029] Figure 1 FIG. 1 is a structural schematic diagram of the photocatalytic microbial fuel cell sensor of the application embodiment 1.

[0030] Figure 2 FIG. 2 is an effect diagram of the current of the photocatalytic microbial fuel cell sensor in the application embodiment 2 changing with time under different conditions.

[0031] Figure 3 FIG. 3 is a comparison effect diagram of the current inhibition rate of the photocatalytic microbial fuel cell sensor in the application embodiment 2 when detecting solutions containing Cd 2+ of different concentrations.

[0032] Figure 4 FIG. 4 is a linear relationship diagram of the concentration and the current inhibition rate of the photocatalytic microbial fuel cell sensor in the application embodiment 2 when detecting Cd 2+ in the water body.

[0033] Figure 5 FIG. 5 is a comparison effect diagram of the current inhibition rate of the photocatalytic microbial fuel cell sensor in the application embodiment 2 when detecting different heavy metal solutions.

[0034] Figure 6 This is a comparison chart showing the effect of current changing over time on the photocatalytic microbial fuel cell sensor (CuO / ZnO-PMFC) constructed in Example 1 of the present invention and the photocatalytic microbial fuel cell (CuO-PMFC) constructed in Comparative Example 1.

[0035] Legend:

[0036] 1. Microbial anode; 2. Cathode; 3. Proton exchange membrane; 4. External load and data acquisition device; 5. Illumination device. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0038] Example 1:

[0039] like Figure 1 As shown, a photocatalytic microbial fuel cell sensor of the present invention includes an anode chamber with a microbial anode 1 and a cathode chamber with a cathode 2. The cathode 2 includes a cathode support material and a semiconductor material loaded on the cathode support material. The semiconductor material is a narrow bandgap semiconductor material, which enables the cathode to generate a stable current under illumination, and the generated stable current is the same as or close to the current generated by the microbial anode. Specifically, the cathode 2 includes FTO conductive glass and a CuO / ZnO composite semiconductor material loaded on the FTO conductive glass. This CuO / ZnO composite semiconductor material enables the cathode 2 to generate a stable current under illumination, and the generated stable current is the same as or close to the current generated by the microbial anode 1. In this invention, any narrow bandgap semiconductor material that can generate a stable current under illumination can be used as a semiconductor material for constructing cathode 2. In addition to CuO / ZnO composite semiconductor materials, such as one of TiO2, Fe2O3, CdS and Cu2S, or heterojunction semiconductor materials composed of two or three of CuO / ZnO, TiO2, Fe2O3, CdS and Cu2S, can all be used as semiconductor materials for constructing cathode 2.

[0040] The preparation method of the cathode in the photocatalytic microbial fuel cell sensor of the embodiment comprises the following steps: taking FTO conductive glass as a working electrode, a saturated calomel electrode as a reference electrode, and a platinum electrode as a counter electrode, placing them in a mixed solution of zinc nitrate and copper acetate (electrolytic solution), and performing electrodeposition on an electrochemical workstation by using a constant current deposition method for 15 min, so that CuO / ZnO is deposited on the surface of the FTO conductive glass, and then the cathode is obtained by annealing in a muffle furnace at 500 DEG C for 1 h. In the mixed solution of zinc nitrate and copper acetate, the molar ratio of zinc nitrate to copper acetate is 5:1, the zinc nitrate is zinc nitrate hexahydrate, and the copper acetate is anhydrous copper acetate.

[0041] In the photocatalytic microbial fuel cell sensor of the embodiment, the microbial anode 1 comprises carbon felt (anode carrier material) and a microbial membrane loaded on the carbon felt (anode carrier material), and the microbial anode 1 is obtained by mixing the carbon felt with sludge and then culturing, comprising the following steps: placing the carbon felt in residual sludge in a secondary sedimentation tank of a sewage treatment plant, adding 1M sodium acetate solution according to a volume ratio of 1:1, culturing for 3 days, so that the microorganisms are loaded on the carbon felt and form a microbial membrane, and then the microbial anode is obtained.

[0042] As shown in Figure 1 In the photocatalytic microbial fuel cell sensor of the embodiment, the anode chamber and the cathode chamber are separated by a proton exchange membrane 3 and are located between the microbial anode 1 and the cathode 2, and the distance between the microbial anode 1 and the cathode 2 is 6 cm. In the embodiment, the anode chamber and the cathode chamber constitute a double-chamber structure, and the length, width and height thereof are 80*60*40 mm respectively. The material is organic glass, and a quartz glass window is arranged on one side of the cathode chamber to improve the light transmission performance. The effective volume of the anode chamber and the cathode chamber is 50 ml. The top of the anode chamber and the cathode chamber is provided with a sampling hole, which facilitates the injection of the to-be-measured substance and the sampling analysis.

[0043] As shown in Figure 1 In the photocatalytic microbial fuel cell sensor of the embodiment, the microbial anode 1 and the cathode 2 are connected by wires, and the microbial anode 1 and the cathode 2 are further connected with an electrochemical workstation, thereby forming a circuit external load and a data acquisition device 4 for monitoring the current generated by the photocatalytic microbial fuel cell. In the embodiment, the resistance of the wire for connecting the microbial anode 1 and the cathode 2 is 1000 Ω, which is a titanium wire.

[0044] As shown in Figure 1 In the photocatalytic microbial fuel cell sensor of the embodiment, the photocatalytic microbial fuel cell sensor further comprises an illumination device 5 for providing a light source for the cathode 2. In the embodiment, the illumination device 5 uses a xenon lamp as a light source, which has the advantages of high spectral matching degree, fast light response speed, high luminous brightness, and high luminous efficiency.

[0045] In the photocatalytic microbial fuel cell sensor of the embodiment, the electrolyte used in the anode chamber is obtained by mixing sodium acetate, vitamins, minerals and phosphate buffer solution, and has a pH value of 6.96; the electrolyte used in the cathode chamber is obtained by mixing potassium ferricyanide and phosphate buffer solution.

[0046] In the present application, the CuO / ZnO composite semiconductor material capable of generating stable current under light conditions is loaded on the FTO conductive glass to form the cathode 2, and the photocatalytic microbial fuel cell constructed in this way can generate a larger stable current, so that when it is used as a sensor for detection, the current change signal is stronger, and thus the accurate detection of the target substance can be realized by obtaining the current change data of the battery. At the same time, the CuO / ZnO composite semiconductor material used can generate a larger stable current, has stronger light corrosion resistance, and exhibits very excellent light stability, thus being beneficial to improving the stability and service life of the photocatalytic microbial fuel cell sensor. In addition, in the present application, the microbial anode 1 and the cathode 2 have a synergistic promotion effect, which is beneficial to improving the detection range, detection accuracy and detection sensitivity of the photocatalytic microbial fuel cell sensor. Specifically, on the one hand, the microbial anode 1 and the cathode 2 can both generate a larger stable current, and the stable currents generated by the two are the same or close to each other, which makes the photocatalytic microbial fuel cell have better power generation performance, and is beneficial to improving the detection accuracy and detection range of the sensor; on the other hand, when the cathode 2 composed of the CuO / ZnO composite semiconductor material is irradiated with visible light, the electrons are excited by the light and jump from the valence band to the conduction band, thereby generating photoelectrons and holes. Due to the PN junction formed by CuO and ZnO, the electron-hole separation efficiency of the CuO / ZnO semiconductor electrode is improved. At the same time, the electrons generated by the microbial anode 1 are transmitted to the cathode 2 through an external circuit and can combine with the photo-generated holes on the cathode 2, further promoting the separation of the photo-generated electrons-holes on the cathode 2, thereby making the photocatalytic microbial fuel cell sensor have a faster electrical signal change, so that the detection sensitivity of the photocatalytic microbial fuel cell sensor can be significantly improved. In addition, in the present application, the microbial anode 1 and the cathode 2 are respectively arranged in two chambers, which can avoid the damage and inactivation of the microorganisms in the microbial anode 1 by the semiconductor material (such as the CuO / ZnO composite semiconductor material), so that the sensing element will not be damaged. The photocatalytic microbial fuel cell sensor of the present application has the advantages of wide detection range, high detection sensitivity, wide application range, high stability and good repeatability, and can be widely applied to the monitoring and early warning of water quality, has high use value and good application prospect.

[0047] Example 2:

[0048] Application of a photocatalytic microbial fuel cell sensor in water quality monitoring and early warning, specifically using the photocatalytic microbial fuel cell sensor prepared in Example 1 to detect the content of heavy metal elements (Cd 2+ ) in water, comprising the following steps:

[0049] (1) Start the photocatalytic microbial fuel cell sensor in Example 1 under light conditions until the current generated by the photocatalytic microbial fuel cell sensor reaches a steady state.

[0050] (2) Add the water to be tested containing Cd 2+ to the anode chamber of the photocatalytic microbial fuel cell sensor whose current has reached a steady state, and after the current stabilizes, obtain the current inhibition rate of Cd 2+ in the water to be tested;

[0051] (3) According to the current inhibition rate of Cd 2+ obtained in step (2), use the linear equation of Cd 2+ concentration and current inhibition rate to calculate the concentration of Cd 2+ in the water to be tested, completing the monitoring and early warning of water quality.

[0052] In this example, when the target detection substance is cadmium ions, the linear equation of Cd 2+ concentration and current inhibition rate is:

[0053] IR = 12.425C + 14.847 (R 2 = 0.973) (1);

[0054] In equation (1), IR is the current inhibition rate, calculated from equation (2), and C is the concentration of Cd 2+ in the water to be tested;

[0055] Equation (2) is:

[0056] IR = (I1-I2) x 100% / I2 (2);

[0057] In equation (2), I1 and I2 are the current values when the water to be tested containing Cd 2+ is added and after 30 minutes when the water to be tested containing Cd 2+ is added, respectively. That is, by obtaining the current values before and after the addition of the water to be tested containing the target detection substance, the current inhibition rate data corresponding to different concentrations of the target detection substance is obtained.

[0058] In this example, the method for constructing the linear equation of Cd 2+ concentration and current inhibition rate is: after the current generated by the photocatalytic microbial fuel cell sensor reaches a steady state, add Cd2+ standard solution, so that the initial concentration of Cd 2+ in the anode chamber is 0.1 mg / L, 1 mg / L, 2 mg / L, 3 mg / L, 3.5 mg / L, 4 mg / L respectively, the current values before and after adding the Cd 2+ standard solution are obtained by using an electrochemical workstation, the current inhibition rates corresponding to the Cd 2+ standard solutions of different standard concentrations are obtained, and further according to the data of the Cd 2+ standard solutions of different standard concentrations and the current inhibition rates, a linear relationship between the Cd 2+ concentration and the current inhibition rate is constructed, and the results are shown in Figures 2-4 .

[0059] Figure 2 is an effect diagram of the current of the photocatalytic microbial fuel cell sensor corresponding to different conditions in Example 2 of the present application changing with time. From Figure 2 it can be seen that after the Cd 2+ standard solution with a concentration of 0.1 mg / L is injected, whether in dark conditions or in light conditions, the current generated by the photocatalytic microbial fuel cell sensor becomes smaller, but can be restored to a stable state in a short time, which shows that the addition of Cd 2+ inhibits the electricity generation performance of the microbial anode, and at the same time, it also shows that a stable microbial membrane is formed in the microbial anode. At the same time, Figure 2 it can also be seen that: compared with the light conditions, the current generated by the photocatalytic microbial fuel cell sensor under dark conditions is smaller, because the CuO / ZnO composite semiconductor material loaded in the cathode can convert light energy into current under light conditions, thereby improving the electricity generation performance of the photocatalytic microbial fuel cell sensor, so that the photocatalytic microbial fuel cell sensor has a larger stable current under light conditions. Therefore, when the CuO / ZnO composite semiconductor material is used to construct a photocatalytic cathode, the photocatalytic microbial fuel cell formed can be used as a sensor to detect cadmium ions in water.

[0060] Figure 3 is a comparison effect diagram of the current inhibition rate of the photocatalytic microbial fuel cell sensor when detecting solutions with different concentrations of Cd 2+ in Example 2 of the present application. From Figure 3 it can be seen that the concentration of the Cd 2+The addition of the standard solution of cadmium ions, under light conditions, has a higher inhibition rate, indicating that the introduction of sunlight improves the detection sensitivity of the sensor compared to dark conditions, and as the concentration increases, the corresponding current inhibition rate is higher, which indicates that the photocatalytic microbial fuel cell sensor of the application can detect higher concentrations of cadmium ion solution. Figure 3 It can be seen that the standard solution containing Cd 2+ with a concentration of 0.1 mg / L, 1 mg / L, 2 mg / L, 3 mg / L, and 4 mg / L has a corresponding current inhibition rate of 16.17%, 25.72%, 45.77%, 52.52%, and 61.63%, respectively, under light conditions.

[0061] Figure 4 The linear relationship between the concentration and the current inhibition rate when the photocatalytic microbial fuel cell sensor of the application is used to detect Cd 2+ in water in Example 2 of the application. As can be seen from Figure 4 , the photocatalytic microbial fuel cell sensor of the application exhibits a good linear relationship for Cd 2+ containing solutions in the concentration range of 0.1 mg / L to 4 mg / L.

[0062] In Example 2, the cadmium ion-containing test solution with a cadmium ion concentration of 2.5 mg / L was detected, and the results are shown in Table 1. At the same time, the cadmium ion-containing test solution with a cadmium ion concentration of 2.5 mg / L was also detected using the flame atomic absorption method, and the results are shown in Table 1.

[0063] Table 1 Comparison of detection results of different detection methods for Cd 2+

[0064]

[0065] As can be seen from Table 1, both the national standard method "GB / T 15337-2008" and the photocatalytic microbial fuel cell sensor of the application can be used to detect cadmium ion-containing test solutions. Taking the cadmium ion-containing test solution with a cadmium ion concentration of 2.5 mg / L as an example, the photocatalytic microbial fuel cell sensor of the application can accurately detect the content of cadmium ions in the test solution, showing high detection accuracy and reaching the detection accuracy of the national standard method. At the same time, compared to the national standard method, the photocatalytic microbial fuel cell sensor of the application is more simple, fast, and has higher value in use.

[0066] According to the method in Example 2, the Hg 2+ containing test solution with a concentration of 1 mg / L, the Zn 2+ containing test solution, and the Cr 6+ ​The detection results of the to-be-tested solution are shown in Table 1. Figure 5

[0067] Figure 5 Figure 2 is a comparison chart of current inhibition rates of the photocatalytic microbial fuel cell sensor in Example 2 of the present application when detecting different heavy metal solutions. Figure 5 As can be seen from Figure 2, the photocatalytic microbial fuel cell sensor of the present application can be used to detect solutions containing Hg 2+ , Zn 2+ , and Cr 6+ , which indicates the feasibility of the photocatalytic microbial fuel cell sensor of the present application for detecting different heavy metals; in combination with the results in Table 1, Figure 5 , it can be seen that the photocatalytic microbial fuel cell sensor of the present application has high detection sensitivity to Cd 2+ , Hg 2+ , Zn 2+ , and Cr 6+ .

[0068] In addition to the detection of solutions containing heavy metals, the photocatalytic microbial fuel cell sensor of the present application can also be used to detect organic pollutants, especially organic pollutants with strong toxic effects on microorganisms. It can be seen that the photocatalytic microbial fuel cell sensor constructed in the present application not only can effectively detect heavy metals, but also can detect toxic and effective organic pollutants, and has universality for the detection of toxic substances.

[0069] Comparative Example 1

[0070] A photocatalytic microbial fuel cell, which is basically the same as Example 1, differs only in that the semiconductor material loaded on the FTO conductive glass in Comparative Example 1 is CuO.

[0071] The photocatalytic microbial fuel cell constructed in Comparative Example 2 is denoted as CuO-PMFC.

[0072] Figure 6 Figure 3 is a comparison chart of current changes over time of the photocatalytic microbial fuel cell sensor (CuO / ZnO-PMFC) constructed in Example 1 of the present application and the photocatalytic microbial fuel cell (CuO-PMFC) constructed in Comparative Example 1. As can be seen from Figure 3, the photocatalytic microbial fuel cell sensor (CuO / ZnO-PMFC) constructed in Example 1 of the present application has higher current than the photocatalytic microbial fuel cell (CuO-PMFC) constructed in Comparative Example 1. Figure 6 ​It can be seen that after 5000s of light, the current of CuO-PMFC decreases by 52%, the current loss is too large, it is difficult to form a larger stable current, if it is used as a sensor for detection, the current change signal may be disturbed, and the accurate detection of the target substance cannot be realized by obtaining the current change data of the battery, therefore, CuO-PMFC cannot be used as a sensor to monitor water quality, in particular, the reason for the excessive current loss of CuO-PMFC is that CuO is prone to photo corrosion, that is, it is prone to redox reaction, at this time, CuO will also be converted into other components, and the result is that the cathode of the photocatalytic microbial fuel cell (CuO-PMFC) does not contain a semiconductor material. The current of the photocatalytic microbial fuel cell sensor (CuO / ZnO-PMFC) constructed in Example 1 of the present application only decreases by 13%, and then reaches a gradually stable state, indicating that CuO / ZnO-PMFC can generate a stable current to a certain extent, which is suitable for the construction of a sensor, and verifies the stability of its operation under 5000s of light. In the present application, the reason why the photocatalytic microbial fuel cell sensor (CuO / ZnO-PMFC) has higher stability can be attributed to the p-n heterojunction formed between CuO and ZnO, wherein the formation of the p-n heterojunction effectively promotes the transfer of electrode charges, inhibits the reduction of CuO itself, and reduces the probability of photo corrosion.

[0073] In the present application, the semiconductor material loaded on the cathode carrier material in Example 1 is replaced by one of TiO2, Fe2O3, CdS and Cu2S, or a heterojunction semiconductor material composed of two or three of CuO / ZnO, TiO2, Fe2O3, CdS and Cu2S, and a photocatalytic microbial fuel cell sensor with a wide detection range, high detection sensitivity, wide application range, high stability and good repeatability can also be constructed, and it can also be widely applied to the monitoring and early warning of water quality and can realize accurate detection of different target substances.

[0074] The above examples are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above examples. Any technical solution falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that improvements and refinements made by ordinary skilled persons in the art without departing from the principles of the present application should also be considered as falling within the protection scope of the present application.

Claims

1. The application of photocatalytic microbial fuel cell sensor in water quality monitoring and early warning, characterized in that, The application discloses a photocatalytic microbial fuel cell sensor for detecting a target detection object in water, which comprises the following steps: (1) adding the water containing the target detection object into the anode chamber of the photocatalytic microbial fuel cell sensor, and obtaining the current inhibition rate of the target detection object in the water after the current is stabilized; (2) according to the current inhibition rate of the target detection object obtained in step (1), the concentration of the target detection object in the water is calculated by using a linear equation of the concentration of the target detection object and the current inhibition rate, so that the water quality monitoring and early warning are completed. The target detection object is cadmium ion, and the linear equation of the concentration of the target detection object and the current inhibition rate is as follows: IR = 12.425C + 14.847 (1). In formula (1), IR is the current inhibition rate, calculated from formula (2), C is the Cd 2+ concentration in the water body to be measured 2 = 0.973; The equation (2) is as follows: IR = (I1 - I2) * 100% / I2 (2). In the equation (2), I1 and I2 are current values before and after the water containing the target detection object is added. The photocatalytic microbial fuel cell sensor comprises an anode chamber provided with a microbial anode and a cathode chamber provided with a cathode, the cathode comprises a cathode carrier material and a CuO / ZnO composite semiconductor material loaded on the cathode carrier material; the CuO / ZnO composite semiconductor material can make the cathode generate a stable current under light conditions, and the generated stable current is the same as or close to the current generated by the microbial anode.

2. Use according to claim 1, characterized in that, In step (1), before the water containing the target detection object is added, the following treatment is further included: under light conditions, the photocatalytic microbial fuel cell sensor is started until the generated current of the photocatalytic microbial fuel cell sensor reaches a stable state.

3. Use according to claim 1, characterized in that, The preparation method of the cathode comprises the following steps: taking the cathode carrier material as a working electrode, placing the working electrode, a reference electrode and a counter electrode in a mixed solution of zinc nitrate and copper acetate, performing electrodeposition by adopting a constant current deposition method, so that the CuO / ZnO composite semiconductor material is deposited on the surface of the cathode carrier material, and annealing to obtain the cathode; the electrodeposition time is 15 min; the annealing is performed at a temperature of 500 DEG C; the annealing time is 1 h; the reference electrode is a saturated calomel electrode; the counter electrode is a platinum electrode; the molar ratio of the zinc nitrate and the copper acetate is 5:1; the zinc nitrate is zinc nitrate hexahydrate; the copper acetate is anhydrous copper acetate; the cathode carrier material is any one of conductive glass, carbon felt and stainless steel mesh; and the conductive glass is any one of FTO conductive glass and ITO conductive glass.

4. Use according to claim 1 or 3, characterized in that, The microbial anode comprises an anode carrier material and a microbial membrane loaded on the anode carrier material; the microbial anode is prepared by mixing the anode carrier material with sludge and then culturing; the preparation method of the microbial anode comprises the following steps: placing the anode carrier material in sludge for culturing, so that the microorganisms are loaded on the anode carrier material and form a microbial membrane, and the microbial anode is obtained; the sludge is residual sludge in a secondary sedimentation tank of a sewage treatment plant; during the culturing, a sodium acetate aqueous solution is further added, the volume ratio of the sodium acetate solution to the sludge is 1:1, the concentration of the sodium acetate solution is 1M; the culturing time is 3 days; and the anode carrier material is any one of carbon felt and a stainless steel mesh.

5. Use according to claim 1 or 3, characterized in that, The microbial anode and the cathode are connected by a wire, the resistance of the wire is 1000Ω, the wire is a titanium wire, a proton exchange membrane is arranged between the anode chamber and the cathode chamber, sampling holes are arranged at the top of the anode chamber and the cathode chamber, the electrolyte used in the anode chamber is obtained by mixing sodium acetate, vitamins, minerals and a phosphate buffer solution, and the electrolyte used in the cathode chamber is obtained by mixing potassium ferricyanide and a phosphate buffer solution.

6. Use according to claim 1 or 3, characterized in that, The photocatalytic microbial fuel cell sensor further comprises an illumination device, and a xenon lamp is used as the light source in the illumination device.

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