A soil self-powered sensor device and heavy metal detection method

Abstract

The present invention belongs to the technical field of soil pollution detection, and specifically relates to a soil self-powered sensor device and a heavy metal detection method. The present invention constructs a soil self-powered sensor as a new type of soil microbial fuel cell sensor. It relies on the abundant organic matter and electricity-producing microorganisms in the soil, does not require an external carbon source, and realizes long-term and stable power supply of the soil microbial fuel cell. The present invention fills heavy metal solutions of different concentrations into the soil microbial fuel cell sensor, and the originally stable soil microbial fuel cell voltage rises rapidly to reach a stable peak value. Because the voltage difference before and after the addition of heavy metals has a good correlation with the toxicity of soil pollution, it can be used as a soil pollution early warning indicator, and then through the change of the electricity generation signal caused by water layer pollution, the soil pollution situation can be judged to achieve long-term early warning of soil pollution.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil pollution detection, and in particular relates to a soil self-powered sensor device and a heavy metal detection method. Background Art

[0002] Soil is the most fundamental resource for human survival. Soil pollution not only seriously endangers ecological security, but also threatens human life safety at all times. How to protect the soil environment is a severe challenge facing all mankind. To carry out soil pollution control, we must first fully understand the quality of the soil environment. At present, soil environmental monitoring mainly adopts the method of on-site sampling and laboratory offline analysis. Although this method can achieve accurate quantitative detection of different pollutants, it often has problems such as long time consumption, expensive instrument requirements, and high cost. It is difficult to use for rapid detection of soil pollution sites and in-situ long-term monitoring of soil quality. However, in-situ, rapid detection and in-situ long-term monitoring are essential for real-time grasp of soil pollution processes and rapid early warning of soil pollution. Environmental pollution toxicity early warning is the most critical link for early detection of pollution, early prevention and control, and reduction of safety risks. Therefore, it is urgent to develop a rapid, in-situ, and long-term monitoring method for soil pollution toxicity. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a soil self-powered sensor device and a heavy metal detection method. In order to be able to monitor soil pollution toxicity in situ, quickly and for a long time, the present invention constructs a soil microbial fuel cell and uses it as a soil self-powered sensor device to detect heavy metals in the soil, realize long-term monitoring of soil pollution toxicity, and provide a basis for mastering soil environmental quality.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] In one aspect, the present invention provides a soil microbial fuel cell self-powered device, the device comprising an anode, a cathode, a wire and a load; the anode is placed in a soil layer, the cathode is immersed in an overlying water layer, and the cathode is wrapped with pearl cotton. Furthermore, the anode and cathode are both carbon felt.

[0006] The height of the soil layer is 6-10 cm, the height of the overlying water layer is 4-6 cm, and the distance between the cathode and the anode is 4-9 cm.

[0007] The load is a resistor of 1000-2000Ω.

[0008] On the other hand, the present invention also provides a method for detecting heavy metals in soil, comprising the following steps:

[0009] (1) Place the anode in the soil layer and immerse the cathode wrapped in pearl cotton in the overlying water layer;

[0010] (2) The anode and cathode are connected in series with the load through wires to operate the soil microbial fuel cell, and the voltage across the load is continuously recorded using a data logger;

[0011] (3) When the output voltage of the soil microbial fuel cell is stable, inject the heavy metal standard solution into the overlying water layer and record the voltage change;

[0012] (4) The toxicity of soil overlying water pollution is determined based on the difference in the electrical generation signal of the soil microbial fuel cell. The higher the difference in voltage change before and after the addition of the heavy metal standard solution, the greater the toxicity of the soil pollution.

[0013] In step (1), the height of the soil layer is 6-10 cm, the height of the overlying water layer is 4-6 cm, and the distance between the cathode and the anode is 4-9 cm.

[0014] The load in step (2) is a resistor of 1000-2000Ω; the cathode and anode are both carbon felt.

[0015] The continuous recording described in step (2) is to record one data every minute using a data logger.

[0016] The heavy metal standard solution described in step (3) is Cd 2+ 、Zn 2+ or Pb 2+ Standard solution.

[0017] The recording of voltage changes in step (3) is to record the output voltage data one hour before and after the injection of the heavy metal standard solution.

[0018] The difference of the power generation signal described in step (4) is the average value of the voltage 20 minutes, 10 minutes and 0 minutes before the injection of the metal standard solution, which is recorded as the power generation signal before pollution, and the average value of the voltage 10 minutes, 20 minutes and 30 minutes after the injection of the metal standard solution, which is recorded as the power generation signal after pollution.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The soil microbial fuel cell of the present invention buries the anode in a soil layer at a certain height, enriching electroactive microorganisms while avoiding the addition of an external carbon source. The cathode is wrapped with pearl cotton and placed in the overlying water layer to form a non-biological cathode. The present invention charges heavy metals of different concentrations into the soil microbial fuel cell sensor device, and the originally stable voltage of the soil microbial fuel cell will rise rapidly to reach a stable peak value. The voltage difference before and after the addition of heavy metals has a good correlation with the toxicity of soil pollution, and can be used as a soil pollution early warning indicator. The change in the power generation signal caused by water layer pollution can be used to judge the soil pollution situation and realize rapid early warning of soil pollution. The constructed soil self-powered sensor device has a simple structure and is easy to operate. It can use the large amount of organic matter in the soil to achieve long-term self-power supply. Compared with the existing method of modifying the cathode with a coating catalyst, the present invention uses pearl cotton to wrap the cathode to form a non-biological cathode, which is cheap, solves the problem that the catalyst needs to be replaced over time, and reduces the maintenance cost. It has the advantages of low detection cost and easy maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the soil self-powered sensor device constructed by the present invention, wherein 1-soil layer, 2-overlying water layer, 3-anode material, 4-electrode pearl cotton, 5-cathode material, 6-load, 7-conductor;

[0022] Figure 2 It is the stable operation diagram of the soil self-powered sensor device;

[0023] Figure 3 The soil self-powered sensor device is 2+ Standard curve graph of the test;

[0024] Figure 4 The soil self-powered sensor device is for Zn 2+ Standard curve graph of the test;

[0025] Figure 5 The soil self-powered sensor device is Pb 2+ Standard curve plot of the assay. DETAILED DESCRIPTION

[0026] The present invention discloses a soil self-powered sensor device and a heavy metal detection method. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all deemed to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. The methods, equipment, and materials in the following implementation cases, unless otherwise specified, are conventional methods, equipment, and materials in the art, and can all be purchased on the market.

[0027] The present invention constructs a Figure 1 The soil self-powered sensor device shown. The height of the soil layer in the constructed soil self-powered sensor device is 6-10cm, and the height of the overlying water layer is 4-6cm; the anode and cathode are both carbon felt, and the specifications are both 20*5*0.5cm. The cathode is wrapped with pearl cotton to form an abiotic cathode. The center spacing of the electrodes is 4-9cm, and a load resistor of 1000-2000Ω is connected between the electrodes. The soil was collected from the silt in the lake water of Jiangsu University campus.

[0028] Example 1: Construction of a soil self-powered sensor device

[0029] A soil self-powered sensor device was constructed. The inner wall specifications were a cylinder with a diameter of 6 cm and a height of 18 cm. Carbon felt was used as the anode and cathode, with specifications of 20*5*0.5 cm. The cathode was wrapped with pearl cotton to form an abiotic cathode. The center spacing of the electrodes was 9 cm, and a 1000Ω load was connected between the electrodes. The voltage across the load was continuously recorded using a data logger, and the data was recorded every one minute.

[0030] 10 mL of deionized water was quantitatively added to the single-chamber soil microbial fuel cell every day to acclimate the soil microbial fuel cell so that the battery could operate stably. Figure 2 is the stable operation diagram of soil microbial fuel cell; Figure 2 As shown, the soil microbial fuel cell has been operating stably for more than half a year without an external carbon source; when an external 1000Ω resistor is added, the output voltage reaches about 480mV, indicating that the prepared soil microbial fuel cell can operate efficiently and stably.

[0031] Example 2: Soil self-powered sensor for Cd 2+ Conduct testing

[0032] The soil microbial fuel cell constructed in Example 1 was used to assemble the soil self-powered sensor for Cd 2+The specific detection steps are to record the output voltage data for one hour when the output voltage of the soil microbial fuel cell is stable, and take the average value of the voltage at 40 minutes, 50 minutes, and 60 minutes as the power generation signal before pollution; 2+ The standard solution was injected into the overlying water layer, and the output voltage data was recorded for one hour. The average value of the voltage at 10min, 20min, and 30min was taken as the power generation signal after pollution. 2+ The difference in the electrical signal before and after the addition of the standard solution is used as the data for judging the toxicity of soil water layer pollution. The difference in the electrical signal can preliminarily determine whether the soil water layer is polluted, and qualitatively and quantitatively determine the amount of low-concentration heavy metal pollution. Figure 3 Soil microbial fuel cells to Cd 2+ Standard curve of the test; equation: y=a+b*x, residual sum of squares: 0.26717, Pearson'sr: 0.99942, R square (COD) 0.99884, adjusted R square: 0.99856; Figure 3 As shown, the heavy metal Cd 2+ When the concentration of the standard solution was 1-30 mg / L, the prepared soil microbial fuel cell had a significant effect on the degradation of Cd 2+ There is a good linear response, indicating that the soil microbial fuel cell sensor is sensitive to low concentrations of Cd 2+ The response has a higher sensitivity.

[0033] Example 3: Soil self-powered sensor for Zn 2+ Conduct testing

[0034] This example uses the same detection method as in Example 2 to detect heavy metal Zn 2+ The main difference from Example 2 is that the same concentration of Zn 2+ Standard solution replaces Cd 2+ The standard solutions were injected into the overlying water layer for detection. Figure 4 Soil microbial fuel cells for Zn 2+ Standard curve of the test; equation: y=a+b*x, residual sum of squares: 2.09165, Pearson'sr: 0.99651, R square (COD) 0.99303, adjusted R square: 0.99071; Figure 4 As shown in the figure, the soil microbial fuel cell sensor is sensitive to Zn concentrations of 1~30 mg / L. 2+ The sensor has a good linear response to low concentration Zn 2 + The response is more sensitive.

[0035] Example 4: Soil self-powered sensor for Pb2+ Conduct testing

[0036] This example uses the same detection method as in Example 2 to detect heavy metal Pb 2+ The main difference from Example 2 is that the same concentration of Pb 2+ Standard solution replaces Cd 2+ The standard solutions were injected into the overlying water layer for testing. The results showed that the voltage of the power generation signal was 470mV before pollution. 2+ After that, the voltage of the electrical signal after pollution was 473 mV; 2+ Afterwards, the voltage of the electrical signal generated after pollution was 518mV.

[0037] Figure 5 Soil microbial fuel cells for Pb 2+ Standard curve of the test; equation: y=a+b*x, residual sum of squares: 1.15639, Pearson'sr: 0.99986, R square (COD) 0.99973, adjusted R square: 0.99964; Figure 5 As shown in the figure, the soil microbial fuel cell sensor is sensitive to Pb concentrations of 1~30 mg / L 2+ The sensor has a good linear response to low concentrations of Pb 2+ The response is more sensitive.

[0038] The above embodiments are preferred implementation modes of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A soil self-powered sensor device, characterized in that: The soil self-powered sensor device comprises an anode, a cathode, a wire and a load; the anode is placed in a soil layer, and the cathode is immersed in an overlying water layer; the anode and the cathode are both carbon felt, and the cathode is wrapped with pearl cotton; the height of the soil layer is 6-10 cm, the height of the overlying water layer is 4-6 cm, and the distance between the cathode and the anode is 4-9 cm; the load is a resistor of 1000-2000 Ω.

2. A method for detecting heavy metals in soil, characterized in that: The steps include: (1) Place the anode in the soil layer and immerse the cathode wrapped in pearl cotton in the overlying water layer; (2) The anode and cathode are connected in series with the load through wires to operate the soil microbial fuel cell, and the voltage across the load is continuously recorded using a data logger; (3) When the output voltage of the soil microbial fuel cell is stable, inject the heavy metal standard solution into the overlying water layer and record the voltage change; (4) Determine the toxicity of soil overlying water pollution based on the difference in electricity generation signals from soil microbial fuel cells; The higher the voltage change difference before and after the addition of the heavy metal standard solution, the greater the toxicity of the soil pollution. The height of the soil layer in step (1) is 6-10 cm, the height of the overlying water layer is 4-6 cm, the distance between the cathode and the anode is 4-9 cm, and the load in step (2) is a resistor of 1000-2000 Ω; the cathode and the anode are both carbon felt.

3. The method according to claim 2, characterized in that The continuous recording described in step (2) is to record one data every minute using a data logger.

4. The method according to claim 2, characterized in that: The heavy metal standard solution described in step (3) is Cd 2+ 、Zn 2+ or Pb 2+ Standard solution.

5. The method according to claim 2, characterized in that: The recording of voltage changes in step (3) is to record the output voltage data one hour before and after the injection of the heavy metal standard solution.

6. The method according to claim 2, characterized in that The difference of the power generation signal described in step (4) is the average value of the voltage 20 minutes, 10 minutes and 0 minutes before the injection of the metal standard solution, which is recorded as the power generation signal before pollution, and the average value of the voltage 10 minutes, 20 minutes and 30 minutes after the injection of the metal standard solution, which is recorded as the power generation signal after pollution.

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