CN113219014A

CN113219014A - MFC toxicity sensor and application thereof

Info

Publication number: CN113219014A
Application number: CN202110514604.8A
Authority: CN
Inventors: 张可; 曹慧玲; 陈佳; 罗鸿兵; 陈伟; 马丹丹; 安晓婵; 陈凤辉
Original assignee: Sichuan Agricultural University
Current assignee: Sichuan Agricultural University
Priority date: 2021-05-11
Filing date: 2021-05-11
Publication date: 2021-08-06

Abstract

The invention discloses an MFC toxicity sensor and application thereof, and the MFC toxicity sensor comprises a body and an external circuit, wherein the body comprises a first member to a fourth member which are sequentially connected, a proton exchange membrane is arranged between the second member and the third member, the upper surfaces of the second member and the third member are provided with water inlets, the external circuit comprises a lead and a resistance box, and a titanium wire and the resistance box are connected through the lead to form a loop. The toxicity sensor of the invention does not depend on a power supply and an instrument, and the sensor device can move freely and is not restricted by conditions. Therefore, the in-situ detection of the nickel element can be realized, the information can be conveniently and timely transmitted, and the real-time monitoring is facilitated.

Description

MFC toxicity sensor and application thereof

Technical Field

The invention relates to the technical field of new energy and environmental engineering, in particular to an MFC toxicity sensor and application thereof.

Background

The current industry is rapidly developing and the accompanying environmental pollution is becoming more and more serious. Electroplating wastewater, which is one of three industrial wastewater, has been treated as a major problem, and metallic nickel is a major component in electroplating wastewater. The traditional nickel element detection methods include atomic absorption spectrometry, inductively coupled plasma mass spectrometry, capillary electrophoresis, microprobe, adsorption method and the like. However, these detection techniques are performed in a laboratory, which is expensive and cannot achieve continuous monitoring, and cannot reflect the concentration change in real time. Microbial Fuel Cells (MFCs) are a water treatment concept that converts chemical energy into electrical energy under the catalytic action of microorganisms. MFCs are divided into two types, a single-chamber MFC and a dual-chamber MFC, which are separated into two chambers, a positive chamber and a negative chamber, by a Proton Exchange Membrane (PEM). The sewage flows into the anode chamber and finishes the degradation process under the action of the electrogenesis microorganisms. Meanwhile, the electricity generating microorganism transfers electrons to the cathode through an external circuit in the process of decomposing organic matters to generate H⁺And is transferred to the cathode through the proton exchange membrane, and electrons and protons generate water molecules at the cathode. MFC has led to extensive research because it can degrade pollutants and at the same time produce electrical energy through the action of electrogenic microorganisms.

The sensor is one of the research directions of MFC, utilizes the sensitivity of electrogenesis microorganism to toxic substance to monitor water quality and can degrade the pollutant simultaneously, retrieves the electric energy. When toxic substances exist in the water body, the activity of the electricity generating microorganisms is inhibited, and the electricity generating amount is reduced. The higher the concentration of toxic substances, the stronger the inhibitory effect on microorganisms. The metabolism activity of the electrogenic microorganisms is influenced by the water inflow of the anode chamber, the higher the toxicity is, the stronger the inhibition effect on the electrogenic microorganisms is, and the lower the electricity generation amount of the MFC is.

The traditional nickel element detection technology mainly comprises an atomic absorption spectrometry, a potentiometric titration method, an inductively coupled plasma mass spectrometry method, a capillary electrophoresis method and the like.

Atomic absorption spectroscopy is used for detecting the same elements by utilizing the absorption phenomenon of characteristic wavelength light emitted by the same atom, and is widely applied to the detection of metal ions and the determination of trace elements at present. Potentiometric titration is a common way of detecting solutions using chemical titration. When the titration of the divalent nickel ions in the solution is complete, a sudden jump in the electrode potential occurs in the solution, indicating the end point of the titration. Inductively coupled plasma mass spectrometry is a method of analyzing by using a light source that generates plasma discharge through high-frequency inductive coupling, and is widely applied to detection of trace metals and isotopes. The capillary electrophoresis method is an electrophoretic separation analysis method which takes an elastic quartz capillary as a separation channel, takes a high-voltage direct-current electric field as a driving force and realizes separation according to the difference of mobility and distribution of components in a sample.

In addition to these detection methods, there are many methods for detecting nickel ions. These methods are based on the use of instrumentation and chemical experimental procedures. The inevitable needs are carried out in a laboratory, so that the requirements of real-time monitoring and timely data feedback on the water body cannot be met. Secondly, the cost of using chemical and instrumental assays is high. In particular, the instrument detection method has high instrument price and high maintenance cost. Moreover, the conventional detection method has high requirements on the knowledge base of a detector, which limits the application range of the detection method. Finally, as a simple detection method, the method cannot achieve the purposes of energy recovery and stable treatment of electroplating wastewater.

Therefore, the establishment of the rapid and in-situ detection method for the heavy metal has important significance for emergency treatment of sudden water body heavy metal pollution accidents.

Disclosure of Invention

The invention aims to provide an MFC toxicity sensor for in-situ and rapid detection of nickel concentration in electroplating wastewater, so as to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides an MFC toxicity sensor, which comprises a body and an external circuit, wherein the body comprises a first member, a second member, a third member and a fourth member which are sequentially connected, a proton exchange membrane is arranged between the second member and the third member, a first water inlet and a first orifice are formed in the upper surface of the second member, a second orifice and a second water inlet are formed in the upper surface of the third member, rubber stoppers are respectively installed on the first water inlet, the first orifice and the second orifice, titanium wires are installed in the rubber stoppers in the first orifice and the second orifice, and the lower parts of the two titanium wires are respectively connected with a carbon felt; the external circuit comprises a lead and a resistance box, and the upper ends of the two titanium wires are connected with the resistance box through the lead to form a loop.

Further, the first member, the second member, the third member and the fourth member are all made of acrylic materials.

Further, the first member and the fourth member have the same structure and are cuboids with the length of 1-3cm, the width of 6-10cm and the height of 6-10 cm; the second and third members have the same structure, the outer part is a cuboid with the length of 6-7cm, the width of 7-8cm and the height of 7-8cm, and the inner part is a cylinder with the centroid of the cuboid as the center and the volume of 50-55 mL.

Further, the radiuses of the first water inlet, the first hole opening, the second hole opening and the second water inlet are all 0.5 cm. The first water inlet, the second water inlet, the first hole and the second hole are identical in structure.

The invention also provides application of the MFC toxicity sensor, and the MFC toxicity sensor is used for detecting the concentration of metal ions in wastewater.

Further, the anode fluid of the MFC toxicity sensor is 1.6g/L NaC₂H₃O₂、0.31g/L NH₄Cl、4.4g/L KH₂PO4、3.4g/L K₂HPO₄·3H₂O、0.1g/L CaCl₂、0.1g/L MgCl₂·6H₂O and 10ml trace elements; the catholyte is 16.64g/L K₃[Fe(CN)₆]、4.4g/L KH₂PO4、3.4g/L K₂HPO₄·3H₂O。

The MFC toxicity sensor has small volume and can operate without an external power supply. Wastewater is introduced into the anode of the MFC at the site of the body of water that needs to be tested. The electricity-generating microorganism takes C, N, P and organic matters in water as life source to convert the organic matters intoThe learning energy is converted into electric energy. Transferring electrons to the anode by means of extracellular electron transfer, and decomposing organic matter to form H⁺Is also secreted into the anolyte. The electrons on the anode are transported to the cathode with an external circuit. H in anolyte⁺Penetrates through the proton exchange membrane to participate in the oxidation-reduction reaction of the cathode, so that the cathode is consumed. Electrons and H⁺The movement of (a) causes a closed circuit to be formed in the MFC and a current is generated. And collecting the current by a current collecting device (or an universal meter). The content of the heavy metal concentration in the water body can be judged through the linear relation between the current and the Ni ion concentration.

Further, the MFC toxicity sensor is used for detecting the concentration of nickel in electroplating wastewater.

The invention discloses the following technical effects:

1. the traditional detection method needs to be carried out under laboratory conditions, and the content of nickel element in the water body cannot be transmitted in time. The toxicity sensor of the invention does not depend on a power supply and an instrument, and the sensor device can move freely and is not restricted by conditions. Therefore, the in-situ detection of the nickel element can be realized, and the real-time monitoring is facilitated while the information is transmitted in time.

2. The traditional detection method belongs to an instrument analysis method, but the instrument price is high, the material consumption and maintenance cost are high, and the operation process is complex. The toxicity sensor can greatly reduce the cost, and is simple to operate and easy to detect.

3. The traditional detection method only can play a role in detection and cannot perform stabilization treatment on the wastewater. MFC has the ability to degrade organic substances, reduce the nitrogen concentration in water by assimilation, and the like. Therefore, the toxicity sensor can detect nickel ions and degrade organic matters in the wastewater, reduce the concentration of pollutants in the wastewater and play a role in treating the wastewater.

4. The invention can convert chemical energy into electric energy through the metabolism of the electrogenesis microorganisms on the basis of detecting and degrading the wastewater, thereby realizing the resource utilization of the sewage. The anode power density can reach 38.81W/m at most through experiments³。

5. Finally, the toxicity sensor is small in size, can be flexibly installed at any place of a drainage area, is convenient to use, and can also play a role in detecting water quality of different sites.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of the construction of a sensor according to the present invention;

FIG. 2 is a schematic view of the structure of the components 1-4 and the proton exchange membrane 8;

1-a first component, 2-a second component, 3-a third component, 4-a fourth component, 5-a rubber plug, 6-a titanium wire, 7-a carbon felt, 8-a proton exchange membrane, 9-a first water inlet, 10-a first orifice, 11-a second orifice, 12-a second water inlet, 13-a wire and 14-a resistance box;

FIG. 3 is a linear function fitting data of nickel ion concentration between 0.01 and 15 mg/L;

FIG. 4 is a linear function fitting data of nickel ion concentration between 0.1 and 12 mg/L;

FIG. 5 is linear function fit data for MFC1, MFC2, and MFC 3.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The trace elements are trace elements which are commonly added in the anolyte.

Example 1

The MFC toxicity sensor of the embodiment is divided into a body and an external circuit, wherein the body comprises an acrylic first member 1, an acrylic second member 2, an acrylic third member 3 and an acrylic fourth member 4 which are sequentially connected, the acrylic first member 1 and the acrylic fourth member 4 have the same structure, and the acrylic first member 1 and the acrylic fourth member 4 are cuboids with the length of 1cm, the width of 8cm and the height of 8 cm; the second acrylic member 2 and the third acrylic member 3 have the same structure, the outer part of the second acrylic member is a cuboid which is 6.8cm long, 8cm wide and 8cm high, the inner part of the second acrylic member is a cylinder which takes the centroid of the cuboid as the center of a circle and has the volume of 50mL, the radiuses of water inlets 9-12 are all 0.5cm, and the corner parts of the members 1-4 are provided with through holes (not shown in figures 1 and 2) for fixing the members 1-4 by long screws; the second member 2 and the third member 3 are hollowed out in the middle to form a cylinder. In order to ensure that the cylindrical chambers of the second member 2 and the third member 3 can form a closed space, and store the anode and the cathode liquid, the cylindrical chambers are closed by the first member 1 and the fourth member 4. The anolyte is replaced from the first water inlet 9 and the catholyte is replaced from the second water inlet 12. The final device is 15.6cm long, 8cm wide and 8cm high, and the volumes of the yin and yang chambers are 50mL respectively; a proton exchange membrane 8 is arranged between the acrylic second component 2 and the acrylic third component 3; the upper surface of the second component 2 is provided with a first water inlet 9 and a first hole opening 10; the chamber of the third structure 4 can form a closed space and can store the cathode and the anode liquid; a second orifice 11 and a second water inlet 12 are formed in the upper surface of the member 3, and the first water inlet 9, the first orifice 10, the second orifice 11 and the second water inlet 12 have the same structure; first water inlet 9 first drill way 10 with all install in the second drill way 11 the rubber buffer 5, first drill way 10 with in the second drill way 11 install in the rubber buffer 5 titanium wire 6, the effect in first drill way 10, second drill way 11 lies in fixed carbon felt. Two carbon felts of negative and positive poles have stringed a titanium silk respectively (the titanium silk plays the effect of transmission electron simultaneously), in order to keep the upright state of titanium silk, stringed the titanium silk into rubber buffer 5, then in inserting first drill way 10 and second drill way 11 respectively with rubber buffer 5. The titanium wire 6 lower part with carbon felt 7 links to each other, outer circuit includes wire 13 and resistance box 14, and wire 13 links to each other resistance box 14 and titanium wire 6, and the fixed titanium wire 6 that has run through carbon felt 7 of rubber buffer 5 has attached to a large amount of microorganisms on positive pole, carbon felt 7. Among them, the electricity-generating microorganisms generate electrons in the metabolic process. The electrons are transferred to the carbon felt 7 by means of direct transfer and indirect transfer. The anode carbon felt 7 is used for collecting the current generated by the electrogenic microorganisms, so that an external circuit is connected with the anode and the cathode to form a loop. The actual voltage of the device can be measured by the universal meter red and black pen contact resistance box 14 cathode and anode interfaces.

The structure is assembled into a biofuel cell (MFC), and the anode and the cathode are connected by a circuit with an externally-loaded 1000 omega resistor. Inoculating activated sludge to MFC anode, preparing artificial wasteWater (1.6g/L NaC)₂H₃O₂、0.31g/L NH₄Cl、4.4g/L KH₂PO₄、3.4g/L K₂HPO₄·3H₂O、0.1g/L CaCl₂、0.1g/L MgCl₂·6H₂O and 10mL trace elements as anolyte) to acclimate the activated sludge. The cathode of MFC adopts 16.64g/LK₃[Fe(CN)₆]、4.4g/L KH₂PO₄、3.4g/L K₂HPO₄·3H₂O is the catholyte to accept electrons. And the cathode and the anode liquid are replaced regularly to make the MFC anode hang a biological film. The MFC which is successfully filmed and stably generates electricity is applied to the position of the water body to be detected. The water body to be measured enters the anode of the MFC sensor, and the electrogenesis microorganisms in the anode are impacted by nickel ions in the water. The biological activity is inhibited and a drop in output voltage is exhibited. The simulated electroplating wastewater enters the anode chamber from the first water inlet 9, and microorganisms attached to the anode carbon felt 7 degrade organic substances in the electroplating wastewater to maintain the metabolism of the microorganisms, so that protons and electrons are generated in the process. The proton permeates into the cathode chamber through proton exchange membrane 8(PEM), the electron is transferred to the cathode chamber through an external circuit, the electron transferred to the cathode along with the external circuit and potassium ferricyanide in catholyte undergo redox reaction, and the potassium ferricyanide is reduced into [ Fe (CN)₆]^4-. The whole device forms a closed loop to generate current. The heavy metal nickel is biologically toxic. By changing the concentration of nickel in the inlet water, the metabolism of the anode biomembrane can be influenced, thereby influencing the electric quantity generated by the device. The higher the concentration of nickel ions, the greater the inhibition of the electrogenic microorganisms, which in turn results in a lower charge being detected by the multimeter.

The concentration of nickel ions in water was changed, the maximum voltage of the device was measured at different inlet water concentrations, and the experimental data were tabulated as shown in table 1.

TABLE 1 concentration and Voltage

According to the data in table 1, the concentration of nickel ions in the feed water is plotted on the abscissa and the maximum output voltage in the period is plotted on the ordinate, and the data is fitted with a linear function of one degree. As shown in fig. 3 and 4.

As can be seen from fig. 3, when the concentration of nickel ions is in the range of 0.01-15mg/L, the fitting equation is that y is 0.0175x +0.615, and R is²0.7459. The deviation from the fit equation was large at concentrations of 0.01mg/L and 15 mg/L. However, in the concentration range of 0.1-12mg/L, the linear dependence of the concentration on the maximum voltage is stronger, and the fitting equation is that y is 0.0117x +0.617, and R is²0.954, as shown in fig. 4. According to the data, the toxicity sensor can be used within 0.01-15mg/L of nickel ion concentration theoretically, and can indicate the toxicity of the water body to a certain extent. According to the water pollutant emission limit regulation of newly-built enterprises in GB21900-2008, the emission concentration of total nickel is not higher than 1.0mg/L, and the significance of an excessively high concentration detection value is not great. Therefore, the present invention uses 0.1-12mg/L as the preferred range of the toxicity sensor.

The electrogenesis microorganism in the MFC sensor anode chamber plays a role of a biological recognition element and can play a role of degrading COD in water in the process of maintaining the growth activity of the microorganism. The COD degradation efficiency is detected by adopting a potassium dichromate method. The method takes resorufin as an indicator, 0.40 mol/L1/6 potassium dichromate as a titrant and 1mol/L ammonium ferrous sulfate as a standard solution.

The concentration of the ammonium ferrous sulfate solution needs to be calibrated before use, and the method comprises the following steps: 5mL of potassium dichromate was taken in an Erlenmeyer flask, diluted to 30mL with distilled water, and 5mL of concentrated sulfuric acid was slowly added. After mixing and cooling, 2 drops of ferron indicator are added, and ammonium ferrous sulfate is used for titration. The titration end point is determined when the solution turns from yellow to reddish brown. The volume consumed is denoted V.

Water sampling V_{Water sample}Taking the ferroxyl as an indicator, titrating the water sample by using a calibrated ammonium ferrous sulfate solution, and determining the titration end point when the color of the solution is changed from yellow to reddish brown. Calculating COD concentration (O) in water sample according to consumed ferrous ammonium sulfate₂，mg/L)。

Wherein: v₀Volume of ferrous ammonium sulfate solution consumed by a blank water sample;

V₁volume of ferrous ammonium sulfate solution consumed by the water sample.

COD data of inlet and outlet water in three different concentration gradients are shown in Table 2.

TABLE 2 COD data of inlet and outlet water in three different concentration gradients

As can be seen from the COD test data in Table 2, the MFC sensor can effectively remove COD in water while detecting water quality, and the efficiency can reach 45.01-57.61%.

Example 2

The MFC toxicity sensor used in this example has the same structure as that of example 1, and detects only nickel ions (denoted as MFC1) in the inlet water, and four heavy metal ions including nickel, copper, zinc, and cadmium in the inlet water, respectively. Fixing the inlet water concentration of the three heavy metal ions, changing the inlet water concentration of the nickel ions (marked as MFC2), changing the inlet water concentration of the three heavy metal ions, and fixing the inlet water concentration of the nickel ions (marked as MFC 3). Details of the specific heavy metal concentration gradient are shown in table 3.

TABLE 3 heavy metal concentration gradient

The power generation maximum results for each concentration gradient MFC1, MFC2, and MFC3 are shown in table 4.

TABLE 4 maximum values of electricity generation

The concentration gradient was plotted on the abscissa and the maximum output voltage of the device on the ordinate, and a linear relationship was fitted, and the result is shown in fig. 5. MFC1 has a good linear relationship (R) in gradients 4-12²0.9869), MFC2 and MFC3 have a good linear relationship (R) in gradients 6-12²＝0.9733，R²0.9469). Therefore, the MFC is used as a sensor and has theoretical basis in detecting actual wastewater.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. An MFC toxicity sensor is characterized by comprising a body and an external circuit, the body comprises a first member (1), a second member (2), a third member (3) and a fourth member (4) which are connected in sequence, a proton exchange membrane (8) is arranged between the second component (2) and the third component (3), the upper surface of the second component (2) is provided with a first water inlet (9) and a first hole opening (10), the upper surface of the third component (3) is provided with a second hole (11) and a second water inlet (12), the rubber stopper (5) is arranged on the first water inlet (9), the first hole (10) and the second hole (11), titanium wires (6) are arranged in the rubber plugs (5) in the first hole openings (10) and the second hole openings (11), and the lower parts of the two titanium wires (6) are respectively connected with a carbon felt (7); the outer circuit comprises a lead (13) and a resistance box (14), and the upper ends of the two titanium wires (6) are connected with the resistance box (14) through the lead (13) to form a loop.

2. The MFC toxicity sensor of claim 1, characterized in that the first (1), second (2), third (3) and fourth (4) members are all acrylic material.

3. The MFC toxicity sensor of claim 2, characterized in that the first member (1) and the fourth member (4) are identical in structure, and are each a cuboid with a length of 1-3cm, a width of 6-10cm, and a height of 6-10 cm; the second member (2) and the third member (3) are identical in structure, the outer part of the second member is a cuboid with the length of 6-7cm, the width of 7-8cm and the height of 7-8cm, and the inner part of the second member is a cylinder with the center of the cuboid as the center and the volume of 50-55 mL.

4. The MFC toxicity sensor of claim 1, characterized in that the first water inlet (9), the first aperture (10), the second aperture (11) and the second water inlet (12) all have a radius of 0.5 cm.

5. Use of an MFC toxicity sensor according to any of claims 1-4, characterized in that the MFC toxicity sensor is used for detecting metal ion concentration in wastewater.

6. Use according to claim 5, wherein the MFC toxicity sensor is used for detecting the concentration of nickel in electroplating wastewater.