Preparation method of acetylene black combined with polypyrrole loaded multi-walled carbon nanotube auxiliary electrode and application thereof in soil electrokinetic remediation

Abstract

The application discloses a preparation method of an acetylene black combined polypyrrone loaded multi-walled carbon nanotube auxiliary electrode and application of the auxiliary electrode in soil electrokinetic remediation, and belongs to the technical field of electrokinetic remediation of organic matter contaminated soil. The auxiliary electrode is prepared by mixing acetylene black and multi-walled carbon nanotubes and then in-situ polymerizing polypyrrone and pressing into a sheet by a powder pressing method. The auxiliary electrode has a large specific surface area, excellent conductivity and rate performance, and can be used in electrokinetic remediation of contaminated soil, can effectively increase the current intensity, maximally reduce the interface side reaction with electrolyte, improve the current efficiency in the electrokinetic remediation process, reduce the energy consumption of electrokinetic remediation, and improve the organic matter treatment capacity of contaminated soil, so as to achieve the purposes of small environmental disturbance, green environmental protection, high economic benefits and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrokinetic remediation of organic contaminated soil, and particularly relates to a preparation method of an auxiliary electrode used in an electrokinetic remediation process of soil, and especially relates to a preparation method of an auxiliary electrode of acetylene black (AB) combined with polypyrrole (PPy) loaded multi-walled carbon nanotubes (MWCNT) and application of the auxiliary electrode in electrokinetic remediation of soil. BACKGROUND

[0002] Remediation of organic contaminated soil is one of the important tasks in the field of environmental protection. Traditional remediation methods include chemical, biological and physical methods. However, these methods usually require a long time and are costly, and in some cases may not be complete, making it difficult to completely remove organic contaminants from soil. Electrokinetic remediation technology, as a new soil remediation method, has attracted widespread attention. This technology uses electrochemical principles to achieve soil remediation by migrating, oxidizing or reducing organic contaminants under the action of an appropriate electric field. However, electrokinetic remediation technology has problems such as high energy consumption and low treatment efficiency, so it is necessary to select appropriate auxiliary electrode materials to improve remediation efficiency and reduce energy consumption.

[0003] Currently, auxiliary electrode materials commonly used in electrokinetic remediation mainly include graphene, conductive polymers, etc. The use of graphene as an auxiliary electrode can increase the service life of the auxiliary electrode and achieve high oxidation efficiency, but it can cause high energy consumption during electrokinetic remediation, and has problems such as low current efficiency and weak processing capacity. Considering the limitations of current auxiliary electrode in enhancing current capacity, MWCNT is selected as the auxiliary electrode matrix material, which has the properties of strong conductivity. Multi-walled carbon nanotubes (MWCNT) have excellent charge transport characteristics and are excellent semiconductor carriers, making them a hot topic in semiconductor electronics research. MWCNT has a tubular structure and a large specific surface area, which can absorb and store electrolyte and improve the electrode's resistance to damage, thereby improving the overall electrochemical performance of the electrode material. However, traditional MWCNT has the disadvantages of poor dispersibility and easy agglomeration. In addition, these auxiliary electrode materials also have some problems during remediation, such as oxidation and reduction reactions on the electrode surface leading to a decrease in electrode performance, and uneven current distribution between electrodes. Therefore, it is of great theoretical and practical significance to find a new type of auxiliary electrode material to improve the efficiency of electrokinetic remediation and reduce energy consumption.

[0004] PPy (poly pyrrole) is a common conductive polymer, which has many excellent properties such as simple preparation, excellent air stability, high conductivity, environmental non-toxicity and reversible oxidation-reduction, especially electrical properties, so that PPy has good application prospect in electromagnetic materials, sensors, microelectronics, electrochemistry and other fields. Especially, nanostructured PPy has special mechanical, thermal and electrochemical activity.

[0005] AB (acetylene black) is a special porous structure carbon black, which is prepared by continuous pyrolysis of acetylene with extremely high purity obtained by decomposition of by-product gas during pyrolysis of calcium carbide. Compared with other carbon blacks, AB has the following characteristics: light weight, small specific gravity; large specific surface area, strong adsorption; stable chemical properties; good surface activity, high conductivity; high purity, low ash and volatile content, so it is widely used in electrode modification materials to improve the conductivity of the electrode.

[0006] In order to solve the problems of weak processing capacity, low current efficiency and high energy consumption of traditional auxiliary electrode, the application innovatively loads AB and PPy on MWCNT to prepare a new type of composite multi-walled carbon nanotube auxiliary electrode for electric remediation. SUMMARY

[0007] In order to solve the problems of weak processing capacity, low current efficiency and high energy consumption of traditional auxiliary electrode, the application proposes a preparation method of a new type of auxiliary electrode material for organic matter contaminated soil electrokinetic remediation, and the purpose of the application is to provide a preparation method of AB (acetylene black) combined with PPy (poly pyrrole) loaded MWCNT (multi-walled carbon nanotube) auxiliary electrode and its application in soil electrokinetic remediation, which can fully utilize the advantages of good conductivity and adsorption of PPy and AB, and the characteristics of large specific surface area and high charge transport of MWCNT, aiming at solving the problems of traditional auxiliary electrode material and improving the remediation efficiency and energy utilization rate.

[0008] In order to achieve the above-mentioned purpose of the application, the technical scheme adopted by the application is as follows:

[0009] A preparation method of an AB combined PPy loaded MWCNT auxiliary electrode, comprising the following steps:

[0010] (1) uniformly mix AB powder and MWCNT powder without static electricity to obtain a mixed powder.

[0011] The MWCNT powder is destaticized by spray wetting. In some exemplary embodiments of the application, the MWCNT powder is wetted using a humidifier device for 1 min and is allowed to stand for 60 min to eliminate the static electricity inside the MWCNT electrode. The MWCNT material needs to be destaticized by humidification, otherwise it cannot be effectively contacted with the AB powder.

[0012] The purity of the MWCNT powder is ≥99%, the length is 3-12 μm, and the diameter is 10-20 nm.

[0013] (2) Dissolve pyrrole (Py) in an ethanol aqueous solution to obtain a Py solution; add the mixed powder of step (1) to the Py solution and stir uniformly to prepare a suspension.

[0014] The ethanol aqueous solution is prepared by mixing anhydrous ethanol and water at a volume ratio of 1:1.

[0015] The mass ratio of MWCNT: AB: Py is 14-16: 0.8-1: 5.5-6.

[0016] The mass concentration of Py in the Py solution is 9-10 mg / mL.

[0017] (3) Slowly drop the (NH4)2S2O8 solution into the suspension of step (2) and continuously stir to fully react, so that the Py is in-situ polymerized to synthesize polypyrrole (PPy); collect the product by filtration and dry to prepare an anhydrous auxiliary electrode powder.

[0018] The (NH4)2S2O8 solution is prepared by dissolving (NH4)2S2O8 powder in ultrapure water, and the molar concentration is 0.4-0.5 mmol / mL.

[0019] The volume ratio of the (NH4)2S2O8 solution to the Py solution is 1:3.

[0020] The drying is as follows: place the product in a vacuum drying oven, heat to 85°C at a heating rate of 8°C / min, and dry for 24 h to remove the excess orange-yellow solution.

[0021] (4) Press the auxiliary electrode: grind the anhydrous auxiliary electrode powder prepared in step (3) and mix with a binder, and press to obtain an auxiliary electrode with AB combined PPy loaded on MWCNT using a powder tablet press.

[0022] The mass ratio of the anhydrous auxiliary electrode powder to the binder is 18:1.

[0023] The binder is sodium polyacrylate, (C3H3NaO2) n The molecular weight is ≥3×10 7 .

[0024] The powder tablet press, the size of the die casting is 5cm*3.5cm*3cm, the powder tablet press is slowly pressed to 22Mpa and waits for 5min, and the square tablet-shaped electrode can be formed under the action of the pressure, because the auxiliary electrode has the advantages of strong anti-pressure capacity and not easy to tear, etc., so that the electrode material has strong plasticity.

[0025] The auxiliary electrode of AB combined PPy loaded on MWCNT is prepared through the above steps.

[0026] The application further provides application of the auxiliary electrode of AB combined PPy loaded on MWCNT in electrokinetic remediation of contaminated soil or water body.

[0027] Specifically, the auxiliary electrode is located in the anode chamber and is deviated to the side of the contaminated soil, and does not contact the anode electrode and does not need to be powered.

[0028] The pollution is pollution of organic pollutants such as pesticides and plastics, such as phenolic organic pollutants, and more specifically, 2,4-dichlorophenol contaminated soil or water body.

[0029] The application mixes AB and MWCNT, generates PPy on the surface of AB and MWCNT in situ through a chemical polymerization method, and can form a van der Waals force physical action between PPy and MWCNT, can better improve the dispersibility of MWCNT, and form a good transverse conductive network, can effectively increase the current intensity, and maximally reduce the interface side reaction with electrolyte, compared with other single wire electrode performance limitations, has obvious improvement, thereby improving the current efficiency in the electrokinetic remediation process. It can also fill the groove defects between MWCNT, play a role in heat transmission relay, build a more stable heat transfer channel, and improve the electrical conductivity of MWCNT material. The advantages of MWCNT, AB and PPy are complementary, not only reduce the treatment cost of physical methods, and the disturbance to the soil itself is small, but also not easy to cause secondary pollution, provide multiple continuous conductive channels, reduce the tortuosity of charge transmission, thereby improve the electrokinetic remediation effect, reduce the energy consumption of electrokinetic remediation, improve the organic matter treatment capacity of the contaminated soil, so as to achieve the purpose of small environmental disturbance, green environmental protection, economic benefit and the like.

[0030] Compared with the prior art, the application has the following advantages and technical effects:

[0031] (1) PPy generated by polymerization method is loaded on MWCNT-AB, and a transverse conductive network can be formed, this method forms a kind of electrode that can improve electronic conductivity and minimize the interface side reaction with electrolyte, compared with other single wire electrode performance limitation has obvious improvement. Functionally, this method provides multiple continuous conductive channels, reduces the tortuosity of charge transport. This method can also fill the groove defects between carbon nanotubes, play a role in heat transfer relay, build more stable heat transfer channel, and improve the conductivity of MWCNT-based materials.

[0032] (2) The application provides a preparation of auxiliary electrode, for the needs of current pesticide, plastic and other pollutant treatment, AB combined with PPy loaded on MWCNT auxiliary electrode is used to solve the problem of excessive power loss in the process of electrokinetic remediation, improve the treatment effect of organic matter pollution in contaminated soil, and has the comprehensive advantages of corrosion resistance, long service life, high electrocatalytic activity, and can be used for organic matter (2,4-dichlorophenol) water treatment.

[0033] (3) The application overcomes the problem of excessive power loss caused by the limitation of current size in the process of electrokinetic remediation of existing electrode, because the specific surface area of traditional electrode is smaller than that of MWCNT electrode, as the anode of electrokinetic remediation, it is difficult to greatly improve the current to promote the migration of heavy metals in contaminated soil.

[0034] (4) The specific surface area of the auxiliary electrode described in the application is free from the constraints of the contact area of traditional graphite electrode, so that the specific surface area of the composite material is larger, and the auxiliary electrode has a larger pore size, which can increase the contact area of electrolyte during electrokinetic remediation, so that the contact area of the electrode is free from the limitation of the planar area of the original graphite electrode, and further creates application space for the auxiliary electrode made of AB combined with PPy loaded on MWCNT. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The flow chart for preparing the auxiliary electrode of example 1 and the physical diagram of the auxiliary electrode, wherein the specific parameters of the auxiliary electrode are height 5 cm, width 3.5 cm and thickness 0.4 cm;

[0036] Figure 2 The scanning electron microscope (SEM) image of the auxiliary electrode prepared in example 1. Figure a shows that the auxiliary electrode material has obvious tubular pore structure, figure b shows that AB material is loaded on MWCNT due to van der Waals force, figures c-d show that Py better combines AB and MWCNT together in the process of synthesizing PPy, and the overall structure tends to be stable;

[0037] Figure 3Cyclic voltammetry (CV) curves of the auxiliary electrode prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0038] Figure 4 FTIR images of the auxiliary electrode material prepared in Example 1 in Test Example 2;

[0039] Figure 5 X-ray diffraction (XRD) images of the auxiliary electrode material prepared in Example 1 in Test Example 3;

[0040] Figure 6 BET images of the auxiliary electrode material prepared in Example 1 in Test Example 4;

[0041] Figure 7 Electrode and partition schematic diagram in Application Example 1; wherein 1-cathode chamber, 2-anode chamber, S1-S5 are five partitions of soil, 3-cathode plate, 4-auxiliary electrode, 5-anode plate. DETAILED DESCRIPTION

[0042] 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 part of the embodiments of the present application, rather than all the embodiments of the present application.

[0043] The room temperature of the present application refers to 20±3℃.

[0044] The MWCNT powder used in the specific embodiments of the present application has a purity of ≥99%, an average length of 11 μm and an average diameter of 12 nm, and is purchased from Nanchang Yifeng Nanometer Material Co., Ltd., model: YFT-201. Example 1

[0045] (1) Preparation of MWCNT electrode base material: 8g of MWCNT powder was weighed in a 1L beaker and wetted for 1 min using a humidifier device to eliminate static electricity inside the MWCNT electrode and waited for 60 min to obtain MWCNT powder, denoted as P1;

[0046] (2) Addition of AB material: 0.5g of AB black powder was placed in the prepared P1 and continuously stirred to mix the two uniformly, to obtain a material denoted as P2;

[0047] (3) Weighing of Py: 3ml of Py was added to 300ml of 50% (v / v) prepared ethanol aqueous solution and shaken uniformly to make Py completely dissolved in the ethanol aqueous solution;

[0048] (4) Preparation of (NH4)2S2O8 solution: 9.6g of (NH4)2S2O8 powder was dissolved in 100ml of ultrapure water, and stirred thoroughly until (NH4)2S2O8 was completely dissolved, to obtain a material denoted as P3;

[0049] (5) Preparation of AB-MWCNT / Py suspension: Py solution dissolved in C2H6O was mixed with material P2, and stirred uniformly to prepare a suspension, and the material was recorded as P4;

[0050] (6) Preparation of PPy and auxiliary electrode material: P3 material was slowly added to material P4, and a magnetic stirrer was used for continuous stirring for 24 h, and Py was synthesized into PPy after sufficient reaction;

[0051] (7) Preparation of auxiliary electrode material: the reaction solution was filtered by a suction filtration device, and the excess solution was filtered, and the suspension was collected and placed in a beaker;

[0052] (8) Drying of auxiliary electrode material: the suspension product was placed in a vacuum drying oven, and the temperature was raised to 85°C at a heating rate of 8°C / min for 24 h, and the excess orange yellow solution was removed to prepare anhydrous auxiliary electrode powder;

[0053] (9) Preparation of auxiliary electrode powder: the dried anhydrous auxiliary electrode material was placed in a marume grinding pestle, and was ground into a powder, and 1 g of binder (C3H3NaO2) was mixed into the auxiliary electrode material; n

[0054] (10) Pressing into auxiliary electrode: the AB combined PPy loaded MWCNT auxiliary electrode material prepared in step (9) was placed in a 5 cm x 3.5 cm x 3 cm pressure casting, and a powder tablet press was used to slowly press to 22 MPa for 5 min, and a square sheet-shaped electrode was formed under the action of pressure.

[0055] Comparative Example 1

[0056] 3 mL of Py was dissolved in 300 mL of 50% ethanol aqueous solution, and 8 g of MWCNT was mixed to prepare a suspension; 9.6 g of (NH4)2S2O8 powder was dissolved in 100 ml of ultrapure water, and was stirred until (NH4)2S2O8 was completely dissolved to prepare a (NH4)2S2O8 solution; the (NH4)2S2O8 solution was slowly added to the suspension, and was stirred for 24 h, and was then suction filtered and dried. Finally, 0.5 g of AB was added and uniformly mixed, and was stirred with water and then dried, and the remaining operations were the same as in Example 1 to prepare a comparative auxiliary electrode 1.

[0057] Comparative Example 2

[0058] ​Take 1.5mL of Py dissolved in 300mL 50% ethanol solution with 8g MWCNT and 0.5g AB mixed to make a suspension; take 9.6g (NH4)2S2O8 powder dissolved in 100ml ultrapure water, fully stirred until (NH4)2S2O8 completely dissolved, prepared (NH4)2S2O8 solution; slowly add (NH4)2S2O8 solution to the suspension, fully stirred for 24h, suction filtration and drying, the rest of the operation is the same as example 1, prepared comparative auxiliary electrode 2.

[0059] The prepared electrode is characterized by morphology and electrochemistry, and the application is further described in detail below with reference to the drawings.

[0060] Test example 1

[0061] The CV curves of the auxiliary electrodes prepared in example 1, comparative example 1 and comparative example 2 in 0.1mol / L K3Fe(CN)6+0.1mol / L NaCl solution, with silver chloride electrode as reference electrode and platinum wire electrode as auxiliary electrode (counter electrode), are shown in Figure 3 The greater the area around the known curve, the greater the specific capacity. As can be observed from the figure, the area around the auxiliary electrode curve is greater than that of the two comparative electrodes. PPy attached to the MWCNT-AB structure helps to form a new matrix material with higher charge transfer capacity, which is conducive to the transmission of electric charge. Among them, the auxiliary electrode curve has the largest area around, which indicates that PPy loaded on the surface of MWCNT-AB material is conducive to the performance improvement of auxiliary electrode, and it is proved that the auxiliary electrode material has better rate performance than the two auxiliary electrodes prepared in the comparative examples.

[0062] Test example 2

[0063] As Figure 4 , the auxiliary electrode prepared in example 1 is the transmittance peak graph in the wavelength range of 500~4000 in FTIR. Since the molecular formula of PPy is H(C4H2NH) n H, there are a large number of C-N, C=C, C-H bonds. At 3447.52 interval, a strong peak is highlighted and the peak width span is large. Since the synthesized PPy and AB produce a main peak at 3200~3500, the characteristic peaks of AB and PPy of the auxiliary electrode material can be found at this time, which indicates that AB and PPy are successfully loaded and Py is synthesized into PPy, and AB and PPy are not simply physically coated but produce certain physical and chemical interactions in the combination of the two, and the chemical bond between them can affect the vibration frequency of the entire molecular chain.

[0064] Test example 3

[0065] As Figure 5X-ray diffraction (XRD) image of the auxiliary electrode prepared in Example 1, 2θ = 26° is the peak value of PPy, the main peak of PPy reaches about 3000, which shows that PPy has been successfully synthesized; the remaining peaks can be seen that the AB crystal loaded on the MWCNT has high integrity.

[0066] Test Example 4

[0067] As Figure 6 The N2 adsorption-desorption isotherm image of the auxiliary electrode prepared in Example 1 shows a typical type IV isotherm, indicating that the auxiliary electrode has abundant mesoporous structure. When the relative pressure (P / P0) is greater than 0.5, due to capillary condensation, the adsorption and desorption isotherms do not coincide, forming a H3 type hysteresis loop. The specific surface area of the auxiliary electrode is 58.67 m 2 / g, and the average pore size is 7.98 nm.

[0068] Experimental device, preparation of contaminated soil and detection method

[0069] (1) Preparation of contaminated soil: After the yellow-brown soil is naturally air-dried for 20 days, various impurities, plant roots, and gravel are removed; pass through a 100-mesh sieve and add water to stir into a thin mud every day. 60 mg of 2,4-DCP (2,4-dichlorophenol) is dissolved in methanol solution, slowly added to the soil, and the soil contains 120 mg / kg of 2,4-DCP. Put it into a 65°C oven and sinter for 72 hours.

[0070] (2) Preparation of aged contaminated soil: After the prepared contaminated soil is aged at room temperature for 60 days, the aged contaminated soil is obtained. The aged contaminated soil is divided into four parts according to 500g / can and placed in a planetary ball mill. Adjust the speed to 4200r / min and grind for 30 minutes. Grind through an 80-mesh sieve to obtain the prepared aged contaminated soil. The purpose is to simulate the environment of pesticide and other organic pollutants remaining in the contaminated soil.

[0071] Application Example 1

[0072] This embodiment provides an application mode of the auxiliary electrode prepared by AB combined PPy loaded on MWCNT in electrodynamic remediation: the electrode distribution and soil zoning schematic diagram is shown in Figure 7, the anode and the cathode are both graphite electrodes, the auxiliary electrode is placed in the anode chamber and is biased to the contaminated soil side, does not contact the anode electrode, and does not need to be powered on. During the electrokinetic remediation process, 0.01 mol / L NaCl solution is used as the electrolyte, and the conductivity meter is used to measure the EC values of the solution in the anode chamber, the solution in the cathode chamber, and the five partitions (S1, S2, S3, S4, S5), wherein the EC of the anode solution and the cathode solution is directly measured, and the EC of the five partitions (S1, S2, S3, S4, S5) is measured after 2 mL of the mud-water mixture is added to 18 mL of ultrapure water and centrifuged at a low-speed centrifuge speed of 3200 r / min for 6 min.

[0073] Table 1: Conductivity values of the seven partitions of the device

[0074]

[0075] The EC value measured in the electrokinetic remediation of the electrokinetic remediation device using the auxiliary electrode prepared by AB combined with PPy loaded on MWCNT is low in the initial period, which may be due to the fact that the overall pH of the original contaminated soil is weakly alkaline, and the electrocatalytic ability is insufficient; when electrolysis is continuously performed, S3, S4, S5 and the anode chamber gradually show a trend of continuously decreasing pH (S3>S4>S5>anode solution), and the electrolytic ability is improved, and the EC values of the contaminated soil and the cathode anode solution are continuously increased.

[0076] Application Example 2

[0077] The present embodiment provides an application mode of the auxiliary electrode prepared by AB combined with PPy loaded on MWCNT in electrokinetic remediation: recording the current data of the power supply device.

[0078] Table 2: Current data of the device at different times

[0079]

[0080] The current size displayed on the power supply device is recorded during the electrokinetic remediation process, and after the data is arranged, it is shown that the current size slowly increases from the initial 64 mA to about 150 mA to reach the peak value, and the anode solution in the anode chamber is consumed greatly, and it can be observed that the anode solution seeps into the contaminated soil chamber. After the experiment is performed, the current will slowly decrease and will not increase again, and the experiment is stopped after about 7 days, and the electrokinetic remediation is completed, and the content of 2,4-DCP in the soil can be measured.

[0081] Application Example 3

[0082] The embodiment provides an application mode of the auxiliary electrode prepared from AB combined with PPy loaded on MWCNT in electromotion repair: after the electromotion repair is completed, 1 mL of cathode liquid and anode liquid are directly drawn out by using a needle tube, 1 mL of sludge-water mixed liquid is drawn out by using the needle tube in five sub-zones (S1, S2, S3, S4 and S5) and is put into seven centrifuge tubes, 5 mL of methanol is drawn out and put into the seven centrifuge tubes, is mixed and is ultrasonically treated for 50 min, and then the supernatant 1.5 mL is drawn out by adjusting the rotation speed of a low-speed centrifuge to 3200 r / min for 6 min and is put into a brown chromatographic bottle.

[0083] Table 3 2,4-DCP concentration of seven sub-zones of the device

[0084]

[0085] It is found through the measurement of the 2,4-DCP concentration in the seven brown bottles by using a high-performance liquid chromatograph at 230 nm wavelength that the 2,4-DCP treatment efficiency in S1, S2 and S3 is extremely high, most of the 2,4-DCP is concentrated in the soil in the S4 region, the reason may be that the 2,4-DCP migrates to the anode under the action of the electric field in the electromotion repair process, but as the electromotion repair proceeds, the pH of S4, S5 and the anode liquid rapidly decreases to strong acidity, so that the 2,4-DCP is enriched in S4, and part of the 2,4-DCP has migrated to the anode plate, which meets the expectation of the experiment.

[0086] Table 4 2,4-DCP concentration of seven sub-zones of the device without auxiliary electrode

[0087]

[0088] It is known that the 2,4-DCP migrates to the anode from the cathode under the action of the electric field, and it can be found that when the 2,4-DCP is treated by using the device without auxiliary electrode, only a small amount of 2,4-DCP is enriched in S4, which shows that the pollutant migration efficiency in S1, S2 and S3 is higher than that of the device with auxiliary electrode, and the 2,4-DCP concentration in the two anode liquids is compared, and it is found that the 2,4-DCP concentration in the device without auxiliary electrode is not higher than that in the device with auxiliary electrode. Compared with the device without auxiliary electrode, the 2,4-DCP migration efficiency of the auxiliary electrode device prepared from AB combined with PPy loaded on MWCNT is obviously stronger, which shows that the prepared auxiliary electrode improves the electromotion repair capacity and can strengthen the treatment capacity of the organic matter.

[0089] The above only describes the preferred embodiments of the present application, and it should be noted that some improvements and refinements can be made by those skilled in the art without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method for preparing an auxiliary electrode for electro-repair, characterized in that, The specific steps include the following: (1) Mix acetylene black (AB) powder with antistatic multi-walled carbon nanotube (MWCNT) powder evenly to obtain a mixed powder; (2) Dissolve pyrrole (Py) in ethanol / water solution to obtain Py solution; add the mixed powder from step (1) to pyrrole solution and stir evenly to obtain suspension; (3) The (NH4)2S2O8 solution was slowly added dropwise to the suspension in step (2), and the mixture was stirred continuously to allow the reaction to proceed fully, so that Py was polymerized in situ to synthesize polypyrrole (PPy); the product was collected by filtration and dried to obtain anhydrous auxiliary electrode powder; (4) Grind the anhydrous auxiliary electrode powder obtained in step (3), add a binder and mix, and press it with a powder press to obtain an auxiliary electrode of acetylene black and polypyrrole loaded on multi-walled carbon nanotubes.

2. The method for preparing the auxiliary electrode for electro-repair according to claim 1, characterized in that, The static-eliminating MWCNT powder is obtained by spraying and allowing it to stand for more than 1 hour to eliminate internal static electricity.

3. The method for preparing the auxiliary electrode for electro-repair according to claim 1, characterized in that, The purity of MWCNT powder is ≥99%, with a length of 3-12μm and a diameter of 10-20nm.

4. The method for preparing the auxiliary electrode for electro-repair according to claim 1, characterized in that, The mass ratio of MWCNT:AB:Py is 14-16:0.8-1:5.5~6.

5. The method for preparing the auxiliary electrode for electro-repair according to claim 1, characterized in that, The ethanol / water solution is prepared by mixing anhydrous ethanol and water in a volume ratio of 1:1; the mass concentration of Py in the Py solution is 9~10 mg / mL.

6. The method for preparing the auxiliary electrode for electro-repair according to claim 1, characterized in that, The (NH4)2S2O8 solution was added with a molar concentration of 0.4~0.5 mmol / mL; the volume ratio of (NH4)2S2O8 solution to Py solution was 1:

3.

7. The method for preparing the auxiliary electrode for electro-repair according to claim 1, characterized in that, The mass ratio of anhydrous auxiliary electrode powder to binder is 18:1; the binder is sodium polyacrylate (C3H3NaO2). n Molecular weight ≥ 3 × 10 7 .

8. An auxiliary electrode for electro-repair, characterized in that, An auxiliary electrode made of acetylene black and polypyrrole supported on multi-walled carbon nanotubes, prepared by the method described in any one of claims 1-7.

9. The application of the auxiliary electrode for electroremediation as described in claim 8 in the electroremediation of organically contaminated soil or water.

10. The application according to claim 9, characterized in that, The auxiliary electrode for electro-repair is located on the side of the anode chamber near the contaminant and does not come into contact with the anode electrode.

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