Preparation method of polyfunctional group modified flowing electrode for removing lead in water based on electro-adsorption

Abstract

The invention discloses a preparation method of a polyfunctional group modified flowing electrode for removing lead in water based on electro-adsorption, which comprises the following steps: preparing a flowing electrode of polypyrrole biochar coupled MXene and constructing a flowing electrode deionization system, firstly preparing an MXene suspension, then dispersing pyrrole and BC in an HCl solution, activating by using an activating agent, and modifying by using functional groups to prepare polyfunctional group powder; and then mixing the MXene / PPy (at) BC with a NaCl electrolyte to form the MXene / PPy (at) BC flowing electrode. The carbon paste is pumped into the carbon paste inlet pipe through the carbon paste storage tank and fills the cathode chamber and the anode chamber through the inlet, the carbon paste flows out from the lower end of the S-shaped channel and is converged into the carbon paste storage tank, and lead wastewater enters the middle chamber from the water inlet of the middle chamber and fills the middle chamber, then flows out from the water outlet and circularly enters to complete adsorption removal. The concentration of Pb < 2 + > treated by the method is lower than 0.01 mg / L, and the national sewage discharge standard is met.

Description

Technical Field

[0001] The present invention relates to the technical field of lead-containing wastewater treatment, and specifically to a preparation method of a multi-functional group modified flow electrode for removing lead in water based on electro-adsorption. Background Art

[0002] Heavy metal treatment is a key issue in modern industrial development and environmental governance. Lead (II) has become one of the most harmful pollutants to the human body due to its high toxicity, wide spread, and non-degradability. The disadvantages of bioaccumulation also exacerbate the irreversible damage to human organs and the risk of cancer caused by lead. There are lead-containing wastewater treatment links in industrial fields such as metallurgy, automobiles, batteries, and paints. In industrial wastewater, lead mostly exists in the form of +2-valent Pb(II) and its concentration ranges from 1 to 50 mg / L. Although it is widely used in the industrial field now, there are few effective recycling methods. Therefore, it is of crucial significance to design a treatment method for the recycling of lead-containing wastewater.

[0003] Common methods for treating lead-containing wastewater include chemical precipitation, ion exchange, and adsorption, etc., but the recovery of lead still cannot achieve an ideal effect. In recent years, the electro-deionization technology gradually tested has been gradually regarded as a green process because of its good adsorption effect, simple regeneration conditions, and low energy consumption. Among them, the flow cell deionization technology (FCDI) provides better target ion removal efficiency and a continuous working mode for the whole process by changing the solid electrode into a flow electrode. Traditional flow electro-deionization uses activated carbon electrodes, but due to the lack of selectivity and poor conductivity of the porous activated carbon electrodes. MXene is a two-dimensional material composed of transition metal carbides and nitrides, which shows excellent performance in the electrochemistry field. However, there is little use of MXene materials as electrodes and modification of related electrodes in fields such as FCDI. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a multi-functional group modified flow electrode for removing lead in water based on electro-adsorption, and use the flow electro-deionization technology to realize the adsorption and recovery of lead-containing wastewater, so as to solve the deficiencies of the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A preparation method of a multi-functional group modified flow electrode for removing lead in water based on electro-adsorption, including the following steps:

[0006] S1: Prepare an MXene suspension. Dissolve LiF in HCl and stir at room temperature, then add Ti3AlC2 powder. And put the mixed solution in a polytetrafluoroethylene beaker to etch the Al layer in the solid phase. Wash the precipitate with deionized water, oscillate the solution with an oscillator for 1 h, then ultrasonicate it for 1 h under an inert gas N2 and collect the stable dark green supernatant. Redisperse the precipitate in deionized water and collect the MXene suspension;

[0007] S2: Prepare PPy / BC. Completely disperse pyrrole monomer and BC in HCl solution, and after ultrasonic treatment for 2 hours, slowly add ammonium persulfate solution while keeping the temperature of the mixed solution at 5°C. After thorough mixing, add sodium dodecylbenzenesulfonate as a surfactant to obtain PPy / BC solid;

[0008] S3: Modify PPy / BC: Pour the PPy / BC solid powder prepared in S2 into a boric acid beaker, seal it and continuously stir at 80°C for 24 h. Dry the sample at 80°C for 24 h to obtain B-PPy / BC powder; Add an appropriate amount of 96% concentrated sulfuric acid, stir in an oil bath and perform water-cooled reflux. Control the mixture at 1500 rpm and 25°C for 3 h continuously, filter under vacuum and dry at 80°C for 24 h to obtain SO3H-PPy / BC powder. Dissolve it in a mixed solution of NaOH and C7H7NO2, continuously stir at 80°C for 8 h, add NaNO2 and stir at 80°C for 2 h, quickly pour in HCl and stir for 2 h, filter under vacuum and dry for 24 h to obtain COOH-PPy / BC powder;

[0009] S4: Prepare a multi-functional flow electrode. At the same time, dissolve a certain amount of MXene in the mixed solution and ultrasonic treatment to make it uniform. Mix MXene with B-PPy / BC, SO3H-PPy / BC, and COOH-PPy / BC respectively, wash it clean with absolute ethanol, filter and dry deionized water in turn. Mix the multi-functional flow electrode with NaCl electrolyte. The powder passes through a 100-mesh sieve before electrolyte mixing, and continuously stir the particles for 10 hours to ensure complete wetting to obtain a multi-functional flow electrode.

[0010] Furthermore, the multi-functional flow electrode prepared in S4 is realized based on a flow electrode deionization system. The outermost sides of the flow electrode deionization system are organic glass bottom plate A and organic glass bottom plate B. Organic glass bottom plate A and organic glass bottom plate B are two identical and symmetrically arranged glass plates. The internal part of the flow electrode deionization system is divided into a cathode chamber, a middle chamber, and an anode chamber. The cathode chamber is composed of organic glass bottom plate A, the first nylon waterproof gasket, and the first current collector titanium sheet. The middle chamber is composed of the second nylon waterproof gasket, cation exchange membrane, organic glass plate, anion exchange membrane, and the fourth nylon waterproof gasket stacked in sequence. The anode chamber is composed of the fifth nylon waterproof gasket, the second current collector titanium sheet, and organic glass bottom plate B. All components used in the entire flow electrode deionization system are drilled with eight small holes on the upper, two sides, and lower parts, and are reinforced and combined with nylon screws and wing nuts.

[0011] Further, the outermost plexiglass bottom plates A and B of the flow electrode deionization system are respectively provided with two inlets and outlets for the flow of the flow electrode slurry. The flow electrode slurry enters from the inlets and respectively fills the cathode chamber composed of the plexiglass bottom plate A, the first nylon waterproof gasket and the first current collector titanium sheet, and the anode chamber composed of the fifth nylon waterproof gasket, the second current collector titanium sheet and the plexiglass bottom plate B. During the operation of the flow electrode deionization system, the flow electrode slurry is pumped into the two electrodes from the carbon slurry storage tank in a cycle to form a flow electrode.

[0012] Further, the two sides of the plexiglass plate are provided with an inlet and an outlet. The lead-containing wastewater enters from the inlet and flows out from the outlet. The solution completes the adsorption process in the middle chamber composed of the second nylon waterproof gasket, the cation exchange membrane, the plexiglass plate, the anion exchange membrane and the fourth nylon waterproof gasket stacked in sequence. The cation exchange membrane and the anion exchange membrane are used to prevent opposite ions from entering during operation, and the second nylon waterproof gasket and the fourth nylon waterproof gasket are used to block water from entering the electrode chamber.

[0013] Further, the first current collector titanium sheet and the second current collector titanium sheet are made of corrosion-resistant metal titanium sheets. Before treatment, the titanium sheets are soaked in a mixed solution of ethanol and nitric acid to remove the oxides on the surface. The titanium sheets are etched by a machine tool to form complete serpentine channels, which are beneficial to the flow of the flow electrode slurry in the electrode chamber and increase the adsorption effect of the entire flow electrode deionization system.

[0014] Further, the inlets and outlets of the plexiglass bottom plate A, the plexiglass bottom plate B and the plexiglass plate are all drilled by a machine tool and connected with inner octagonal tower joints and raw tape. The inlet pipe and the outlet pipe, the inlet carbon slurry pipe and the outlet carbon slurry pipe are all connected with plastic hoses.

[0015] Further, a carbon slurry passage is formed in the flow electrode deionization system: the carbon slurry storage tank pumps the inlet carbon slurry pipe to respectively pass through the inlets on the plexiglass bottom plate A and the plexiglass bottom plate B, and fills the cathode chamber through the serpentine channels of the first nylon waterproof gasket and the first current collector titanium sheet; fills the anode chamber through the serpentine channels of the fifth nylon waterproof gasket and the second current collector titanium sheet. When the carbon slurry flows out, it flows out from the lower ends of the first current collector titanium sheet, the second current collector titanium sheet, the first nylon waterproof gasket and the fifth nylon waterproof gasket in a gravity flow manner from the lower ends of the serpentine channels, and then flows out from the outlets at the lower ends of the plexiglass bottom plate A and the plexiglass bottom plate B, and converges into the carbon slurry storage tank.

[0016] Furthermore, a water inlet passage is formed in the flow-through electrode deionization system: the lead-containing wastewater enters from the water inlet of the plexiglass plate into the middle chamber composed of a second nylon waterproof gasket, a cation exchange membrane, a plexiglass plate, an anion exchange membrane, and a fourth nylon waterproof gasket stacked in sequence, and then flows out from the water outlet of the plexiglass plate, circulates and enters to complete the adsorption and removal.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The preparation method of the multi-functional group modified flow-through electrode for electro-adsorptive removal of lead in water according to the present invention uses the multi-functional group MXene / PPy@BC electrode to synergistically remove lead in the Faraday reaction and flow-through electrode deionization, can efficiently adsorb lead, and realizes the efficient regeneration of the electrode. The MXene / PPy@BC electrode, as the Faraday reaction electrode, uses the redox reaction of the electrode to adsorb specific ions, has a large adsorption capacity, a fast adsorption rate, and can fully utilize the adsorption sites of the electrode through the flow adsorption pumped by the circulation pump to remove a large amount of lead ions. The Pb concentration after treatment by the present invention 2+ is lower than 0.01 mg / L, meeting the national sewage discharge standard. Description of the Drawings

[0019] Figure 1 is the framework diagram of the flow-through electrode deionization system of the present invention.

[0020] In the figure: 1. Plexiglass bottom plate A; 2. First nylon waterproof gasket; 3. First current collector titanium sheet; 4. Second nylon waterproof gasket; 5. Cation exchange membrane; 6. Plexiglass plate; 7. Anion exchange membrane; 8. Fourth nylon waterproof gasket; 9. Fifth nylon waterproof gasket; 10. Second current collector titanium sheet; 11. Plexiglass bottom plate B; 12. Carbon paste storage tank. Specific Embodiments

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] In view of the fact that there are few studies on using MXene materials as electrodes and modifying related electrodes in the existing FCDI and other fields, the preparation method of the multi-functional group modified flow-through electrode for electro-adsorptive removal of lead in water provided in this embodiment includes the following steps:

[0023] S1: Prepare the MXene suspension. Dissolve LiF in HCl and stir at room temperature. Then add Ti3AlC2 powder. Place the mixed solution in a polytetrafluoroethylene beaker to etch the Al layer in the solid phase. Wash the precipitate with deionized water. Oscillate the solution with an oscillator for 1 h. Then ultrasonicate for 1 h under inert gas N2 and collect the stable dark green supernatant. Redisperse the precipitate in deionized water and collect the MXene suspension.

[0024] S2: Prepare PPy / BC. Completely disperse pyrrole monomer and BC in HCl solution and ultrasonicate for 2 h. Then slowly add ammonium persulfate solution while keeping the temperature of the mixed solution at 5 °C. After thorough mixing, add sodium dodecylbenzenesulfonate as a surfactant to obtain PPy / BC solid.

[0025] S3: Modify PPy / BC. Pour the PPy / BC solid powder prepared in S2 into a boric acid beaker, seal it and continuously stir at 80 °C for 24 h. Dry the sample at 80 °C for 24 h to obtain B-PPy / BC powder. Add an appropriate amount of 96% concentrated sulfuric acid, stir in an oil bath and perform water-cooled reflux. Control the mixture at 1500 rpm and 25 °C for 3 h continuously. Filter under vacuum and dry at 80 °C for 24 h to obtain SO3H-PPy / BC powder. Dissolve it in a mixed solution of NaOH and C7H7NO2, continuously stir at 80 °C for 8 h, add NaNO2 and stir at 80 °C for 2 h. Quickly pour HCl into the mixture and stir for 2 h. Filter under vacuum and dry for 24 h to obtain COOH-PPy / BC powder.

[0026] For this step, this embodiment further provides the following parts ratio for further illustration: Weigh 0.5 g of the prepared PPy / BC solid powder and pour it into a boric acid beaker containing 60 ml of 2 mol / L acid used. Seal it and continuously stir at 80 °C for 24 h. Dry the obtained sample in an oven at 80 °C for 24 h to obtain B-PPy / BC powder. Take 0.5 g of the above-prepared PPy / BC solid powder, add an appropriate amount of 96% concentrated sulfuric acid, stir in an oil bath and perform water-cooled reflux. Control the mixture at 1500 rpm and 25 °C for 3 h continuously. Filter under vacuum and dry the obtained sample in an oven at 80 °C for 24 h to obtain SO3H-PPy / BC powder. Take 0.5 g of the above-prepared PPy / BC solid powder, dissolve it in a mixed solution of 1 mol / L NaOH and 2 mol / L C7H7NO2, seal it and continuously stir at 80 °C for 8 h. Then add NaNO2 and stir at a temperature of 80 °C for 2 h. Subsequently, quickly pour 6 mL of HCl into the mixed solution and stir for 2 h. Filter under vacuum and dry the obtained sample in an oven at 80 °C for 24 h to obtain COOH-PPy / BC powder.

[0027] S4: Prepare a multi-functional flow electrode. Meanwhile, dissolve a certain amount of MXene in a mixed solution and ultrasonically treat it evenly. Mix MXene with B-PPy / BC, SO3H-PPy / BC, and COOH-PPy / BC respectively, wash them clean with absolute ethanol, filter and dry deionized water in sequence. Mix the multi-functional flow electrode with NaCl electrolyte. The powder passes through a 100-mesh sieve before electrolyte mixing, and continuously stir the particles for 10 hours to ensure complete wetting to obtain the multi-functional flow electrode.

[0028] After the preparation through the above S1-S4, the MXene / PPy@BC flow electrode is formed in the present invention. The multi-functional flow electrode is realized based on a flow electrode deionization system. As Figure 1 shown, the outermost sides of the flow electrode deionization system are plexiglass bottom plate A1 and plexiglass bottom plate B11. The plexiglass bottom plate A1 and plexiglass bottom plate B11 are two identical and symmetrically arranged glass plates. The internal part of the flow electrode deionization system is divided into a cathode chamber, a middle chamber, and an anode chamber. The cathode chamber is composed of the plexiglass bottom plate A1, the first nylon waterproof gasket 2, and the first current collector titanium sheet 3. The middle chamber is composed of the second nylon waterproof gasket 4, the cation exchange membrane 5, the plexiglass plate 6, the anion exchange membrane 7, and the fourth nylon waterproof gasket 8 stacked in sequence. The anode chamber is composed of the fifth nylon waterproof gasket 9, the second current collector titanium sheet 10, and the plexiglass bottom plate B11. Eight small holes are drilled in the upper, two sides, and lower parts of all components used in the entire flow electrode deionization system, and they are reinforced and combined with nylon screws and wing nuts.

[0029] In the above flow electrode deionization system, the plexiglass bottom plate A1 and plexiglass bottom plate B11 are respectively provided with two inlets and outlets for the flow of the flow electrode slurry. The flow electrode slurry enters from the inlet and fills the cathode chamber composed of the plexiglass bottom plate A1, the first nylon waterproof gasket 2, and the first current collector titanium sheet 3, as well as the anode chamber composed of the fifth nylon waterproof gasket 9, the second current collector titanium sheet 10, and the plexiglass bottom plate B11 respectively. During the operation of the flow electrode deionization system, the flow electrode slurry is pumped into the two end electrodes from the carbon slurry storage tank 12 in a cycle to form a flow electrode.

[0030] Among them, the two sides of the organic glass plate 6 are provided with an inlet and an outlet, and the lead-containing wastewater enters from the inlet and flows out from the outlet. The solution completes the adsorption process in the middle chamber which is composed of the second nylon waterproof gasket 4, the cation exchange membrane 5, the organic glass plate 6, the anion exchange membrane 7 and the fourth nylon waterproof gasket 8 stacked in sequence. The cation exchange membrane 5 and the anion exchange membrane 7 are used to prevent the entry of opposite ions during operation, and the second nylon waterproof gasket 4 and the fourth nylon waterproof gasket 8 are used to prevent water from entering the electrode chamber; and the first collector titanium sheet 3 and the second collector titanium sheet 10 are made of corrosion-resistant metal. The titanium sheet is made of titanium sheets. Before treatment, the titanium sheets are soaked in a mixed solution of ethanol and nitric acid to remove the oxide on the surface. The titanium sheets are etched by the machine tool to form a complete serpentine channel, which is beneficial to the flow of the flowing electrode slurry in the electrode chamber, prevents the slurry from accumulating and hardening, and effectively increases the contact area, thereby increasing the adsorption effect of the entire flowing electrode deionization system. In addition, the water inlet and outlet of the organic glass bottom plate A1, the organic glass bottom plate B11 and the organic glass plate 6 are drilled by the machine tool, connected with an inner eight-pointed pagoda joint and a raw tape, and the water inlet pipe and the water outlet pipe, the carbon slurry inlet pipe and the carbon slurry outlet pipe are all connected with a plastic hose.

[0031] like Figure 1 As shown, a carbon slurry passage is formed in the mobile electrode deionization system: the carbon slurry storage tank 12 is pumped into the carbon slurry pipe through the water inlets on the organic glass bottom plate A1 and the organic glass bottom plate B11, and fills the cathode chamber through the serpentine channel of the first nylon waterproof gasket 2 and the first collector titanium sheet 3; the anode chamber is filled through the serpentine channel of the fifth nylon waterproof gasket 9 and the second collector titanium sheet 10. When the carbon slurry flows out, it flows out of the lower ends of the first collector titanium sheet 3, the second collector titanium sheet 10, the first nylon waterproof gasket 2 and the fifth nylon waterproof gasket 9 respectively from the lower end of the serpentine channel by gravity, and then flows out from the water outlets at the lower ends of the organic glass bottom plates A1 and B11, and merges into the carbon slurry storage tank 12.

[0032] Secondly, a water inlet passage is also formed in the mobile electrode deionization system: the lead-containing wastewater enters from the water inlet of the organic glass plate 6 and is filled with the middle chamber composed of the second nylon waterproof gasket 4, the cation exchange membrane 5, the organic glass plate 6, the anion exchange membrane 7 and the fourth nylon waterproof gasket 8 stacked in sequence, and then flows out from the water outlet of the organic glass plate 6, circulates in, and completes the adsorption and removal.

[0033] Specifically, in the above-mentioned flowing electrode deionization system (FCDI), the positive and negative terminals of the external power supply are connected to the collector. When sufficient voltage is applied, the anions and cations in the solution will move toward the two poles under the driving force of the electric field. However, due to the presence of the anion and cation exchange membrane, the carriers cannot pass through the opposite ion exchange membrane, while the target ions (Pb2+) pass through the cation exchange membrane into the cathode chamber and are adsorbed by the MXene / PPy@BC flowing electrode.

[0034] To further verify the effectiveness of the multi-functional flow electrode prepared by the present invention through the flow electrode deionization system, the following specific experimental tests are also provided:

[0035] The flow electrode deionization system (FCDI) of this embodiment is used to treat lead-containing wastewater. During the experimental stage, deionized water is used to simulate actual wastewater, and the dissolved oxygen in the water is removed. The feed reservoir equipped with a pressure reducing valve is fully injected with nitrogen until the dissolved oxygen concentration at the outlet is lower than 0.5 mg / L.

[0036] Before the experiment starts, the flow electrode deionization system (FCDI) is soaked in a mixed solution of ethanol and dilute nitric acid for more than two hours to remove surface impurities, and then repeatedly rinsed with deionized water to reduce the influence on the adsorption experiment; after the flow electrode deionization system is assembled, the carbon paste pipeline and the water inlet pipeline are subjected to a circulation test. MXene / PPy@BC flow carbon paste and deionized water are circulated between the two pipelines for 2 hours to ensure the stable operation of the system.

[0037] Taking the simulated wastewater of Pb(NO3)2 with a concentration of 10 mg / L as the target solution, it is placed in the feed reservoir equipped with a pressure reducing valve and isolated from the air, and nitrogen is continuously introduced to remove the dissolved oxygen in the water and maintain the gas phase stability. A peristaltic pump is used to pump it into the system at a flow rate of 10 ml / min.

[0038] The applied voltage configured by the experimental device is to adjust the applied potential with a CHI 600E potentiostat, and an inductively coupled plasma mass spectrometer (ICP-MS) is used to measure the lead concentration of the collected samples.

[0039] The principle of lead removal in the present invention is that the flow electrode mainly uses Faraday electrode reaction and double-layer adsorption as the adsorption mechanism. The addition of polypyrrole enhances the conductivity of the electrode and promotes the electrostatic attraction on the electrode surface. The hydroxyl groups in MXene 2+ carry out ion exchange with Pb, and compared with traditional electrodes, the flow electrode has stronger conductivity and faster ion transfer rate. After the pseudocapacitance reaction, Pb 2+ is loaded onto the particle surface and reduced to neutral particles to complete the adsorption process. During the regeneration process, by applying an opposite voltage, the lead ions bound to the particle surface can be desorbed under the action of the opposite voltage.

[0040] In summary: The preparation method of the multi-functional modified flow electrode for removing lead in water based on electroadsorption provided by the present invention uses the flow electrode pumped at both ends as the adsorption main body during the removal process of the FCDI system. The lead-containing wastewater enters the system from the middle chamber. After applying a certain degree of voltage, the charged ions contained in the water such as (Pb 2+It will move towards the opposite electrode under the drive of the electric field, while other anions will be blocked by the cation exchange membrane, and lead ions will enter the cathode chamber through the cation exchange membrane. The MXene / PPy@BC flow electrode utilizes the electric double layer adsorption and Faraday reaction to remove Pb2+. The adsorbed flow electrode is recycled to the carbon paste reservoir for regeneration to achieve ion removal.

[0041] As described above, it is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a multi-functional group-modified flow electrode for removing lead from water based on electrosorption, characterized in that: The following steps are involved: S1: Prepare MXene suspension, dissolve LiF in HCl and stir at room temperature, add Ti3AlC2 powder, and place the mixed solution in a polytetrafluoroethylene beaker to etch the Al layer in the solid phase, wash the precipitate with deionized water, oscillate the solution with an oscillator for 1 hour, and then collect the stable dark green supernatant after ultrasonication under inert gas N2 for 1 hour, redisperse the precipitate in deionized water, and collect the MXene suspension; S2: Preparation of PPy / BC: Pyrrole monomer and BC were completely dispersed in HCl solution, and after ultrasonic treatment for 2 hours, ammonium persulfate solution was slowly added dropwise to keep the temperature of the mixed solution at 5°C. After thorough mixing, sodium dodecylbenzene sulfonate was added as a surfactant to obtain PPy / BC solid; S3: Modified PPy / BC: Pour the PPy / BC solid powder prepared in S2 into a boric acid beaker, seal and stir continuously at 80℃ for 24h, dry the sample at 80℃ for 24h to obtain B-PPy / BC powder; add an appropriate amount of 96% concentrated sulfuric acid in an oil bath, stir and reflux with water cooling, control the mixture at 1500rpm and 25℃ for 3h, vacuum filter and dry at 80℃ for 24h to obtain SO3H-PPy / BC powder, dissolve in a mixed solution of NaOH and C7H7NO2, stir continuously at 80℃ for 8h, add NaNO2 and stir at 80℃ for 2h, quickly pour HCl and stir for 2h, vacuum filter and dry for 24h to obtain COOH-PPy / BC powder; S4: Prepare a multifunctional mobile electrode. Dissolve a certain amount of MXene in the mixed solution and ultrasonically treat it evenly. Mix MXene with B-PPy / BC, SO3H-PPy / BC, and COOH-PPy / BC respectively, wash them with anhydrous ethanol, filter and dry them with deionized water in turn, mix the multifunctional mobile electrode with NaCl electrolyte, and pass the powder through a 100-mesh sieve before mixing with the electrolyte. Stir the particles continuously for 10 hours to ensure complete wetting to obtain a multifunctional mobile electrode.

2. The method for preparing a multi-functional group-modified flow electrode for removing lead from water based on electrosorption according to claim 1, characterized in that: The multifunctional mobile electrode prepared in S4 is realized based on a mobile electrode deionization system. The outermost parts of the mobile electrode deionization system are organic glass bottom plate A (1) and organic glass bottom plate B (11). The organic glass bottom plate A (1) and organic glass bottom plate B (11) are two identical and symmetrically arranged glass plates. The interior of the mobile electrode deionization system is divided into a cathode chamber, a middle chamber and an anode chamber. The cathode chamber is composed of the organic glass bottom plate A (1), a first nylon waterproof gasket (2) and a first current collector titanium sheet (3). The middle chamber is composed of a second nylon waterproof gasket (4), a cation exchange membrane (5), an organic glass plate (6), an anion exchange membrane (7) and a fourth nylon waterproof gasket (8) stacked in sequence. The anode chamber is composed of a fifth nylon waterproof gasket (9), a second current collector titanium sheet (10) and the organic glass bottom plate B (11). The components used in the entire mobile electrode deionization system are all drilled with eight small holes on the top, both sides and the bottom, and are reinforced and assembled with nylon screws and butterfly nuts.

3. The method for preparing a multi-functional group-modified flow electrode for removing lead from water based on electrosorption according to claim 2, characterized in that: The outermost organic glass bottom plate A (1) and organic glass bottom plate B (11) of the mobile electrode deionization system are respectively provided with two water inlets and water outlets for the flow of mobile electrode slurry. The mobile electrode slurry enters from the water inlets and fills the cathode chamber composed of the organic glass bottom plate A (1), the first nylon waterproof gasket (2) and the first current collector titanium sheet (3) and the anode chamber composed of the fifth nylon waterproof gasket (9), the second current collector titanium sheet (10) and the organic glass bottom plate B (11). During the operation of the mobile electrode deionization system, the mobile electrode slurry is circulated and pumped from the carbon slurry storage tank (12) into the electrodes at both ends to form mobile electrodes.

4. The method for preparing a multi-functional group-modified mobile electrode for removing lead from water based on electrosorption according to claim 2, characterized in that: A water inlet and a water outlet are provided on both sides of the organic glass plate (6). Lead-containing wastewater enters from the water inlet and flows out from the water outlet. The solution completes the adsorption process in a middle chamber formed by stacking the second nylon waterproof gasket (4), the cation exchange membrane (5), the organic glass plate (6), the anion exchange membrane (7) and the fourth nylon waterproof gasket (8) in sequence. The cation exchange membrane (5) and the anion exchange membrane (7) are used to prevent the entry of opposite ions during operation. The second nylon waterproof gasket (4) and the fourth nylon waterproof gasket (8) are used to prevent water from entering the electrode chamber.

5. The method for preparing a multi-functional group-modified flow electrode for removing lead from water based on electrosorption according to claim 2, characterized in that: The first current collector titanium sheet (3) and the second current collector titanium sheet (10) are made of corrosion-resistant metal titanium sheets. Before treatment, the titanium sheets are soaked in a mixed solution of ethanol and nitric acid to remove oxides on the surface. The titanium sheets are etched by a machine tool to form a complete serpentine channel, which is beneficial for the flow of flowing electrode slurry in the electrode chamber and increases the adsorption effect of the entire flowing electrode deionization system.

6. The method for preparing a multi-functional group-modified flow electrode for removing lead from water based on electrosorption as claimed in claim 3, characterized in that: The water inlet and outlet of the plexiglass base plate A (1), the plexiglass base plate B (11) and the plexiglass plate (6) are all drilled by a machine tool and connected with an inner eight-pointed pagoda joint and a raw material tape. The water inlet pipe and the water outlet pipe, the carbon slurry inlet pipe and the carbon slurry outlet pipe are all connected with a plastic hose.

7. The method for preparing a multi-functional group-modified mobile electrode for removing lead from water based on electrosorption according to claim 6, characterized in that: A carbon slurry passage is formed in the mobile electrode deionization system: the carbon slurry storage tank (12) is pumped into the carbon slurry pipe through the water inlets on the organic glass bottom plate A (1) and the organic glass bottom plate B (11), and fills the cathode chamber through the first nylon waterproof gasket (2) and the serpentine channel of the first current collector titanium sheet (3); fills the anode chamber through the serpentine channel of the fifth nylon waterproof gasket (9) and the second current collector titanium sheet (10); when the carbon slurry flows out, it flows out of the lower ends of the first current collector titanium sheet (3), the second current collector titanium sheet (10), the first nylon waterproof gasket (2) and the fifth nylon waterproof gasket (9) respectively from the lower end of the serpentine channel in a gravity self-flowing manner, and then flows out from the water outlets at the lower ends of the organic glass bottom plate A (1) and the organic glass bottom plate B (11), and merges into the carbon slurry storage tank (12).

8. The method for preparing a multi-functional group-modified mobile electrode for removing lead from water based on electrosorption according to claim 6, characterized in that: A water inlet passage is formed in the mobile electrode deionization system: the lead-containing wastewater enters from the water inlet of the organic glass plate (6) into the middle chamber which is composed of the second nylon waterproof gasket (4), the cation exchange membrane (5), the organic glass plate (6), the anion exchange membrane (7) and the fourth nylon waterproof gasket (8) stacked in sequence, and then flows out from the water outlet of the organic glass plate (6), circulates and enters, completing adsorption and removal.

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