Modified electrode, its preparation method and application in electrochemical reductive dehalogenization device

Abstract

The application discloses a modified electrode and a preparation method and application thereof in an electrochemical reductive dehalogenization device, and relates to the technical field of water pollution control. The modified electrode is prepared by an electrodeposition technology, a sulfite is used as an electron donor to construct a self-driven direct electron transfer electrochemical system, and a bipolar chamber floating type device with a cation exchange membrane is matched, so that the dehalogenization of halogenated organic matters in open water bodies is realized without external energy and with high efficiency and in-situ.

Description

Technical Field

[0001] This invention relates to the field of water pollution control technology, and in particular to a modified electrode, its preparation method, and its application in an electrochemical reduction dehalogenation device. Background Technology

[0002] Halogenated organic compounds (such as polychlorinated biphenyls, fluorinated drugs, and brominated flame retardants) are compounds in which one or more hydrogen atoms bonded to carbon are replaced by halogen elements. Their molecular structure contains carbon-halogen bonds (CX, X = Cl, Br, I). They are highly toxic, difficult to degrade, and bioaccumulate, making them a class of persistent organic pollutants. With the advancement of modern industry, especially the development of chemical, pharmaceutical, and electronics industries, large amounts of halogenated organic compounds are discharged or leaked into various environmental media during production, transfer, and use, causing serious environmental damage. Currently, halogenated organic compounds are widely present in industrial wastewater, medical wastewater, and groundwater, and are among the most frequently detected pollutants in water bodies. These pollutants not only accumulate in water bodies through the food chain, threatening the balance and stability of aquatic ecosystems, but also enter the human body through drinking water and skin contact, causing health risks such as teratogenicity, carcinogenicity, and mutagenicity. This is a key problem that urgently needs to be solved in the field of water pollution control.

[0003] Traditional water treatment technologies, such as activated carbon adsorption, can only achieve the physical transfer of pollutants and cannot completely mineralize and decompose them. Advanced oxidation processes are easily affected by the complex composition of water and may generate more toxic halogenated byproducts, making it difficult to meet the stringent requirements of current water quality control. Electrochemical reduction dehalogenation technology has attracted attention due to its simple operation and environmental friendliness, but existing technologies have significant drawbacks: traditional metal electrodes (such as pure copper and iron) suffer from metal leaching and poor stability; carbon-based electrodes, while stable, lack active sites, resulting in low dehalogenation efficiency; free radical pathways are easily affected by water quality; external power supplies and circulation pumps increase energy consumption costs and narrow applicable scenarios. Currently, many studies have applied electrochemical dehalogenation to practical applications by improving electrode materials or innovating experimental devices, but some defects and shortcomings still exist. For example, Chinese utility model patent with publication number CN221254109U is a cathode internal circulation electroreduction dehalogenation device. It uses an external peristaltic pump to circulate the reactor cathode and the treated water, accelerating the electroreduction dehalogenation reaction, and can achieve continuous operation by replacing the external waste liquid tank. Its active components rely on precious metals such as ruthenium, rhodium, and palladium, or transition metal sulfides, resulting in high costs and susceptibility to poisoning, and it lacks provisions for controlling metal leaching. Due to structural limitations and dependence on external power sources and pumps, its applicability is relatively limited. Against this backdrop, developing highly stable, low-cost, and widely applicable high-efficiency dehalogenation devices has become a key measure to solve the problem of halogenated organic pollutants in water bodies and ensure water environment safety. It also has significant practical implications for promoting the full-scenario application of water pollution control technologies and the sustainable development of the ecological environment. Summary of the Invention

[0004] The purpose of this invention is to provide a modified electrode, its preparation method, and its application in an electrochemical reduction dehalogenation device to solve the problems existing in the prior art. This invention prepares a modified electrode (acid-etched nitrogen-doped carbon-coated copper (NC@Cu) modified carbon substrate (preferably carbon felt) electrode) using electrodeposition technology, employing sulfite as a highly efficient electron donor to construct a self-driven direct electron transfer electrochemical system. Combined with a bipolar chamber floating device containing a cation exchange membrane, this invention solves the dual problems of low metal leaching and electron transfer efficiency in existing electrochemical reduction dehalogenation technologies. It achieves highly efficient in-situ mineralization and dehalogenation of halogenated organic matter in wastewater without an external power source, and is particularly suitable for in-situ remediation of open water bodies. The floating self-driven electrochemical reduction dehalogenation device of the present invention is a bipolar integrated structure, which uses foam material as a supporting float to achieve overall floating. The core includes two sets of electrodes, an isolated reaction chamber and connecting components: the modified electrode (cathode) is immersed in the reaction chamber at the bottom covered with a cation exchange membrane (CEM), and the reaction chamber is filled with sulfite electrolyte; the original carbon felt (CF) electrode (anode) is directly immersed in the open polluted water body. The two electrodes are connected by wires to form a self-driven circuit. With the ion transport and material isolation functions of the CEM membrane, the reaction is highly efficient and free from secondary pollution.

[0005] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention: a method for preparing a modified electrode, comprising the following steps: Cu(BTC)(H2O)3MOF powder was mixed with a nitrogen source and calcined to obtain nitrogen-doped carbon-coated copper (abbreviated as NC@Cu). The nitrogen-doped carbon-coated copper is mixed with a solvent and an electrolyte to obtain an electrophoretic solution; The pretreated carbon substrate is placed in the electrophoretic solution for electrophoretic deposition; The carbon substrate after electrophoretic deposition is annealed to obtain a nitrogen-doped carbon copper-coated modified carbon substrate electrode. The nitrogen-doped carbon copper-coated modified carbon substrate electrode is then acid-etched to obtain the modified electrode.

[0006] This invention obtains nitrogen-doped carbon-coated copper by calcining Cu(BTC)(H2O)3MOF powder with a nitrogen source. In this copper, the nitrogen-doped carbon layer completely coats the Cu nanoparticles, reducing Cu dissolution compared to traditional electrodes and significantly improving the electrode's long-term stability. Furthermore, the nitrogen-doped carbon layer not only inhibits metal dissolution through its encapsulation structure, providing protection, but also allows nitrogen atoms to form stable Cu atoms with copper. + The -N4 coordination structure enhances its activation ability for sulfites, causing a significant negative shift in the anolyte potential and thus amplifying the potential difference in the system. Furthermore, acid etching of the nitrogen-doped carbon-coated copper-modified carbon substrate electrode reduces the loose surface layer, further improving the reduction dehalogenation efficiency.

[0007] Furthermore, the nitrogen source includes dicyandiamide.

[0008] Furthermore, the mass ratio of the Cu(BTC)(H2O)3MOF powder to the nitrogen source is 1:10.

[0009] Furthermore, the calcination temperature is 800-1000 ℃, and the time is 5 h.

[0010] Furthermore, after the calcination is completed, the process further includes soaking the calcined product in an acid solution, followed by washing and drying.

[0011] Furthermore, the acid solution is an HCl solution with a concentration of 5 wt%.

[0012] Furthermore, the soaking time is 4 hours.

[0013] Furthermore, the solvent includes a mixture of isopropanol and water.

[0014] Furthermore, the volume ratio of isopropanol to water is 4:1.

[0015] Furthermore, the electrolyte includes magnesium nitrate.

[0016] Furthermore, the ratio of the nitrogen-doped carbon-coated copper, the solvent, and the electrolyte is 1 mg:1 mL:10 mg.

[0017] Furthermore, the carbon substrate includes carbon felt (CF), and the resulting nitrogen-doped carbon-coated copper-modified carbon substrate electrode is a nitrogen-doped carbon-coated copper-modified carbon felt electrode (abbreviated as NC@Cu / CF electrode).

[0018] Furthermore, the pretreatment includes cutting, ultrasonic cleaning, and drying.

[0019] Furthermore, the electrophoretic deposition voltage is 30-35 V, and the time is 10-30 min.

[0020] Furthermore, the annealing treatment is performed at a temperature of 300 °C for 2 hours.

[0021] Furthermore, prior to the annealing process, the process also includes rinsing and drying the carbon substrate after electrophoretic deposition.

[0022] Furthermore, the acid etching process includes immersing the nitrogen-doped carbon-coated copper-modified carbon substrate electrode in a sulfuric acid solution with a concentration of 0.4-0.6 M for 5-15 min.

[0023] The second technical solution of the present invention: a modified electrode prepared according to the above-described method for preparing modified electrodes.

[0024] The third technical solution of the present invention: the application of the above-mentioned modified electrode in the construction of an electrochemical reduction dehalogenation device.

[0025] The fourth technical solution of the present invention: a floating self-driven electrochemical reduction dehalogenation device, comprising an anode, a cathode, a reaction chamber, a cation exchange membrane (CEM), wires, and a supporting float; The anode and the reaction chamber are fixed by the supporting float; The cathode is inserted into the reaction chamber and connected to the anode via the wire; The cation exchange membrane covers the bottom of the reaction chamber (i.e., the reaction chamber is a reaction vessel (specifically a glass tube) with the bottom covered by a cation exchange membrane, serving as a sulfite oxidation zone. The cation exchange membrane is used to isolate the reaction chamber from the open water body, allowing ion transport but preventing substance exchange). The cathode is the modified electrode described above.

[0026] Furthermore, the anode is a carbon felt electrode (which is directly immersed in open water during the wastewater removal process).

[0027] Furthermore, the supporting float comprises ethyl vinyl acetate (EVA) foam, which provides buoyancy so that the device floats on the water surface.

[0028] Furthermore, the conductor comprises copper wire.

[0029] The fifth technical solution of the present invention: a method for removing halogenated organic compounds from wastewater based on the above-mentioned floating self-driven electrochemical reduction dehalogenation device, comprising the following steps: The floating self-driven electrochemical reduction dehalogenation device is placed in open wastewater. Under the buoyancy provided by the supporting float, the electrochemical reduction dehalogenation device floats on the water surface. The anode is in direct contact with the open wastewater. A mixed aqueous solution of sulfite and NaCl is added to the reaction chamber as the cathode liquid. The removal reaction of halogenated organic compounds is carried out under the self-drive of the floating self-driven electrochemical reduction dehalogenation device.

[0030] Furthermore, the cation exchange membrane is in direct contact with the open wastewater.

[0031] Furthermore, the sulfite includes Na2SO3.

[0032] Furthermore, the concentrations of both sulfite and NaCl in the mixed aqueous solution of sulfite and NaCl are 10 mM.

[0033] Furthermore, the cathode is immersed in cathodic liquid in the reaction chamber.

[0034] This invention achieves efficient in-situ dehalogenation of halogenated organic matter in open water bodies without external energy by constructing a dehalogenation system and designing a floating device. Specifically: Construction of the dehalogenation system: Using sulfite, a byproduct of industrial desulfurization, as an electron donor, and sodium chloride electrolyte, a self-driven direct electron transfer electrochemical system is constructed. Through electrode interface design, electrons are directed to halogenated organic compounds, achieving targeted CX bond breaking. This direct electron transfer electrochemical system eliminates the need for intermediate carriers such as free radicals or active hydrogen. Driven by energy level matching and a sufficient potential difference between the electron donor and the pollutant, electrons migrate directly from the donor to the pollutant. It drives pollutant oxidation-reduction through electrode spatial isolation, avoiding the intervention of chemical reagents, and combining high efficiency with environmental compatibility. Sulfite, as a byproduct of industrial desulfurization, poses a significantly lower environmental risk than sulfate byproducts of traditional technologies and can serve as a highly efficient electron donor, achieving the reductive dehalogenation of halogenated organic compounds under catalytic site action.

[0035] Floating device design: The bipolar chamber integrated floating device is designed with foam material as the supporting float. The core includes a reaction chamber with CEM (with built-in modified cathode and catholyte) and a raw carbon felt anode immersed in open water. The two electrodes are connected to form a self-driving circuit. The CEM membrane realizes ion transport and material isolation. The device adopts a modular architecture, which can flexibly expand the processing scale.

[0036] The present invention discloses the following technical effects: (1) This invention achieves innovation in electrode materials. Through electrodeposition technology, copper-nitrogen active materials (nitrogen-doped carbon-coated copper) are uniformly loaded onto the surface of a carbon substrate to form a stable covalent bond interface, significantly reducing the risk of metal leaching. At the same time, a unique dual-active-site synergistic mechanism is constructed. The Cu-N4 site-dominated anodic oxidation significantly pulls the electrode potential in the negative direction; the N-doped carbon site-dominated cathodic reduction slightly pushes the electrode potential in the positive direction. The synergy of the two amplifies the potential difference between the two electrodes, providing sufficient driving force for direct electron transfer (DET) without external power, and providing core support for the efficient dehalogenation of halogenated organic compounds. Moreover, after obtaining the nitrogen-doped carbon-coated copper-modified carbon substrate electrode, this invention also performs acid etching treatment on it. The acid etching treatment can reduce the loose bonding layer on the surface, further improving the reduction dehalogenation efficiency of the electrode material.

[0037] (2) This invention achieves collaborative innovation in device design and scenario adaptation. It adopts a foam floating design, which allows the device to float directly in open water bodies to achieve in-situ remediation. It utilizes a cation exchange membrane to simultaneously achieve ion transport and material isolation functions, separating the sulfite oxidation zone from the open water body to avoid secondary pollution. It can be modularly designed to flexibly adapt to the pollution control needs of different volumes.

[0038] (3) The present invention has outstanding dehalogenation efficiency and universality. Relying on the synergistic effect of dual active sites and the direct electron transfer mechanism driven by self-generated potential difference, the dehalogenation rate of halogenated organic matter exceeds 70%, which is significantly improved compared with the traditional electrochemical system. The reaction is less affected by water pH and impurity ions, and can still maintain stable treatment effect in complex water body scenarios, thus overcoming the limitations of traditional technology.

[0039] (4) The present invention has significant environmental and economic benefits. It requires no external energy input and uses sulfite, a byproduct of industrial desulfurization, as a low-cost electron donor. Compared with traditional electrochemical reduction technology, the present invention requires no external energy input and has an energy consumption of 0 kWh / m³. 3 It has a low carbon footprint. This invention achieves targeted dehalogenation through a direct electron transfer mechanism, without generating toxic byproducts, aligning with the principles of green chemistry and sustainable development. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the floating self-driven electrochemical reduction dehalogenation device of the present invention, wherein: 1-anode, 2-cathode, 3-reaction chamber, 4-cation exchange membrane, 5-wire, 6-supporting float.

[0042] Figure 2 This is a SEM-EDS image of the NC@Cu powder prepared in Example 1.

[0043] Figure 3 The image shows the XPS spectrum of the NC@Cu powder prepared in Example 1.

[0044] Figure 4 This is a surface SEM image of the modified electrode prepared in Example 1.

[0045] Figure 5 The degradation curves of norfloxacin on the NC@Cu / CF electrode before and after acid etching are shown. Detailed Implementation

[0046] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0047] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0049] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0050] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0051] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0052] This invention provides a modified electrode, a method for preparing the modified electrode, the application of the modified electrode in constructing an electrochemical reduction dehalogenation device, a floating self-driven electrochemical reduction dehalogenation device including the modified electrode, and a method for removing halogenated organic compounds from wastewater based on the floating self-driven electrochemical reduction dehalogenation device. This invention, through the design of the modified electrode and the floating self-driven electrochemical reduction dehalogenation device, uses sulfite as an electron donor and achieves a targeted and efficient direct electron transfer dehalogenation process through electrode interface design.

[0053] In a preferred embodiment of the present invention, an NC@Cu / CF electrode is prepared by electrodeposition. The deposition process is controlled under constant pressure. Surface impurities are removed through a pretreatment of carbon felt cleaning. The loading of the NC@Cu active material and the deposition time are precisely controlled to ensure a single layer of uniform particles adheres to the carbon felt surface, avoiding insufficient active sites that could limit electron transfer efficiency and enabling synergistic direct electron transfer and dehalogenation reactions. Finally, acid etching of the NC@Cu / CF electrode reduces the loose surface layer, further improving the reduction and dehalogenation efficiency. In the reaction apparatus, the anode uses an acid-etched NC@Cu / CF electrode (i.e., a modified electrode), the cathode uses a raw carbon felt (CF) electrode, and the membrane module uses a cation exchange membrane (CEM) to isolate the reaction chamber from the open water body, allowing only Na+ to pass through. + / H + Transmembrane migration balances the charge, while the reaction chamber contains sulfite and sodium chloride to ensure stable electron transport. The electrode exhibits good adaptability and buffering properties to water pH, broadening the pH range applicable to the dehalogenation reaction and eliminating the need for additional acid or alkali adjustments. Simultaneously, both the modified and original CF electrodes are fixed to the EVA foam float, achieving full contact of reactants through natural ion migration, shortening electron transfer paths and reaction time. Dehalogenation products naturally separate with the water flow, eliminating the need for complex post-treatment and preventing electrode contamination caused by in-situ pollutant deposition, thus improving electrode recycling efficiency.

[0054] A schematic diagram of the floating self-driven electrochemical reduction dehalogenation device in this invention is shown below. Figure 1 As shown.

[0055] The technical principle of dehalogenation in this invention is as follows: Taking the dehalogenation reaction of norfloxacin (NOR) as an example, the complete redox reaction is as follows (Formula 1): (1) Due to the spatial separation of organic contaminants and oxidants in the galvanic cell structure, the removal of NOR is attributed to the participation of non-radical redox reactions between the NC@Cu / S(Ⅳ) and CF / NOR pairs. Based on experimental results and analysis, the dehalogenation reaction of this invention follows the following four core pathways, constituting a complete potential difference-driven electron transfer chain: The first step is the anodic reaction, SO3 2- It is adsorbed on the electrode and then oxidized to SO4. 2- Simultaneously, it releases 2 electrons (Formula 2), Cu + Oxidized to Cu 2+ (Formula 3); (2) (3) The second step is the electron transfer process, in which the released electrons migrate from the anode to the CF cathode through the external circuit; The third step is the cathode reaction, where NOR gains electrons at the cathode, causing the CF bond to break and generating the defluorination product rpNOR (Formula 4). (4) The fourth step is cation migration, Na + / H + The CEM migrates across the membrane to balance the charge in the system and maintain the continuous progress of the reaction.

[0056] Unless otherwise specified, the room temperature mentioned in the following embodiments and application examples of the present invention refers to 20-30°C.

[0057] All raw materials used in the following embodiments and application examples of the present invention are commercially available products. Among them, the carbon felt is purchased graphite carbon felt with a thickness of 2 mm.

[0058] Example 1 A modified electrode is prepared by the following steps: Carbon felt pretreatment: Cut the carbon felt into squares of 2 cm × 2 cm in size, and ultrasonically clean them in acetone, ethanol and deionized water for 30 min each time. After each ultrasonic cleaning, rinse the carbon felt repeatedly with distilled water. Place the cleaned carbon felt in a vacuum drying oven at 60℃ to dry for later use.

[0059] Preparation of Cu(BTC)(H2O)3MOF: 2.092 g of copper acetate (Cu(C2H3O2)2) and 0.771 g of glutamic acid (C5H9NO4) were dissolved evenly in 500 mL of deionized water to obtain solution A. 1.16 g of 1,3,5-benzenetricarboxylic acid was mixed with 450 mL of deionized water and 50 mL of ethanol and dissolved under ultrasonication to obtain solution B. Then, solutions A and B were mixed together and stirred at room temperature for 2 hours. The mixture was centrifuged, and the resulting blue powder was washed three times with deionized water and dried at 60 °C for 12 h to obtain Cu(BTC)(H2O)3MOF powder.

[0060] Preparation of NC@Cu powder: 0.2 g of Cu(BTC)(H2O)3MOF powder was mixed with 2 g of dicyandiamide (DCD) and ground in an agate mortar for 10 min. The ground mixture was then calcined at 800 °C for 5 h under an argon atmosphere at a rate of 5 °C / min. The calcined powder was then soaked in 40 mL of HCl solution (5 wt%) at room temperature for 4 h to remove residues. The collected powder was then washed several times with deionized water and dried to obtain NC@Cu powder.

[0061] Preparation of nitrogen-doped carbon-coated copper-modified carbon felt electrode (NC@Cu / CF): 50 mg of NC@Cu powder was dispersed in 50 mL of isopropanol / water mixed solvent (volume ratio 4:1) and sonicated for 30 min. 500 mg of magnesium nitrate (Mg(NO3)2) was added as the electrolyte, and the mixture was magnetically stirred for 30 min to obtain the electrophoretic solution. Using the pretreated carbon felt as the cathode and stainless steel as the anode, electrophoretic deposition was performed at a constant voltage of 32 V for 30 min. After deposition, the carbon felt surface was rinsed with deionized water and dried, then annealed in a tube furnace at 300 ℃ for 2 h to obtain the NC@Cu / CF electrode.

[0062] Acid etching treatment: The NC@Cu / CF electrode was immersed in 50 mL of 0.5 M sulfuric acid for 10 min and then dried to obtain the acid-etched NC@Cu / CF electrode, which is the modified electrode.

[0063] Figure 2 The image shown is a SEM-EDS image of the NC@Cu powder prepared in this embodiment. It can be seen that the nitrogen-doped carbon layer completely coats the Cu nanoparticles.

[0064] Figure 3 The XPS spectrum of the NC@Cu powder prepared in this embodiment shows that Cu is present in the NC@Cu powder. +and Cu 2+ Two valence states, of which Cu + This is the primary valence state.

[0065] Figure 4 The image shows a surface SEM image of the modified electrode prepared in this embodiment. It can be seen that nitrogen-doped carbon coated with copper was successfully modified on the carbon felt surface.

[0066] Comparative Example 1 A modified electrode is prepared by the following steps: Carbon felt pretreatment: Same as in Example 1.

[0067] Preparation of copper-modified carbon felt electrode (Cu / CF): 100 mL of 0.1 M copper nitrate trihydrate (Cu(NO3)2·3H2O) solution was used as the electrophoretic solvent. Pretreated carbon felt was used as the cathode, and stainless steel as the anode. Electrophoretic deposition was performed at a constant voltage of 32 V for 30 min. After deposition, the carbon felt surface was rinsed with deionized water and dried. Then, it was annealed in a tube furnace at 300 °C for 2 h to obtain the Cu / CF electrode.

[0068] Acid etching treatment: The Cu / CF electrode was immersed in 50 mL of 0.5 M sulfuric acid for 10 min and then dried to obtain the acid-etched Cu / CF electrode, which is the modified electrode.

[0069] Comparative Example 2 A modified electrode is prepared by the following steps: Carbon felt pretreatment: Same as in Example 1.

[0070] Preparation of Cu(BTC)(H2O)3MOF: Same as in Example 1.

[0071] Preparation of C@Cu powder: Cu(BTC)(H2O)3MOF powder was calcined at 800 °C for 5 h under an argon atmosphere at a rate of 5 °C / min. Then, the calcined powder was soaked in 40 mL of HCl solution (5 wt%) at room temperature for 4 h to remove residues. Afterwards, the collected powder was washed several times with deionized water and dried to obtain C@Cu powder.

[0072] Preparation of carbon-coated copper-modified carbon felt electrode (C@Cu / CF): 50 mg of C@Cu powder was dispersed in 50 mL of isopropanol / water mixed solvent (volume ratio 4:1) and sonicated for 30 min. 500 mg of magnesium nitrate (Mg(NO3)2) was added as the electrolyte, and the mixture was magnetically stirred for 30 min to obtain the electrophoretic solution. Using the pretreated carbon felt as the cathode and stainless steel as the anode, electrophoretic deposition was performed at a constant voltage of 32 V for 30 min. After deposition, the carbon felt surface was rinsed with deionized water and dried, then annealed in a tube furnace at 300 ℃ for 2 h to obtain the C@Cu / CF electrode.

[0073] Acid etching treatment: The C@Cu / CF electrode was immersed in 50 mL of 0.5 M sulfuric acid for 10 min and then dried to obtain the acid-etched C@Cu / CF electrode, which is the modified electrode.

[0074] Application Example 1 (1) Floating self-driven electrochemical reduction dehalogenation device (schematic diagram shown) Figure 1 Construction of (as shown): The floating self-driven electrochemical reduction dehalogenation device consists of an anode, a cathode, a reaction chamber, a cation exchange membrane (CEM), wires, and a supporting float. in: The anode is a carbon felt electrode; the cathode is the modified electrode prepared in Example 1 (NC@Cu / CF electrode after acid etching); the reaction chamber is a glass tube; the wire is a copper wire; and the supporting float is EVA foam. The anode and reaction chamber are fixed by a supporting float; The cathode is inserted into the reaction chamber and connected to the anode via a wire; The cation exchange membrane covers the bottom of the reaction chamber (i.e., the reaction chamber is a glass tube with the cation exchange membrane covering the bottom).

[0075] (2) Removal of halogenated organic compounds from wastewater: An aqueous solution of norfloxacin with an initial concentration of 10 mg / L and pH=5 (without other interfering ions) was prepared as simulated wastewater.

[0076] 1 L of simulated wastewater was placed in a glass tank as the anolyte. A floating self-driven electrochemical reduction dehalogenation device was placed in the wastewater. Under the buoyancy provided by the supporting float, the device floated on the water surface, with the anode and cation exchange membrane in direct contact with the wastewater. 50 mL of a mixed aqueous solution of Na₂SO₃ and NaCl (both 10 mM) was added to the reaction chamber of the device as the catholyte. The removal of halogenated organic compounds was carried out at 25 °C under the self-driven operation of the device. The results showed that the removal rate of norfloxacin was 83% after 72 h (the degradation curve of norfloxacin is shown in Figure 1). Figure 5 As shown in the NC@Cu / CF (Acid Treatment) diagram.

[0077] Comparative Application Example 1 Similar to Application Example 1, except that the cathode was replaced with the modified electrode (acid-etched NC@Cu / CF electrode) prepared in Example 1 before acid etching, instead of the NC@Cu / CF electrode in Example 1 before acid etching. The degradation curve of norfloxacin in this comparative application example is shown in [reference needed]. Figure 5 NC@Cu / CF (before treatment). Results showed that the removal rate of norfloxacin was 64% at 72 h.

[0078] Comparative Application Example 2 Similar to Application Example 1, except that the cathode was replaced with the modified electrode (acid-etched NC@Cu / CF electrode) prepared in Example 1 (acid-etched Cu / CF electrode) prepared in Comparative Example 1. The results showed that the removal rate of norfloxacin was 19% after 72 h.

[0079] Comparative Application Example 3 Similar to Application Example 1, except that the cathode was replaced with the modified electrode (acid-etched NC@Cu / CF electrode) prepared in Example 1, which was replaced with the modified electrode (acid-etched C@Cu / CF electrode) prepared in Comparative Example 2. The results showed that the removal rate of norfloxacin was 32% after 72 h.

[0080] Application Example 2 Similar to Application Example 1, the only difference was that an equal volume of simulated wastewater was replaced with an artificially prepared diclofenac (DCF) aqueous solution with an initial concentration of 5 mg / L and pH=7 (without other interfering ions). The results showed that the diclofenac removal rate was 78% after 72 h.

[0081] Application Example 3 Similar to Application Example 1, the only difference was that an equal volume of simulated wastewater was replaced with an artificially prepared mixed aqueous solution of chlorophenol, bromophenol, and iodophenol (initial concentrations of chlorophenol, bromophenol, and iodophenol were all 20 μM, pH=9.2, with no other interfering ions) as the water sample to be treated. The results showed that after 72 h, the removal rates of bromophenol and iodophenol were both 92%, while the removal rate of chlorophenol was 81%.

[0082] Application Example 4 Similar to Application Example 1, the only difference was that an equal volume of simulated wastewater was replaced with an artificially prepared mixed aqueous solution of florfenicol (FLO), 2-chlorophenol, 4-bromophenol, and 3-iodophenol (the initial concentrations of florfenicol, 2-chlorophenol, 4-bromophenol, and 3-iodophenol were all 15 μM, pH=7.5, and there were no other interfering ions) as the water sample to be treated. The results showed that after 72 h, the removal rates of 3-iodophenol were 85%, 4-bromophenol 80%, 2-chlorophenol 75%, and florfenicol 70%.

[0083] Application Example 5 Similar to Application Example 1, the only difference is that an equal volume of simulated wastewater was replaced with actual industrial wastewater from a chemical industrial park as the water sample to be treated. The water quality was as follows: pH=7.2, COD=50 mg / L, and adsorbable organic chlorine (AOX-Cl)=0.6 mg / L. Typical pollutants included chlorinated phenols, chlorinated acyl chlorides, dichloroethane, viscose short fibers, and other chlorinated and large-molecule recalcitrant organic compounds. The results showed that the COD removal rate was 55% and the adsorbable organic chlorine (AOX-Cl) removal rate was 75% after 72 h.

[0084] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a modified electrode, characterized in that, Includes the following steps: Cu(BTC)(H2O)3 MOF powder was mixed with a nitrogen source and calcined to obtain nitrogen-doped carbon-coated copper. The nitrogen-doped carbon-coated copper is mixed with a solvent and an electrolyte to obtain an electrophoretic solution; The pretreated carbon substrate is placed in the electrophoretic solution for electrophoretic deposition; The carbon substrate after electrophoretic deposition is annealed to obtain a nitrogen-doped carbon copper-coated modified carbon substrate electrode. The nitrogen-doped carbon copper-coated modified carbon substrate electrode is then acid-etched to obtain the modified electrode.

2. The method for preparing the modified electrode as described in claim 1, characterized in that, The nitrogen source includes dicyandiamide; And / or, the mass ratio of the Cu(BTC)(H2O)3 MOF powder to the nitrogen source is 1:10; And / or, the calcination temperature is 800-1000 ℃ and the time is 5 h.

3. The method for preparing the modified electrode as described in claim 1, characterized in that, The solvent includes a mixture of isopropanol and water; And / or, the electrolyte includes magnesium nitrate; And / or, the ratio of the nitrogen-doped carbon-coated copper, the solvent, and the electrolyte is 1 mg:1 mL:10 mg.

4. The method for preparing the modified electrode as described in claim 1, characterized in that, The carbon substrate includes a carbon felt; And / or, the pretreatment includes cutting, ultrasonic cleaning, and drying; And / or, the electrophoretic deposition voltage is 30-35 V, and the time is 10-30 min; And / or, the annealing treatment is performed at a temperature of 300 °C for 2 h; And / or, the acid etching process includes: immersing the nitrogen-doped carbon-coated copper-modified carbon substrate electrode in a sulfuric acid solution with a concentration of 0.4-0.6 M for 5-15 min.

5. A modified electrode prepared by the method of any one of claims 1-4.

6. The application of the modified electrode as described in claim 5 in the construction of an electrochemical reduction dehalogenation device.

7. A floating, self-driven electrochemical reduction dehalogenation device, characterized in that, It includes an anode (1), a cathode (2), a reaction chamber (3), a cation exchange membrane (4), a wire (5), and a supporting float (6); The anode (1) and the reaction chamber (3) are fixed by the supporting float (6); The cathode (2) is inserted into the reaction chamber (3) and connected to the anode (1) via the wire (5); The cation exchange membrane (4) covers the bottom of the reaction chamber (3); The cathode (2) is the modified electrode as described in claim 5.

8. The floating self-driven electrochemical reduction dehalogenation device as described in claim 7, characterized in that, The anode (1) is a carbon felt electrode; And / or, the supporting float (6) comprises ethyl vinyl acetate foam.

9. A method for removing halogenated organic compounds from wastewater based on the floating self-driven electrochemical reduction dehalogenation device according to claim 7 or 8, characterized in that, Includes the following steps: The floating self-driven electrochemical reduction dehalogenation device is placed in open wastewater. Under the buoyancy provided by the supporting float, the electrochemical reduction dehalogenation device floats on the water surface. The anode (1) is in direct contact with the open wastewater. A mixed aqueous solution of Na2SO3 and NaCl is added to the reaction chamber (3) as the cathode liquid. The removal reaction of halogenated organic compounds is carried out under the self-drive of the floating self-driven electrochemical reduction dehalogenation device.

10. The method as described in claim 9, characterized in that, The concentrations of sulfite and NaCl in the mixed aqueous solution of Na₂SO₃ and NaCl are both 10 mM.

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