Preparation method and application of ferromagnesium lead cerium meso-entropy oxide electrode material

Abstract

The application relates to the technical field of electrode material preparation, in particular to a preparation method and application of a Fe-Mg-Pb-Ce meso-entropy oxide electrode material. The preparation method comprises the following steps: (1) preparing a mixed salt solution and a sol; (2) preparing a coated titanium substrate; (3) preparing a FeMgPbCe coated titanium substrate; (4) preparing a FeMgPbCeO x electrode material. The FeMgPbCeO x electrode material is prepared by utilizing a molten salt to assist in lattice regulation, realizes uniform element distribution and precise regulation of lattice distortion degree through a molten salt medium, improves the stability of the electrode in a high-salt-strength corrosive environment, optimizes the structure of a catalytic active site of the electrode, realizes deep removal of COD in NF concentrated water at a low current density, especially efficient mineralization of characteristic pollutants such as phenols and cyanides, reduces the influence of organic matters in the NF concentrated water on salt purity, simultaneously reduces the energy consumption and scale of an evaporation system, and realizes resource utilization of coking wastewater.

Description

Technical Field

[0001] This invention relates to the field of electrode material preparation technology, and in particular to a method for preparing and applying an iron-magnesium-lead-cerium entropy oxide electrode material. Background Technology

[0002] The coking industry is a crucial link in the steel industry chain, but the coking wastewater it produces is complex in composition and highly toxic, containing large amounts of recalcitrant pollutants such as phenols, cyanides, polycyclic aromatic hydrocarbons, and heterocyclic compounds, as well as high salt content, making it extremely difficult to treat. Currently, the treatment of coking wastewater typically employs a "pretreatment-biological treatment-advanced treatment" process route. Nanofiltration (NF) technology, due to its highly efficient desalination and pollutant retention capabilities, has become one of the core units in advanced treatment. However, NF systems generate 30%–50% nanofiltration concentrate in the influent, which exhibits a triple characteristic of "high salinity, high COD, and high toxicity": salinity generally reaches 15,000–35,000 mg / L, mainly composed of inorganic salts such as NaCl and Na₂SO₄; COD concentration reaches 1,000–3,000 mg / L, primarily consisting of recalcitrant organic compounds such as phenols, quinoline, and pyridine; and it also contains 5–15 mg / L of cyanide, exhibiting strong biological toxicity.

[0003] To achieve zero discharge and resource recovery of coking wastewater, NF concentrate typically needs to be treated in an evaporation crystallization system for salt extraction to recover inorganic salt resources. However, existing treatment technologies face two major bottlenecks: First, the residual recalcitrant organic matter in the concentrate severely affects the quality of the inorganic salts subsequently evaporated and crystallized. During evaporation, organic matter easily adheres to the surface of salt crystals or embeds itself in the crystal lattice, resulting in an inorganic salt purity of only 85%–90%, which fails to meet industrial-grade salt standards (purity ≥98%) and can only be disposed of as hazardous waste, increasing disposal costs. Second, the viscosity of high-COD concentrate is 15%–25% higher than that of pure water, and organic matter easily forms scale on the surface of heating tubes, leading to a 20%–30% reduction in the heat transfer coefficient of the evaporation crystallization system. This significantly increases the energy consumption per unit of water evaporation, far exceeding the energy consumption of conventional brine evaporation (1600–1800 kJ / kg), resulting in poor economic efficiency.

[0004] Electro-oxidation technology utilizes hydroxyl radicals (OH) and superoxide anion radicals (O2) generated at the anode. － • Highly oxidizing active species enable complete mineralization of recalcitrant organic matter without the need for chemical additives, offering significant advantages in the treatment of high-salinity, recalcitrant wastewater. However, traditional electro-oxidation electrodes also have limitations when used for treating NF concentrate from coking plants. Firstly, their stability is insufficient, especially given the high salinity (especially high Cl-) of NF concentrate from coking plants. －Highly corrosive environments (containing cyanides and phenols) accelerate electrode corrosion. For example, after 100–150 hours of continuous operation in this type of wastewater, the active layer of a traditional SnO2 electrode exhibits a peeling rate of 15%–20%, with Sn ion leaching concentrations exceeding 0.02 mg / L. While the DSA electrode (RuO2-InF2 coating) shows slightly better corrosion resistance, Cl… － It easily triggers the chlorine evolution reaction, producing ClO － This will damage the coating structure, and the activity decay rate exceeds 30% after 150 hours of continuous operation. Furthermore, the anode has low catalytic activity, the active sites of traditional electrodes are unevenly distributed, and the electron transfer efficiency is low, requiring a range of 30–40 mA / cm². 2 Effective COD removal can only be achieved under high current density, with a processing energy consumption of 6-8 kWh / kgCOD. At the same time, the mineralization rate of pollutants such as phenols and quinolines is less than 75%, which cannot meet the organic residue requirements for subsequent evaporation, crystallization and salt extraction.

[0005] Medium-entropy oxide materials, due to their lattice distortion and high mixing entropy, can enhance chemical stability and catalytic activity through electronic structure modulation, making them an emerging type of electro-oxidation electrode material. However, existing medium-entropy oxide electrode preparation methods, such as sol-gel or solid-state sintering, suffer from two main problems: first, uneven elemental distribution easily leads to the formation of segregated phases of certain elements, resulting in fewer active sites and insufficient structural stability; second, the degree of lattice distortion is difficult to precisely control (typically only 1%–2%), failing to fully leverage the advantages of the medium-entropy effect. Molten salt, as a high-temperature ionic solvent, possesses high ionic conductivity and strong solubility, promoting the full dissolution and uniform mixing of metal oxide precursors. Simultaneously, by precisely controlling the degree of lattice distortion through salt ion insertion, the stability and catalytic performance of medium-entropy materials can be enhanced. Currently, the application of molten salt modulation technology in the preparation of medium-entropy oxide electrodes has not been reported, especially for the synergistic "purification-salt extraction" requirements of NF concentrate from coking plants, lacking systematic electrode design and process optimization schemes.

[0006] This invention employs molten salt lattice manipulation technology to prepare iron-magnesium-lead-cerium intermediate-entropy oxides (FeMgPbCeO). x The electrode, by optimizing the molten salt composition, sintering process and electrode component ratio, achieves precise control of lattice distortion and uniform distribution of elements, thereby improving the stability and catalytic activity of the electrode when used in NF concentrate in coking plants. At the same time, it reduces the interference of organic matter in NF concentrate on subsequent evaporation and crystallization, achieving the synergistic goal of "deep purification - efficient salt extraction - energy consumption reduction", and providing technical support for zero discharge of coking wastewater. Summary of the Invention

[0007] This invention addresses the problems of poor stability and incomplete organic matter removal associated with traditional electro-oxidation electrodes used in the treatment of NF concentrate in coking plants. It proposes a method for preparing and applying a FeMgPbCeO medium-entropy oxide electrode material, utilizing molten salt-assisted lattice modulation. x The electrode material achieves uniform element distribution and precise control of lattice distortion through a molten salt medium, improving the stability of the electrode in a high-salt, highly corrosive environment. The structure of the catalytic active sites of the electrode is optimized to achieve deep removal of COD from NF concentrate at low current density, especially the efficient mineralization of characteristic pollutants such as phenols and cyanides. This reduces the impact of organic matter in NF concentrate on salt purity, while also reducing energy consumption and scale buildup in the evaporation system, thus enabling the resource utilization of coking wastewater.

[0008] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing an iron-magnesium-lead-cerium entropy oxide electrode material includes the following steps: (1) Using metal inorganic salts including ferric nitrate, magnesium nitrate, lead nitrate and cerium nitrate as precursors, each metal inorganic salt is added to anhydrous ethanol in sequence and stirred thoroughly to dissolve, thus obtaining a mixed salt solution; citric acid is added to the mixed salt solution and stirred continuously until a uniform and transparent sol is formed. (2) The titanium substrate after surface pretreatment is vertically immersed in the sol and kept for a period of time to allow the sol to be fully adsorbed on the surface of the titanium substrate; then the titanium substrate is slowly and uniformly lifted to allow the sol to form a uniform film on the surface of the titanium substrate; the coated titanium substrate is placed horizontally in a clean petri dish and dried at room temperature to allow the solvent to fully evaporate and the sol to initially gel, thus obtaining the coated titanium substrate. (3) The pre-gelled coated titanium substrate is placed in a muffle furnace and slowly heated to 200-400°C at a heating rate of 1-10°C / min. The temperature is maintained at this temperature for 0.5-3h to allow the organic components to decompose fully. Then the temperature is raised to 500-700°C at a heating rate of 1-10°C / min and maintained for 0.5-3h to allow the coating to be further cured and form a stable oxide structure, finally obtaining the FeMgPbCe coated titanium substrate. (4) Using a Na2CO3-K2CO3 mixed salt as the control medium, the FeMgPbCe coated titanium substrate was placed in a flat-bottomed crucible and covered with the Na2CO3-K2CO3 mixed salt; then it was placed in a tube furnace, and the temperature was slowly increased to 600-1000°C at a heating rate of 1-10°C / min under an inert gas protective atmosphere. The reaction was carried out at a constant temperature for 0.5-3 hours. After the reaction was completed, it was naturally cooled to room temperature. After being taken out, it was ultrasonically treated and dried to obtain FeMgPbCeO. x Electrode materials.

[0009] In step (1), ferric nitrate, magnesium nitrate, lead nitrate, and cerium nitrate are added in a Fe:Mg:Pb:Ce molar ratio of 1-5:1-5:1-5:1-5; the ratio of anhydrous ethanol volume to total inorganic salt molar amount is 1L:0.5mol to 1L:3mol.

[0010] In step (1), the ratio of the total molar amount of metal ions to the molar amount of citric acid in the mixed salt solution is 1:1 to 1:5.

[0011] In step (1), the surface pretreatment process of the titanium substrate is as follows: first, the surface oxide layer and impurities are removed by sandblasting, then the titanium substrate is placed in acetone and anhydrous ethanol in sequence, ultrasonically cleaned in an ultrasonic cleaner for 5 to 30 minutes, and finally rinsed with deionized water and dried for later use.

[0012] In step (2), the titanium substrate after surface pretreatment is immersed in sol for 1 to 30 minutes, and then pulled up at a speed of 1 to 10 cm / min. The drying time at room temperature is not less than 12 hours.

[0013] In step (4), the molar ratio of Na2CO3 to K2CO3 in the Na2CO3-K2CO3 mixed salt is 10:1 to 1:10.

[0014] In step (4), the inert gas is argon.

[0015] In step (4), the ultrasonic treatment time is 5 to 30 minutes, and the drying is carried out in a forced-air oven at 50 to 70°C.

[0016] Application of iron, magnesium, lead, and cerium middle entropy oxide electrode materials, with FeMgPbCeO x An electro-oxidation system is constructed using an electrode material as the anode and a titanium mesh as the cathode, with an electrode spacing of 0.5–3 cm; it operates in a constant current mode with a current density of 5–30 mA / cm². 2 The nanofiltration concentrate from a coking plant was used as the target water body for continuous degradation, with a hydraulic retention time of 0.5–1 h and a reaction time of 1–72 h.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention uses molten salt regulation to form a uniform FeMgPbCeO electrode active layer. x The solid solution structure reduces the elemental segregation rate to below 3% (compared to >15% in traditional solid-state sintering), while precisely controlling the lattice distortion within the range of 3.2%–5.8%, effectively suppressing Cl. － CN － Penetration and erosion by corrosive ions; after continuous operation for 72 hours in coking NF concentrate, the electrode activity decay rate was less than 2%, Pb2+ The dissolution concentration is <0.005 mg / L, which is far superior to traditional PbO2 electrodes (activity decay rate >30% after 150 h, Pb 2+ Dissolution>0.02mg / L).

[0018] (2) FeMgPbCeO x In solid solution structures, Fe 3+ / Fe 2+ The Redox potential (0.77 V vs SHE) is moderate, which promotes the formation of •OH, while the high Fe-O bond binding energy (approximately 400 kJ / mol) enhances the bonding force between the active layer and the matrix. Mg 2+ The small ionic radius of MgO allows it to embed into lattice defects, increasing the number of active sites. Furthermore, MgO exhibits excellent resistance to scale deposition, reducing the amount of calcium deposits. 2+ Mg 2+ Adhesion on the electrode surface. PbO2 has a high oxygen evolution overpotential (approximately 1.7 V vs SHE), which can suppress oxygen generation, improve the utilization rate of ·OH, and reduce Pb through the medium entropy effect and molten salt regulation. 2+ The risk of leaching. Ce 3+ / Ce 4+ CeO2 has a high redox potential (1.61V vs SHE), which can accelerate electron transfer. At the same time, CeO2 has oxygen storage-release capabilities, which can enhance the catalytic reaction.

[0019] (3) A Na2CO3-K2CO3 mixed salt was chosen as the regulating medium because the mixed salt has a low eutectic point (approximately 680℃), which allows it to form a stable molten state at a lower temperature, thus preventing excessive oxidation of the matrix; CO3 2- It can interact weakly with metal oxide precursors, promoting precursor dissolution and ion diffusion, thus achieving a uniform elemental distribution; furthermore, Na + K + The ionic radii (0.102 nm and 0.138 nm, respectively) and Fe 3+ (0.064nm), Mg 2+ (0.072nm), Pb 2+ (0.119nm), Ce 4+ The ionic radius difference of (0.097nm) is significant, which can generate moderate distortion (3.2% to 5.8%) by embedding into the crystal lattice, thereby improving stability and avoiding the obstruction of electron conduction caused by excessive lattice distortion.

[0020] (4) This invention utilizes the synergistic effect of the intermediate entropy effect and molten salt regulation to significantly enhance the active sites on the electrode surface; simultaneously, the ·OH generation rate reaches 4.2 μmol / (L·min), at a current density of 5–30 mA / cm². 2At this level, the COD removal rate can reach over 50%, significantly improving the purity of inorganic salt products in subsequent salt extraction processes. Low current density operation can significantly reduce system energy consumption, decreasing it by 30% to 40% compared to traditional electro-oxidation technology (6–8 kWh / kg COD). Furthermore, it eliminates the need to adjust solution pH or add oxidants, further reducing reagent and energy costs.

[0021] (5) FeMgPbCeO x An electro-oxidation system was constructed using electrode materials as the anode and titanium mesh as the cathode, operating in a constant current mode. Continuous degradation tests were conducted on two types of nanofiltration concentrate from coking plants with COD values ​​of 200–2000 mg / L and 2000–5000 mg / L, respectively, and the COD removal rate in the effluent remained above 50% in both cases. Detailed Implementation

[0022] The preparation method of the iron-magnesium-lead-cerium entropy oxide electrode material of the present invention includes the following steps: (1) Using metal inorganic salts including ferric nitrate, magnesium nitrate, lead nitrate and cerium nitrate as precursors, each metal inorganic salt is added to anhydrous ethanol in sequence and stirred thoroughly to dissolve, resulting in a mixed salt solution; citric acid is added to the mixed salt solution and stirred continuously until a uniform and transparent sol is formed.

[0023] Preferably, ferric nitrate, magnesium nitrate, lead nitrate, and cerium nitrate are added in a Fe:Mg:Pb:Ce molar ratio of 1–5:1–5:1–5:1–5; the ratio of anhydrous ethanol volume to total inorganic salt molar amount is 1L:0.5mol to 1L:3mol.

[0024] Preferably, the ratio of the total molar amount of metal ions to the molar amount of citric acid in the mixed salt solution is 1:1 to 1:5.

[0025] As a preferred embodiment, the surface pretreatment process of the titanium substrate is as follows: first, the surface oxide layer and impurities are removed by sandblasting; then, the titanium substrate is placed in acetone and anhydrous ethanol in sequence, ultrasonically cleaned in an ultrasonic cleaner for 5 to 30 minutes, and finally rinsed with deionized water and dried for later use.

[0026] (2) The surface-pretreated titanium substrate is vertically immersed in the sol and kept for a period of time to allow the sol to be fully adsorbed on the surface of the titanium substrate; then the titanium substrate is slowly and uniformly lifted to allow the sol to form a uniform film on the surface of the titanium substrate; the coated titanium substrate is placed horizontally in a clean petri dish and dried at room temperature to allow the solvent to fully evaporate and the sol to initially gel, thus obtaining the coated titanium substrate.

[0027] Preferably, the titanium substrate after surface pretreatment is immersed in sol for 1 to 30 minutes, and then pulled up at a speed of 1 to 10 cm / min, and dried at room temperature for no less than 12 hours.

[0028] (3) The pre-gelled coated titanium substrate is placed in a muffle furnace and slowly heated to 200-400°C at a heating rate of 1-10°C / min. The temperature is maintained at this temperature for 0.5-3h to allow the organic components to fully decompose. Then the temperature is raised to 500-700°C at a heating rate of 1-10°C / min and maintained for 0.5-3h to allow the coating to further solidify and form a stable oxide structure, finally obtaining the FeMgPbCe coated titanium substrate.

[0029] (4) Using a Na2CO3-K2CO3 mixed salt as the control medium, the FeMgPbCe coated titanium substrate was placed in a flat-bottomed crucible and covered with the Na2CO3-K2CO3 mixed salt; then it was placed in a tube furnace, and the temperature was slowly increased to 600-1000°C at a heating rate of 1-10°C / min under an inert gas protective atmosphere. The reaction was carried out at a constant temperature for 0.5-3 hours. After the reaction was completed, it was naturally cooled to room temperature. After being taken out, it was ultrasonically treated and dried to obtain FeMgPbCeO. x Electrode materials.

[0030] Preferably, the molar ratio of Na2CO3 to K2CO3 in the Na2CO3-K2CO3 mixed salt is 10:1 to 1:10.

[0031] Argon is preferred as the inert gas.

[0032] Preferably, the ultrasonic treatment time is 5 to 30 minutes, and the drying is carried out in a forced-air oven at 50 to 70°C.

[0033] The application of the iron-magnesium-lead-cerium middle-entropy oxide electrode material obtained by the preparation method described in this invention, with FeMgPbCeO x An electro-oxidation system is constructed using an electrode material as the anode and a titanium mesh as the cathode, with an electrode spacing of 0.5–3 cm; it operates in a constant current mode with a current density of 5–30 mA / cm². 2 The nanofiltration concentrate from a coking plant was used as the target water body for continuous degradation, with a hydraulic retention time of 0.5–1 h and a reaction time of 1–72 h.

[0034] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0035] Example 1:

[0036] In this embodiment, the preparation process of the iron-magnesium-lead-cerium entropy oxide electrode material is as follows: Using ferric nitrate, magnesium nitrate, lead nitrate, and cerium nitrate as precursors (collectively referred to as metallic inorganic salts), with molar amounts of 0.2 mol, 0.2 mol, 0.22 mol, and 0.28 mol respectively, the above metallic inorganic salts were sequentially added to 2 L of anhydrous ethanol and stirred on a magnetic stirrer at a speed of 300 r / min until they were fully dissolved to form a mixed salt solution.

[0037] Citric acid was added to a mixed salt solution, with the ratio of the total molar amount of metal ions to the molar amount of citric acid in the mixed salt solution being 1:1.5. After stirring continuously for 2.5 hours, a uniform and transparent sol was formed.

[0038] The titanium substrate is pretreated by first removing the oxide layer and impurities on the surface using a sandblasting process. Then, the titanium substrate is placed in acetone and anhydrous ethanol in sequence and ultrasonically cleaned for 15 minutes in an ultrasonic cleaner to thoroughly remove surface oil and other impurities. Finally, it is rinsed with deionized water and dried for later use.

[0039] The pre-treated titanium substrate was vertically immersed in the sol and held for 1.5 minutes to allow the sol to fully adsorb onto the substrate surface. Then, the substrate was lifted at a constant speed of 5 cm / min to allow the sol to form a uniform film on the substrate surface, thus obtaining the coated titanium substrate. The coated titanium substrate was then placed horizontally in a clean petri dish and dried at room temperature for 12 hours to allow the solvent to evaporate completely and the sol to initially gel.

[0040] The pre-gelled coated titanium substrate was placed in a muffle furnace and slowly heated to 300°C at a rate of 1°C / min. It was held at this temperature for 1 hour to allow the organic components to fully decompose. Then, the temperature was increased to 600°C at a rate of 2°C / min and held for 2 hours to further solidify the coating and form a stable oxide structure, ultimately yielding a FeMgPbCe coated titanium substrate.

[0041] A Na₂CO₃-K₂CO₃ mixed salt was selected as the control medium, with a molar ratio of 1:2. The FeMgPbCe-coated titanium substrate was placed in a flat-bottomed crucible and covered with the Na₂CO₃-K₂CO₃ mixed salt. Then, it was placed in a tube furnace under an argon atmosphere, and the temperature was slowly increased to 750℃ at a rate of 1℃ / min. The reaction was held at this temperature for 2 hours, and then allowed to cool naturally to room temperature after the reaction. After removal, it was ultrasonicated for 10 minutes and dried in a forced-air oven at 60℃ to obtain FeMgPbCeO₂. x Electrode materials.

[0042] XRD analysis revealed that FeMgPbCeO x The active layer of the electrode material is mainly composed of Fe. 0.2 Mg 0.2 Pb 0.22 Ce 0.28 O3-750 (750 indicates that the calcination temperature of the mixed salt is 750℃), with a lattice distortion of 4.5%.

[0043] Example 2:

[0044] This embodiment uses the same method as Example 1 to prepare the FeMgPbCeO medium-entropy oxide electrode material, except that the molar amounts of ferric nitrate, magnesium nitrate, lead nitrate, and cerium nitrate added are 0.2 mol, 0.2 mol, 0.2 mol, and 0.3 mol, respectively. The prepared FeMgPbCeO x The active layer of the electrode material is mainly composed of Fe. 0.2 Mg 0.2 Pb 0.2 Ce 0.3 O3-750.

[0045] Example 3:

[0046] This embodiment uses the same method as Example 1 to prepare the FeMgPbCeO medium-entropy oxide electrode material, except that the molar amounts of ferric nitrate, magnesium nitrate, lead nitrate, and cerium nitrate added are 0.2 mol, 0.2 mol, 0.25 mol, and 0.25 mol, respectively. The prepared FeMgPbCeO x The active layer of the electrode material is mainly composed of Fe. 0.2 Mg 0.2 Pb 0.25 Ce 0.25 O3-750.

[0047] Example 4:

[0048] In this embodiment, two FeMgPbCeOx electrode materials were prepared using the method described in this invention. The main phase of the active layer was Fe, respectively. 0.2 Mg 0.2 Pb 0.22 Ce 0.28 O3-700, Fe 0.2 Mg 0.2 Pb0 .22 Ce 0.28 The lattice distortion of the active layer in O3-800 is 2.4% and 3.3%, respectively.

[0049] Example 5:

[0050] In this embodiment, the FeMgPbCeO prepared in Example 1 is used. xElectrode materials are used to construct an electro-oxidation system for degrading NF concentrate from coking plants, as detailed below: FeMgPbCeO x An electro-oxidative degradation system was constructed using a series of electrode materials as the anode and a titanium mesh as the cathode, with an electrode spacing of 1 cm. The system operated under a constant current mode with a current density of 15 mA / cm². 2 Continuous degradation tests were conducted using NF concentrate from a coking plant with a COD concentration of 1500 mg / L as the target water body. The hydraulic retention time was 0.5 h, and the reaction time was 72 h. The effluent was sampled every 60 min. After filtration through a 0.45 μm water membrane, 20 mL of the sample was collected and placed in a sample bottle for COD removal performance testing. After the reaction was completed, another 20 mL of the effluent was filtered through a 0.45 μm water membrane and used as the TOC test sample.

[0051] The COD of the effluent was tested using the national standard method. The test results showed that FeMgPbCeO x The electrode material achieved a COD removal rate of 50%–65% in the NF concentrate from coking plants. This indicates that the anode using this electrode material has high removal performance for recalcitrant organic matter in the NF concentrate from coking plants, and its degradation performance is stable.

[0052] Further comparison revealed that under the conditions of a mixed salt calcination temperature of 750℃ and suitable precursor dosage (0.2 mol of ferric nitrate, 0.2 mol of magnesium nitrate, 0.22 mol of lead nitrate, and 0.28 mol of cerium nitrate), FeMgPbCeO x The COD removal rate of the electrode material was 65%, indicating that under suitable conditions (the amount of metal inorganic salt precursor added and the calcination temperature of the mixed salt), the COD removal rate of FeMgPbCeO can be effectively controlled. x The surface active sites and structural stability of the electrode material enable the stable removal of recalcitrant organic matter from high-salt wastewater.

[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an iron-magnesium-lead-cerium entropy oxide electrode material, characterized in that, Includes the following steps: (1) Using metal inorganic salts including ferric nitrate, magnesium nitrate, lead nitrate and cerium nitrate as precursors, each metal inorganic salt is added to anhydrous ethanol in sequence and stirred thoroughly to dissolve, thus obtaining a mixed salt solution; citric acid is added to the mixed salt solution and stirred continuously until a uniform and transparent sol is formed. (2) The titanium substrate after surface pretreatment is vertically immersed in the sol and kept for a period of time to allow the sol to be fully adsorbed on the surface of the titanium substrate; then the titanium substrate is slowly and uniformly lifted to allow the sol to form a uniform film on the surface of the titanium substrate; the coated titanium substrate is placed horizontally in a clean petri dish and dried at room temperature to allow the solvent to fully evaporate and the sol to initially gel, thus obtaining the coated titanium substrate. (3) The pre-gelled coated titanium substrate is placed in a muffle furnace and slowly heated to 200-400°C at a heating rate of 1-10°C / min. The temperature is maintained at this temperature for 0.5-3h to allow the organic components to decompose fully. Then the temperature is raised to 500-700°C at a heating rate of 1-10°C / min and maintained for 0.5-3h to allow the coating to be further cured and form a stable oxide structure, finally obtaining the FeMgPbCe coated titanium substrate. (4) Using a Na2CO3-K2CO3 mixed salt as the control medium, the FeMgPbCe coated titanium substrate was placed in a flat-bottomed crucible and covered with the Na2CO3-K2CO3 mixed salt; then it was placed in a tube furnace, and the temperature was slowly increased to 600-1000°C at a heating rate of 1-10°C / min under an inert gas protective atmosphere. The reaction was carried out at a constant temperature for 0.5-3 hours. After the reaction was completed, it was naturally cooled to room temperature. After being taken out, it was ultrasonically treated and dried to obtain FeMgPbCeO. x Electrode materials.

2. The method for preparing a medium entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (1), ferric nitrate, magnesium nitrate, lead nitrate, and cerium nitrate are added in a Fe:Mg:Pb:Ce molar ratio of 1-5:1-5:1-5:1-5; the ratio of anhydrous ethanol volume to total inorganic salt molar amount is 1L:0.5mol to 1L:3mol.

3. The method for preparing a medium entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (1), the ratio of the total molar amount of metal ions to the molar amount of citric acid in the mixed salt solution is 1:1 to 1:

5.

4. The method for preparing a medium entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (1), the surface pretreatment process of the titanium substrate is as follows: first, the surface oxide layer and impurities are removed by sandblasting, then the titanium substrate is placed in acetone and anhydrous ethanol in sequence, ultrasonically cleaned in an ultrasonic cleaner for 5 to 30 minutes, and finally rinsed with deionized water and dried for later use.

5. The method for preparing a medium entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (2), the titanium substrate after surface pretreatment is immersed in sol for 1 to 30 minutes, and then pulled up at a speed of 1 to 10 cm / min. The drying time at room temperature is not less than 12 hours.

6. The method for preparing a medium entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (4), the molar ratio of Na2CO3 to K2CO3 in the Na2CO3-K2CO3 mixed salt is 10:1 to 1:

10.

7. The method for preparing a medium-entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (4), the inert gas is argon.

8. The method for preparing a medium entropy oxide electrode material of iron, magnesium, lead, and cerium according to claim 1, characterized in that, In step (4), the ultrasonic treatment time is 5 to 30 minutes, and the drying is carried out in a forced-air oven at 50 to 70°C.

9. The application of the iron-magnesium-lead-cerium medium-entropy oxide electrode material obtained by the preparation method of the iron-magnesium-lead-cerium medium-entropy oxide electrode material according to any one of claims 1 to 8, characterized in that, FeMgPbCeO x An electro-oxidation system is constructed by using an electrode material as the anode and a titanium mesh as the cathode, with an electrode spacing of 0.5–3 cm. It operates in constant current mode with a current density of 5–30 mA / cm². 2 The nanofiltration concentrate from a coking plant was used as the target water body for continuous degradation, with a hydraulic retention time of 0.5–1 h and a reaction time of 1–72 h.